NCURSES-Programming-HOWTO.html revision 262685
1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd"> 2<HTML 3><HEAD 4><TITLE 5> NCURSES Programming HOWTO </TITLE 6><META 7NAME="GENERATOR" 8CONTENT="Modular DocBook HTML Stylesheet Version 1.79"></HEAD 9><BODY 10CLASS="ARTICLE" 11BGCOLOR="#FFFFFF" 12TEXT="#000000" 13LINK="#0000FF" 14VLINK="#840084" 15ALINK="#0000FF" 16><DIV 17CLASS="ARTICLE" 18><DIV 19CLASS="TITLEPAGE" 20><H1 21CLASS="TITLE" 22><A 23NAME="AEN2" 24>NCURSES Programming HOWTO</A 25></H1 26><H3 27CLASS="AUTHOR" 28><A 29NAME="AEN4" 30> Pradeep Padala </A 31></H3 32><DIV 33CLASS="AFFILIATION" 34><DIV 35CLASS="ADDRESS" 36><P 37CLASS="ADDRESS" 38><CODE 39CLASS="EMAIL" 40><<A 41HREF="mailto:ppadala@gmail.com" 42>ppadala@gmail.com</A 43>></CODE 44></P 45></DIV 46></DIV 47><P 48CLASS="PUBDATE" 49>v1.9, 2005-06-20<BR></P 50><DIV 51CLASS="REVHISTORY" 52><TABLE 53WIDTH="100%" 54BORDER="0" 55><TR 56><TH 57ALIGN="LEFT" 58VALIGN="TOP" 59COLSPAN="3" 60><B 61>Revision History</B 62></TH 63></TR 64><TR 65><TD 66ALIGN="LEFT" 67>Revision 1.9</TD 68><TD 69ALIGN="LEFT" 70>2005-06-20</TD 71><TD 72ALIGN="LEFT" 73>Revised by: ppadala</TD 74></TR 75><TR 76><TD 77ALIGN="LEFT" 78COLSPAN="3" 79>The license has been changed to the MIT-style license used 80 by NCURSES. Note that the programs are also re-licensed under this.</TD 81></TR 82><TR 83><TD 84ALIGN="LEFT" 85>Revision 1.8</TD 86><TD 87ALIGN="LEFT" 88>2005-06-17</TD 89><TD 90ALIGN="LEFT" 91>Revised by: ppadala</TD 92></TR 93><TR 94><TD 95ALIGN="LEFT" 96COLSPAN="3" 97>Lots of updates. Added references and perl examples. 98 Changes to examples. Many grammatical and stylistic changes to the 99 content. Changes to NCURSES history.</TD 100></TR 101><TR 102><TD 103ALIGN="LEFT" 104>Revision 1.7.1</TD 105><TD 106ALIGN="LEFT" 107>2002-06-25</TD 108><TD 109ALIGN="LEFT" 110>Revised by: ppadala</TD 111></TR 112><TR 113><TD 114ALIGN="LEFT" 115COLSPAN="3" 116>Added a README file for building and instructions 117 for building from source.</TD 118></TR 119><TR 120><TD 121ALIGN="LEFT" 122>Revision 1.7</TD 123><TD 124ALIGN="LEFT" 125>2002-06-25</TD 126><TD 127ALIGN="LEFT" 128>Revised by: ppadala</TD 129></TR 130><TR 131><TD 132ALIGN="LEFT" 133COLSPAN="3" 134>Added "Other formats" section and made a lot of fancy 135 changes to the programs. Inlining of programs is gone.</TD 136></TR 137><TR 138><TD 139ALIGN="LEFT" 140>Revision 1.6.1</TD 141><TD 142ALIGN="LEFT" 143>2002-02-24</TD 144><TD 145ALIGN="LEFT" 146>Revised by: ppadala</TD 147></TR 148><TR 149><TD 150ALIGN="LEFT" 151COLSPAN="3" 152>Removed the old Changelog section, cleaned the makefiles</TD 153></TR 154><TR 155><TD 156ALIGN="LEFT" 157>Revision 1.6</TD 158><TD 159ALIGN="LEFT" 160>2002-02-16</TD 161><TD 162ALIGN="LEFT" 163>Revised by: ppadala</TD 164></TR 165><TR 166><TD 167ALIGN="LEFT" 168COLSPAN="3" 169>Corrected a lot of spelling mistakes, added ACS variables 170 section</TD 171></TR 172><TR 173><TD 174ALIGN="LEFT" 175>Revision 1.5</TD 176><TD 177ALIGN="LEFT" 178>2002-01-05</TD 179><TD 180ALIGN="LEFT" 181>Revised by: ppadala</TD 182></TR 183><TR 184><TD 185ALIGN="LEFT" 186COLSPAN="3" 187>Changed structure to present proper TOC</TD 188></TR 189><TR 190><TD 191ALIGN="LEFT" 192>Revision 1.3.1</TD 193><TD 194ALIGN="LEFT" 195>2001-07-26</TD 196><TD 197ALIGN="LEFT" 198>Revised by: ppadala</TD 199></TR 200><TR 201><TD 202ALIGN="LEFT" 203COLSPAN="3" 204>Corrected maintainers paragraph, Corrected stable release number</TD 205></TR 206><TR 207><TD 208ALIGN="LEFT" 209>Revision 1.3</TD 210><TD 211ALIGN="LEFT" 212>2001-07-24</TD 213><TD 214ALIGN="LEFT" 215>Revised by: ppadala</TD 216></TR 217><TR 218><TD 219ALIGN="LEFT" 220COLSPAN="3" 221>Added copyright notices to main document (LDP license) 222 and programs (GPL), Corrected 223 printw_example.</TD 224></TR 225><TR 226><TD 227ALIGN="LEFT" 228>Revision 1.2</TD 229><TD 230ALIGN="LEFT" 231>2001-06-05</TD 232><TD 233ALIGN="LEFT" 234>Revised by: ppadala</TD 235></TR 236><TR 237><TD 238ALIGN="LEFT" 239COLSPAN="3" 240>Incorporated ravi's changes. Mainly to introduction, menu, 241 form, justforfun sections</TD 242></TR 243><TR 244><TD 245ALIGN="LEFT" 246>Revision 1.1</TD 247><TD 248ALIGN="LEFT" 249>2001-05-22</TD 250><TD 251ALIGN="LEFT" 252>Revised by: ppadala</TD 253></TR 254><TR 255><TD 256ALIGN="LEFT" 257COLSPAN="3" 258>Added "a word about window" section, Added scanw_example.</TD 259></TR 260></TABLE 261></DIV 262><DIV 263><DIV 264CLASS="ABSTRACT" 265><P 266></P 267><A 268NAME="AEN67" 269></A 270><P 271> <SPAN 272CLASS="emphasis" 273><I 274CLASS="EMPHASIS" 275>This document is intended to be an "All in One" guide for programming with 276ncurses and its sister libraries. We graduate from a simple "Hello World" 277program to more complex form manipulation. No prior experience in ncurses is 278assumed. Send comments to <A 279HREF="mailto:ppadala@gmail.com" 280TARGET="_top" 281>this address</A 282> 283 </I 284></SPAN 285> 286 </P 287><P 288></P 289></DIV 290></DIV 291><HR></DIV 292><DIV 293CLASS="TOC" 294><DL 295><DT 296><B 297>Table of Contents</B 298></DT 299><DT 300>1. <A 301HREF="#INTRO" 302>Introduction</A 303></DT 304><DD 305><DL 306><DT 307>1.1. <A 308HREF="#WHATIS" 309>What is NCURSES?</A 310></DT 311><DT 312>1.2. <A 313HREF="#WHATCANWEDO" 314>What we can do with NCURSES</A 315></DT 316><DT 317>1.3. <A 318HREF="#WHERETOGETIT" 319>Where to get it</A 320></DT 321><DT 322>1.4. <A 323HREF="#PURPOSE" 324>Purpose/Scope of the document</A 325></DT 326><DT 327>1.5. <A 328HREF="#ABOUTPROGRAMS" 329>About the Programs</A 330></DT 331><DT 332>1.6. <A 333HREF="#OTHERFORMATS" 334>Other Formats of the document</A 335></DT 336><DD 337><DL 338><DT 339>1.6.1. <A 340HREF="#LISTFORMATS" 341>Readily available formats from tldp.org</A 342></DT 343><DT 344>1.6.2. <A 345HREF="#BUILDSOURCE" 346>Building from source</A 347></DT 348></DL 349></DD 350><DT 351>1.7. <A 352HREF="#CREDITS" 353>Credits</A 354></DT 355><DT 356>1.8. <A 357HREF="#WISHLIST" 358>Wish List</A 359></DT 360><DT 361>1.9. <A 362HREF="#COPYRIGHT" 363>Copyright</A 364></DT 365></DL 366></DD 367><DT 368>2. <A 369HREF="#HELLOWORLD" 370>Hello World !!!</A 371></DT 372><DD 373><DL 374><DT 375>2.1. <A 376HREF="#COMPILECURSES" 377>Compiling With the NCURSES Library</A 378></DT 379><DT 380>2.2. <A 381HREF="#DISSECTION" 382>Dissection</A 383></DT 384><DD 385><DL 386><DT 387>2.2.1. <A 388HREF="#ABOUT-INITSCR" 389>About initscr()</A 390></DT 391><DT 392>2.2.2. <A 393HREF="#MYST-REFRESH" 394>The mysterious refresh()</A 395></DT 396><DT 397>2.2.3. <A 398HREF="#ABOUT-ENDWIN" 399>About endwin()</A 400></DT 401></DL 402></DD 403></DL 404></DD 405><DT 406>3. <A 407HREF="#GORY" 408>The Gory Details</A 409></DT 410><DT 411>4. <A 412HREF="#INIT" 413>Initialization</A 414></DT 415><DD 416><DL 417><DT 418>4.1. <A 419HREF="#ABOUTINIT" 420>Initialization functions</A 421></DT 422><DT 423>4.2. <A 424HREF="#RAWCBREAK" 425>raw() and cbreak()</A 426></DT 427><DT 428>4.3. <A 429HREF="#ECHONOECHO" 430>echo() and noecho()</A 431></DT 432><DT 433>4.4. <A 434HREF="#KEYPAD" 435>keypad()</A 436></DT 437><DT 438>4.5. <A 439HREF="#HALFDELAY" 440>halfdelay()</A 441></DT 442><DT 443>4.6. <A 444HREF="#MISCINIT" 445>Miscellaneous Initialization functions</A 446></DT 447><DT 448>4.7. <A 449HREF="#INITEX" 450>An Example</A 451></DT 452></DL 453></DD 454><DT 455>5. <A 456HREF="#AWORDWINDOWS" 457>A Word about Windows</A 458></DT 459><DT 460>6. <A 461HREF="#PRINTW" 462>Output functions</A 463></DT 464><DD 465><DL 466><DT 467>6.1. <A 468HREF="#ADDCHCLASS" 469>addch() class of functions</A 470></DT 471><DT 472>6.2. <A 473HREF="#AEN298" 474>mvaddch(), waddch() and mvwaddch()</A 475></DT 476><DT 477>6.3. <A 478HREF="#PRINTWCLASS" 479>printw() class of functions</A 480></DT 481><DD 482><DL 483><DT 484>6.3.1. <A 485HREF="#PRINTWMVPRINTW" 486>printw() and mvprintw</A 487></DT 488><DT 489>6.3.2. <A 490HREF="#WPRINTWMVWPRINTW" 491>wprintw() and mvwprintw</A 492></DT 493><DT 494>6.3.3. <A 495HREF="#VWPRINTW" 496>vwprintw()</A 497></DT 498><DT 499>6.3.4. <A 500HREF="#SIMPLEPRINTWEX" 501>A Simple printw example</A 502></DT 503></DL 504></DD 505><DT 506>6.4. <A 507HREF="#ADDSTRCLASS" 508>addstr() class of functions</A 509></DT 510><DT 511>6.5. <A 512HREF="#ACAUTION" 513>A word of caution</A 514></DT 515></DL 516></DD 517><DT 518>7. <A 519HREF="#SCANW" 520>Input functions</A 521></DT 522><DD 523><DL 524><DT 525>7.1. <A 526HREF="#GETCHCLASS" 527>getch() class of functions</A 528></DT 529><DT 530>7.2. <A 531HREF="#SCANWCLASS" 532>scanw() class of functions</A 533></DT 534><DD 535><DL 536><DT 537>7.2.1. <A 538HREF="#SCANWMVSCANW" 539>scanw() and mvscanw</A 540></DT 541><DT 542>7.2.2. <A 543HREF="#WSCANWMVWSCANW" 544>wscanw() and mvwscanw()</A 545></DT 546><DT 547>7.2.3. <A 548HREF="#VWSCANW" 549>vwscanw()</A 550></DT 551></DL 552></DD 553><DT 554>7.3. <A 555HREF="#GETSTRCLASS" 556>getstr() class of functions</A 557></DT 558><DT 559>7.4. <A 560HREF="#GETSTREX" 561>Some examples</A 562></DT 563></DL 564></DD 565><DT 566>8. <A 567HREF="#ATTRIB" 568>Attributes</A 569></DT 570><DD 571><DL 572><DT 573>8.1. <A 574HREF="#ATTRIBDETAILS" 575>The details</A 576></DT 577><DT 578>8.2. <A 579HREF="#ATTRONVSATTRSET" 580>attron() vs attrset()</A 581></DT 582><DT 583>8.3. <A 584HREF="#ATTR_GET" 585>attr_get()</A 586></DT 587><DT 588>8.4. <A 589HREF="#ATTR_FUNCS" 590>attr_ functions</A 591></DT 592><DT 593>8.5. <A 594HREF="#WATTRFUNCS" 595>wattr functions</A 596></DT 597><DT 598>8.6. <A 599HREF="#CHGAT" 600>chgat() functions</A 601></DT 602></DL 603></DD 604><DT 605>9. <A 606HREF="#WINDOWS" 607>Windows</A 608></DT 609><DD 610><DL 611><DT 612>9.1. <A 613HREF="#WINDOWBASICS" 614>The basics</A 615></DT 616><DT 617>9.2. <A 618HREF="#LETBEWINDOW" 619>Let there be a Window !!!</A 620></DT 621><DT 622>9.3. <A 623HREF="#BORDEREXEXPL" 624>Explanation</A 625></DT 626><DT 627>9.4. <A 628HREF="#OTHERSTUFF" 629>The other stuff in the example</A 630></DT 631><DT 632>9.5. <A 633HREF="#OTHERBORDERFUNCS" 634>Other Border functions</A 635></DT 636></DL 637></DD 638><DT 639>10. <A 640HREF="#COLOR" 641>Colors</A 642></DT 643><DD 644><DL 645><DT 646>10.1. <A 647HREF="#COLORBASICS" 648>The basics</A 649></DT 650><DT 651>10.2. <A 652HREF="#CHANGECOLORDEFS" 653>Changing Color Definitions</A 654></DT 655><DT 656>10.3. <A 657HREF="#COLORCONTENT" 658>Color Content</A 659></DT 660></DL 661></DD 662><DT 663>11. <A 664HREF="#KEYS" 665>Interfacing with the key board</A 666></DT 667><DD 668><DL 669><DT 670>11.1. <A 671HREF="#KEYSBASICS" 672>The Basics</A 673></DT 674><DT 675>11.2. <A 676HREF="#SIMPLEKEYEX" 677>A Simple Key Usage example</A 678></DT 679></DL 680></DD 681><DT 682>12. <A 683HREF="#MOUSE" 684>Interfacing with the mouse</A 685></DT 686><DD 687><DL 688><DT 689>12.1. <A 690HREF="#MOUSEBASICS" 691>The Basics</A 692></DT 693><DT 694>12.2. <A 695HREF="#GETTINGEVENTS" 696>Getting the events</A 697></DT 698><DT 699>12.3. <A 700HREF="#MOUSETOGETHER" 701>Putting it all Together</A 702></DT 703><DT 704>12.4. <A 705HREF="#MISCMOUSEFUNCS" 706>Miscellaneous Functions</A 707></DT 708></DL 709></DD 710><DT 711>13. <A 712HREF="#SCREEN" 713>Screen Manipulation</A 714></DT 715><DD 716><DL 717><DT 718>13.1. <A 719HREF="#GETYX" 720>getyx() functions</A 721></DT 722><DT 723>13.2. <A 724HREF="#SCREENDUMP" 725>Screen Dumping</A 726></DT 727><DT 728>13.3. <A 729HREF="#WINDOWDUMP" 730>Window Dumping</A 731></DT 732></DL 733></DD 734><DT 735>14. <A 736HREF="#MISC" 737>Miscellaneous features</A 738></DT 739><DD 740><DL 741><DT 742>14.1. <A 743HREF="#CURSSET" 744>curs_set()</A 745></DT 746><DT 747>14.2. <A 748HREF="#TEMPLEAVE" 749>Temporarily Leaving Curses mode</A 750></DT 751><DT 752>14.3. <A 753HREF="#ACSVARS" 754>ACS_ variables</A 755></DT 756></DL 757></DD 758><DT 759>15. <A 760HREF="#OTHERLIB" 761>Other libraries</A 762></DT 763><DT 764>16. <A 765HREF="#PANELS" 766>Panel Library</A 767></DT 768><DD 769><DL 770><DT 771>16.1. <A 772HREF="#PANELBASICS" 773>The Basics</A 774></DT 775><DT 776>16.2. <A 777HREF="#COMPILEPANELS" 778>Compiling With the Panels Library</A 779></DT 780><DT 781>16.3. <A 782HREF="#PANELBROWSING" 783>Panel Window Browsing</A 784></DT 785><DT 786>16.4. <A 787HREF="#USERPTRUSING" 788>Using User Pointers</A 789></DT 790><DT 791>16.5. <A 792HREF="#PANELMOVERESIZE" 793>Moving and Resizing Panels</A 794></DT 795><DT 796>16.6. <A 797HREF="#PANELSHOWHIDE" 798>Hiding and Showing Panels</A 799></DT 800><DT 801>16.7. <A 802HREF="#PANELABOVE" 803>panel_above() and panel_below() Functions</A 804></DT 805></DL 806></DD 807><DT 808>17. <A 809HREF="#MENUS" 810>Menus Library</A 811></DT 812><DD 813><DL 814><DT 815>17.1. <A 816HREF="#MENUBASICS" 817>The Basics</A 818></DT 819><DT 820>17.2. <A 821HREF="#COMPILEMENUS" 822>Compiling With the Menu Library</A 823></DT 824><DT 825>17.3. <A 826HREF="#MENUDRIVER" 827>Menu Driver: The work horse of the menu system</A 828></DT 829><DT 830>17.4. <A 831HREF="#MENUWINDOWS" 832>Menu Windows</A 833></DT 834><DT 835>17.5. <A 836HREF="#SCROLLMENUS" 837>Scrolling Menus</A 838></DT 839><DT 840>17.6. <A 841HREF="#MULTICOLUMN" 842>Multi Columnar Menus</A 843></DT 844><DT 845>17.7. <A 846HREF="#MULTIVALUEMENUS" 847>Multi Valued Menus</A 848></DT 849><DT 850>17.8. <A 851HREF="#MENUOPT" 852>Menu Options</A 853></DT 854><DT 855>17.9. <A 856HREF="#MENUUSERPTR" 857>The useful User Pointer</A 858></DT 859></DL 860></DD 861><DT 862>18. <A 863HREF="#FORMS" 864>Forms Library</A 865></DT 866><DD 867><DL 868><DT 869>18.1. <A 870HREF="#FORMBASICS" 871>The Basics</A 872></DT 873><DT 874>18.2. <A 875HREF="#COMPILEFORMS" 876>Compiling With the Forms Library</A 877></DT 878><DT 879>18.3. <A 880HREF="#PLAYFIELDS" 881>Playing with Fields</A 882></DT 883><DD 884><DL 885><DT 886>18.3.1. <A 887HREF="#FETCHINFO" 888>Fetching Size and Location of Field</A 889></DT 890><DT 891>18.3.2. <A 892HREF="#MOVEFIELD" 893>Moving the field</A 894></DT 895><DT 896>18.3.3. <A 897HREF="#JUSTIFYFIELD" 898>Field Justification</A 899></DT 900><DT 901>18.3.4. <A 902HREF="#FIELDDISPATTRIB" 903>Field Display Attributes</A 904></DT 905><DT 906>18.3.5. <A 907HREF="#FIELDOPTIONBITS" 908>Field Option Bits</A 909></DT 910><DT 911>18.3.6. <A 912HREF="#FIELDSTATUS" 913>Field Status</A 914></DT 915><DT 916>18.3.7. <A 917HREF="#FIELDUSERPTR" 918>Field User Pointer</A 919></DT 920><DT 921>18.3.8. <A 922HREF="#VARIABLESIZEFIELDS" 923>Variable-Sized Fields</A 924></DT 925></DL 926></DD 927><DT 928>18.4. <A 929HREF="#FORMWINDOWS" 930>Form Windows</A 931></DT 932><DT 933>18.5. <A 934HREF="#FILEDVALIDATE" 935>Field Validation</A 936></DT 937><DT 938>18.6. <A 939HREF="#FORMDRIVER" 940>Form Driver: The work horse of the forms system</A 941></DT 942><DD 943><DL 944><DT 945>18.6.1. <A 946HREF="#PAGENAVREQ" 947>Page Navigation Requests</A 948></DT 949><DT 950>18.6.2. <A 951HREF="#INTERFIELDNAVREQ" 952>Inter-Field Navigation Requests</A 953></DT 954><DT 955>18.6.3. <A 956HREF="#INTRAFIELDNAVREQ" 957>Intra-Field Navigation Requests</A 958></DT 959><DT 960>18.6.4. <A 961HREF="#SCROLLREQ" 962>Scrolling Requests</A 963></DT 964><DT 965>18.6.5. <A 966HREF="#EDITREQ" 967>Editing Requests</A 968></DT 969><DT 970>18.6.6. <A 971HREF="#ORDERREQ" 972>Order Requests</A 973></DT 974><DT 975>18.6.7. <A 976HREF="#APPLICCOMMANDS" 977>Application Commands</A 978></DT 979></DL 980></DD 981></DL 982></DD 983><DT 984>19. <A 985HREF="#TOOLS" 986>Tools and Widget Libraries</A 987></DT 988><DD 989><DL 990><DT 991>19.1. <A 992HREF="#CDK" 993>CDK (Curses Development Kit)</A 994></DT 995><DD 996><DL 997><DT 998>19.1.1. <A 999HREF="#WIDGETLIST" 1000>Widget List</A 1001></DT 1002><DT 1003>19.1.2. <A 1004HREF="#CDKATTRACT" 1005>Some Attractive Features</A 1006></DT 1007><DT 1008>19.1.3. <A 1009HREF="#CDKCONCLUSION" 1010>Conclusion</A 1011></DT 1012></DL 1013></DD 1014><DT 1015>19.2. <A 1016HREF="#DIALOG" 1017>The dialog</A 1018></DT 1019><DT 1020>19.3. <A 1021HREF="#PERLCURSES" 1022>Perl Curses Modules CURSES::FORM and CURSES::WIDGETS</A 1023></DT 1024></DL 1025></DD 1026><DT 1027>20. <A 1028HREF="#JUSTFORFUN" 1029>Just For Fun !!!</A 1030></DT 1031><DD 1032><DL 1033><DT 1034>20.1. <A 1035HREF="#GAMEOFLIFE" 1036>The Game of Life</A 1037></DT 1038><DT 1039>20.2. <A 1040HREF="#MAGIC" 1041>Magic Square</A 1042></DT 1043><DT 1044>20.3. <A 1045HREF="#HANOI" 1046>Towers of Hanoi</A 1047></DT 1048><DT 1049>20.4. <A 1050HREF="#QUEENS" 1051>Queens Puzzle</A 1052></DT 1053><DT 1054>20.5. <A 1055HREF="#SHUFFLE" 1056>Shuffle</A 1057></DT 1058><DT 1059>20.6. <A 1060HREF="#TT" 1061>Typing Tutor</A 1062></DT 1063></DL 1064></DD 1065><DT 1066>21. <A 1067HREF="#REF" 1068>References</A 1069></DT 1070></DL 1071></DIV 1072><DIV 1073CLASS="SECT1" 1074><H2 1075CLASS="SECT1" 1076><A 1077NAME="INTRO" 1078>1. Introduction</A 1079></H2 1080><P 1081>In the olden days of teletype terminals, terminals were away from computers and 1082were connected to them through serial cables. The terminals could be configured 1083by sending a series of bytes. All the capabilities (such as 1084moving the cursor to a new location, erasing part of the screen, scrolling the 1085screen, changing modes etc.) of terminals could be accessed through these 1086series of bytes. These control seeuqnces are usually called escape sequences, 1087because they start 1088with an escape(0x1B) character. Even today, with proper emulation, we can send 1089escape sequences to the emulator and achieve the same effect on a terminal 1090window.</P 1091><P 1092>Suppose you wanted to print a line in color. Try typing this on your console.</P 1093><PRE 1094CLASS="PROGRAMLISTING" 1095>echo "^[[0;31;40mIn Color"</PRE 1096><P 1097>The first character is an escape character, which looks like two characters ^ 1098and [. To be able to print it, you have to press CTRL+V and then the ESC key. 1099All the others are normal printable characters. You should be able to see the 1100string "In Color" in red. It stays that way and to revert back to the original 1101mode type this.</P 1102><PRE 1103CLASS="PROGRAMLISTING" 1104>echo "^[[0;37;40m"</PRE 1105><P 1106>Now, what do these magic characters mean? Difficult to comprehend? They might 1107even be different for different terminals. So the designers of UNIX invented a 1108mechanism named <TT 1109CLASS="LITERAL" 1110>termcap</TT 1111>. It is a file that 1112lists all the capabilities of a particular terminal, along with the escape 1113sequences needed to achieve a particular effect. In the later years, this was 1114replaced by <TT 1115CLASS="LITERAL" 1116>terminfo</TT 1117>. Without delving too 1118much into details, this mechanism allows application 1119programs to query the terminfo database and obtain the control characters to be 1120sent to a terminal or terminal emulator.</P 1121><DIV 1122CLASS="SECT2" 1123><HR><H3 1124CLASS="SECT2" 1125><A 1126NAME="WHATIS" 1127>1.1. What is NCURSES?</A 1128></H3 1129><P 1130> 1131You might be wondering, what the import of all this technical gibberish is. In 1132the above scenario, every application program is supposed to query the terminfo 1133and perform the necessary stuff (sending control characters etc.). It soon became 1134difficult to manage this complexity and this gave birth to 'CURSES'. Curses is 1135a pun on the name "cursor optimization". The Curses library forms a wrapper 1136over working with raw terminal codes, and provides highly flexible and 1137efficient API (Application Programming Interface). It provides functions to 1138move the cursor, create windows, produce colors, play with mouse etc. The 1139application programs need not worry about the underlying terminal capabilities.</P 1140><P 1141>So what is NCURSES? NCURSES is a clone of the original System V Release 4.0 1142(SVr4) curses. It is a freely distributable library, fully compatible with 1143older version of curses. In short, it is a library of functions that manages 1144an application's display on character-cell terminals. In the remainder of the 1145document, the terms curses and ncurses are used interchangeably. </P 1146><P 1147>A detailed history of NCURSES can be found in the NEWS file from the source 1148distribution. The current package is maintained by 1149<A 1150HREF="mailto:dickey@his.com" 1151TARGET="_top" 1152>Thomas Dickey</A 1153>. 1154You can contact the maintainers at <A 1155HREF="mailto:bug-ncurses@gnu.org" 1156TARGET="_top" 1157>bug-ncurses@gnu.org</A 1158>.</P 1159></DIV 1160><DIV 1161CLASS="SECT2" 1162><HR><H3 1163CLASS="SECT2" 1164><A 1165NAME="WHATCANWEDO" 1166>1.2. What we can do with NCURSES</A 1167></H3 1168><P 1169>NCURSES not only creates a wrapper over terminal capabilities, but also gives a 1170robust framework to create nice looking UI (User Interface)s in text mode. It 1171provides functions to create windows etc. Its sister libraries panel, menu and 1172form provide an extension to the basic curses library. These libraries usually 1173come along with curses. One can create applications that contain multiple 1174windows, menus, panels and forms. Windows can be managed independently, can 1175provide 'scrollability' and even can be hidden.</P 1176><P 1177> 1178Menus provide the user with an easy command selection option. Forms allow the 1179creation of easy-to-use data entry and display windows. Panels extend the 1180capabilities of ncurses to deal with overlapping and stacked windows.</P 1181><P 1182>These are just some of the basic things we can do with ncurses. As we move 1183along, We will see all the capabilities of these libraries. </P 1184></DIV 1185><DIV 1186CLASS="SECT2" 1187><HR><H3 1188CLASS="SECT2" 1189><A 1190NAME="WHERETOGETIT" 1191>1.3. Where to get it</A 1192></H3 1193><P 1194>All right, now that you know what you can do with ncurses, you must be rearing 1195to get started. NCURSES is usually shipped with your installation. In case 1196you don't have the library or want to compile it on your own, read on.</P 1197><P 1198><SPAN 1199CLASS="emphasis" 1200><I 1201CLASS="EMPHASIS" 1202>Compiling the package</I 1203></SPAN 1204> </P 1205><P 1206>NCURSES can be obtained from <A 1207HREF="ftp://ftp.gnu.org/pub/gnu/ncurses/ncurses.tar.gz" 1208TARGET="_top" 1209>ftp://ftp.gnu.org/pub/gnu/ncurses/ncurses.tar.gz</A 1210> or any of the ftp 1211sites mentioned in <A 1212HREF="http://www.gnu.org/order/ftp.html" 1213TARGET="_top" 1214>http://www.gnu.org/order/ftp.html</A 1215>. </P 1216><P 1217>Read the README and INSTALL files for details on to how to install it. It 1218usually involves the following operations.</P 1219><PRE 1220CLASS="PROGRAMLISTING" 1221> tar zxvf ncurses<version>.tar.gz # unzip and untar the archive 1222 cd ncurses<version> # cd to the directory 1223 ./configure # configure the build according to your 1224 # environment 1225 make # make it 1226 su root # become root 1227 make install # install it</PRE 1228><P 1229><SPAN 1230CLASS="emphasis" 1231><I 1232CLASS="EMPHASIS" 1233>Using the RPM </I 1234></SPAN 1235></P 1236><P 1237>NCURSES RPM can be found and downloaded from <A 1238HREF="http://rpmfind.net" 1239TARGET="_top" 1240>http://rpmfind.net </A 1241>. The RPM can be installed with the following 1242command after becoming root.</P 1243><PRE 1244CLASS="PROGRAMLISTING" 1245> rpm -i <downloaded rpm></PRE 1246></DIV 1247><DIV 1248CLASS="SECT2" 1249><HR><H3 1250CLASS="SECT2" 1251><A 1252NAME="PURPOSE" 1253>1.4. Purpose/Scope of the document</A 1254></H3 1255><P 1256>This document is intended to be a "All in One" guide for programming with 1257ncurses and its sister libraries. We graduate from a simple "Hello World" 1258program to more complex form manipulation. No prior experience in ncurses is 1259assumed. The writing is informal, but a lot of detail is provided for 1260each of the examples.</P 1261></DIV 1262><DIV 1263CLASS="SECT2" 1264><HR><H3 1265CLASS="SECT2" 1266><A 1267NAME="ABOUTPROGRAMS" 1268>1.5. About the Programs</A 1269></H3 1270><P 1271>All the programs in the document are available in zipped form 1272<A 1273HREF="http://www.tldp.org/HOWTO/NCURSES-Programming-HOWTO/ncurses_programs.tar.gz" 1274TARGET="_top" 1275>here</A 1276>. Unzip and untar it. The directory structure looks like this.</P 1277><PRE 1278CLASS="PROGRAMLISTING" 1279>ncurses 1280 | 1281 |----> JustForFun -- just for fun programs 1282 |----> basics -- basic programs 1283 |----> demo -- output files go into this directory after make 1284 | | 1285 | |----> exe -- exe files of all example programs 1286 |----> forms -- programs related to form library 1287 |----> menus -- programs related to menus library 1288 |----> panels -- programs related to panels library 1289 |----> perl -- perl equivalents of the examples (contributed 1290 | by Anuradha Ratnaweera) 1291 |----> Makefile -- the top level Makefile 1292 |----> README -- the top level README file. contains instructions 1293 |----> COPYING -- copyright notice</PRE 1294><P 1295>The individual directories contain the following files.</P 1296><PRE 1297CLASS="PROGRAMLISTING" 1298>Description of files in each directory 1299-------------------------------------- 1300JustForFun 1301 | 1302 |----> hanoi.c -- The Towers of Hanoi Solver 1303 |----> life.c -- The Game of Life demo 1304 |----> magic.c -- An Odd Order Magic Square builder 1305 |----> queens.c -- The famous N-Queens Solver 1306 |----> shuffle.c -- A fun game, if you have time to kill 1307 |----> tt.c -- A very trivial typing tutor 1308 1309 basics 1310 | 1311 |----> acs_vars.c -- ACS_ variables example 1312 |----> hello_world.c -- Simple "Hello World" Program 1313 |----> init_func_example.c -- Initialization functions example 1314 |----> key_code.c -- Shows the scan code of the key pressed 1315 |----> mouse_menu.c -- A menu accessible by mouse 1316 |----> other_border.c -- Shows usage of other border functions apa 1317 | -- rt from box() 1318 |----> printw_example.c -- A very simple printw() example 1319 |----> scanw_example.c -- A very simple getstr() example 1320 |----> simple_attr.c -- A program that can print a c file with 1321 | -- comments in attribute 1322 |----> simple_color.c -- A simple example demonstrating colors 1323 |----> simple_key.c -- A menu accessible with keyboard UP, DOWN 1324 | -- arrows 1325 |----> temp_leave.c -- Demonstrates temporarily leaving curses mode 1326 |----> win_border.c -- Shows Creation of windows and borders 1327 |----> with_chgat.c -- chgat() usage example 1328 1329 forms 1330 | 1331 |----> form_attrib.c -- Usage of field attributes 1332 |----> form_options.c -- Usage of field options 1333 |----> form_simple.c -- A simple form example 1334 |----> form_win.c -- Demo of windows associated with forms 1335 1336 menus 1337 | 1338 |----> menu_attrib.c -- Usage of menu attributes 1339 |----> menu_item_data.c -- Usage of item_name() etc.. functions 1340 |----> menu_multi_column.c -- Creates multi columnar menus 1341 |----> menu_scroll.c -- Demonstrates scrolling capability of menus 1342 |----> menu_simple.c -- A simple menu accessed by arrow keys 1343 |----> menu_toggle.c -- Creates multi valued menus and explains 1344 | -- REQ_TOGGLE_ITEM 1345 |----> menu_userptr.c -- Usage of user pointer 1346 |----> menu_win.c -- Demo of windows associated with menus 1347 1348 panels 1349 | 1350 |----> panel_browse.c -- Panel browsing through tab. Usage of user 1351 | -- pointer 1352 |----> panel_hide.c -- Hiding and Un hiding of panels 1353 |----> panel_resize.c -- Moving and resizing of panels 1354 |----> panel_simple.c -- A simple panel example 1355 1356 perl 1357 |----> 01-10.pl -- Perl equivalents of first ten example programs</PRE 1358><P 1359>There is a top level Makefile included in the main directory. It builds all the 1360files and puts the ready-to-use exes in demo/exe directory. You can also 1361do selective make by going into the corresponding directory. Each directory 1362contains a README file explaining the purpose of each c file in the directory.</P 1363><P 1364>For every example, I have included path name for the file relative to the 1365examples directory. </P 1366><P 1367> If you prefer browsing individual programs, point your browser to 1368<A 1369HREF="http://tldp.org/HOWTO/NCURSES-Programming-HOWTO/ncurses_programs/" 1370TARGET="_top" 1371>http://tldp.org/HOWTO/NCURSES-Programming-HOWTO/ncurses_programs/</A 1372></P 1373><P 1374>All the programs are released under the same license that is used by ncurses 1375(MIT-style). This gives you the ability to do pretty much anything other than 1376claiming them as yours. Feel free to use them in your programs as appropriate.</P 1377></DIV 1378><DIV 1379CLASS="SECT2" 1380><HR><H3 1381CLASS="SECT2" 1382><A 1383NAME="OTHERFORMATS" 1384>1.6. Other Formats of the document</A 1385></H3 1386><P 1387>This howto is also availabe in various other formats on the tldp.org site. 1388Here are the links to other formats of this document.</P 1389><DIV 1390CLASS="SECT3" 1391><HR><H4 1392CLASS="SECT3" 1393><A 1394NAME="LISTFORMATS" 1395>1.6.1. Readily available formats from tldp.org</A 1396></H4 1397><P 1398></P 1399><UL 1400><LI 1401><P 1402><A 1403HREF="http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/pdf/NCURSES-Programming-HOWTO.pdf" 1404TARGET="_top" 1405>Acrobat PDF Format</A 1406></P 1407></LI 1408><LI 1409><P 1410><A 1411HREF="http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/ps/NCURSES-Programming-HOWTO.ps.gz" 1412TARGET="_top" 1413>PostScript Format</A 1414></P 1415></LI 1416><LI 1417><P 1418><A 1419HREF="http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/html/NCURSES-Programming-HOWTO-html.tar.gz" 1420TARGET="_top" 1421>In Multiple HTML pages</A 1422></P 1423></LI 1424><LI 1425><P 1426><A 1427HREF="http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/html_single/NCURSES-Programming-HOWTO.html" 1428TARGET="_top" 1429>In One big HTML format</A 1430></P 1431></LI 1432></UL 1433></DIV 1434><DIV 1435CLASS="SECT3" 1436><HR><H4 1437CLASS="SECT3" 1438><A 1439NAME="BUILDSOURCE" 1440>1.6.2. Building from source</A 1441></H4 1442><P 1443>If above links are broken or if you want to experiment with sgml read on. 1444<PRE 1445CLASS="PROGRAMLISTING" 1446> Get both the source and the tar,gzipped programs, available at 1447 http://cvsview.tldp.org/index.cgi/LDP/howto/docbook/ 1448 NCURSES-HOWTO/NCURSES-Programming-HOWTO.sgml 1449 http://cvsview.tldp.org/index.cgi/LDP/howto/docbook/ 1450 NCURSES-HOWTO/ncurses_programs.tar.gz 1451 1452 Unzip ncurses_programs.tar.gz with 1453 tar zxvf ncurses_programs.tar.gz 1454 1455 Use jade to create various formats. For example if you just want to create 1456 the multiple html files, you would use 1457 jade -t sgml -i html -d <path to docbook html stylesheet> 1458 NCURSES-Programming-HOWTO.sgml 1459 to get pdf, first create a single html file of the HOWTO with 1460 jade -t sgml -i html -d <path to docbook html stylesheet> -V nochunks 1461 NCURSES-Programming-HOWTO.sgml > NCURSES-ONE-BIG-FILE.html 1462 then use htmldoc to get pdf file with 1463 htmldoc --size universal -t pdf --firstpage p1 -f <output file name.pdf> 1464 NCURSES-ONE-BIG-FILE.html 1465 for ps, you would use 1466 htmldoc --size universal -t ps --firstpage p1 -f <output file name.ps> 1467 NCURSES-ONE-BIG-FILE.html</PRE 1468></P 1469><P 1470>See <A 1471HREF="http://www.tldp.org/LDP/LDP-Author-Guide/" 1472TARGET="_top" 1473>LDP Author guide</A 1474> for more details. If all else failes, mail me at 1475<A 1476HREF="ppadala@gmail.com" 1477TARGET="_top" 1478>ppadala@gmail.com</A 1479></P 1480></DIV 1481></DIV 1482><DIV 1483CLASS="SECT2" 1484><HR><H3 1485CLASS="SECT2" 1486><A 1487NAME="CREDITS" 1488>1.7. Credits</A 1489></H3 1490><P 1491>I thank <A 1492HREF="mailto:sharath_1@usa.net" 1493TARGET="_top" 1494>Sharath</A 1495> and Emre Akbas for 1496helping me with few sections. The introduction was initially written by sharath. 1497I rewrote it with few excerpts taken from his initial work. Emre helped in 1498writing printw and scanw sections.</P 1499><P 1500>Perl equivalents of the example programs are contributed by <A 1501HREF="mailto:Aratnaweera@virtusa.com" 1502TARGET="_top" 1503>Anuradha Ratnaweera</A 1504>. </P 1505><P 1506>Then comes <A 1507HREF="mailto:parimi@ece.arizona.edu" 1508TARGET="_top" 1509>Ravi Parimi</A 1510>, my 1511dearest friend, who has been on this project before even one line was written. 1512He constantly bombarded me with suggestions and patiently reviewed the whole 1513text. He also checked each program on Linux and Solaris. </P 1514></DIV 1515><DIV 1516CLASS="SECT2" 1517><HR><H3 1518CLASS="SECT2" 1519><A 1520NAME="WISHLIST" 1521>1.8. Wish List</A 1522></H3 1523><P 1524>This is the wish list, in the order of priority. If you have a wish or you want 1525to work on completing the wish, mail <A 1526HREF="mailto:ppadala@gmail.com" 1527TARGET="_top" 1528>me</A 1529>. </P 1530><P 1531></P 1532><UL 1533><LI 1534><P 1535>Add examples to last parts of forms section.</P 1536></LI 1537><LI 1538><P 1539>Prepare a Demo showing all the programs and allow the user to browse through 1540description of each program. Let the user compile and see the program in action. 1541A dialog based interface is preferred.</P 1542></LI 1543><LI 1544><P 1545>Add debug info. _tracef, _tracemouse stuff.</P 1546></LI 1547><LI 1548><P 1549>Accessing termcap, terminfo using functions provided by ncurses 1550package.</P 1551></LI 1552><LI 1553><P 1554>Working on two terminals simultaneously.</P 1555></LI 1556><LI 1557><P 1558>Add more stuff to miscellaneous section.</P 1559></LI 1560></UL 1561></DIV 1562><DIV 1563CLASS="SECT2" 1564><HR><H3 1565CLASS="SECT2" 1566><A 1567NAME="COPYRIGHT" 1568>1.9. Copyright</A 1569></H3 1570><P 1571>Copyright © 2001 by Pradeep Padala. </P 1572><P 1573>Permission is hereby granted, free of charge, to any person obtaining a copy 1574of this software and associated documentation files (the "Software"), to deal 1575in the Software without restriction, including without limitation the rights 1576to use, copy, modify, merge, publish, distribute, distribute with 1577modifications, sublicense, and/or sell copies of the Software, and to permit 1578persons to whom the Software is furnished to do so, subject to the following 1579conditions:</P 1580><P 1581>The above copyright notice and this permission notice shall be included in all 1582copies or substantial portions of the Software.</P 1583><P 1584>THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 1585IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 1586FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 1587ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, 1588WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR 1589IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.</P 1590><P 1591>Except as contained in this notice, the name(s) of the above copyright holders 1592shall not be used in advertising or otherwise to promote the sale, use or 1593other dealings in this Software without prior written authorization. </P 1594></DIV 1595></DIV 1596><DIV 1597CLASS="SECT1" 1598><HR><H2 1599CLASS="SECT1" 1600><A 1601NAME="HELLOWORLD" 1602>2. Hello World !!!</A 1603></H2 1604><P 1605>Welcome to the world of curses. Before we plunge into the library and look into 1606its various features, let's write a simple program and say 1607hello to the world. </P 1608><DIV 1609CLASS="SECT2" 1610><HR><H3 1611CLASS="SECT2" 1612><A 1613NAME="COMPILECURSES" 1614>2.1. Compiling With the NCURSES Library</A 1615></H3 1616><P 1617>To use ncurses library functions, you have to include ncurses.h in your 1618programs. To link the 1619program with ncurses the flag -lncurses should be added.</P 1620><PRE 1621CLASS="PROGRAMLISTING" 1622> #include <ncurses.h> 1623 . 1624 . 1625 . 1626 1627 compile and link: gcc <program file> -lncurses</PRE 1628><DIV 1629CLASS="EXAMPLE" 1630><A 1631NAME="BHW" 1632></A 1633><P 1634><B 1635>Example 1. The Hello World !!! Program </B 1636></P 1637><PRE 1638CLASS="PROGRAMLISTING" 1639><SPAN 1640CLASS="INLINEMEDIAOBJECT" 1641>#include <ncurses.h> 1642 1643int main() 1644{ 1645 initscr(); /* Start curses mode */ 1646 printw("Hello World !!!"); /* Print Hello World */ 1647 refresh(); /* Print it on to the real screen */ 1648 getch(); /* Wait for user input */ 1649 endwin(); /* End curses mode */ 1650 1651 return 0; 1652}</SPAN 1653></PRE 1654></DIV 1655></DIV 1656><DIV 1657CLASS="SECT2" 1658><HR><H3 1659CLASS="SECT2" 1660><A 1661NAME="DISSECTION" 1662>2.2. Dissection</A 1663></H3 1664><P 1665> 1666The above program prints "Hello World !!!" to the screen and exits. This 1667program shows how to initialize curses and do screen manipulation and 1668end curses mode. Let's dissect it line by line. </P 1669><DIV 1670CLASS="SECT3" 1671><HR><H4 1672CLASS="SECT3" 1673><A 1674NAME="ABOUT-INITSCR" 1675>2.2.1. About initscr()</A 1676></H4 1677><P 1678>The function initscr() initializes the terminal in curses mode. In some 1679implementations, it clears the screen and presents a blank screen. To do any 1680screen manipulation using curses package this has to be called first. This 1681function initializes the curses system and allocates memory for our present 1682window (called <TT 1683CLASS="LITERAL" 1684>stdscr</TT 1685>) and some other data-structures. Under extreme 1686cases this function might fail due to insufficient memory to allocate memory 1687for curses library's data structures. </P 1688><P 1689> 1690After this is done, we can do a variety of initializations to customize 1691our curses settings. These details will be explained <A 1692HREF="#INIT" 1693>later </A 1694>.</P 1695></DIV 1696><DIV 1697CLASS="SECT3" 1698><HR><H4 1699CLASS="SECT3" 1700><A 1701NAME="MYST-REFRESH" 1702>2.2.2. The mysterious refresh()</A 1703></H4 1704><P 1705>The next line printw prints the string "Hello World !!!" on to the screen. This 1706function is analogous to normal printf in all respects except that it prints 1707the data on a window called stdscr at the current (y,x) co-ordinates. Since our 1708present co-ordinates are at 0,0 the string is printed at the left hand corner 1709of the window.</P 1710><P 1711>This brings us to that mysterious refresh(). Well, when we called printw 1712the data is actually written to an imaginary window, which is not updated 1713on the screen yet. The job of printw is to update a few flags 1714and data structures and write the data to a buffer corresponding to stdscr. 1715In order to show it on the screen, we need to call refresh() and tell the 1716curses system to dump the contents on the screen.</P 1717><P 1718>The philosophy behind all this is to allow the programmer to do multiple updates 1719on the imaginary screen or windows and do a refresh once all his screen update 1720is done. refresh() checks the window and updates only the portion which has been 1721changed. This improves performance and offers greater flexibility too. But, it is 1722sometimes frustrating to beginners. A common mistake committed by beginners is 1723to forget to call refresh() after they did some update through printw() class of 1724functions. I still forget to add it sometimes :-) </P 1725></DIV 1726><DIV 1727CLASS="SECT3" 1728><HR><H4 1729CLASS="SECT3" 1730><A 1731NAME="ABOUT-ENDWIN" 1732>2.2.3. About endwin()</A 1733></H4 1734><P 1735>And finally don't forget to end the curses mode. Otherwise your terminal might 1736behave strangely after the program quits. endwin() frees the memory taken by 1737curses sub-system and its data structures and puts the terminal in normal 1738mode. This function must be called after you are done with the curses mode. </P 1739></DIV 1740></DIV 1741></DIV 1742><DIV 1743CLASS="SECT1" 1744><HR><H2 1745CLASS="SECT1" 1746><A 1747NAME="GORY" 1748>3. The Gory Details</A 1749></H2 1750><P 1751>Now that we have seen how to write a simple curses program let's get into the 1752details. There are many functions that help customize what you see on screen and 1753many features which can be put to full use. </P 1754><P 1755>Here we go...</P 1756></DIV 1757><DIV 1758CLASS="SECT1" 1759><HR><H2 1760CLASS="SECT1" 1761><A 1762NAME="INIT" 1763>4. Initialization</A 1764></H2 1765><P 1766>We now know that to initialize curses system the function initscr() has to be 1767called. There are functions which can be called after this initialization to 1768customize our curses session. We may ask the curses system to set the terminal 1769in raw mode or initialize color or initialize the mouse etc.. Let's discuss some 1770of the functions that are normally called immediately after initscr();</P 1771><DIV 1772CLASS="SECT2" 1773><HR><H3 1774CLASS="SECT2" 1775><A 1776NAME="ABOUTINIT" 1777>4.1. Initialization functions</A 1778></H3 1779><P 1780> </P 1781></DIV 1782><DIV 1783CLASS="SECT2" 1784><HR><H3 1785CLASS="SECT2" 1786><A 1787NAME="RAWCBREAK" 1788>4.2. raw() and cbreak()</A 1789></H3 1790><P 1791>Normally the terminal driver buffers the characters a user types until a new 1792line or carriage return is encountered. But most programs require that the 1793characters be available as soon as the user types them. The above two functions 1794are used to disable line buffering. The difference between these two functions 1795is in the way control characters like suspend (CTRL-Z), interrupt and quit 1796(CTRL-C) are passed to the program. In the raw() mode these characters are 1797directly passed to the program without generating a signal. In the 1798<TT 1799CLASS="LITERAL" 1800>cbreak()</TT 1801> mode these control characters are 1802interpreted as any other character by the terminal driver. I personally prefer 1803to use raw() as I can exercise greater control over what the user does.</P 1804></DIV 1805><DIV 1806CLASS="SECT2" 1807><HR><H3 1808CLASS="SECT2" 1809><A 1810NAME="ECHONOECHO" 1811>4.3. echo() and noecho()</A 1812></H3 1813><P 1814> 1815These functions control the echoing of characters typed by the user to the 1816terminal. <TT 1817CLASS="LITERAL" 1818>noecho()</TT 1819> switches off echoing. The 1820reason you might want to do this is to gain more control over echoing or to 1821suppress unnecessary echoing while taking input from the user through the 1822getch() etc. functions. Most of the interactive programs call 1823<TT 1824CLASS="LITERAL" 1825>noecho()</TT 1826> at initialization and do the echoing 1827of characters in a controlled manner. It gives the programmer the flexibility 1828of echoing characters at any place in the window without updating current (y,x) 1829co-ordinates. </P 1830></DIV 1831><DIV 1832CLASS="SECT2" 1833><HR><H3 1834CLASS="SECT2" 1835><A 1836NAME="KEYPAD" 1837>4.4. keypad()</A 1838></H3 1839><P 1840>This is my favorite initialization function. It enables the reading of function 1841keys like F1, F2, arrow keys etc. Almost every interactive program enables this, 1842as arrow keys are a major part of any User Interface. Do 1843<TT 1844CLASS="LITERAL" 1845>keypad(stdscr, TRUE) </TT 1846> to enable this feature 1847for the regular screen (stdscr). You will learn more about key management in 1848later sections of this document.</P 1849></DIV 1850><DIV 1851CLASS="SECT2" 1852><HR><H3 1853CLASS="SECT2" 1854><A 1855NAME="HALFDELAY" 1856>4.5. halfdelay()</A 1857></H3 1858><P 1859>This function, though not used very often, is a useful one at times. 1860halfdelay()is called to enable the half-delay mode, which is similar to the 1861cbreak() mode in that characters typed are immediately available to program. 1862However, it waits for 'X' tenths of a second for input and then returns ERR, if 1863no input is available. 'X' is the timeout value passed to the function 1864halfdelay(). This function is useful when you want to ask the user for input, 1865and if he doesn't respond with in certain time, we can do some thing else. One 1866possible example is a timeout at the password prompt. </P 1867></DIV 1868><DIV 1869CLASS="SECT2" 1870><HR><H3 1871CLASS="SECT2" 1872><A 1873NAME="MISCINIT" 1874>4.6. Miscellaneous Initialization functions</A 1875></H3 1876><P 1877>There are few more functions which are called at initialization to 1878customize curses behavior. They are not used as extensively as those mentioned 1879above. Some of them are explained where appropriate.</P 1880></DIV 1881><DIV 1882CLASS="SECT2" 1883><HR><H3 1884CLASS="SECT2" 1885><A 1886NAME="INITEX" 1887>4.7. An Example</A 1888></H3 1889><P 1890>Let's write a program which will clarify the usage of these functions.</P 1891><DIV 1892CLASS="EXAMPLE" 1893><A 1894NAME="BINFU" 1895></A 1896><P 1897><B 1898>Example 2. Initialization Function Usage example </B 1899></P 1900><PRE 1901CLASS="PROGRAMLISTING" 1902><SPAN 1903CLASS="INLINEMEDIAOBJECT" 1904>#include <ncurses.h> 1905 1906int main() 1907{ int ch; 1908 1909 initscr(); /* Start curses mode */ 1910 raw(); /* Line buffering disabled */ 1911 keypad(stdscr, TRUE); /* We get F1, F2 etc.. */ 1912 noecho(); /* Don't echo() while we do getch */ 1913 1914 printw("Type any character to see it in bold\n"); 1915 ch = getch(); /* If raw() hadn't been called 1916 * we have to press enter before it 1917 * gets to the program */ 1918 if(ch == KEY_F(1)) /* Without keypad enabled this will */ 1919 printw("F1 Key pressed");/* not get to us either */ 1920 /* Without noecho() some ugly escape 1921 * charachters might have been printed 1922 * on screen */ 1923 else 1924 { printw("The pressed key is "); 1925 attron(A_BOLD); 1926 printw("%c", ch); 1927 attroff(A_BOLD); 1928 } 1929 refresh(); /* Print it on to the real screen */ 1930 getch(); /* Wait for user input */ 1931 endwin(); /* End curses mode */ 1932 1933 return 0; 1934}</SPAN 1935></PRE 1936></DIV 1937><P 1938>This program is self-explanatory. But I used functions which aren't explained 1939yet. The function <TT 1940CLASS="LITERAL" 1941>getch()</TT 1942> is used to get a 1943character from user. It is equivalent to normal 1944<TT 1945CLASS="LITERAL" 1946>getchar()</TT 1947> except that we can disable the line 1948buffering to avoid <enter> after input. Look for more about 1949<TT 1950CLASS="LITERAL" 1951>getch()</TT 1952>and reading keys in the <A 1953HREF="#KEYS" 1954> key management section </A 1955>. The functions attron and attroff 1956are used to switch some attributes on and off respectively. In the example I 1957used them to print the character in bold. These functions are explained in detail 1958later.</P 1959></DIV 1960></DIV 1961><DIV 1962CLASS="SECT1" 1963><HR><H2 1964CLASS="SECT1" 1965><A 1966NAME="AWORDWINDOWS" 1967>5. A Word about Windows</A 1968></H2 1969><P 1970> 1971Before we plunge into the myriad ncurses functions, let me clear few things 1972about windows. Windows are explained in detail in following <A 1973HREF="#WINDOWS" 1974> sections </A 1975></P 1976><P 1977>A Window is an imaginary screen defined by curses system. A window does not mean 1978a bordered window which you usually see on Win9X platforms. When curses is 1979initialized, it creates a default window named 1980<TT 1981CLASS="LITERAL" 1982>stdscr</TT 1983> which represents your 80x25 (or the size 1984of window in which you are running) screen. If you are doing simple tasks like 1985printing few strings, reading input etc., you can safely use this single window 1986for all of your purposes. You can also create windows and call functions which 1987explicitly work on the specified window.</P 1988><P 1989>For example, if you call</P 1990><PRE 1991CLASS="PROGRAMLISTING" 1992> printw("Hi There !!!"); 1993 refresh();</PRE 1994><P 1995>It prints the string on stdscr at the present cursor position. Similarly the 1996call to refresh(), works on stdscr only. </P 1997><P 1998>Say you have created <A 1999HREF="#WINDOWS" 2000>windows</A 2001> then you have to 2002call a function with a 'w' added to the usual function.</P 2003><PRE 2004CLASS="PROGRAMLISTING" 2005> wprintw(win, "Hi There !!!"); 2006 wrefresh(win);</PRE 2007><P 2008>As you will see in the rest of the document, naming of functions follow the 2009same convention. For each function there usually are three more functions.</P 2010><PRE 2011CLASS="PROGRAMLISTING" 2012> printw(string); /* Print on stdscr at present cursor position */ 2013 mvprintw(y, x, string);/* Move to (y, x) then print string */ 2014 wprintw(win, string); /* Print on window win at present cursor position */ 2015 /* in the window */ 2016 mvwprintw(win, y, x, string); /* Move to (y, x) relative to window */ 2017 /* co-ordinates and then print */</PRE 2018><P 2019>Usually the w-less functions are macros which expand to corresponding w-function 2020with stdscr as the window parameter.</P 2021></DIV 2022><DIV 2023CLASS="SECT1" 2024><HR><H2 2025CLASS="SECT1" 2026><A 2027NAME="PRINTW" 2028>6. Output functions</A 2029></H2 2030><P 2031>I guess you can't wait any more to see some action. Back to our odyssey of 2032curses functions. Now that curses is initialized, let's interact with 2033world.</P 2034><P 2035>There are three classes of functions which you can use to do output on screen. 2036<P 2037></P 2038><OL 2039TYPE="1" 2040><LI 2041><P 2042>addch() class: Print single character with attributes </P 2043></LI 2044><LI 2045><P 2046>printw() class: Print formatted output similar to printf()</P 2047></LI 2048><LI 2049><P 2050>addstr() class: Print strings</P 2051></LI 2052></OL 2053></P 2054><P 2055>These functions can be used interchangeably and it's a matter of style as to 2056which class is used. Let's see each one in detail.</P 2057><DIV 2058CLASS="SECT2" 2059><HR><H3 2060CLASS="SECT2" 2061><A 2062NAME="ADDCHCLASS" 2063>6.1. addch() class of functions</A 2064></H3 2065><P 2066>These functions put a single character into the current cursor location and 2067advance the position of the cursor. You can give the character to be printed but 2068they usually are used to print a character with some attributes. Attributes are 2069explained in detail in later <A 2070HREF="#ATTRIB" 2071> sections </A 2072> of the 2073document. If a character is associated with an attribute(bold, reverse video 2074etc.), when curses prints the character, it is printed in that attribute.</P 2075><P 2076>In order to combine a character with some attributes, you have two options:</P 2077><P 2078></P 2079><UL 2080><LI 2081><P 2082>By OR'ing a single character with the desired attribute macros. These attribute 2083macros could be found in the header file 2084<TT 2085CLASS="LITERAL" 2086>ncurses.h</TT 2087>. For example, you want to print a 2088character ch(of type char) bold and underlined, you would call addch() as below. 2089<PRE 2090CLASS="PROGRAMLISTING" 2091> addch(ch | A_BOLD | A_UNDERLINE);</PRE 2092></P 2093></LI 2094><LI 2095><P 2096>By using functions like <TT 2097CLASS="LITERAL" 2098>attrset(),attron(),attroff()</TT 2099>. These functions are explained in the <A 2100HREF="#ATTRIB" 2101>Attributes</A 2102> section. Briefly, they manipulate the current attributes of 2103the given window. Once set, the character printed in the window are associated 2104with the attributes until it is turned off.</P 2105></LI 2106></UL 2107><P 2108>Additionally, <TT 2109CLASS="LITERAL" 2110>curses</TT 2111> provides some special 2112characters for character-based graphics. You can draw tables, horizontal or 2113vertical lines, etc. You can find all avaliable characters in the header file 2114<TT 2115CLASS="LITERAL" 2116>ncurses.h</TT 2117>. Try looking for macros beginning 2118with <TT 2119CLASS="LITERAL" 2120>ACS_</TT 2121> in this file. </P 2122></DIV 2123><DIV 2124CLASS="SECT2" 2125><HR><H3 2126CLASS="SECT2" 2127><A 2128NAME="AEN298" 2129>6.2. mvaddch(), waddch() and mvwaddch()</A 2130></H3 2131><P 2132><TT 2133CLASS="LITERAL" 2134>mvaddch()</TT 2135> is used to move the cursor to a 2136given point, and then print. Thus, the calls: 2137<PRE 2138CLASS="PROGRAMLISTING" 2139> move(row,col); /* moves the cursor to row<SPAN 2140CLASS="emphasis" 2141><I 2142CLASS="EMPHASIS" 2143>th</I 2144></SPAN 2145> row and col<SPAN 2146CLASS="emphasis" 2147><I 2148CLASS="EMPHASIS" 2149>th</I 2150></SPAN 2151> column */ 2152 addch(ch);</PRE 2153> 2154can be replaced by 2155<PRE 2156CLASS="PROGRAMLISTING" 2157> mvaddch(row,col,ch);</PRE 2158></P 2159><P 2160><TT 2161CLASS="LITERAL" 2162>waddch()</TT 2163> is similar to 2164<TT 2165CLASS="LITERAL" 2166>addch()</TT 2167>, except that it adds a character into 2168the given window. (Note that <TT 2169CLASS="LITERAL" 2170>addch()</TT 2171> adds a 2172character into the window <TT 2173CLASS="LITERAL" 2174>stdscr</TT 2175>.)</P 2176><P 2177>In a similar fashion <TT 2178CLASS="LITERAL" 2179>mvwaddch()</TT 2180> function is 2181used to add a character into the given window at the given coordinates.</P 2182><P 2183>Now, we are familiar with the basic output function 2184<TT 2185CLASS="LITERAL" 2186>addch()</TT 2187>. But, if we want to print a string, it 2188would be very annoying to print it character by character. Fortunately, 2189<TT 2190CLASS="LITERAL" 2191>ncurses</TT 2192> provides <TT 2193CLASS="LITERAL" 2194>printf</TT 2195><SPAN 2196CLASS="emphasis" 2197><I 2198CLASS="EMPHASIS" 2199>-like</I 2200></SPAN 2201> or 2202<TT 2203CLASS="LITERAL" 2204>puts</TT 2205><SPAN 2206CLASS="emphasis" 2207><I 2208CLASS="EMPHASIS" 2209>-like</I 2210></SPAN 2211> functions.</P 2212></DIV 2213><DIV 2214CLASS="SECT2" 2215><HR><H3 2216CLASS="SECT2" 2217><A 2218NAME="PRINTWCLASS" 2219>6.3. printw() class of functions</A 2220></H3 2221><P 2222>These functions are similar to <TT 2223CLASS="LITERAL" 2224>printf()</TT 2225> with 2226the added capability of printing at any position on the screen. </P 2227><DIV 2228CLASS="SECT3" 2229><HR><H4 2230CLASS="SECT3" 2231><A 2232NAME="PRINTWMVPRINTW" 2233>6.3.1. printw() and mvprintw</A 2234></H4 2235><P 2236>These two functions work much like <TT 2237CLASS="LITERAL" 2238>printf()</TT 2239>. 2240<TT 2241CLASS="LITERAL" 2242>mvprintw()</TT 2243> can be used to move the cursor to a 2244position and then print. If you want to move the cursor first and then print 2245using <TT 2246CLASS="LITERAL" 2247>printw()</TT 2248> function, use 2249<TT 2250CLASS="LITERAL" 2251>move() </TT 2252> first and then use 2253<TT 2254CLASS="LITERAL" 2255>printw()</TT 2256> though I see no point why one should 2257avoid using <TT 2258CLASS="LITERAL" 2259>mvprintw()</TT 2260>, you have the 2261flexibility to manipulate. </P 2262></DIV 2263><DIV 2264CLASS="SECT3" 2265><HR><H4 2266CLASS="SECT3" 2267><A 2268NAME="WPRINTWMVWPRINTW" 2269>6.3.2. wprintw() and mvwprintw</A 2270></H4 2271><P 2272>These two functions are similar to above two except that they print in the 2273corresponding window given as argument. </P 2274></DIV 2275><DIV 2276CLASS="SECT3" 2277><HR><H4 2278CLASS="SECT3" 2279><A 2280NAME="VWPRINTW" 2281>6.3.3. vwprintw()</A 2282></H4 2283><P 2284>This function is similar to <TT 2285CLASS="LITERAL" 2286>vprintf()</TT 2287>. This can 2288be used when variable number of arguments are to be printed.</P 2289></DIV 2290><DIV 2291CLASS="SECT3" 2292><HR><H4 2293CLASS="SECT3" 2294><A 2295NAME="SIMPLEPRINTWEX" 2296>6.3.4. A Simple printw example</A 2297></H4 2298><DIV 2299CLASS="EXAMPLE" 2300><A 2301NAME="BPREX" 2302></A 2303><P 2304><B 2305>Example 3. A Simple printw example </B 2306></P 2307><PRE 2308CLASS="PROGRAMLISTING" 2309><SPAN 2310CLASS="INLINEMEDIAOBJECT" 2311>#include <ncurses.h> /* ncurses.h includes stdio.h */ 2312#include <string.h> 2313 2314int main() 2315{ 2316 char mesg[]="Just a string"; /* message to be appeared on the screen */ 2317 int row,col; /* to store the number of rows and * 2318 * the number of colums of the screen */ 2319 initscr(); /* start the curses mode */ 2320 getmaxyx(stdscr,row,col); /* get the number of rows and columns */ 2321 mvprintw(row/2,(col-strlen(mesg))/2,"%s",mesg); 2322 /* print the message at the center of the screen */ 2323 mvprintw(row-2,0,"This screen has %d rows and %d columns\n",row,col); 2324 printw("Try resizing your window(if possible) and then run this program again"); 2325 refresh(); 2326 getch(); 2327 endwin(); 2328 2329 return 0; 2330}</SPAN 2331></PRE 2332></DIV 2333><P 2334>Above program demonstrates how easy it is to use <TT 2335CLASS="LITERAL" 2336>printw</TT 2337>. You just feed the coordinates and the message to be appeared 2338on the screen, then it does what you want.</P 2339><P 2340>The above program introduces us to a new function 2341<TT 2342CLASS="LITERAL" 2343>getmaxyx()</TT 2344>, a macro defined in 2345<TT 2346CLASS="LITERAL" 2347>ncurses.h</TT 2348>. It gives the number of columns and 2349the number of rows in a given window. 2350<TT 2351CLASS="LITERAL" 2352>getmaxyx()</TT 2353> does this by updating the variables 2354given to it. Since <TT 2355CLASS="LITERAL" 2356>getmaxyx()</TT 2357> is not a function 2358we don't pass pointers to it, we just give two integer variables. </P 2359></DIV 2360></DIV 2361><DIV 2362CLASS="SECT2" 2363><HR><H3 2364CLASS="SECT2" 2365><A 2366NAME="ADDSTRCLASS" 2367>6.4. addstr() class of functions</A 2368></H3 2369><P 2370><TT 2371CLASS="LITERAL" 2372>addstr()</TT 2373> is used to put a character string into 2374a given window. This function is similar to calling 2375<TT 2376CLASS="LITERAL" 2377>addch()</TT 2378> once for each character in a given 2379string. This is true for all output functions. There are other functions from 2380this family such as <TT 2381CLASS="LITERAL" 2382>mvaddstr(),mvwaddstr()</TT 2383> and 2384<TT 2385CLASS="LITERAL" 2386>waddstr()</TT 2387>, which obey the naming convention of 2388curses.(e.g. mvaddstr() is similar to the respective calls move() and then 2389addstr().) Another function of this family is addnstr(), which takes an integer 2390parameter(say n) additionally. This function puts at most n characters into the 2391screen. If n is negative, then the entire string will be added. </P 2392></DIV 2393><DIV 2394CLASS="SECT2" 2395><HR><H3 2396CLASS="SECT2" 2397><A 2398NAME="ACAUTION" 2399>6.5. A word of caution</A 2400></H3 2401><P 2402>All these functions take y co-ordinate first and then x in their arguments. 2403A common mistake by beginners is to pass x,y in that order. If you are 2404doing too many manipulations of (y,x) co-ordinates, think of dividing the 2405screen into windows and manipulate each one separately. Windows are explained 2406in the <A 2407HREF="#WINDOWS" 2408> windows </A 2409> section.</P 2410></DIV 2411></DIV 2412><DIV 2413CLASS="SECT1" 2414><HR><H2 2415CLASS="SECT1" 2416><A 2417NAME="SCANW" 2418>7. Input functions</A 2419></H2 2420><P 2421>Well, printing without taking input, is boring. Let's see functions which 2422allow us to get input from user. These functions also can be divided into 2423three categories.</P 2424><P 2425></P 2426><OL 2427TYPE="1" 2428><LI 2429><P 2430>getch() class: Get a character</P 2431></LI 2432><LI 2433><P 2434>scanw() class: Get formatted input</P 2435></LI 2436><LI 2437><P 2438>getstr() class: Get strings</P 2439></LI 2440></OL 2441><DIV 2442CLASS="SECT2" 2443><HR><H3 2444CLASS="SECT2" 2445><A 2446NAME="GETCHCLASS" 2447>7.1. getch() class of functions</A 2448></H3 2449><P 2450>These functions read a single character from the terminal. But there are several 2451subtle facts to consider. For example if you don't use the function cbreak(), 2452curses will not read your input characters contiguously but will begin read them 2453only after a new line or an EOF is encountered. In order to avoid this, the 2454cbreak() function must used so that characters are immediately available to your 2455program. Another widely used function is noecho(). As the name suggests, when 2456this function is set (used), the characters that are keyed in by the user will 2457not show up on the screen. The two functions cbreak() and noecho() are typical 2458examples of key management. Functions of this genre are explained in the 2459<A 2460HREF="#KEYS" 2461>key management section </A 2462>.</P 2463></DIV 2464><DIV 2465CLASS="SECT2" 2466><HR><H3 2467CLASS="SECT2" 2468><A 2469NAME="SCANWCLASS" 2470>7.2. scanw() class of functions</A 2471></H3 2472><P 2473>These functions are similar to <TT 2474CLASS="LITERAL" 2475>scanf()</TT 2476> with the 2477added capability of getting the input from any location on the screen.</P 2478><DIV 2479CLASS="SECT3" 2480><HR><H4 2481CLASS="SECT3" 2482><A 2483NAME="SCANWMVSCANW" 2484>7.2.1. scanw() and mvscanw</A 2485></H4 2486><P 2487>The usage of these functions is similar to that of 2488<TT 2489CLASS="LITERAL" 2490>sscanf()</TT 2491>, where the line to be scanned is 2492provided by <TT 2493CLASS="LITERAL" 2494>wgetstr()</TT 2495> function. That is, these 2496functions call to <TT 2497CLASS="LITERAL" 2498>wgetstr()</TT 2499> function(explained 2500below) and uses the resulting line for a scan. </P 2501></DIV 2502><DIV 2503CLASS="SECT3" 2504><HR><H4 2505CLASS="SECT3" 2506><A 2507NAME="WSCANWMVWSCANW" 2508>7.2.2. wscanw() and mvwscanw()</A 2509></H4 2510><P 2511>These are similar to above two functions except that they read from a window, 2512which is supplied as one of the arguments to these functions. </P 2513></DIV 2514><DIV 2515CLASS="SECT3" 2516><HR><H4 2517CLASS="SECT3" 2518><A 2519NAME="VWSCANW" 2520>7.2.3. vwscanw()</A 2521></H4 2522><P 2523>This function is similar to <TT 2524CLASS="LITERAL" 2525>vscanf()</TT 2526>. This can 2527be used when a variable number of arguments are to be scanned.</P 2528></DIV 2529></DIV 2530><DIV 2531CLASS="SECT2" 2532><HR><H3 2533CLASS="SECT2" 2534><A 2535NAME="GETSTRCLASS" 2536>7.3. getstr() class of functions</A 2537></H3 2538><P 2539>These functions are used to get strings from the terminal. In essence, this 2540function performs the same task as would be achieved by a series of calls to 2541<TT 2542CLASS="LITERAL" 2543>getch()</TT 2544> until a newline, carriage return, or 2545end-of-file is received. The resulting string of characters are pointed to by 2546<TT 2547CLASS="LITERAL" 2548>str</TT 2549>, which is a character pointer provided by 2550the user.</P 2551></DIV 2552><DIV 2553CLASS="SECT2" 2554><HR><H3 2555CLASS="SECT2" 2556><A 2557NAME="GETSTREX" 2558>7.4. Some examples</A 2559></H3 2560><DIV 2561CLASS="EXAMPLE" 2562><A 2563NAME="BSCEX" 2564></A 2565><P 2566><B 2567>Example 4. A Simple scanw example </B 2568></P 2569><PRE 2570CLASS="PROGRAMLISTING" 2571><SPAN 2572CLASS="INLINEMEDIAOBJECT" 2573>#include <ncurses.h> /* ncurses.h includes stdio.h */ 2574#include <string.h> 2575 2576int main() 2577{ 2578 char mesg[]="Enter a string: "; /* message to be appeared on the screen */ 2579 char str[80]; 2580 int row,col; /* to store the number of rows and * 2581 * the number of colums of the screen */ 2582 initscr(); /* start the curses mode */ 2583 getmaxyx(stdscr,row,col); /* get the number of rows and columns */ 2584 mvprintw(row/2,(col-strlen(mesg))/2,"%s",mesg); 2585 /* print the message at the center of the screen */ 2586 getstr(str); 2587 mvprintw(LINES - 2, 0, "You Entered: %s", str); 2588 getch(); 2589 endwin(); 2590 2591 return 0; 2592}</SPAN 2593></PRE 2594></DIV 2595></DIV 2596></DIV 2597><DIV 2598CLASS="SECT1" 2599><HR><H2 2600CLASS="SECT1" 2601><A 2602NAME="ATTRIB" 2603>8. Attributes</A 2604></H2 2605><P 2606>We have seen an example of how attributes can be used to print characters with 2607some special effects. Attributes, when set prudently, can present information in 2608an easy, understandable manner. The following program takes a C file as input 2609and prints the file with comments in bold. Scan through the code. </P 2610><DIV 2611CLASS="EXAMPLE" 2612><A 2613NAME="BSIAT" 2614></A 2615><P 2616><B 2617>Example 5. A Simple Attributes example </B 2618></P 2619><PRE 2620CLASS="PROGRAMLISTING" 2621><SPAN 2622CLASS="INLINEMEDIAOBJECT" 2623>/* pager functionality by Joseph Spainhour" <spainhou@bellsouth.net> */ 2624#include <ncurses.h> 2625#include <stdlib.h> 2626 2627int main(int argc, char *argv[]) 2628{ 2629 int ch, prev, row, col; 2630 prev = EOF; 2631 FILE *fp; 2632 int y, x; 2633 2634 if(argc != 2) 2635 { 2636 printf("Usage: %s <a c file name>\n", argv[0]); 2637 exit(1); 2638 } 2639 fp = fopen(argv[1], "r"); 2640 if(fp == NULL) 2641 { 2642 perror("Cannot open input file"); 2643 exit(1); 2644 } 2645 initscr(); /* Start curses mode */ 2646 getmaxyx(stdscr, row, col); /* find the boundaries of the screeen */ 2647 while((ch = fgetc(fp)) != EOF) /* read the file till we reach the end */ 2648 { 2649 getyx(stdscr, y, x); /* get the current curser position */ 2650 if(y == (row - 1)) /* are we are at the end of the screen */ 2651 { 2652 printw("<-Press Any Key->"); /* tell the user to press a key */ 2653 getch(); 2654 clear(); /* clear the screen */ 2655 move(0, 0); /* start at the beginning of the screen */ 2656 } 2657 if(prev == '/' && ch == '*') /* If it is / and * then only 2658 * switch bold on */ 2659 { 2660 attron(A_BOLD); /* cut bold on */ 2661 getyx(stdscr, y, x); /* get the current curser position */ 2662 move(y, x - 1); /* back up one space */ 2663 printw("%c%c", '/', ch); /* The actual printing is done here */ 2664 } 2665 else 2666 printw("%c", ch); 2667 refresh(); 2668 if(prev == '*' && ch == '/') 2669 attroff(A_BOLD); /* Switch it off once we got * 2670 * and then / */ 2671 prev = ch; 2672 } 2673 endwin(); /* End curses mode */ 2674 fclose(fp); 2675 return 0; 2676}</SPAN 2677></PRE 2678></DIV 2679><P 2680> 2681Don't worry about all those initialization and other crap. Concentrate on 2682the while loop. It reads each character in the file and searches for the 2683pattern /*. Once it spots the pattern, it switches the BOLD attribute on with 2684<TT 2685CLASS="LITERAL" 2686> attron()</TT 2687> . When we get the pattern */ it is 2688switched off by <TT 2689CLASS="LITERAL" 2690> attroff()</TT 2691> .</P 2692><P 2693> 2694The above program also introduces us to two useful functions 2695<TT 2696CLASS="LITERAL" 2697>getyx() </TT 2698> and 2699<TT 2700CLASS="LITERAL" 2701>move()</TT 2702>. The first function gets the 2703co-ordinates of the present cursor into the variables y, x. Since getyx() is a 2704macro we don't have to pass pointers to variables. The function 2705<TT 2706CLASS="LITERAL" 2707>move()</TT 2708> moves the cursor to the co-ordinates 2709given to it. </P 2710><P 2711> 2712The above program is really a simple one which doesn't do much. On these lines 2713one could write a more useful program which reads a C file, parses it and prints 2714it in different colors. One could even extend it to other languages as well.</P 2715><DIV 2716CLASS="SECT2" 2717><HR><H3 2718CLASS="SECT2" 2719><A 2720NAME="ATTRIBDETAILS" 2721>8.1. The details</A 2722></H3 2723><P 2724>Let's get into more details of attributes. The functions <TT 2725CLASS="LITERAL" 2726>attron(), attroff(), attrset() </TT 2727>, and their sister functions 2728<TT 2729CLASS="LITERAL" 2730> attr_get()</TT 2731> etc.. can be used to switch 2732attributes on/off , get attributes and produce a colorful display.</P 2733><P 2734>The functions attron and attroff take a bit-mask of attributes and switch them 2735on or off, respectively. The following video attributes, which are defined in 2736<curses.h> can be passed to these functions. </P 2737><PRE 2738CLASS="PROGRAMLISTING" 2739> 2740 A_NORMAL Normal display (no highlight) 2741 A_STANDOUT Best highlighting mode of the terminal. 2742 A_UNDERLINE Underlining 2743 A_REVERSE Reverse video 2744 A_BLINK Blinking 2745 A_DIM Half bright 2746 A_BOLD Extra bright or bold 2747 A_PROTECT Protected mode 2748 A_INVIS Invisible or blank mode 2749 A_ALTCHARSET Alternate character set 2750 A_CHARTEXT Bit-mask to extract a character 2751 COLOR_PAIR(n) Color-pair number n 2752 </PRE 2753><P 2754> 2755The last one is the most colorful one :-) Colors are explained in the 2756<A 2757HREF="#color" 2758TARGET="_top" 2759>next sections</A 2760>.</P 2761><P 2762>We can OR(|) any number of above attributes to get a combined effect. If you 2763wanted reverse video with blinking characters you can use</P 2764><PRE 2765CLASS="PROGRAMLISTING" 2766> attron(A_REVERSE | A_BLINK);</PRE 2767></DIV 2768><DIV 2769CLASS="SECT2" 2770><HR><H3 2771CLASS="SECT2" 2772><A 2773NAME="ATTRONVSATTRSET" 2774>8.2. attron() vs attrset()</A 2775></H3 2776><P 2777>Then what is the difference between attron() and attrset()? attrset sets the 2778attributes of window whereas attron just switches on the attribute given to it. 2779So attrset() fully overrides whatever attributes the window previously had and 2780sets it to the new attribute(s). Similarly attroff() just switches off the 2781attribute(s) given to it as an argument. This gives us the flexibility of 2782managing attributes easily.But if you use them carelessly you may loose track of 2783what attributes the window has and garble the display. This is especially true 2784while managing menus with colors and highlighting. So decide on a consistent 2785policy and stick to it. You can always use <TT 2786CLASS="LITERAL" 2787> standend()</TT 2788> which is equivalent to <TT 2789CLASS="LITERAL" 2790> attrset(A_NORMAL)</TT 2791> which turns off all attributes and brings you to normal mode.</P 2792></DIV 2793><DIV 2794CLASS="SECT2" 2795><HR><H3 2796CLASS="SECT2" 2797><A 2798NAME="ATTR_GET" 2799>8.3. attr_get()</A 2800></H3 2801><P 2802> The function attr_get() gets the current attributes and color pair of the 2803window. Though we might not use this as often as the above functions, this is 2804useful in scanning areas of screen. Say we wanted to do some complex update on 2805screen and we are not sure what attribute each character is associated with. 2806Then this function can be used with either attrset or attron to produce the 2807desired effect. </P 2808></DIV 2809><DIV 2810CLASS="SECT2" 2811><HR><H3 2812CLASS="SECT2" 2813><A 2814NAME="ATTR_FUNCS" 2815>8.4. attr_ functions</A 2816></H3 2817><P 2818>There are series of functions like attr_set(), attr_on etc.. These are similar 2819to above functions except that they take parameters of type 2820<TT 2821CLASS="LITERAL" 2822>attr_t</TT 2823>.</P 2824></DIV 2825><DIV 2826CLASS="SECT2" 2827><HR><H3 2828CLASS="SECT2" 2829><A 2830NAME="WATTRFUNCS" 2831>8.5. wattr functions</A 2832></H3 2833><P 2834>For each of the above functions we have a corresponding function with 'w' which 2835operates on a particular window. The above functions operate on stdscr. </P 2836></DIV 2837><DIV 2838CLASS="SECT2" 2839><HR><H3 2840CLASS="SECT2" 2841><A 2842NAME="CHGAT" 2843>8.6. chgat() functions</A 2844></H3 2845><P 2846>The function chgat() is listed in the end of the man page curs_attr. It actually 2847is a useful one. This function can be used to set attributes for a group of 2848characters without moving. I mean it !!! without moving the cursor :-) It 2849changes the attributes of a given number of characters starting at the current 2850cursor location.</P 2851><P 2852>We can give -1 as the character count to update till end of line. If you want to 2853change attributes of characters from current position to end of line, just use 2854this.</P 2855><PRE 2856CLASS="PROGRAMLISTING" 2857> chgat(-1, A_REVERSE, 0, NULL);</PRE 2858><P 2859> 2860This function is useful when changing attributes for characters that are 2861already on the screen. Move to the character from which you want to change and 2862change the attribute. </P 2863><P 2864>Other functions wchgat(), mvchgat(), wchgat() behave similarly except that the w 2865functions operate on the particular window. The mv functions first move the 2866cursor then perform the work given to them. Actually chgat is a macro which is 2867replaced by a wchgat() with stdscr as the window. Most of the "w-less" functions 2868are macros.</P 2869><DIV 2870CLASS="EXAMPLE" 2871><A 2872NAME="BWICH" 2873></A 2874><P 2875><B 2876>Example 6. Chgat() Usage example </B 2877></P 2878><PRE 2879CLASS="PROGRAMLISTING" 2880><SPAN 2881CLASS="INLINEMEDIAOBJECT" 2882>#include <ncurses.h> 2883 2884int main(int argc, char *argv[]) 2885{ initscr(); /* Start curses mode */ 2886 start_color(); /* Start color functionality */ 2887 2888 init_pair(1, COLOR_CYAN, COLOR_BLACK); 2889 printw("A Big string which i didn't care to type fully "); 2890 mvchgat(0, 0, -1, A_BLINK, 1, NULL); 2891 /* 2892 * First two parameters specify the position at which to start 2893 * Third parameter number of characters to update. -1 means till 2894 * end of line 2895 * Forth parameter is the normal attribute you wanted to give 2896 * to the charcter 2897 * Fifth is the color index. It is the index given during init_pair() 2898 * use 0 if you didn't want color 2899 * Sixth one is always NULL 2900 */ 2901 refresh(); 2902 getch(); 2903 endwin(); /* End curses mode */ 2904 return 0; 2905}</SPAN 2906></PRE 2907></DIV 2908><P 2909>This example also introduces us to the color world of curses. Colors will be 2910explained in detail later. Use 0 for no color.</P 2911></DIV 2912></DIV 2913><DIV 2914CLASS="SECT1" 2915><HR><H2 2916CLASS="SECT1" 2917><A 2918NAME="WINDOWS" 2919>9. Windows</A 2920></H2 2921><P 2922>Windows form the most important concept in curses. You have seen the standard 2923window stdscr above where all the functions implicitly operated on this window. 2924Now to make design even a simplest GUI, you need to resort to windows. The main 2925reason you may want to use windows is to manipulate parts of the screen 2926separately, for better efficiency, by updating only the windows that need to be 2927changed and for a better design. I would say the last reason is the most 2928important in going for windows. You should always strive for a better and 2929easy-to-manage design in your programs. If you are writing big, complex GUIs 2930this is of pivotal importance before you start doing anything.</P 2931><DIV 2932CLASS="SECT2" 2933><HR><H3 2934CLASS="SECT2" 2935><A 2936NAME="WINDOWBASICS" 2937>9.1. The basics</A 2938></H3 2939><P 2940>A Window can be created by calling the function 2941<TT 2942CLASS="LITERAL" 2943>newwin()</TT 2944>. It doesn't create any thing on the 2945screen actually. It allocates memory for a structure to manipulate the window 2946and updates the structure with data regarding the window like it's size, beginy, 2947beginx etc.. Hence in curses, a window is just an abstraction of an imaginary 2948window, which can be manipulated independent of other parts of screen. The 2949function newwin() returns a pointer to structure WINDOW, which can be passed to 2950window related functions like wprintw() etc.. Finally the window can be 2951destroyed with delwin(). It will deallocate the memory associated with the 2952window structure.</P 2953></DIV 2954><DIV 2955CLASS="SECT2" 2956><HR><H3 2957CLASS="SECT2" 2958><A 2959NAME="LETBEWINDOW" 2960>9.2. Let there be a Window !!!</A 2961></H3 2962><P 2963>What fun is it, if a window is created and we can't see it. So the fun part 2964begins by displaying the window. The function 2965<TT 2966CLASS="LITERAL" 2967>box()</TT 2968> can be used to draw a border around the 2969window. Let's explore these functions in more detail in this example.</P 2970><DIV 2971CLASS="EXAMPLE" 2972><A 2973NAME="BWIBO" 2974></A 2975><P 2976><B 2977>Example 7. Window Border example </B 2978></P 2979><PRE 2980CLASS="PROGRAMLISTING" 2981><SPAN 2982CLASS="INLINEMEDIAOBJECT" 2983>#include <ncurses.h> 2984 2985 2986WINDOW *create_newwin(int height, int width, int starty, int startx); 2987void destroy_win(WINDOW *local_win); 2988 2989int main(int argc, char *argv[]) 2990{ WINDOW *my_win; 2991 int startx, starty, width, height; 2992 int ch; 2993 2994 initscr(); /* Start curses mode */ 2995 cbreak(); /* Line buffering disabled, Pass on 2996 * everty thing to me */ 2997 keypad(stdscr, TRUE); /* I need that nifty F1 */ 2998 2999 height = 3; 3000 width = 10; 3001 starty = (LINES - height) / 2; /* Calculating for a center placement */ 3002 startx = (COLS - width) / 2; /* of the window */ 3003 printw("Press F1 to exit"); 3004 refresh(); 3005 my_win = create_newwin(height, width, starty, startx); 3006 3007 while((ch = getch()) != KEY_F(1)) 3008 { switch(ch) 3009 { case KEY_LEFT: 3010 destroy_win(my_win); 3011 my_win = create_newwin(height, width, starty,--startx); 3012 break; 3013 case KEY_RIGHT: 3014 destroy_win(my_win); 3015 my_win = create_newwin(height, width, starty,++startx); 3016 break; 3017 case KEY_UP: 3018 destroy_win(my_win); 3019 my_win = create_newwin(height, width, --starty,startx); 3020 break; 3021 case KEY_DOWN: 3022 destroy_win(my_win); 3023 my_win = create_newwin(height, width, ++starty,startx); 3024 break; 3025 } 3026 } 3027 3028 endwin(); /* End curses mode */ 3029 return 0; 3030} 3031 3032WINDOW *create_newwin(int height, int width, int starty, int startx) 3033{ WINDOW *local_win; 3034 3035 local_win = newwin(height, width, starty, startx); 3036 box(local_win, 0 , 0); /* 0, 0 gives default characters 3037 * for the vertical and horizontal 3038 * lines */ 3039 wrefresh(local_win); /* Show that box */ 3040 3041 return local_win; 3042} 3043 3044void destroy_win(WINDOW *local_win) 3045{ 3046 /* box(local_win, ' ', ' '); : This won't produce the desired 3047 * result of erasing the window. It will leave it's four corners 3048 * and so an ugly remnant of window. 3049 */ 3050 wborder(local_win, ' ', ' ', ' ',' ',' ',' ',' ',' '); 3051 /* The parameters taken are 3052 * 1. win: the window on which to operate 3053 * 2. ls: character to be used for the left side of the window 3054 * 3. rs: character to be used for the right side of the window 3055 * 4. ts: character to be used for the top side of the window 3056 * 5. bs: character to be used for the bottom side of the window 3057 * 6. tl: character to be used for the top left corner of the window 3058 * 7. tr: character to be used for the top right corner of the window 3059 * 8. bl: character to be used for the bottom left corner of the window 3060 * 9. br: character to be used for the bottom right corner of the window 3061 */ 3062 wrefresh(local_win); 3063 delwin(local_win); 3064}</SPAN 3065></PRE 3066></DIV 3067></DIV 3068><DIV 3069CLASS="SECT2" 3070><HR><H3 3071CLASS="SECT2" 3072><A 3073NAME="BORDEREXEXPL" 3074>9.3. Explanation</A 3075></H3 3076><P 3077>Don't scream. I know it's a big example. But I have to explain some important 3078things here :-). This program creates a rectangular window that can be moved 3079with left, right, up, down arrow keys. It repeatedly creates and destroys 3080windows as user press a key. Don't go beyond the screen limits. Checking for 3081those limits is left as an exercise for the reader. Let's dissect it by line by line.</P 3082><P 3083>The <TT 3084CLASS="LITERAL" 3085>create_newwin()</TT 3086> function creates a window 3087with <TT 3088CLASS="LITERAL" 3089>newwin() </TT 3090> and displays a border around it 3091with box. The function <TT 3092CLASS="LITERAL" 3093> destroy_win()</TT 3094> first 3095erases the window from screen by painting a border with ' ' character and then 3096calling <TT 3097CLASS="LITERAL" 3098>delwin()</TT 3099> to deallocate memory related 3100to it. Depending on the key the user presses, starty or startx is changed and a 3101new window is created.</P 3102><P 3103>In the destroy_win, as you can see, I used wborder instead of box. The reason is 3104written in the comments (You missed it. I know. Read the code :-)). wborder 3105draws a border around the window with the characters given to it as the 4 corner 3106points and the 4 lines. To put it clearly, if you have called wborder as below: 3107<PRE 3108CLASS="PROGRAMLISTING" 3109> wborder(win, '|', '|', '-', '-', '+', '+', '+', '+');</PRE 3110></P 3111><P 3112>it produces some thing like </P 3113><PRE 3114CLASS="PROGRAMLISTING" 3115> +------------+ 3116 | | 3117 | | 3118 | | 3119 | | 3120 | | 3121 | | 3122 +------------+</PRE 3123></DIV 3124><DIV 3125CLASS="SECT2" 3126><HR><H3 3127CLASS="SECT2" 3128><A 3129NAME="OTHERSTUFF" 3130>9.4. The other stuff in the example</A 3131></H3 3132><P 3133>You can also see in the above examples, that I have used the variables COLS, 3134LINES which are initialized to the screen sizes after initscr(). They can be 3135useful in finding screen dimensions and finding the center co-ordinate of the 3136screen as above. The function <TT 3137CLASS="LITERAL" 3138>getch()</TT 3139> as usual 3140gets the key from keyboard and according to the key it does the corresponding 3141work. This type of switch- case is very common in any GUI based programs.</P 3142></DIV 3143><DIV 3144CLASS="SECT2" 3145><HR><H3 3146CLASS="SECT2" 3147><A 3148NAME="OTHERBORDERFUNCS" 3149>9.5. Other Border functions</A 3150></H3 3151><P 3152>Above program is grossly inefficient in that with each press of a key, a window 3153is destroyed and another is created. So let's write a more efficient program 3154which uses other border related functions.</P 3155><P 3156>The following program uses <TT 3157CLASS="LITERAL" 3158>mvhline()</TT 3159> and 3160<TT 3161CLASS="LITERAL" 3162>mvvline()</TT 3163> to achieve similar effect. These two 3164functions are simple. They create a horizontal or vertical line of the specified 3165length at the specified position.</P 3166><DIV 3167CLASS="EXAMPLE" 3168><A 3169NAME="BOTBO" 3170></A 3171><P 3172><B 3173>Example 8. More border functions</B 3174></P 3175><PRE 3176CLASS="PROGRAMLISTING" 3177><SPAN 3178CLASS="INLINEMEDIAOBJECT" 3179>#include <ncurses.h> 3180 3181typedef struct _win_border_struct { 3182 chtype ls, rs, ts, bs, 3183 tl, tr, bl, br; 3184}WIN_BORDER; 3185 3186typedef struct _WIN_struct { 3187 3188 int startx, starty; 3189 int height, width; 3190 WIN_BORDER border; 3191}WIN; 3192 3193void init_win_params(WIN *p_win); 3194void print_win_params(WIN *p_win); 3195void create_box(WIN *win, bool flag); 3196 3197int main(int argc, char *argv[]) 3198{ WIN win; 3199 int ch; 3200 3201 initscr(); /* Start curses mode */ 3202 start_color(); /* Start the color functionality */ 3203 cbreak(); /* Line buffering disabled, Pass on 3204 * everty thing to me */ 3205 keypad(stdscr, TRUE); /* I need that nifty F1 */ 3206 noecho(); 3207 init_pair(1, COLOR_CYAN, COLOR_BLACK); 3208 3209 /* Initialize the window parameters */ 3210 init_win_params(&win); 3211 print_win_params(&win); 3212 3213 attron(COLOR_PAIR(1)); 3214 printw("Press F1 to exit"); 3215 refresh(); 3216 attroff(COLOR_PAIR(1)); 3217 3218 create_box(&win, TRUE); 3219 while((ch = getch()) != KEY_F(1)) 3220 { switch(ch) 3221 { case KEY_LEFT: 3222 create_box(&win, FALSE); 3223 --win.startx; 3224 create_box(&win, TRUE); 3225 break; 3226 case KEY_RIGHT: 3227 create_box(&win, FALSE); 3228 ++win.startx; 3229 create_box(&win, TRUE); 3230 break; 3231 case KEY_UP: 3232 create_box(&win, FALSE); 3233 --win.starty; 3234 create_box(&win, TRUE); 3235 break; 3236 case KEY_DOWN: 3237 create_box(&win, FALSE); 3238 ++win.starty; 3239 create_box(&win, TRUE); 3240 break; 3241 } 3242 } 3243 endwin(); /* End curses mode */ 3244 return 0; 3245} 3246void init_win_params(WIN *p_win) 3247{ 3248 p_win->height = 3; 3249 p_win->width = 10; 3250 p_win->starty = (LINES - p_win->height)/2; 3251 p_win->startx = (COLS - p_win->width)/2; 3252 3253 p_win->border.ls = '|'; 3254 p_win->border.rs = '|'; 3255 p_win->border.ts = '-'; 3256 p_win->border.bs = '-'; 3257 p_win->border.tl = '+'; 3258 p_win->border.tr = '+'; 3259 p_win->border.bl = '+'; 3260 p_win->border.br = '+'; 3261 3262} 3263void print_win_params(WIN *p_win) 3264{ 3265#ifdef _DEBUG 3266 mvprintw(25, 0, "%d %d %d %d", p_win->startx, p_win->starty, 3267 p_win->width, p_win->height); 3268 refresh(); 3269#endif 3270} 3271void create_box(WIN *p_win, bool flag) 3272{ int i, j; 3273 int x, y, w, h; 3274 3275 x = p_win->startx; 3276 y = p_win->starty; 3277 w = p_win->width; 3278 h = p_win->height; 3279 3280 if(flag == TRUE) 3281 { mvaddch(y, x, p_win->border.tl); 3282 mvaddch(y, x + w, p_win->border.tr); 3283 mvaddch(y + h, x, p_win->border.bl); 3284 mvaddch(y + h, x + w, p_win->border.br); 3285 mvhline(y, x + 1, p_win->border.ts, w - 1); 3286 mvhline(y + h, x + 1, p_win->border.bs, w - 1); 3287 mvvline(y + 1, x, p_win->border.ls, h - 1); 3288 mvvline(y + 1, x + w, p_win->border.rs, h - 1); 3289 3290 } 3291 else 3292 for(j = y; j <= y + h; ++j) 3293 for(i = x; i <= x + w; ++i) 3294 mvaddch(j, i, ' '); 3295 3296 refresh(); 3297 3298}</SPAN 3299></PRE 3300></DIV 3301></DIV 3302></DIV 3303><DIV 3304CLASS="SECT1" 3305><HR><H2 3306CLASS="SECT1" 3307><A 3308NAME="COLOR" 3309>10. Colors</A 3310></H2 3311><DIV 3312CLASS="SECT2" 3313><H3 3314CLASS="SECT2" 3315><A 3316NAME="COLORBASICS" 3317>10.1. The basics</A 3318></H3 3319><P 3320>Life seems dull with no colors. Curses has a nice mechanism to handle colors. 3321Let's get into the thick of the things with a small program.</P 3322><DIV 3323CLASS="EXAMPLE" 3324><A 3325NAME="BSICO" 3326></A 3327><P 3328><B 3329>Example 9. A Simple Color example </B 3330></P 3331><PRE 3332CLASS="PROGRAMLISTING" 3333><SPAN 3334CLASS="INLINEMEDIAOBJECT" 3335>#include <ncurses.h> 3336 3337void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string); 3338int main(int argc, char *argv[]) 3339{ initscr(); /* Start curses mode */ 3340 if(has_colors() == FALSE) 3341 { endwin(); 3342 printf("Your terminal does not support color\n"); 3343 exit(1); 3344 } 3345 start_color(); /* Start color */ 3346 init_pair(1, COLOR_RED, COLOR_BLACK); 3347 3348 attron(COLOR_PAIR(1)); 3349 print_in_middle(stdscr, LINES / 2, 0, 0, "Viola !!! In color ..."); 3350 attroff(COLOR_PAIR(1)); 3351 getch(); 3352 endwin(); 3353} 3354void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string) 3355{ int length, x, y; 3356 float temp; 3357 3358 if(win == NULL) 3359 win = stdscr; 3360 getyx(win, y, x); 3361 if(startx != 0) 3362 x = startx; 3363 if(starty != 0) 3364 y = starty; 3365 if(width == 0) 3366 width = 80; 3367 3368 length = strlen(string); 3369 temp = (width - length)/ 2; 3370 x = startx + (int)temp; 3371 mvwprintw(win, y, x, "%s", string); 3372 refresh(); 3373} 3374</SPAN 3375></PRE 3376></DIV 3377><P 3378>As you can see, to start using color, you should first call the function 3379<TT 3380CLASS="LITERAL" 3381> start_color()</TT 3382>. After that, you can use color 3383capabilities of your terminals using various functions. To find out whether a 3384terminal has color capabilities or not, you can use 3385<TT 3386CLASS="LITERAL" 3387>has_colors()</TT 3388> function, which returns FALSE if 3389the terminal does not support color. </P 3390><P 3391>Curses initializes all the colors supported by terminal when start_color() is 3392called. These can be accessed by the define constants like 3393<TT 3394CLASS="LITERAL" 3395>COLOR_BLACK </TT 3396> etc. Now to actually start using 3397colors, you have to define pairs. Colors are always used in pairs. That means 3398you have to use the function <TT 3399CLASS="LITERAL" 3400>init_pair() </TT 3401> to 3402define the foreground and background for the pair number you give. After that 3403that pair number can be used as a normal attribute with <TT 3404CLASS="LITERAL" 3405>COLOR_PAIR()</TT 3406>function. This may seem to be cumbersome at first. 3407But this elegant solution allows us to manage color pairs very easily. To 3408appreciate it, you have to look into the the source code of "dialog", a utility 3409for displaying dialog boxes from shell scripts. The developers have defined 3410foreground and background combinations for all the colors they might need and 3411initialized at the beginning. This makes it very easy to set attributes just by 3412accessing a pair which we already have defined as a constant.</P 3413><P 3414>The following colors are defined in <TT 3415CLASS="LITERAL" 3416>curses.h</TT 3417>. 3418You can use these as parameters for various color functions. 3419<PRE 3420CLASS="PROGRAMLISTING" 3421> COLOR_BLACK 0 3422 COLOR_RED 1 3423 COLOR_GREEN 2 3424 COLOR_YELLOW 3 3425 COLOR_BLUE 4 3426 COLOR_MAGENTA 5 3427 COLOR_CYAN 6 3428 COLOR_WHITE 7</PRE 3429></P 3430></DIV 3431><DIV 3432CLASS="SECT2" 3433><HR><H3 3434CLASS="SECT2" 3435><A 3436NAME="CHANGECOLORDEFS" 3437>10.2. Changing Color Definitions</A 3438></H3 3439><P 3440>The function <TT 3441CLASS="LITERAL" 3442>init_color()</TT 3443>can be used to change 3444the rgb values for the colors defined by curses initially. Say you wanted to 3445lighten the intensity of red color by a minuscule. Then you can use this 3446function as</P 3447><PRE 3448CLASS="PROGRAMLISTING" 3449> init_color(COLOR_RED, 700, 0, 0); 3450 /* param 1 : color name 3451 * param 2, 3, 4 : rgb content min = 0, max = 1000 */</PRE 3452><P 3453>If your terminal cannot change the color definitions, the function returns ERR. 3454The function <TT 3455CLASS="LITERAL" 3456>can_change_color()</TT 3457> can be used to 3458find out whether the terminal has the capability of changing color content or 3459not. The rgb content is scaled from 0 to 1000. Initially RED color is defined 3460with content 1000(r), 0(g), 0(b). </P 3461></DIV 3462><DIV 3463CLASS="SECT2" 3464><HR><H3 3465CLASS="SECT2" 3466><A 3467NAME="COLORCONTENT" 3468>10.3. Color Content</A 3469></H3 3470><P 3471>The functions <TT 3472CLASS="LITERAL" 3473>color_content()</TT 3474> and 3475<TT 3476CLASS="LITERAL" 3477>pair_content()</TT 3478> can be used to find the color 3479content and foreground, background combination for the pair. </P 3480></DIV 3481></DIV 3482><DIV 3483CLASS="SECT1" 3484><HR><H2 3485CLASS="SECT1" 3486><A 3487NAME="KEYS" 3488>11. Interfacing with the key board</A 3489></H2 3490><DIV 3491CLASS="SECT2" 3492><H3 3493CLASS="SECT2" 3494><A 3495NAME="KEYSBASICS" 3496>11.1. The Basics</A 3497></H3 3498><P 3499>No GUI is complete without a strong user interface and to interact with the 3500user, a curses program should be sensitive to key presses or the mouse actions 3501done by the user. Let's deal with the keys first.</P 3502><P 3503>As you have seen in almost all of the above examples, it's very easy to get key 3504input from the user. A simple way of getting key presses is to use 3505<TT 3506CLASS="LITERAL" 3507>getch()</TT 3508> function. The cbreak mode should be 3509enabled to read keys when you are interested in reading individual key hits 3510rather than complete lines of text (which usually end with a carriage return). 3511keypad should be enabled to get the Functions keys, arrow keys etc. See the 3512initialization section for details.</P 3513><P 3514><TT 3515CLASS="LITERAL" 3516>getch()</TT 3517> returns an integer corresponding to the 3518key pressed. If it is a normal character, the integer value will be equivalent 3519to the character. Otherwise it returns a number which can be matched with the 3520constants defined in <TT 3521CLASS="LITERAL" 3522>curses.h</TT 3523>. For example if 3524the user presses F1, the integer returned is 265. This can be checked using the 3525macro KEY_F() defined in curses.h. This makes reading keys portable and easy to 3526manage.</P 3527><P 3528>For example, if you call getch() like this</P 3529><PRE 3530CLASS="PROGRAMLISTING" 3531> int ch; 3532 3533 ch = getch();</PRE 3534><P 3535>getch() will wait for the user to press a key, (unless you specified a timeout) 3536and when user presses a key, the corresponding integer is returned. Then you can 3537check the value returned with the constants defined in curses.h to match against 3538the keys you want.</P 3539><P 3540>The following code piece will do that job.</P 3541><PRE 3542CLASS="PROGRAMLISTING" 3543> if(ch == KEY_LEFT) 3544 printw("Left arrow is pressed\n");</PRE 3545><P 3546>Let's write a small program which creates a menu which can be navigated by up 3547and down arrows.</P 3548></DIV 3549><DIV 3550CLASS="SECT2" 3551><HR><H3 3552CLASS="SECT2" 3553><A 3554NAME="SIMPLEKEYEX" 3555>11.2. A Simple Key Usage example</A 3556></H3 3557><DIV 3558CLASS="EXAMPLE" 3559><A 3560NAME="BSIKE" 3561></A 3562><P 3563><B 3564>Example 10. A Simple Key Usage example </B 3565></P 3566><PRE 3567CLASS="PROGRAMLISTING" 3568><SPAN 3569CLASS="INLINEMEDIAOBJECT" 3570>#include <stdio.h> 3571#include <ncurses.h> 3572 3573#define WIDTH 30 3574#define HEIGHT 10 3575 3576int startx = 0; 3577int starty = 0; 3578 3579char *choices[] = { 3580 "Choice 1", 3581 "Choice 2", 3582 "Choice 3", 3583 "Choice 4", 3584 "Exit", 3585 }; 3586int n_choices = sizeof(choices) / sizeof(char *); 3587void print_menu(WINDOW *menu_win, int highlight); 3588 3589int main() 3590{ WINDOW *menu_win; 3591 int highlight = 1; 3592 int choice = 0; 3593 int c; 3594 3595 initscr(); 3596 clear(); 3597 noecho(); 3598 cbreak(); /* Line buffering disabled. pass on everything */ 3599 startx = (80 - WIDTH) / 2; 3600 starty = (24 - HEIGHT) / 2; 3601 3602 menu_win = newwin(HEIGHT, WIDTH, starty, startx); 3603 keypad(menu_win, TRUE); 3604 mvprintw(0, 0, "Use arrow keys to go up and down, Press enter to select a choice"); 3605 refresh(); 3606 print_menu(menu_win, highlight); 3607 while(1) 3608 { c = wgetch(menu_win); 3609 switch(c) 3610 { case KEY_UP: 3611 if(highlight == 1) 3612 highlight = n_choices; 3613 else 3614 --highlight; 3615 break; 3616 case KEY_DOWN: 3617 if(highlight == n_choices) 3618 highlight = 1; 3619 else 3620 ++highlight; 3621 break; 3622 case 10: 3623 choice = highlight; 3624 break; 3625 default: 3626 mvprintw(24, 0, "Charcter pressed is = %3d Hopefully it can be printed as '%c'", c, c); 3627 refresh(); 3628 break; 3629 } 3630 print_menu(menu_win, highlight); 3631 if(choice != 0) /* User did a choice come out of the infinite loop */ 3632 break; 3633 } 3634 mvprintw(23, 0, "You chose choice %d with choice string %s\n", choice, choices[choice - 1]); 3635 clrtoeol(); 3636 refresh(); 3637 endwin(); 3638 return 0; 3639} 3640 3641 3642void print_menu(WINDOW *menu_win, int highlight) 3643{ 3644 int x, y, i; 3645 3646 x = 2; 3647 y = 2; 3648 box(menu_win, 0, 0); 3649 for(i = 0; i < n_choices; ++i) 3650 { if(highlight == i + 1) /* High light the present choice */ 3651 { wattron(menu_win, A_REVERSE); 3652 mvwprintw(menu_win, y, x, "%s", choices[i]); 3653 wattroff(menu_win, A_REVERSE); 3654 } 3655 else 3656 mvwprintw(menu_win, y, x, "%s", choices[i]); 3657 ++y; 3658 } 3659 wrefresh(menu_win); 3660} 3661</SPAN 3662></PRE 3663></DIV 3664></DIV 3665></DIV 3666><DIV 3667CLASS="SECT1" 3668><HR><H2 3669CLASS="SECT1" 3670><A 3671NAME="MOUSE" 3672>12. Interfacing with the mouse</A 3673></H2 3674><P 3675>Now that you have seen how to get keys, lets do the same thing from mouse. 3676Usually each UI allows the user to interact with both keyboard and mouse. </P 3677><DIV 3678CLASS="SECT2" 3679><HR><H3 3680CLASS="SECT2" 3681><A 3682NAME="MOUSEBASICS" 3683>12.1. The Basics</A 3684></H3 3685><P 3686>Before you do any thing else, the events you want to receive have to be enabled 3687with <TT 3688CLASS="LITERAL" 3689>mousemask()</TT 3690>.</P 3691><PRE 3692CLASS="PROGRAMLISTING" 3693> mousemask( mmask_t newmask, /* The events you want to listen to */ 3694 mmask_t *oldmask) /* The old events mask */</PRE 3695><P 3696>The first parameter to above function is a bit mask of events you would like to 3697listen. By default, all the events are turned off. The bit mask <TT 3698CLASS="LITERAL" 3699> ALL_MOUSE_EVENTS</TT 3700> can be used to get all the events.</P 3701><P 3702>The following are all the event masks:</P 3703><PRE 3704CLASS="PROGRAMLISTING" 3705> Name Description 3706 --------------------------------------------------------------------- 3707 BUTTON1_PRESSED mouse button 1 down 3708 BUTTON1_RELEASED mouse button 1 up 3709 BUTTON1_CLICKED mouse button 1 clicked 3710 BUTTON1_DOUBLE_CLICKED mouse button 1 double clicked 3711 BUTTON1_TRIPLE_CLICKED mouse button 1 triple clicked 3712 BUTTON2_PRESSED mouse button 2 down 3713 BUTTON2_RELEASED mouse button 2 up 3714 BUTTON2_CLICKED mouse button 2 clicked 3715 BUTTON2_DOUBLE_CLICKED mouse button 2 double clicked 3716 BUTTON2_TRIPLE_CLICKED mouse button 2 triple clicked 3717 BUTTON3_PRESSED mouse button 3 down 3718 BUTTON3_RELEASED mouse button 3 up 3719 BUTTON3_CLICKED mouse button 3 clicked 3720 BUTTON3_DOUBLE_CLICKED mouse button 3 double clicked 3721 BUTTON3_TRIPLE_CLICKED mouse button 3 triple clicked 3722 BUTTON4_PRESSED mouse button 4 down 3723 BUTTON4_RELEASED mouse button 4 up 3724 BUTTON4_CLICKED mouse button 4 clicked 3725 BUTTON4_DOUBLE_CLICKED mouse button 4 double clicked 3726 BUTTON4_TRIPLE_CLICKED mouse button 4 triple clicked 3727 BUTTON_SHIFT shift was down during button state change 3728 BUTTON_CTRL control was down during button state change 3729 BUTTON_ALT alt was down during button state change 3730 ALL_MOUSE_EVENTS report all button state changes 3731 REPORT_MOUSE_POSITION report mouse movement</PRE 3732></DIV 3733><DIV 3734CLASS="SECT2" 3735><HR><H3 3736CLASS="SECT2" 3737><A 3738NAME="GETTINGEVENTS" 3739>12.2. Getting the events</A 3740></H3 3741><P 3742>Once a class of mouse events have been enabled, getch() class of functions 3743return KEY_MOUSE every time some mouse event happens. Then the mouse event can 3744be retrieved with <TT 3745CLASS="LITERAL" 3746>getmouse()</TT 3747>.</P 3748><P 3749>The code approximately looks like this:</P 3750><PRE 3751CLASS="PROGRAMLISTING" 3752> MEVENT event; 3753 3754 ch = getch(); 3755 if(ch == KEY_MOUSE) 3756 if(getmouse(&event) == OK) 3757 . /* Do some thing with the event */ 3758 . 3759 .</PRE 3760><P 3761> 3762getmouse() returns the event into the pointer given to it. It's a structure 3763which contains</P 3764><PRE 3765CLASS="PROGRAMLISTING" 3766> typedef struct 3767 { 3768 short id; /* ID to distinguish multiple devices */ 3769 int x, y, z; /* event coordinates */ 3770 mmask_t bstate; /* button state bits */ 3771 } </PRE 3772><P 3773>The <TT 3774CLASS="LITERAL" 3775>bstate</TT 3776> is the main variable we are 3777interested in. It tells the button state of the mouse.</P 3778><P 3779>Then with a code snippet like the following, we can find out what happened.</P 3780><PRE 3781CLASS="PROGRAMLISTING" 3782> if(event.bstate & BUTTON1_PRESSED) 3783 printw("Left Button Pressed");</PRE 3784></DIV 3785><DIV 3786CLASS="SECT2" 3787><HR><H3 3788CLASS="SECT2" 3789><A 3790NAME="MOUSETOGETHER" 3791>12.3. Putting it all Together</A 3792></H3 3793><P 3794>That's pretty much interfacing with mouse. Let's create the same menu and enable 3795mouse interaction. To make things simpler, key handling is removed.</P 3796><DIV 3797CLASS="EXAMPLE" 3798><A 3799NAME="BMOME" 3800></A 3801><P 3802><B 3803>Example 11. Access the menu with mouse !!! </B 3804></P 3805><PRE 3806CLASS="PROGRAMLISTING" 3807><SPAN 3808CLASS="INLINEMEDIAOBJECT" 3809>#include <ncurses.h> 3810 3811#define WIDTH 30 3812#define HEIGHT 10 3813 3814int startx = 0; 3815int starty = 0; 3816 3817char *choices[] = { "Choice 1", 3818 "Choice 2", 3819 "Choice 3", 3820 "Choice 4", 3821 "Exit", 3822 }; 3823 3824int n_choices = sizeof(choices) / sizeof(char *); 3825 3826void print_menu(WINDOW *menu_win, int highlight); 3827void report_choice(int mouse_x, int mouse_y, int *p_choice); 3828 3829int main() 3830{ int c, choice = 0; 3831 WINDOW *menu_win; 3832 MEVENT event; 3833 3834 /* Initialize curses */ 3835 initscr(); 3836 clear(); 3837 noecho(); 3838 cbreak(); //Line buffering disabled. pass on everything 3839 3840 /* Try to put the window in the middle of screen */ 3841 startx = (80 - WIDTH) / 2; 3842 starty = (24 - HEIGHT) / 2; 3843 3844 attron(A_REVERSE); 3845 mvprintw(23, 1, "Click on Exit to quit (Works best in a virtual console)"); 3846 refresh(); 3847 attroff(A_REVERSE); 3848 3849 /* Print the menu for the first time */ 3850 menu_win = newwin(HEIGHT, WIDTH, starty, startx); 3851 print_menu(menu_win, 1); 3852 /* Get all the mouse events */ 3853 mousemask(ALL_MOUSE_EVENTS, NULL); 3854 3855 while(1) 3856 { c = wgetch(menu_win); 3857 switch(c) 3858 { case KEY_MOUSE: 3859 if(getmouse(&event) == OK) 3860 { /* When the user clicks left mouse button */ 3861 if(event.bstate & BUTTON1_PRESSED) 3862 { report_choice(event.x + 1, event.y + 1, &choice); 3863 if(choice == -1) //Exit chosen 3864 goto end; 3865 mvprintw(22, 1, "Choice made is : %d String Chosen is \"%10s\"", choice, choices[choice - 1]); 3866 refresh(); 3867 } 3868 } 3869 print_menu(menu_win, choice); 3870 break; 3871 } 3872 } 3873end: 3874 endwin(); 3875 return 0; 3876} 3877 3878 3879void print_menu(WINDOW *menu_win, int highlight) 3880{ 3881 int x, y, i; 3882 3883 x = 2; 3884 y = 2; 3885 box(menu_win, 0, 0); 3886 for(i = 0; i < n_choices; ++i) 3887 { if(highlight == i + 1) 3888 { wattron(menu_win, A_REVERSE); 3889 mvwprintw(menu_win, y, x, "%s", choices[i]); 3890 wattroff(menu_win, A_REVERSE); 3891 } 3892 else 3893 mvwprintw(menu_win, y, x, "%s", choices[i]); 3894 ++y; 3895 } 3896 wrefresh(menu_win); 3897} 3898 3899/* Report the choice according to mouse position */ 3900void report_choice(int mouse_x, int mouse_y, int *p_choice) 3901{ int i,j, choice; 3902 3903 i = startx + 2; 3904 j = starty + 3; 3905 3906 for(choice = 0; choice < n_choices; ++choice) 3907 if(mouse_y == j + choice && mouse_x >= i && mouse_x <= i + strlen(choices[choice])) 3908 { if(choice == n_choices - 1) 3909 *p_choice = -1; 3910 else 3911 *p_choice = choice + 1; 3912 break; 3913 } 3914}</SPAN 3915></PRE 3916></DIV 3917></DIV 3918><DIV 3919CLASS="SECT2" 3920><HR><H3 3921CLASS="SECT2" 3922><A 3923NAME="MISCMOUSEFUNCS" 3924>12.4. Miscellaneous Functions</A 3925></H3 3926><P 3927>The functions mouse_trafo() and wmouse_trafo() can be used to convert to mouse 3928co-ordinates to screen relative co-ordinates. See curs_mouse(3X) man page for details.</P 3929><P 3930>The mouseinterval function sets the maximum time (in thousands of a 3931second) that can elapse between press and release events in order for 3932them to be recognized as a click. This function returns the previous 3933interval value. The default is one fifth of a second.</P 3934></DIV 3935></DIV 3936><DIV 3937CLASS="SECT1" 3938><HR><H2 3939CLASS="SECT1" 3940><A 3941NAME="SCREEN" 3942>13. Screen Manipulation</A 3943></H2 3944><P 3945>In this section, we will look into some functions, which allow us to manage the 3946screen efficiently and to write some fancy programs. This is especially 3947important in writing games. </P 3948><DIV 3949CLASS="SECT2" 3950><HR><H3 3951CLASS="SECT2" 3952><A 3953NAME="GETYX" 3954>13.1. getyx() functions</A 3955></H3 3956><P 3957> The function <TT 3958CLASS="LITERAL" 3959>getyx()</TT 3960> can be used to find out 3961the present cursor co-ordinates. It will fill the values of x and y co-ordinates 3962in the arguments given to it. Since getyx() is a macro you don't have to pass 3963the address of the variables. It can be called as</P 3964><PRE 3965CLASS="PROGRAMLISTING" 3966> getyx(win, y, x); 3967 /* win: window pointer 3968 * y, x: y, x co-ordinates will be put into this variables 3969 */</PRE 3970><P 3971>The function getparyx() gets the beginning co-ordinates of the sub window 3972relative to the main window. This is some times useful to update a sub window. 3973When designing fancy stuff like writing multiple menus, it becomes difficult to 3974store the menu positions, their first option co-ordinates etc. A simple solution 3975to this problem, is to create menus in sub windows and later find the starting 3976co-ordinates of the menus by using getparyx().</P 3977><P 3978>The functions getbegyx() and getmaxyx() store current window's beginning and 3979maximum co-ordinates. These functions are useful in the same way as above in 3980managing the windows and sub windows effectively.</P 3981></DIV 3982><DIV 3983CLASS="SECT2" 3984><HR><H3 3985CLASS="SECT2" 3986><A 3987NAME="SCREENDUMP" 3988>13.2. Screen Dumping</A 3989></H3 3990><P 3991>While writing games, some times it becomes necessary to store the state of the 3992screen and restore it back to the same state. The function scr_dump() can be 3993used to dump the screen contents to a file given as an argument. Later it can be 3994restored by scr_restore function. These two simple functions can be used 3995effectively to maintain a fast moving game with changing scenarios. </P 3996></DIV 3997><DIV 3998CLASS="SECT2" 3999><HR><H3 4000CLASS="SECT2" 4001><A 4002NAME="WINDOWDUMP" 4003>13.3. Window Dumping</A 4004></H3 4005><P 4006>To store and restore windows, the functions 4007<TT 4008CLASS="LITERAL" 4009>putwin()</TT 4010> and <TT 4011CLASS="LITERAL" 4012>getwin()</TT 4013> can be used. <TT 4014CLASS="LITERAL" 4015>putwin()</TT 4016> puts 4017the present window state into a file, which can be later restored by 4018<TT 4019CLASS="LITERAL" 4020>getwin()</TT 4021>.</P 4022><P 4023> 4024The function <TT 4025CLASS="LITERAL" 4026>copywin()</TT 4027> can be used to copy a 4028window completely onto another window. It takes the source and destination 4029windows as parameters and according to the rectangle specified, it copies the 4030rectangular region from source to destination window. It's last parameter 4031specifies whether to overwrite or just overlay the contents on to the 4032destination window. If this argument is true, then the copying is 4033non-destructive.</P 4034></DIV 4035></DIV 4036><DIV 4037CLASS="SECT1" 4038><HR><H2 4039CLASS="SECT1" 4040><A 4041NAME="MISC" 4042>14. Miscellaneous features</A 4043></H2 4044><P 4045>Now you know enough features to write a good curses program, with all bells and 4046whistles. There are some miscellaneous functions which are useful in various 4047cases. Let's go headlong into some of those.</P 4048><DIV 4049CLASS="SECT2" 4050><HR><H3 4051CLASS="SECT2" 4052><A 4053NAME="CURSSET" 4054>14.1. curs_set()</A 4055></H3 4056><P 4057>This function can be used to make the cursor invisible. The parameter to this 4058function should be </P 4059><PRE 4060CLASS="PROGRAMLISTING" 4061> 0 : invisible or 4062 1 : normal or 4063 2 : very visible.</PRE 4064></DIV 4065><DIV 4066CLASS="SECT2" 4067><HR><H3 4068CLASS="SECT2" 4069><A 4070NAME="TEMPLEAVE" 4071>14.2. Temporarily Leaving Curses mode</A 4072></H3 4073><P 4074>Some times you may want to get back to cooked mode (normal line buffering mode) 4075temporarily. In such a case you will first need to save the tty modes with a 4076call to <TT 4077CLASS="LITERAL" 4078>def_prog_mode()</TT 4079> and then call 4080<TT 4081CLASS="LITERAL" 4082>endwin()</TT 4083> to end the curses mode. This will 4084leave you in the original tty mode. To get back to curses once you are done, 4085call <TT 4086CLASS="LITERAL" 4087>reset_prog_mode() </TT 4088>. This function returns 4089the tty to the state stored by <TT 4090CLASS="LITERAL" 4091>def_prog_mode()</TT 4092>. Then do refresh(), and you are back to the curses mode. Here 4093is an example showing the sequence of things to be done.</P 4094><DIV 4095CLASS="EXAMPLE" 4096><A 4097NAME="BTELE" 4098></A 4099><P 4100><B 4101>Example 12. Temporarily Leaving Curses Mode </B 4102></P 4103><PRE 4104CLASS="PROGRAMLISTING" 4105><SPAN 4106CLASS="INLINEMEDIAOBJECT" 4107>#include <ncurses.h> 4108 4109int main() 4110{ 4111 initscr(); /* Start curses mode */ 4112 printw("Hello World !!!\n"); /* Print Hello World */ 4113 refresh(); /* Print it on to the real screen */ 4114 def_prog_mode(); /* Save the tty modes */ 4115 endwin(); /* End curses mode temporarily */ 4116 system("/bin/sh"); /* Do whatever you like in cooked mode */ 4117 reset_prog_mode(); /* Return to the previous tty mode*/ 4118 /* stored by def_prog_mode() */ 4119 refresh(); /* Do refresh() to restore the */ 4120 /* Screen contents */ 4121 printw("Another String\n"); /* Back to curses use the full */ 4122 refresh(); /* capabilities of curses */ 4123 endwin(); /* End curses mode */ 4124 4125 return 0; 4126}</SPAN 4127></PRE 4128></DIV 4129></DIV 4130><DIV 4131CLASS="SECT2" 4132><HR><H3 4133CLASS="SECT2" 4134><A 4135NAME="ACSVARS" 4136>14.3. ACS_ variables</A 4137></H3 4138><P 4139>If you have ever programmed in DOS, you know about those nifty characters in 4140extended character set. They are printable only on some terminals. NCURSES 4141functions like <TT 4142CLASS="LITERAL" 4143>box()</TT 4144> use these characters. All 4145these variables start with ACS meaning alternative character set. You might have 4146noticed me using these characters in some of the programs above. Here's an example 4147showing all the characters.</P 4148><DIV 4149CLASS="EXAMPLE" 4150><A 4151NAME="BACSVARS" 4152></A 4153><P 4154><B 4155>Example 13. ACS Variables Example </B 4156></P 4157><PRE 4158CLASS="PROGRAMLISTING" 4159><SPAN 4160CLASS="INLINEMEDIAOBJECT" 4161>#include <ncurses.h> 4162 4163int main() 4164{ 4165 initscr(); 4166 4167 printw("Upper left corner "); addch(ACS_ULCORNER); printw("\n"); 4168 printw("Lower left corner "); addch(ACS_LLCORNER); printw("\n"); 4169 printw("Lower right corner "); addch(ACS_LRCORNER); printw("\n"); 4170 printw("Tee pointing right "); addch(ACS_LTEE); printw("\n"); 4171 printw("Tee pointing left "); addch(ACS_RTEE); printw("\n"); 4172 printw("Tee pointing up "); addch(ACS_BTEE); printw("\n"); 4173 printw("Tee pointing down "); addch(ACS_TTEE); printw("\n"); 4174 printw("Horizontal line "); addch(ACS_HLINE); printw("\n"); 4175 printw("Vertical line "); addch(ACS_VLINE); printw("\n"); 4176 printw("Large Plus or cross over "); addch(ACS_PLUS); printw("\n"); 4177 printw("Scan Line 1 "); addch(ACS_S1); printw("\n"); 4178 printw("Scan Line 3 "); addch(ACS_S3); printw("\n"); 4179 printw("Scan Line 7 "); addch(ACS_S7); printw("\n"); 4180 printw("Scan Line 9 "); addch(ACS_S9); printw("\n"); 4181 printw("Diamond "); addch(ACS_DIAMOND); printw("\n"); 4182 printw("Checker board (stipple) "); addch(ACS_CKBOARD); printw("\n"); 4183 printw("Degree Symbol "); addch(ACS_DEGREE); printw("\n"); 4184 printw("Plus/Minus Symbol "); addch(ACS_PLMINUS); printw("\n"); 4185 printw("Bullet "); addch(ACS_BULLET); printw("\n"); 4186 printw("Arrow Pointing Left "); addch(ACS_LARROW); printw("\n"); 4187 printw("Arrow Pointing Right "); addch(ACS_RARROW); printw("\n"); 4188 printw("Arrow Pointing Down "); addch(ACS_DARROW); printw("\n"); 4189 printw("Arrow Pointing Up "); addch(ACS_UARROW); printw("\n"); 4190 printw("Board of squares "); addch(ACS_BOARD); printw("\n"); 4191 printw("Lantern Symbol "); addch(ACS_LANTERN); printw("\n"); 4192 printw("Solid Square Block "); addch(ACS_BLOCK); printw("\n"); 4193 printw("Less/Equal sign "); addch(ACS_LEQUAL); printw("\n"); 4194 printw("Greater/Equal sign "); addch(ACS_GEQUAL); printw("\n"); 4195 printw("Pi "); addch(ACS_PI); printw("\n"); 4196 printw("Not equal "); addch(ACS_NEQUAL); printw("\n"); 4197 printw("UK pound sign "); addch(ACS_STERLING); printw("\n"); 4198 4199 refresh(); 4200 getch(); 4201 endwin(); 4202 4203 return 0; 4204}</SPAN 4205></PRE 4206></DIV 4207></DIV 4208></DIV 4209><DIV 4210CLASS="SECT1" 4211><HR><H2 4212CLASS="SECT1" 4213><A 4214NAME="OTHERLIB" 4215>15. Other libraries</A 4216></H2 4217><P 4218>Apart from the curses library, there are few text mode libraries, which provide 4219more functionality and a lot of features. The following sections explain three 4220standard libraries which are usually distributed along with curses. </P 4221></DIV 4222><DIV 4223CLASS="SECT1" 4224><HR><H2 4225CLASS="SECT1" 4226><A 4227NAME="PANELS" 4228>16. Panel Library</A 4229></H2 4230><P 4231>Now that you are proficient in curses, you wanted to do some thing big. You 4232created a lot of overlapping windows to give a professional windows-type look. 4233Unfortunately, it soon becomes difficult to manage these. The multiple 4234refreshes, updates plunge you into a nightmare. The overlapping windows create 4235blotches, whenever you forget to refresh the windows in the proper order. </P 4236><P 4237>Don't despair. There's an elegant solution provided in panels library. In the 4238words of developers of ncurses </P 4239><P 4240><SPAN 4241CLASS="emphasis" 4242><I 4243CLASS="EMPHASIS" 4244>When your interface design is such that windows may dive deeper into the 4245visibility stack or pop to the top at runtime, the resulting book-keeping can be 4246tedious and difficult to get right. Hence the panels library.</I 4247></SPAN 4248></P 4249><P 4250>If you have lot of overlapping windows, then panels library is the way to go. It 4251obviates the need of doing series of wnoutrefresh(), doupdate() and relieves the 4252burden of doing it correctly(bottom up). The library maintains information about 4253the order of windows, their overlapping and update the screen properly. So why 4254wait? Let's take a close peek into panels.</P 4255><DIV 4256CLASS="SECT2" 4257><HR><H3 4258CLASS="SECT2" 4259><A 4260NAME="PANELBASICS" 4261>16.1. The Basics</A 4262></H3 4263><P 4264>Panel object is a window that is implicitly treated as part of a deck including 4265all other panel objects. The deck is treated as a stack with the top panel being 4266completely visible and the other panels may or may not be obscured according to 4267their positions. So the basic idea is to create a stack of overlapping panels 4268and use panels library to display them correctly. There is a function similar to 4269refresh() which, when called , displays panels in the correct order. Functions 4270are provided to hide or show panels, move panels, change its size etc.. The 4271overlapping problem is managed by the panels library during all the calls to 4272these functions. </P 4273><P 4274>The general flow of a panel program goes like this: 4275 4276<P 4277></P 4278><OL 4279TYPE="1" 4280><LI 4281><P 4282>Create the windows (with newwin()) to be attached to the panels.</P 4283></LI 4284><LI 4285><P 4286>Create panels with the chosen visibility order. Stack them up according to the 4287desired visibility. The function new_panel() is used to created panels.</P 4288></LI 4289><LI 4290><P 4291>Call update_panels() to write the panels to the virtual screen in correct 4292visibility order. Do a doupdate() to show it on the screen. </P 4293></LI 4294><LI 4295><P 4296>Mainpulate the panels with show_panel(), hide_panel(), move_panel() etc. Make 4297use of helper functions like panel_hidden() and panel_window(). Make use of user 4298pointer to store custom data for a panel. Use the functions set_panel_userptr() 4299and panel_userptr() to set and get the user pointer for a panel.</P 4300></LI 4301><LI 4302><P 4303>When you are done with the panel use del_panel() to delete the panel.</P 4304></LI 4305></OL 4306></P 4307><P 4308>Let's make the concepts clear, with some programs. The following is a simple 4309program which creates 3 overlapping panels and shows them on the screen. </P 4310></DIV 4311><DIV 4312CLASS="SECT2" 4313><HR><H3 4314CLASS="SECT2" 4315><A 4316NAME="COMPILEPANELS" 4317>16.2. Compiling With the Panels Library</A 4318></H3 4319><P 4320>To use panels library functions, you have to include panel.h and to link the 4321program with panels library the flag -lpanel should be added along with 4322-lncurses in that order.</P 4323><PRE 4324CLASS="PROGRAMLISTING" 4325> #include <panel.h> 4326 . 4327 . 4328 . 4329 4330 compile and link: gcc <program file> -lpanel -lncurses</PRE 4331><DIV 4332CLASS="EXAMPLE" 4333><A 4334NAME="PPASI" 4335></A 4336><P 4337><B 4338>Example 14. Panel basics</B 4339></P 4340><PRE 4341CLASS="PROGRAMLISTING" 4342><SPAN 4343CLASS="INLINEMEDIAOBJECT" 4344>#include <panel.h> 4345 4346int main() 4347{ WINDOW *my_wins[3]; 4348 PANEL *my_panels[3]; 4349 int lines = 10, cols = 40, y = 2, x = 4, i; 4350 4351 initscr(); 4352 cbreak(); 4353 noecho(); 4354 4355 /* Create windows for the panels */ 4356 my_wins[0] = newwin(lines, cols, y, x); 4357 my_wins[1] = newwin(lines, cols, y + 1, x + 5); 4358 my_wins[2] = newwin(lines, cols, y + 2, x + 10); 4359 4360 /* 4361 * Create borders around the windows so that you can see the effect 4362 * of panels 4363 */ 4364 for(i = 0; i < 3; ++i) 4365 box(my_wins[i], 0, 0); 4366 4367 /* Attach a panel to each window */ /* Order is bottom up */ 4368 my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */ 4369 my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */ 4370 my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */ 4371 4372 /* Update the stacking order. 2nd panel will be on top */ 4373 update_panels(); 4374 4375 /* Show it on the screen */ 4376 doupdate(); 4377 4378 getch(); 4379 endwin(); 4380} 4381</SPAN 4382></PRE 4383></DIV 4384><P 4385>As you can see, above program follows a simple flow as explained. The windows 4386are created with newwin() and then they are attached to panels with new_panel(). 4387As we attach one panel after another, the stack of panels gets updated. To put 4388them on screen update_panels() and doupdate() are called.</P 4389></DIV 4390><DIV 4391CLASS="SECT2" 4392><HR><H3 4393CLASS="SECT2" 4394><A 4395NAME="PANELBROWSING" 4396>16.3. Panel Window Browsing</A 4397></H3 4398><P 4399>A slightly complicated example is given below. This program creates 3 4400windows which can be cycled through using tab. Have a look at the code.</P 4401><DIV 4402CLASS="EXAMPLE" 4403><A 4404NAME="PPABR" 4405></A 4406><P 4407><B 4408>Example 15. Panel Window Browsing Example </B 4409></P 4410><PRE 4411CLASS="PROGRAMLISTING" 4412><SPAN 4413CLASS="INLINEMEDIAOBJECT" 4414>#include <panel.h> 4415 4416#define NLINES 10 4417#define NCOLS 40 4418 4419void init_wins(WINDOW **wins, int n); 4420void win_show(WINDOW *win, char *label, int label_color); 4421void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color); 4422 4423int main() 4424{ WINDOW *my_wins[3]; 4425 PANEL *my_panels[3]; 4426 PANEL *top; 4427 int ch; 4428 4429 /* Initialize curses */ 4430 initscr(); 4431 start_color(); 4432 cbreak(); 4433 noecho(); 4434 keypad(stdscr, TRUE); 4435 4436 /* Initialize all the colors */ 4437 init_pair(1, COLOR_RED, COLOR_BLACK); 4438 init_pair(2, COLOR_GREEN, COLOR_BLACK); 4439 init_pair(3, COLOR_BLUE, COLOR_BLACK); 4440 init_pair(4, COLOR_CYAN, COLOR_BLACK); 4441 4442 init_wins(my_wins, 3); 4443 4444 /* Attach a panel to each window */ /* Order is bottom up */ 4445 my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */ 4446 my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */ 4447 my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */ 4448 4449 /* Set up the user pointers to the next panel */ 4450 set_panel_userptr(my_panels[0], my_panels[1]); 4451 set_panel_userptr(my_panels[1], my_panels[2]); 4452 set_panel_userptr(my_panels[2], my_panels[0]); 4453 4454 /* Update the stacking order. 2nd panel will be on top */ 4455 update_panels(); 4456 4457 /* Show it on the screen */ 4458 attron(COLOR_PAIR(4)); 4459 mvprintw(LINES - 2, 0, "Use tab to browse through the windows (F1 to Exit)"); 4460 attroff(COLOR_PAIR(4)); 4461 doupdate(); 4462 4463 top = my_panels[2]; 4464 while((ch = getch()) != KEY_F(1)) 4465 { switch(ch) 4466 { case 9: 4467 top = (PANEL *)panel_userptr(top); 4468 top_panel(top); 4469 break; 4470 } 4471 update_panels(); 4472 doupdate(); 4473 } 4474 endwin(); 4475 return 0; 4476} 4477 4478/* Put all the windows */ 4479void init_wins(WINDOW **wins, int n) 4480{ int x, y, i; 4481 char label[80]; 4482 4483 y = 2; 4484 x = 10; 4485 for(i = 0; i < n; ++i) 4486 { wins[i] = newwin(NLINES, NCOLS, y, x); 4487 sprintf(label, "Window Number %d", i + 1); 4488 win_show(wins[i], label, i + 1); 4489 y += 3; 4490 x += 7; 4491 } 4492} 4493 4494/* Show the window with a border and a label */ 4495void win_show(WINDOW *win, char *label, int label_color) 4496{ int startx, starty, height, width; 4497 4498 getbegyx(win, starty, startx); 4499 getmaxyx(win, height, width); 4500 4501 box(win, 0, 0); 4502 mvwaddch(win, 2, 0, ACS_LTEE); 4503 mvwhline(win, 2, 1, ACS_HLINE, width - 2); 4504 mvwaddch(win, 2, width - 1, ACS_RTEE); 4505 4506 print_in_middle(win, 1, 0, width, label, COLOR_PAIR(label_color)); 4507} 4508 4509void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color) 4510{ int length, x, y; 4511 float temp; 4512 4513 if(win == NULL) 4514 win = stdscr; 4515 getyx(win, y, x); 4516 if(startx != 0) 4517 x = startx; 4518 if(starty != 0) 4519 y = starty; 4520 if(width == 0) 4521 width = 80; 4522 4523 length = strlen(string); 4524 temp = (width - length)/ 2; 4525 x = startx + (int)temp; 4526 wattron(win, color); 4527 mvwprintw(win, y, x, "%s", string); 4528 wattroff(win, color); 4529 refresh(); 4530}</SPAN 4531></PRE 4532></DIV 4533></DIV 4534><DIV 4535CLASS="SECT2" 4536><HR><H3 4537CLASS="SECT2" 4538><A 4539NAME="USERPTRUSING" 4540>16.4. Using User Pointers</A 4541></H3 4542><P 4543>In the above example I used user pointers to find out the next window in the 4544cycle. We can attach custom information to the panel by specifying a user 4545pointer, which can point to any information you want to store. In this case I 4546stored the pointer to the next panel in the cycle. User pointer for a panel can 4547be set with the function <TT 4548CLASS="LITERAL" 4549> set_panel_userptr()</TT 4550>. 4551It can be accessed using the function <TT 4552CLASS="LITERAL" 4553>panel_userptr()</TT 4554> which will return the user pointer for the panel given as 4555argument. After finding the next panel in the cycle It's brought to the top by 4556the function top_panel(). This function brings the panel given as argument to 4557the top of the panel stack. </P 4558></DIV 4559><DIV 4560CLASS="SECT2" 4561><HR><H3 4562CLASS="SECT2" 4563><A 4564NAME="PANELMOVERESIZE" 4565>16.5. Moving and Resizing Panels</A 4566></H3 4567><P 4568>The function <TT 4569CLASS="LITERAL" 4570>move_panel()</TT 4571> can be used to move a 4572panel to the desired location. It does not change the position of the panel in 4573the stack. Make sure that you use move_panel() instead mvwin() on the window 4574associated with the panel.</P 4575><P 4576>Resizing a panel is slightly complex. There is no straight forward function 4577just to resize the window associated with a panel. A solution to resize a panel 4578is to create a new window with the desired sizes, change the window associated 4579with the panel using replace_panel(). Don't forget to delete the old window. The 4580window associated with a panel can be found by using the function 4581panel_window().</P 4582><P 4583>The following program shows these concepts, in supposedly simple program. You 4584can cycle through the window with <TAB> as usual. To resize or move the 4585active panel press 'r' for resize 'm' for moving. Then use arrow keys to resize 4586or move it to the desired way and press enter to end your resizing or moving. 4587This example makes use of user data to get the required data to do the 4588operations. </P 4589><DIV 4590CLASS="EXAMPLE" 4591><A 4592NAME="PPARE" 4593></A 4594><P 4595><B 4596>Example 16. Panel Moving and Resizing example </B 4597></P 4598><PRE 4599CLASS="PROGRAMLISTING" 4600><SPAN 4601CLASS="INLINEMEDIAOBJECT" 4602>#include <panel.h> 4603 4604typedef struct _PANEL_DATA { 4605 int x, y, w, h; 4606 char label[80]; 4607 int label_color; 4608 PANEL *next; 4609}PANEL_DATA; 4610 4611#define NLINES 10 4612#define NCOLS 40 4613 4614void init_wins(WINDOW **wins, int n); 4615void win_show(WINDOW *win, char *label, int label_color); 4616void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color); 4617void set_user_ptrs(PANEL **panels, int n); 4618 4619int main() 4620{ WINDOW *my_wins[3]; 4621 PANEL *my_panels[3]; 4622 PANEL_DATA *top; 4623 PANEL *stack_top; 4624 WINDOW *temp_win, *old_win; 4625 int ch; 4626 int newx, newy, neww, newh; 4627 int size = FALSE, move = FALSE; 4628 4629 /* Initialize curses */ 4630 initscr(); 4631 start_color(); 4632 cbreak(); 4633 noecho(); 4634 keypad(stdscr, TRUE); 4635 4636 /* Initialize all the colors */ 4637 init_pair(1, COLOR_RED, COLOR_BLACK); 4638 init_pair(2, COLOR_GREEN, COLOR_BLACK); 4639 init_pair(3, COLOR_BLUE, COLOR_BLACK); 4640 init_pair(4, COLOR_CYAN, COLOR_BLACK); 4641 4642 init_wins(my_wins, 3); 4643 4644 /* Attach a panel to each window */ /* Order is bottom up */ 4645 my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */ 4646 my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */ 4647 my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */ 4648 4649 set_user_ptrs(my_panels, 3); 4650 /* Update the stacking order. 2nd panel will be on top */ 4651 update_panels(); 4652 4653 /* Show it on the screen */ 4654 attron(COLOR_PAIR(4)); 4655 mvprintw(LINES - 3, 0, "Use 'm' for moving, 'r' for resizing"); 4656 mvprintw(LINES - 2, 0, "Use tab to browse through the windows (F1 to Exit)"); 4657 attroff(COLOR_PAIR(4)); 4658 doupdate(); 4659 4660 stack_top = my_panels[2]; 4661 top = (PANEL_DATA *)panel_userptr(stack_top); 4662 newx = top->x; 4663 newy = top->y; 4664 neww = top->w; 4665 newh = top->h; 4666 while((ch = getch()) != KEY_F(1)) 4667 { switch(ch) 4668 { case 9: /* Tab */ 4669 top = (PANEL_DATA *)panel_userptr(stack_top); 4670 top_panel(top->next); 4671 stack_top = top->next; 4672 top = (PANEL_DATA *)panel_userptr(stack_top); 4673 newx = top->x; 4674 newy = top->y; 4675 neww = top->w; 4676 newh = top->h; 4677 break; 4678 case 'r': /* Re-Size*/ 4679 size = TRUE; 4680 attron(COLOR_PAIR(4)); 4681 mvprintw(LINES - 4, 0, "Entered Resizing :Use Arrow Keys to resize and press <ENTER> to end resizing"); 4682 refresh(); 4683 attroff(COLOR_PAIR(4)); 4684 break; 4685 case 'm': /* Move */ 4686 attron(COLOR_PAIR(4)); 4687 mvprintw(LINES - 4, 0, "Entered Moving: Use Arrow Keys to Move and press <ENTER> to end moving"); 4688 refresh(); 4689 attroff(COLOR_PAIR(4)); 4690 move = TRUE; 4691 break; 4692 case KEY_LEFT: 4693 if(size == TRUE) 4694 { --newx; 4695 ++neww; 4696 } 4697 if(move == TRUE) 4698 --newx; 4699 break; 4700 case KEY_RIGHT: 4701 if(size == TRUE) 4702 { ++newx; 4703 --neww; 4704 } 4705 if(move == TRUE) 4706 ++newx; 4707 break; 4708 case KEY_UP: 4709 if(size == TRUE) 4710 { --newy; 4711 ++newh; 4712 } 4713 if(move == TRUE) 4714 --newy; 4715 break; 4716 case KEY_DOWN: 4717 if(size == TRUE) 4718 { ++newy; 4719 --newh; 4720 } 4721 if(move == TRUE) 4722 ++newy; 4723 break; 4724 case 10: /* Enter */ 4725 move(LINES - 4, 0); 4726 clrtoeol(); 4727 refresh(); 4728 if(size == TRUE) 4729 { old_win = panel_window(stack_top); 4730 temp_win = newwin(newh, neww, newy, newx); 4731 replace_panel(stack_top, temp_win); 4732 win_show(temp_win, top->label, top->label_color); 4733 delwin(old_win); 4734 size = FALSE; 4735 } 4736 if(move == TRUE) 4737 { move_panel(stack_top, newy, newx); 4738 move = FALSE; 4739 } 4740 break; 4741 4742 } 4743 attron(COLOR_PAIR(4)); 4744 mvprintw(LINES - 3, 0, "Use 'm' for moving, 'r' for resizing"); 4745 mvprintw(LINES - 2, 0, "Use tab to browse through the windows (F1 to Exit)"); 4746 attroff(COLOR_PAIR(4)); 4747 refresh(); 4748 update_panels(); 4749 doupdate(); 4750 } 4751 endwin(); 4752 return 0; 4753} 4754 4755/* Put all the windows */ 4756void init_wins(WINDOW **wins, int n) 4757{ int x, y, i; 4758 char label[80]; 4759 4760 y = 2; 4761 x = 10; 4762 for(i = 0; i < n; ++i) 4763 { wins[i] = newwin(NLINES, NCOLS, y, x); 4764 sprintf(label, "Window Number %d", i + 1); 4765 win_show(wins[i], label, i + 1); 4766 y += 3; 4767 x += 7; 4768 } 4769} 4770 4771/* Set the PANEL_DATA structures for individual panels */ 4772void set_user_ptrs(PANEL **panels, int n) 4773{ PANEL_DATA *ptrs; 4774 WINDOW *win; 4775 int x, y, w, h, i; 4776 char temp[80]; 4777 4778 ptrs = (PANEL_DATA *)calloc(n, sizeof(PANEL_DATA)); 4779 4780 for(i = 0;i < n; ++i) 4781 { win = panel_window(panels[i]); 4782 getbegyx(win, y, x); 4783 getmaxyx(win, h, w); 4784 ptrs[i].x = x; 4785 ptrs[i].y = y; 4786 ptrs[i].w = w; 4787 ptrs[i].h = h; 4788 sprintf(temp, "Window Number %d", i + 1); 4789 strcpy(ptrs[i].label, temp); 4790 ptrs[i].label_color = i + 1; 4791 if(i + 1 == n) 4792 ptrs[i].next = panels[0]; 4793 else 4794 ptrs[i].next = panels[i + 1]; 4795 set_panel_userptr(panels[i], &ptrs[i]); 4796 } 4797} 4798 4799/* Show the window with a border and a label */ 4800void win_show(WINDOW *win, char *label, int label_color) 4801{ int startx, starty, height, width; 4802 4803 getbegyx(win, starty, startx); 4804 getmaxyx(win, height, width); 4805 4806 box(win, 0, 0); 4807 mvwaddch(win, 2, 0, ACS_LTEE); 4808 mvwhline(win, 2, 1, ACS_HLINE, width - 2); 4809 mvwaddch(win, 2, width - 1, ACS_RTEE); 4810 4811 print_in_middle(win, 1, 0, width, label, COLOR_PAIR(label_color)); 4812} 4813 4814void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color) 4815{ int length, x, y; 4816 float temp; 4817 4818 if(win == NULL) 4819 win = stdscr; 4820 getyx(win, y, x); 4821 if(startx != 0) 4822 x = startx; 4823 if(starty != 0) 4824 y = starty; 4825 if(width == 0) 4826 width = 80; 4827 4828 length = strlen(string); 4829 temp = (width - length)/ 2; 4830 x = startx + (int)temp; 4831 wattron(win, color); 4832 mvwprintw(win, y, x, "%s", string); 4833 wattroff(win, color); 4834 refresh(); 4835}</SPAN 4836></PRE 4837></DIV 4838><P 4839>Concentrate on the main while loop. Once it finds out the type of key pressed, 4840it takes appropriate action. If 'r' is pressed resizing mode is started. After 4841this the new sizes are updated as the user presses the arrow keys. When the user 4842presses <ENTER> present selection ends and panel is resized by using the 4843concept explained. While in resizing mode the program doesn't show how the 4844window is getting resized. It's left as an exercise to the reader to print a 4845dotted border while it gets resized to a new position. </P 4846><P 4847>When the user presses 'm' the move mode starts. This is a bit simpler than 4848resizing. As the arrow keys are pressed the new position is updated and 4849pressing of <ENTER> causes the panel to be moved by calling the function 4850move_panel().</P 4851><P 4852>In this program the user data which is represented as PANEL_DATA, plays very 4853important role in finding the associated information with a panel. As written in 4854the comments, the PANEL_DATA stores the panel sizes, label, label color and a 4855pointer to the next panel in the cycle.</P 4856></DIV 4857><DIV 4858CLASS="SECT2" 4859><HR><H3 4860CLASS="SECT2" 4861><A 4862NAME="PANELSHOWHIDE" 4863>16.6. Hiding and Showing Panels</A 4864></H3 4865><P 4866>A Panel can be hidden by using the function hide_panel(). This function merely 4867removes it form the stack of panels, thus hiding it on the screen once you do 4868update_panels() and doupdate(). It doesn't destroy the PANEL structure 4869associated with the hidden panel. It can be shown again by using the 4870show_panel() function.</P 4871><P 4872>The following program shows the hiding of panels. Press 'a' or 'b' or 'c' to 4873show or hide first, second and third windows respectively. It uses a user data 4874with a small variable hide, which keeps track of whether the window is hidden or 4875not. For some reason the function 4876<TT 4877CLASS="LITERAL" 4878>panel_hidden()</TT 4879> which tells whether a panel is 4880hidden or not is not working. A bug report was also presented by Michael Andres 4881<A 4882HREF="http://www.geocrawler.com/archives/3/344/1999/9/0/2643549/" 4883TARGET="_top" 4884> here</A 4885></P 4886><DIV 4887CLASS="EXAMPLE" 4888><A 4889NAME="PPAHI" 4890></A 4891><P 4892><B 4893>Example 17. Panel Hiding and Showing example </B 4894></P 4895><PRE 4896CLASS="PROGRAMLISTING" 4897><SPAN 4898CLASS="INLINEMEDIAOBJECT" 4899>#include <panel.h> 4900 4901typedef struct _PANEL_DATA { 4902 int hide; /* TRUE if panel is hidden */ 4903}PANEL_DATA; 4904 4905#define NLINES 10 4906#define NCOLS 40 4907 4908void init_wins(WINDOW **wins, int n); 4909void win_show(WINDOW *win, char *label, int label_color); 4910void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color); 4911 4912int main() 4913{ WINDOW *my_wins[3]; 4914 PANEL *my_panels[3]; 4915 PANEL_DATA panel_datas[3]; 4916 PANEL_DATA *temp; 4917 int ch; 4918 4919 /* Initialize curses */ 4920 initscr(); 4921 start_color(); 4922 cbreak(); 4923 noecho(); 4924 keypad(stdscr, TRUE); 4925 4926 /* Initialize all the colors */ 4927 init_pair(1, COLOR_RED, COLOR_BLACK); 4928 init_pair(2, COLOR_GREEN, COLOR_BLACK); 4929 init_pair(3, COLOR_BLUE, COLOR_BLACK); 4930 init_pair(4, COLOR_CYAN, COLOR_BLACK); 4931 4932 init_wins(my_wins, 3); 4933 4934 /* Attach a panel to each window */ /* Order is bottom up */ 4935 my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */ 4936 my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */ 4937 my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */ 4938 4939 /* Initialize panel datas saying that nothing is hidden */ 4940 panel_datas[0].hide = FALSE; 4941 panel_datas[1].hide = FALSE; 4942 panel_datas[2].hide = FALSE; 4943 4944 set_panel_userptr(my_panels[0], &panel_datas[0]); 4945 set_panel_userptr(my_panels[1], &panel_datas[1]); 4946 set_panel_userptr(my_panels[2], &panel_datas[2]); 4947 4948 /* Update the stacking order. 2nd panel will be on top */ 4949 update_panels(); 4950 4951 /* Show it on the screen */ 4952 attron(COLOR_PAIR(4)); 4953 mvprintw(LINES - 3, 0, "Show or Hide a window with 'a'(first window) 'b'(Second Window) 'c'(Third Window)"); 4954 mvprintw(LINES - 2, 0, "F1 to Exit"); 4955 4956 attroff(COLOR_PAIR(4)); 4957 doupdate(); 4958 4959 while((ch = getch()) != KEY_F(1)) 4960 { switch(ch) 4961 { case 'a': 4962 temp = (PANEL_DATA *)panel_userptr(my_panels[0]); 4963 if(temp->hide == FALSE) 4964 { hide_panel(my_panels[0]); 4965 temp->hide = TRUE; 4966 } 4967 else 4968 { show_panel(my_panels[0]); 4969 temp->hide = FALSE; 4970 } 4971 break; 4972 case 'b': 4973 temp = (PANEL_DATA *)panel_userptr(my_panels[1]); 4974 if(temp->hide == FALSE) 4975 { hide_panel(my_panels[1]); 4976 temp->hide = TRUE; 4977 } 4978 else 4979 { show_panel(my_panels[1]); 4980 temp->hide = FALSE; 4981 } 4982 break; 4983 case 'c': 4984 temp = (PANEL_DATA *)panel_userptr(my_panels[2]); 4985 if(temp->hide == FALSE) 4986 { hide_panel(my_panels[2]); 4987 temp->hide = TRUE; 4988 } 4989 else 4990 { show_panel(my_panels[2]); 4991 temp->hide = FALSE; 4992 } 4993 break; 4994 } 4995 update_panels(); 4996 doupdate(); 4997 } 4998 endwin(); 4999 return 0; 5000} 5001 5002/* Put all the windows */ 5003void init_wins(WINDOW **wins, int n) 5004{ int x, y, i; 5005 char label[80]; 5006 5007 y = 2; 5008 x = 10; 5009 for(i = 0; i < n; ++i) 5010 { wins[i] = newwin(NLINES, NCOLS, y, x); 5011 sprintf(label, "Window Number %d", i + 1); 5012 win_show(wins[i], label, i + 1); 5013 y += 3; 5014 x += 7; 5015 } 5016} 5017 5018/* Show the window with a border and a label */ 5019void win_show(WINDOW *win, char *label, int label_color) 5020{ int startx, starty, height, width; 5021 5022 getbegyx(win, starty, startx); 5023 getmaxyx(win, height, width); 5024 5025 box(win, 0, 0); 5026 mvwaddch(win, 2, 0, ACS_LTEE); 5027 mvwhline(win, 2, 1, ACS_HLINE, width - 2); 5028 mvwaddch(win, 2, width - 1, ACS_RTEE); 5029 5030 print_in_middle(win, 1, 0, width, label, COLOR_PAIR(label_color)); 5031} 5032 5033void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color) 5034{ int length, x, y; 5035 float temp; 5036 5037 if(win == NULL) 5038 win = stdscr; 5039 getyx(win, y, x); 5040 if(startx != 0) 5041 x = startx; 5042 if(starty != 0) 5043 y = starty; 5044 if(width == 0) 5045 width = 80; 5046 5047 length = strlen(string); 5048 temp = (width - length)/ 2; 5049 x = startx + (int)temp; 5050 wattron(win, color); 5051 mvwprintw(win, y, x, "%s", string); 5052 wattroff(win, color); 5053 refresh(); 5054}</SPAN 5055></PRE 5056></DIV 5057></DIV 5058><DIV 5059CLASS="SECT2" 5060><HR><H3 5061CLASS="SECT2" 5062><A 5063NAME="PANELABOVE" 5064>16.7. panel_above() and panel_below() Functions</A 5065></H3 5066><P 5067>The functions <TT 5068CLASS="LITERAL" 5069>panel_above()</TT 5070> and 5071<TT 5072CLASS="LITERAL" 5073>panel_below()</TT 5074> can be used to find out the panel 5075above and below a panel. If the argument to these functions is NULL, then they 5076return a pointer to bottom panel and top panel respectively.</P 5077></DIV 5078></DIV 5079><DIV 5080CLASS="SECT1" 5081><HR><H2 5082CLASS="SECT1" 5083><A 5084NAME="MENUS" 5085>17. Menus Library</A 5086></H2 5087><P 5088>The menus library provides a nice extension to basic curses, through which you 5089can create menus. It provides a set of functions to create menus. But they have 5090to be customized to give a nicer look, with colors etc. Let's get into the 5091details.</P 5092><P 5093>A menu is a screen display that assists the user to choose some subset of a 5094given set of items. To put it simple, a menu is a collection of items from which 5095one or more items can be chosen. Some readers might not be aware of multiple 5096item selection capability. Menu library provides functionality to write menus 5097from which the user can chose more than one item as the preferred choice. This 5098is dealt with in a later section. Now it is time for some rudiments.</P 5099><DIV 5100CLASS="SECT2" 5101><HR><H3 5102CLASS="SECT2" 5103><A 5104NAME="MENUBASICS" 5105>17.1. The Basics</A 5106></H3 5107><P 5108>To create menus, you first create items, and then post the menu to the display. 5109After that, all the processing of user responses is done in an elegant function 5110menu_driver() which is the work horse of any menu program. </P 5111><P 5112>The general flow of control of a menu program looks like this. 5113<P 5114></P 5115><OL 5116TYPE="1" 5117><LI 5118><P 5119>Initialize curses</P 5120></LI 5121><LI 5122><P 5123>Create items using new_item(). You can specify a name and description for the 5124items.</P 5125></LI 5126><LI 5127><P 5128>Create the menu with new_menu() by specifying the items to be attached with.</P 5129></LI 5130><LI 5131><P 5132>Post the menu with menu_post() and refresh the screen.</P 5133></LI 5134><LI 5135><P 5136>Process the user requests with a loop and do necessary updates to menu with 5137menu_driver.</P 5138></LI 5139><LI 5140><P 5141>Unpost the menu with menu_unpost()</P 5142></LI 5143><LI 5144><P 5145>Free the memory allocated to menu by free_menu()</P 5146></LI 5147><LI 5148><P 5149>Free the memory allocated to the items with free_item() </P 5150></LI 5151><LI 5152><P 5153>End curses </P 5154></LI 5155></OL 5156></P 5157><P 5158>Let's see a program which prints a simple menu and updates the current selection 5159with up, down arrows. </P 5160></DIV 5161><DIV 5162CLASS="SECT2" 5163><HR><H3 5164CLASS="SECT2" 5165><A 5166NAME="COMPILEMENUS" 5167>17.2. Compiling With the Menu Library</A 5168></H3 5169><P 5170>To use menu library functions, you have to include menu.h and to link the 5171program with menu library the flag -lmenu should be added along with -lncurses 5172in that order.</P 5173><PRE 5174CLASS="PROGRAMLISTING" 5175> #include <menu.h> 5176 . 5177 . 5178 . 5179 5180 compile and link: gcc <program file> -lmenu -lncurses</PRE 5181><DIV 5182CLASS="EXAMPLE" 5183><A 5184NAME="MMESI" 5185></A 5186><P 5187><B 5188>Example 18. Menu Basics </B 5189></P 5190><PRE 5191CLASS="PROGRAMLISTING" 5192><SPAN 5193CLASS="INLINEMEDIAOBJECT" 5194>#include <curses.h> 5195#include <menu.h> 5196 5197#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0])) 5198#define CTRLD 4 5199 5200char *choices[] = { 5201 "Choice 1", 5202 "Choice 2", 5203 "Choice 3", 5204 "Choice 4", 5205 "Exit", 5206 }; 5207 5208int main() 5209{ ITEM **my_items; 5210 int c; 5211 MENU *my_menu; 5212 int n_choices, i; 5213 ITEM *cur_item; 5214 5215 5216 initscr(); 5217 cbreak(); 5218 noecho(); 5219 keypad(stdscr, TRUE); 5220 5221 n_choices = ARRAY_SIZE(choices); 5222 my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *)); 5223 5224 for(i = 0; i < n_choices; ++i) 5225 my_items[i] = new_item(choices[i], choices[i]); 5226 my_items[n_choices] = (ITEM *)NULL; 5227 5228 my_menu = new_menu((ITEM **)my_items); 5229 mvprintw(LINES - 2, 0, "F1 to Exit"); 5230 post_menu(my_menu); 5231 refresh(); 5232 5233 while((c = getch()) != KEY_F(1)) 5234 { switch(c) 5235 { case KEY_DOWN: 5236 menu_driver(my_menu, REQ_DOWN_ITEM); 5237 break; 5238 case KEY_UP: 5239 menu_driver(my_menu, REQ_UP_ITEM); 5240 break; 5241 } 5242 } 5243 5244 free_item(my_items[0]); 5245 free_item(my_items[1]); 5246 free_menu(my_menu); 5247 endwin(); 5248} 5249 </SPAN 5250></PRE 5251></DIV 5252><P 5253>This program demonstrates the basic concepts involved in creating a menu using 5254menus library. First we create the items using new_item() and then attach them 5255to the menu with new_menu() function. After posting the menu and refreshing the 5256screen, the main processing loop starts. It reads user input and takes 5257corresponding action. The function menu_driver() is the main work horse of the 5258menu system. The second parameter to this function tells what's to be done with 5259the menu. According to the parameter, menu_driver() does the corresponding task. 5260The value can be either a menu navigational request, an ascii character, or a 5261KEY_MOUSE special key associated with a mouse event.</P 5262><P 5263>The menu_driver accepts following navigational requests. 5264<PRE 5265CLASS="PROGRAMLISTING" 5266> REQ_LEFT_ITEM Move left to an item. 5267 REQ_RIGHT_ITEM Move right to an item. 5268 REQ_UP_ITEM Move up to an item. 5269 REQ_DOWN_ITEM Move down to an item. 5270 REQ_SCR_ULINE Scroll up a line. 5271 REQ_SCR_DLINE Scroll down a line. 5272 REQ_SCR_DPAGE Scroll down a page. 5273 REQ_SCR_UPAGE Scroll up a page. 5274 REQ_FIRST_ITEM Move to the first item. 5275 REQ_LAST_ITEM Move to the last item. 5276 REQ_NEXT_ITEM Move to the next item. 5277 REQ_PREV_ITEM Move to the previous item. 5278 REQ_TOGGLE_ITEM Select/deselect an item. 5279 REQ_CLEAR_PATTERN Clear the menu pattern buffer. 5280 REQ_BACK_PATTERN Delete the previous character from the pattern buffer. 5281 REQ_NEXT_MATCH Move to the next item matching the pattern match. 5282 REQ_PREV_MATCH Move to the previous item matching the pattern match. </PRE 5283></P 5284><P 5285>Don't get overwhelmed by the number of options. We will see them slowly one 5286after another. The options of interest in this example are REQ_UP_ITEM and 5287REQ_DOWN_ITEM. These two options when passed to menu_driver, menu driver 5288updates the current item to one item up or down respectively.</P 5289></DIV 5290><DIV 5291CLASS="SECT2" 5292><HR><H3 5293CLASS="SECT2" 5294><A 5295NAME="MENUDRIVER" 5296>17.3. Menu Driver: The work horse of the menu system</A 5297></H3 5298><P 5299>As you have seen in the above example, menu_driver plays an important role in 5300updating the menu. It is very important to understand various options it takes 5301and what they do. As explained above, the second parameter to menu_driver() can 5302be either a navigational request, a printable character or a KEY_MOUSE key. 5303Let's dissect the different navigational requests.</P 5304><P 5305></P 5306><UL 5307><LI 5308><P 5309><SPAN 5310CLASS="emphasis" 5311><I 5312CLASS="EMPHASIS" 5313>REQ_LEFT_ITEM and REQ_RIGHT_ITEM</I 5314></SPAN 5315></P 5316><P 5317>A Menu can be displayed with multiple columns for more than one item. This can 5318be done by using the <TT 5319CLASS="LITERAL" 5320>menu_format()</TT 5321>function. 5322When a multi columnar menu is displayed these requests cause the menu driver to 5323move the current selection to left or right.</P 5324></LI 5325><LI 5326><P 5327><SPAN 5328CLASS="emphasis" 5329><I 5330CLASS="EMPHASIS" 5331>REQ_UP_ITEM and REQ_DOWN_ITEM </I 5332></SPAN 5333> </P 5334><P 5335>These two options you have seen in the above example. These options when given, 5336makes the menu_driver to move the current selection to an item up or down.</P 5337></LI 5338><LI 5339><P 5340> <SPAN 5341CLASS="emphasis" 5342><I 5343CLASS="EMPHASIS" 5344>REQ_SCR_* options</I 5345></SPAN 5346> </P 5347><P 5348>The four options REQ_SCR_ULINE, REQ_SCR_DLINE, REQ_SCR_DPAGE, REQ_SCR_UPAGE are 5349related to scrolling. If all the items in the menu cannot be displayed in the 5350menu sub window, then the menu is scrollable. These requests can be given to the 5351menu_driver to do the scrolling either one line up, down or one page down or up 5352respectively. </P 5353></LI 5354><LI 5355><P 5356><SPAN 5357CLASS="emphasis" 5358><I 5359CLASS="EMPHASIS" 5360>REQ_FIRST_ITEM, REQ_LAST_ITEM, REQ_NEXT_ITEM and 5361REQ_PREV_ITEM </I 5362></SPAN 5363> </P 5364><P 5365>These requests are self explanatory.</P 5366></LI 5367><LI 5368><P 5369> <SPAN 5370CLASS="emphasis" 5371><I 5372CLASS="EMPHASIS" 5373>REQ_TOGGLE_ITEM</I 5374></SPAN 5375> </P 5376><P 5377>This request when given, toggles the present selection. This option is to be 5378used only in a multi valued menu. So to use this request the option O_ONEVALUE 5379must be off. This option can be made off or on with set_menu_opts().</P 5380></LI 5381><LI 5382><P 5383> <SPAN 5384CLASS="emphasis" 5385><I 5386CLASS="EMPHASIS" 5387>Pattern Requests </I 5388></SPAN 5389></P 5390><P 5391>Every menu has an associated pattern buffer, which is used to find the nearest 5392match to the ascii characters entered by the user. Whenever ascii characters are 5393given to menu_driver, it puts in to the pattern buffer. It also tries to find 5394the nearest match to the pattern in the items list and moves current selection 5395to that item. The request REQ_CLEAR_PATTERN clears the pattern buffer. The 5396request REQ_BACK_PATTERN deletes the previous character in the pattern buffer. 5397In case the pattern matches more than one item then the matched items can be 5398cycled through REQ_NEXT_MATCH and REQ_PREV_MATCH which move the current 5399selection to the next and previous matches respectively.</P 5400></LI 5401><LI 5402><P 5403> <SPAN 5404CLASS="emphasis" 5405><I 5406CLASS="EMPHASIS" 5407>Mouse Requests</I 5408></SPAN 5409></P 5410><P 5411>In case of KEY_MOUSE requests, according to the mouse position an action is 5412taken accordingly. The action to be taken is explained in the man page as, </P 5413><PRE 5414CLASS="PROGRAMLISTING" 5415><SPAN 5416CLASS="emphasis" 5417><I 5418CLASS="EMPHASIS" 5419> If the second argument is the KEY_MOUSE special key, the 5420 associated mouse event is translated into one of the above 5421 pre-defined requests. Currently only clicks in the user 5422 window (e.g. inside the menu display area or the decora­ 5423 tion window) are handled. If you click above the display 5424 region of the menu, a REQ_SCR_ULINE is generated, if you 5425 doubleclick a REQ_SCR_UPAGE is generated and if you 5426 tripleclick a REQ_FIRST_ITEM is generated. If you click 5427 below the display region of the menu, a REQ_SCR_DLINE is 5428 generated, if you doubleclick a REQ_SCR_DPAGE is generated 5429 and if you tripleclick a REQ_LAST_ITEM is generated. If 5430 you click at an item inside the display area of the menu, 5431 the menu cursor is positioned to that item.</I 5432></SPAN 5433></PRE 5434></LI 5435></UL 5436><P 5437>Each of the above requests will be explained in the following lines with several 5438examples whenever appropriate.</P 5439></DIV 5440><DIV 5441CLASS="SECT2" 5442><HR><H3 5443CLASS="SECT2" 5444><A 5445NAME="MENUWINDOWS" 5446>17.4. Menu Windows</A 5447></H3 5448><P 5449>Every menu created is associated with a window and a sub window. The menu window 5450displays any title or border associated with the menu. The menu sub window 5451displays the menu items currently available for selection. But we didn't specify 5452any window or sub window in the simple example. When a window is not specified, 5453stdscr is taken as the main window, and then menu system calculates the sub 5454window size required for the display of items. Then items are displayed in the 5455calculated sub window. So let's play with these windows and display a menu with 5456a border and a title.</P 5457><DIV 5458CLASS="EXAMPLE" 5459><A 5460NAME="MMEWI" 5461></A 5462><P 5463><B 5464>Example 19. Menu Windows Usage example </B 5465></P 5466><PRE 5467CLASS="PROGRAMLISTING" 5468><SPAN 5469CLASS="INLINEMEDIAOBJECT" 5470>#include <menu.h> 5471 5472#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0])) 5473#define CTRLD 4 5474 5475char *choices[] = { 5476 "Choice 1", 5477 "Choice 2", 5478 "Choice 3", 5479 "Choice 4", 5480 "Exit", 5481 (char *)NULL, 5482 }; 5483void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color); 5484 5485int main() 5486{ ITEM **my_items; 5487 int c; 5488 MENU *my_menu; 5489 WINDOW *my_menu_win; 5490 int n_choices, i; 5491 5492 /* Initialize curses */ 5493 initscr(); 5494 start_color(); 5495 cbreak(); 5496 noecho(); 5497 keypad(stdscr, TRUE); 5498 init_pair(1, COLOR_RED, COLOR_BLACK); 5499 5500 /* Create items */ 5501 n_choices = ARRAY_SIZE(choices); 5502 my_items = (ITEM **)calloc(n_choices, sizeof(ITEM *)); 5503 for(i = 0; i < n_choices; ++i) 5504 my_items[i] = new_item(choices[i], choices[i]); 5505 5506 /* Crate menu */ 5507 my_menu = new_menu((ITEM **)my_items); 5508 5509 /* Create the window to be associated with the menu */ 5510 my_menu_win = newwin(10, 40, 4, 4); 5511 keypad(my_menu_win, TRUE); 5512 5513 /* Set main window and sub window */ 5514 set_menu_win(my_menu, my_menu_win); 5515 set_menu_sub(my_menu, derwin(my_menu_win, 6, 38, 3, 1)); 5516 5517 /* Set menu mark to the string " * " */ 5518 set_menu_mark(my_menu, " * "); 5519 5520 /* Print a border around the main window and print a title */ 5521 box(my_menu_win, 0, 0); 5522 print_in_middle(my_menu_win, 1, 0, 40, "My Menu", COLOR_PAIR(1)); 5523 mvwaddch(my_menu_win, 2, 0, ACS_LTEE); 5524 mvwhline(my_menu_win, 2, 1, ACS_HLINE, 38); 5525 mvwaddch(my_menu_win, 2, 39, ACS_RTEE); 5526 mvprintw(LINES - 2, 0, "F1 to exit"); 5527 refresh(); 5528 5529 /* Post the menu */ 5530 post_menu(my_menu); 5531 wrefresh(my_menu_win); 5532 5533 while((c = wgetch(my_menu_win)) != KEY_F(1)) 5534 { switch(c) 5535 { case KEY_DOWN: 5536 menu_driver(my_menu, REQ_DOWN_ITEM); 5537 break; 5538 case KEY_UP: 5539 menu_driver(my_menu, REQ_UP_ITEM); 5540 break; 5541 } 5542 wrefresh(my_menu_win); 5543 } 5544 5545 /* Unpost and free all the memory taken up */ 5546 unpost_menu(my_menu); 5547 free_menu(my_menu); 5548 for(i = 0; i < n_choices; ++i) 5549 free_item(my_items[i]); 5550 endwin(); 5551} 5552 5553void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color) 5554{ int length, x, y; 5555 float temp; 5556 5557 if(win == NULL) 5558 win = stdscr; 5559 getyx(win, y, x); 5560 if(startx != 0) 5561 x = startx; 5562 if(starty != 0) 5563 y = starty; 5564 if(width == 0) 5565 width = 80; 5566 5567 length = strlen(string); 5568 temp = (width - length)/ 2; 5569 x = startx + (int)temp; 5570 wattron(win, color); 5571 mvwprintw(win, y, x, "%s", string); 5572 wattroff(win, color); 5573 refresh(); 5574}</SPAN 5575></PRE 5576></DIV 5577><P 5578>This example creates a menu with a title, border, a fancy line separating title 5579and the items. As you can see, in order to attach a window to a menu the 5580function set_menu_win() has to be used. Then we attach the sub window also. This 5581displays the items in the sub window. You can also set the mark string which 5582gets displayed to the left of the selected item with set_menu_mark().</P 5583></DIV 5584><DIV 5585CLASS="SECT2" 5586><HR><H3 5587CLASS="SECT2" 5588><A 5589NAME="SCROLLMENUS" 5590>17.5. Scrolling Menus</A 5591></H3 5592><P 5593>If the sub window given for a window is not big enough to show all the items, 5594then the menu will be scrollable. When you are on the last item in the present 5595list, if you send REQ_DOWN_ITEM, it gets translated into REQ_SCR_DLINE and the 5596menu scrolls by one item. You can manually give REQ_SCR_ operations to do 5597scrolling. Let's see how it can be done.</P 5598><DIV 5599CLASS="EXAMPLE" 5600><A 5601NAME="MMESC" 5602></A 5603><P 5604><B 5605>Example 20. Scrolling Menus example </B 5606></P 5607><PRE 5608CLASS="PROGRAMLISTING" 5609><SPAN 5610CLASS="INLINEMEDIAOBJECT" 5611>#include <curses.h> 5612#include <menu.h> 5613 5614#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0])) 5615#define CTRLD 4 5616 5617char *choices[] = { 5618 "Choice 1", 5619 "Choice 2", 5620 "Choice 3", 5621 "Choice 4", 5622 "Choice 5", 5623 "Choice 6", 5624 "Choice 7", 5625 "Choice 8", 5626 "Choice 9", 5627 "Choice 10", 5628 "Exit", 5629 (char *)NULL, 5630 }; 5631void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color); 5632 5633int main() 5634{ ITEM **my_items; 5635 int c; 5636 MENU *my_menu; 5637 WINDOW *my_menu_win; 5638 int n_choices, i; 5639 5640 /* Initialize curses */ 5641 initscr(); 5642 start_color(); 5643 cbreak(); 5644 noecho(); 5645 keypad(stdscr, TRUE); 5646 init_pair(1, COLOR_RED, COLOR_BLACK); 5647 init_pair(2, COLOR_CYAN, COLOR_BLACK); 5648 5649 /* Create items */ 5650 n_choices = ARRAY_SIZE(choices); 5651 my_items = (ITEM **)calloc(n_choices, sizeof(ITEM *)); 5652 for(i = 0; i < n_choices; ++i) 5653 my_items[i] = new_item(choices[i], choices[i]); 5654 5655 /* Crate menu */ 5656 my_menu = new_menu((ITEM **)my_items); 5657 5658 /* Create the window to be associated with the menu */ 5659 my_menu_win = newwin(10, 40, 4, 4); 5660 keypad(my_menu_win, TRUE); 5661 5662 /* Set main window and sub window */ 5663 set_menu_win(my_menu, my_menu_win); 5664 set_menu_sub(my_menu, derwin(my_menu_win, 6, 38, 3, 1)); 5665 set_menu_format(my_menu, 5, 1); 5666 5667 /* Set menu mark to the string " * " */ 5668 set_menu_mark(my_menu, " * "); 5669 5670 /* Print a border around the main window and print a title */ 5671 box(my_menu_win, 0, 0); 5672 print_in_middle(my_menu_win, 1, 0, 40, "My Menu", COLOR_PAIR(1)); 5673 mvwaddch(my_menu_win, 2, 0, ACS_LTEE); 5674 mvwhline(my_menu_win, 2, 1, ACS_HLINE, 38); 5675 mvwaddch(my_menu_win, 2, 39, ACS_RTEE); 5676 5677 /* Post the menu */ 5678 post_menu(my_menu); 5679 wrefresh(my_menu_win); 5680 5681 attron(COLOR_PAIR(2)); 5682 mvprintw(LINES - 2, 0, "Use PageUp and PageDown to scoll down or up a page of items"); 5683 mvprintw(LINES - 1, 0, "Arrow Keys to navigate (F1 to Exit)"); 5684 attroff(COLOR_PAIR(2)); 5685 refresh(); 5686 5687 while((c = wgetch(my_menu_win)) != KEY_F(1)) 5688 { switch(c) 5689 { case KEY_DOWN: 5690 menu_driver(my_menu, REQ_DOWN_ITEM); 5691 break; 5692 case KEY_UP: 5693 menu_driver(my_menu, REQ_UP_ITEM); 5694 break; 5695 case KEY_NPAGE: 5696 menu_driver(my_menu, REQ_SCR_DPAGE); 5697 break; 5698 case KEY_PPAGE: 5699 menu_driver(my_menu, REQ_SCR_UPAGE); 5700 break; 5701 } 5702 wrefresh(my_menu_win); 5703 } 5704 5705 /* Unpost and free all the memory taken up */ 5706 unpost_menu(my_menu); 5707 free_menu(my_menu); 5708 for(i = 0; i < n_choices; ++i) 5709 free_item(my_items[i]); 5710 endwin(); 5711} 5712 5713void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color) 5714{ int length, x, y; 5715 float temp; 5716 5717 if(win == NULL) 5718 win = stdscr; 5719 getyx(win, y, x); 5720 if(startx != 0) 5721 x = startx; 5722 if(starty != 0) 5723 y = starty; 5724 if(width == 0) 5725 width = 80; 5726 5727 length = strlen(string); 5728 temp = (width - length)/ 2; 5729 x = startx + (int)temp; 5730 wattron(win, color); 5731 mvwprintw(win, y, x, "%s", string); 5732 wattroff(win, color); 5733 refresh(); 5734}</SPAN 5735></PRE 5736></DIV 5737><P 5738>This program is self-explanatory. In this example the number of choices has been 5739increased to ten, which is larger than our sub window size which can hold 6 5740items. This message has to be explicitly conveyed to the menu system with the 5741function set_menu_format(). In here we specify the number of rows and columns we 5742want to be displayed for a single page. We can specify any number of items to be 5743shown, in the rows variables, if it is less than the height of the sub window. 5744If the key pressed by the user is a PAGE UP or PAGE DOWN, the menu is scrolled a 5745page due to the requests (REQ_SCR_DPAGE and REQ_SCR_UPAGE) given to 5746menu_driver().</P 5747></DIV 5748><DIV 5749CLASS="SECT2" 5750><HR><H3 5751CLASS="SECT2" 5752><A 5753NAME="MULTICOLUMN" 5754>17.6. Multi Columnar Menus</A 5755></H3 5756><P 5757>In the above example you have seen how to use the function set_menu_format(). I 5758didn't mention what the cols variable (third parameter) does. Well, If your sub 5759window is wide enough, you can opt to display more than one item per row. This 5760can be specified in the cols variable. To make things simpler, the following 5761example doesn't show descriptions for the items.</P 5762><DIV 5763CLASS="EXAMPLE" 5764><A 5765NAME="MMEMUCO" 5766></A 5767><P 5768><B 5769>Example 21. Milt Columnar Menus Example </B 5770></P 5771><PRE 5772CLASS="PROGRAMLISTING" 5773><SPAN 5774CLASS="INLINEMEDIAOBJECT" 5775>#include <curses.h> 5776#include <menu.h> 5777 5778#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0])) 5779#define CTRLD 4 5780 5781char *choices[] = { 5782 "Choice 1", "Choice 2", "Choice 3", "Choice 4", "Choice 5", 5783 "Choice 6", "Choice 7", "Choice 8", "Choice 9", "Choice 10", 5784 "Choice 11", "Choice 12", "Choice 13", "Choice 14", "Choice 15", 5785 "Choice 16", "Choice 17", "Choice 18", "Choice 19", "Choice 20", 5786 "Exit", 5787 (char *)NULL, 5788 }; 5789 5790int main() 5791{ ITEM **my_items; 5792 int c; 5793 MENU *my_menu; 5794 WINDOW *my_menu_win; 5795 int n_choices, i; 5796 5797 /* Initialize curses */ 5798 initscr(); 5799 start_color(); 5800 cbreak(); 5801 noecho(); 5802 keypad(stdscr, TRUE); 5803 init_pair(1, COLOR_RED, COLOR_BLACK); 5804 init_pair(2, COLOR_CYAN, COLOR_BLACK); 5805 5806 /* Create items */ 5807 n_choices = ARRAY_SIZE(choices); 5808 my_items = (ITEM **)calloc(n_choices, sizeof(ITEM *)); 5809 for(i = 0; i < n_choices; ++i) 5810 my_items[i] = new_item(choices[i], choices[i]); 5811 5812 /* Crate menu */ 5813 my_menu = new_menu((ITEM **)my_items); 5814 5815 /* Set menu option not to show the description */ 5816 menu_opts_off(my_menu, O_SHOWDESC); 5817 5818 /* Create the window to be associated with the menu */ 5819 my_menu_win = newwin(10, 70, 4, 4); 5820 keypad(my_menu_win, TRUE); 5821 5822 /* Set main window and sub window */ 5823 set_menu_win(my_menu, my_menu_win); 5824 set_menu_sub(my_menu, derwin(my_menu_win, 6, 68, 3, 1)); 5825 set_menu_format(my_menu, 5, 3); 5826 set_menu_mark(my_menu, " * "); 5827 5828 /* Print a border around the main window and print a title */ 5829 box(my_menu_win, 0, 0); 5830 5831 attron(COLOR_PAIR(2)); 5832 mvprintw(LINES - 3, 0, "Use PageUp and PageDown to scroll"); 5833 mvprintw(LINES - 2, 0, "Use Arrow Keys to navigate (F1 to Exit)"); 5834 attroff(COLOR_PAIR(2)); 5835 refresh(); 5836 5837 /* Post the menu */ 5838 post_menu(my_menu); 5839 wrefresh(my_menu_win); 5840 5841 while((c = wgetch(my_menu_win)) != KEY_F(1)) 5842 { switch(c) 5843 { case KEY_DOWN: 5844 menu_driver(my_menu, REQ_DOWN_ITEM); 5845 break; 5846 case KEY_UP: 5847 menu_driver(my_menu, REQ_UP_ITEM); 5848 break; 5849 case KEY_LEFT: 5850 menu_driver(my_menu, REQ_LEFT_ITEM); 5851 break; 5852 case KEY_RIGHT: 5853 menu_driver(my_menu, REQ_RIGHT_ITEM); 5854 break; 5855 case KEY_NPAGE: 5856 menu_driver(my_menu, REQ_SCR_DPAGE); 5857 break; 5858 case KEY_PPAGE: 5859 menu_driver(my_menu, REQ_SCR_UPAGE); 5860 break; 5861 } 5862 wrefresh(my_menu_win); 5863 } 5864 5865 /* Unpost and free all the memory taken up */ 5866 unpost_menu(my_menu); 5867 free_menu(my_menu); 5868 for(i = 0; i < n_choices; ++i) 5869 free_item(my_items[i]); 5870 endwin(); 5871}</SPAN 5872></PRE 5873></DIV 5874><P 5875>Watch the function call to set_menu_format(). It specifies the number of columns 5876to be 3, thus displaying 3 items per row. We have also switched off the showing 5877descriptions with the function menu_opts_off(). There are couple of functions 5878set_menu_opts(), menu_opts_on() and menu_opts() which can be used to manipulate 5879menu options. The following menu options can be specified.</P 5880><PRE 5881CLASS="PROGRAMLISTING" 5882> O_ONEVALUE 5883 Only one item can be selected for this menu. 5884 5885 O_SHOWDESC 5886 Display the item descriptions when the menu is 5887 posted. 5888 5889 O_ROWMAJOR 5890 Display the menu in row-major order. 5891 5892 O_IGNORECASE 5893 Ignore the case when pattern-matching. 5894 5895 O_SHOWMATCH 5896 Move the cursor to within the item name while pat­ 5897 tern-matching. 5898 5899 O_NONCYCLIC 5900 Don't wrap around next-item and previous-item, 5901 requests to the other end of the menu.</PRE 5902><P 5903>All options are on by default. You can switch specific attributes on or off with 5904menu_opts_on() and menu_opts_off() functions. You can also use set_menu_opts() 5905to directly specify the options. The argument to this function should be a OR ed 5906value of some of those above constants. The function menu_opts() can be used to 5907find out a menu's present options. </P 5908></DIV 5909><DIV 5910CLASS="SECT2" 5911><HR><H3 5912CLASS="SECT2" 5913><A 5914NAME="MULTIVALUEMENUS" 5915>17.7. Multi Valued Menus</A 5916></H3 5917><P 5918>You might be wondering what if you switch off the option O_ONEVALUE. Then the 5919menu becomes multi-valued. That means you can select more than one item. This 5920brings us to the request REQ_TOGGLE_ITEM. Let's see it in action.</P 5921><DIV 5922CLASS="EXAMPLE" 5923><A 5924NAME="MMETO" 5925></A 5926><P 5927><B 5928>Example 22. Multi Valued Menus example </B 5929></P 5930><PRE 5931CLASS="PROGRAMLISTING" 5932><SPAN 5933CLASS="INLINEMEDIAOBJECT" 5934>#include <curses.h> 5935#include <menu.h> 5936 5937#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0])) 5938#define CTRLD 4 5939 5940char *choices[] = { 5941 "Choice 1", 5942 "Choice 2", 5943 "Choice 3", 5944 "Choice 4", 5945 "Choice 5", 5946 "Choice 6", 5947 "Choice 7", 5948 "Exit", 5949 }; 5950 5951int main() 5952{ ITEM **my_items; 5953 int c; 5954 MENU *my_menu; 5955 int n_choices, i; 5956 ITEM *cur_item; 5957 5958 /* Initialize curses */ 5959 initscr(); 5960 cbreak(); 5961 noecho(); 5962 keypad(stdscr, TRUE); 5963 5964 /* Initialize items */ 5965 n_choices = ARRAY_SIZE(choices); 5966 my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *)); 5967 for(i = 0; i < n_choices; ++i) 5968 my_items[i] = new_item(choices[i], choices[i]); 5969 my_items[n_choices] = (ITEM *)NULL; 5970 5971 my_menu = new_menu((ITEM **)my_items); 5972 5973 /* Make the menu multi valued */ 5974 menu_opts_off(my_menu, O_ONEVALUE); 5975 5976 mvprintw(LINES - 3, 0, "Use <SPACE> to select or unselect an item."); 5977 mvprintw(LINES - 2, 0, "<ENTER> to see presently selected items(F1 to Exit)"); 5978 post_menu(my_menu); 5979 refresh(); 5980 5981 while((c = getch()) != KEY_F(1)) 5982 { switch(c) 5983 { case KEY_DOWN: 5984 menu_driver(my_menu, REQ_DOWN_ITEM); 5985 break; 5986 case KEY_UP: 5987 menu_driver(my_menu, REQ_UP_ITEM); 5988 break; 5989 case ' ': 5990 menu_driver(my_menu, REQ_TOGGLE_ITEM); 5991 break; 5992 case 10: /* Enter */ 5993 { char temp[200]; 5994 ITEM **items; 5995 5996 items = menu_items(my_menu); 5997 temp[0] = '\0'; 5998 for(i = 0; i < item_count(my_menu); ++i) 5999 if(item_value(items[i]) == TRUE) 6000 { strcat(temp, item_name(items[i])); 6001 strcat(temp, " "); 6002 } 6003 move(20, 0); 6004 clrtoeol(); 6005 mvprintw(20, 0, temp); 6006 refresh(); 6007 } 6008 break; 6009 } 6010 } 6011 6012 free_item(my_items[0]); 6013 free_item(my_items[1]); 6014 free_menu(my_menu); 6015 endwin(); 6016} 6017 </SPAN 6018></PRE 6019></DIV 6020><P 6021>Whew, A lot of new functions. Let's take them one after another. Firstly, the 6022REQ_TOGGLE_ITEM. In a multi-valued menu, the user should be allowed to select 6023or un select more than one item. The request REQ_TOGGLE_ITEM toggles the present 6024selection. In this case when space is pressed REQ_TOGGLE_ITEM request is sent to 6025menu_driver to achieve the result.</P 6026><P 6027>Now when the user presses <ENTER> we show the items he presently selected. 6028First we find out the items associated with the menu using the function 6029menu_items(). Then we loop through the items to find out if the item is selected 6030or not. The function item_value() returns TRUE if an item is selected. The 6031function item_count() returns the number of items in the menu. The item name can 6032be found with item_name(). You can also find the description associated with an 6033item using item_description().</P 6034></DIV 6035><DIV 6036CLASS="SECT2" 6037><HR><H3 6038CLASS="SECT2" 6039><A 6040NAME="MENUOPT" 6041>17.8. Menu Options</A 6042></H3 6043><P 6044>Well, by this time you must be itching for some difference in your menu, with 6045lots of functionality. I know. You want Colors !!!. You want to create nice 6046menus similar to those text mode <A 6047HREF="http://www.jersey.net/~debinjoe/games/" 6048TARGET="_top" 6049>dos games</A 6050>. The functions 6051set_menu_fore() and set_menu_back() can be used to change the attribute of the 6052selected item and unselected item. The names are misleading. They don't change 6053menu's foreground or background which would have been useless. </P 6054><P 6055>The function set_menu_grey() can be used to set the display attribute for the 6056non-selectable items in the menu. This brings us to the interesting option for 6057an item the one and only O_SELECTABLE. We can turn it off by the function 6058item_opts_off() and after that that item is not selectable. It's like a grayed 6059item in those fancy windows menus. Let's put these concepts in practice with 6060this example</P 6061><DIV 6062CLASS="EXAMPLE" 6063><A 6064NAME="MMEAT" 6065></A 6066><P 6067><B 6068>Example 23. Menu Options example </B 6069></P 6070><PRE 6071CLASS="PROGRAMLISTING" 6072><SPAN 6073CLASS="INLINEMEDIAOBJECT" 6074>#include <menu.h> 6075 6076#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0])) 6077#define CTRLD 4 6078 6079char *choices[] = { 6080 "Choice 1", 6081 "Choice 2", 6082 "Choice 3", 6083 "Choice 4", 6084 "Choice 5", 6085 "Choice 6", 6086 "Choice 7", 6087 "Exit", 6088 }; 6089 6090int main() 6091{ ITEM **my_items; 6092 int c; 6093 MENU *my_menu; 6094 int n_choices, i; 6095 ITEM *cur_item; 6096 6097 /* Initialize curses */ 6098 initscr(); 6099 start_color(); 6100 cbreak(); 6101 noecho(); 6102 keypad(stdscr, TRUE); 6103 init_pair(1, COLOR_RED, COLOR_BLACK); 6104 init_pair(2, COLOR_GREEN, COLOR_BLACK); 6105 init_pair(3, COLOR_MAGENTA, COLOR_BLACK); 6106 6107 /* Initialize items */ 6108 n_choices = ARRAY_SIZE(choices); 6109 my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *)); 6110 for(i = 0; i < n_choices; ++i) 6111 my_items[i] = new_item(choices[i], choices[i]); 6112 my_items[n_choices] = (ITEM *)NULL; 6113 item_opts_off(my_items[3], O_SELECTABLE); 6114 item_opts_off(my_items[6], O_SELECTABLE); 6115 6116 /* Create menu */ 6117 my_menu = new_menu((ITEM **)my_items); 6118 6119 /* Set fore ground and back ground of the menu */ 6120 set_menu_fore(my_menu, COLOR_PAIR(1) | A_REVERSE); 6121 set_menu_back(my_menu, COLOR_PAIR(2)); 6122 set_menu_grey(my_menu, COLOR_PAIR(3)); 6123 6124 /* Post the menu */ 6125 mvprintw(LINES - 3, 0, "Press <ENTER> to see the option selected"); 6126 mvprintw(LINES - 2, 0, "Up and Down arrow keys to naviage (F1 to Exit)"); 6127 post_menu(my_menu); 6128 refresh(); 6129 6130 while((c = getch()) != KEY_F(1)) 6131 { switch(c) 6132 { case KEY_DOWN: 6133 menu_driver(my_menu, REQ_DOWN_ITEM); 6134 break; 6135 case KEY_UP: 6136 menu_driver(my_menu, REQ_UP_ITEM); 6137 break; 6138 case 10: /* Enter */ 6139 move(20, 0); 6140 clrtoeol(); 6141 mvprintw(20, 0, "Item selected is : %s", 6142 item_name(current_item(my_menu))); 6143 pos_menu_cursor(my_menu); 6144 break; 6145 } 6146 } 6147 unpost_menu(my_menu); 6148 for(i = 0; i < n_choices; ++i) 6149 free_item(my_items[i]); 6150 free_menu(my_menu); 6151 endwin(); 6152} 6153 </SPAN 6154></PRE 6155></DIV 6156></DIV 6157><DIV 6158CLASS="SECT2" 6159><HR><H3 6160CLASS="SECT2" 6161><A 6162NAME="MENUUSERPTR" 6163>17.9. The useful User Pointer</A 6164></H3 6165><P 6166>We can associate a user pointer with each item in the menu. It works the same 6167way as user pointer in panels. It's not touched by menu system. You can store 6168any thing you like in that. I usually use it to store the function to be 6169executed when the menu option is chosen (It's selected and may be the user 6170pressed <ENTER>);</P 6171><DIV 6172CLASS="EXAMPLE" 6173><A 6174NAME="MMEUS" 6175></A 6176><P 6177><B 6178>Example 24. Menu User Pointer Usage </B 6179></P 6180><PRE 6181CLASS="PROGRAMLISTING" 6182><SPAN 6183CLASS="INLINEMEDIAOBJECT" 6184>#include <curses.h> 6185#include <menu.h> 6186 6187#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0])) 6188#define CTRLD 4 6189 6190char *choices[] = { 6191 "Choice 1", 6192 "Choice 2", 6193 "Choice 3", 6194 "Choice 4", 6195 "Choice 5", 6196 "Choice 6", 6197 "Choice 7", 6198 "Exit", 6199 }; 6200void func(char *name); 6201 6202int main() 6203{ ITEM **my_items; 6204 int c; 6205 MENU *my_menu; 6206 int n_choices, i; 6207 ITEM *cur_item; 6208 6209 /* Initialize curses */ 6210 initscr(); 6211 start_color(); 6212 cbreak(); 6213 noecho(); 6214 keypad(stdscr, TRUE); 6215 init_pair(1, COLOR_RED, COLOR_BLACK); 6216 init_pair(2, COLOR_GREEN, COLOR_BLACK); 6217 init_pair(3, COLOR_MAGENTA, COLOR_BLACK); 6218 6219 /* Initialize items */ 6220 n_choices = ARRAY_SIZE(choices); 6221 my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *)); 6222 for(i = 0; i < n_choices; ++i) 6223 { my_items[i] = new_item(choices[i], choices[i]); 6224 /* Set the user pointer */ 6225 set_item_userptr(my_items[i], func); 6226 } 6227 my_items[n_choices] = (ITEM *)NULL; 6228 6229 /* Create menu */ 6230 my_menu = new_menu((ITEM **)my_items); 6231 6232 /* Post the menu */ 6233 mvprintw(LINES - 3, 0, "Press <ENTER> to see the option selected"); 6234 mvprintw(LINES - 2, 0, "Up and Down arrow keys to naviage (F1 to Exit)"); 6235 post_menu(my_menu); 6236 refresh(); 6237 6238 while((c = getch()) != KEY_F(1)) 6239 { switch(c) 6240 { case KEY_DOWN: 6241 menu_driver(my_menu, REQ_DOWN_ITEM); 6242 break; 6243 case KEY_UP: 6244 menu_driver(my_menu, REQ_UP_ITEM); 6245 break; 6246 case 10: /* Enter */ 6247 { ITEM *cur; 6248 void (*p)(char *); 6249 6250 cur = current_item(my_menu); 6251 p = item_userptr(cur); 6252 p((char *)item_name(cur)); 6253 pos_menu_cursor(my_menu); 6254 break; 6255 } 6256 break; 6257 } 6258 } 6259 unpost_menu(my_menu); 6260 for(i = 0; i < n_choices; ++i) 6261 free_item(my_items[i]); 6262 free_menu(my_menu); 6263 endwin(); 6264} 6265 6266void func(char *name) 6267{ move(20, 0); 6268 clrtoeol(); 6269 mvprintw(20, 0, "Item selected is : %s", name); 6270} </SPAN 6271></PRE 6272></DIV 6273></DIV 6274></DIV 6275><DIV 6276CLASS="SECT1" 6277><HR><H2 6278CLASS="SECT1" 6279><A 6280NAME="FORMS" 6281>18. Forms Library</A 6282></H2 6283><P 6284>Well. If you have seen those forms on web pages which take input from users and 6285do various kinds of things, you might be wondering how would any one create such 6286forms in text mode display. It's quite difficult to write those nifty forms in 6287plain ncurses. Forms library tries to provide a basic frame work to build and 6288maintain forms with ease. It has lot of features(functions) which manage 6289validation, dynamic expansion of fields etc.. Let's see it in full flow.</P 6290><P 6291>A form is a collection of fields; each field can be either a label(static text) 6292or a data-entry location. The forms also library provides functions to divide 6293forms into multiple pages. </P 6294><DIV 6295CLASS="SECT2" 6296><HR><H3 6297CLASS="SECT2" 6298><A 6299NAME="FORMBASICS" 6300>18.1. The Basics</A 6301></H3 6302><P 6303>Forms are created in much the same way as menus. First the fields related to the 6304form are created with new_field(). You can set options for the fields, so that 6305they can be displayed with some fancy attributes, validated before the field 6306looses focus etc.. Then the fields are attached to form. After this, the form 6307can be posted to display and is ready to receive inputs. On the similar lines to 6308menu_driver(), the form is manipulated with form_driver(). We can send requests 6309to form_driver to move focus to a certain field, move cursor to end of the field 6310etc.. After the user enters values in the fields and validation done, form can 6311be unposted and memory allocated can be freed.</P 6312><P 6313>The general flow of control of a forms program looks like this. 6314 6315<P 6316></P 6317><OL 6318TYPE="1" 6319><LI 6320><P 6321>Initialize curses</P 6322></LI 6323><LI 6324><P 6325>Create fields using new_field(). You can specify the height and 6326width of the field, and its position on the form.</P 6327></LI 6328><LI 6329><P 6330>Create the forms with new_form() by specifying the fields to be 6331attached with.</P 6332></LI 6333><LI 6334><P 6335>Post the form with form_post() and refresh the screen.</P 6336></LI 6337><LI 6338><P 6339>Process the user requests with a loop and do necessary updates 6340to form with form_driver.</P 6341></LI 6342><LI 6343><P 6344>Unpost the menu with form_unpost()</P 6345></LI 6346><LI 6347><P 6348>Free the memory allocated to menu by free_form()</P 6349></LI 6350><LI 6351><P 6352>Free the memory allocated to the items with free_field()</P 6353></LI 6354><LI 6355><P 6356>End curses</P 6357></LI 6358></OL 6359></P 6360><P 6361>As you can see, working with forms library is much similar to handling menu 6362library. The following examples will explore various aspects of form 6363processing. Let's start the journey with a simple example. first.</P 6364></DIV 6365><DIV 6366CLASS="SECT2" 6367><HR><H3 6368CLASS="SECT2" 6369><A 6370NAME="COMPILEFORMS" 6371>18.2. Compiling With the Forms Library</A 6372></H3 6373><P 6374>To use forms library functions, you have to include form.h and to link the 6375program with forms library the flag -lform should be added along with -lncurses 6376in that order.</P 6377><PRE 6378CLASS="PROGRAMLISTING" 6379> #include <form.h> 6380 . 6381 . 6382 . 6383 6384 compile and link: gcc <program file> -lform -lncurses</PRE 6385><DIV 6386CLASS="EXAMPLE" 6387><A 6388NAME="FFOSI" 6389></A 6390><P 6391><B 6392>Example 25. Forms Basics </B 6393></P 6394><PRE 6395CLASS="PROGRAMLISTING" 6396><SPAN 6397CLASS="INLINEMEDIAOBJECT" 6398>#include <form.h> 6399 6400int main() 6401{ FIELD *field[3]; 6402 FORM *my_form; 6403 int ch; 6404 6405 /* Initialize curses */ 6406 initscr(); 6407 cbreak(); 6408 noecho(); 6409 keypad(stdscr, TRUE); 6410 6411 /* Initialize the fields */ 6412 field[0] = new_field(1, 10, 4, 18, 0, 0); 6413 field[1] = new_field(1, 10, 6, 18, 0, 0); 6414 field[2] = NULL; 6415 6416 /* Set field options */ 6417 set_field_back(field[0], A_UNDERLINE); /* Print a line for the option */ 6418 field_opts_off(field[0], O_AUTOSKIP); /* Don't go to next field when this */ 6419 /* Field is filled up */ 6420 set_field_back(field[1], A_UNDERLINE); 6421 field_opts_off(field[1], O_AUTOSKIP); 6422 6423 /* Create the form and post it */ 6424 my_form = new_form(field); 6425 post_form(my_form); 6426 refresh(); 6427 6428 mvprintw(4, 10, "Value 1:"); 6429 mvprintw(6, 10, "Value 2:"); 6430 refresh(); 6431 6432 /* Loop through to get user requests */ 6433 while((ch = getch()) != KEY_F(1)) 6434 { switch(ch) 6435 { case KEY_DOWN: 6436 /* Go to next field */ 6437 form_driver(my_form, REQ_NEXT_FIELD); 6438 /* Go to the end of the present buffer */ 6439 /* Leaves nicely at the last character */ 6440 form_driver(my_form, REQ_END_LINE); 6441 break; 6442 case KEY_UP: 6443 /* Go to previous field */ 6444 form_driver(my_form, REQ_PREV_FIELD); 6445 form_driver(my_form, REQ_END_LINE); 6446 break; 6447 default: 6448 /* If this is a normal character, it gets */ 6449 /* Printed */ 6450 form_driver(my_form, ch); 6451 break; 6452 } 6453 } 6454 6455 /* Un post form and free the memory */ 6456 unpost_form(my_form); 6457 free_form(my_form); 6458 free_field(field[0]); 6459 free_field(field[1]); 6460 6461 endwin(); 6462 return 0; 6463}</SPAN 6464></PRE 6465></DIV 6466><P 6467>Above example is pretty straight forward. It creates two fields with 6468<TT 6469CLASS="LITERAL" 6470>new_field()</TT 6471>. new_field() takes height, width, 6472starty, startx, number of offscreen rows and number of additional working 6473buffers. The fifth argument number of offscreen rows specifies how much of the 6474field to be shown. If it is zero, the entire field is always displayed otherwise 6475the form will be scrollable when the user accesses not displayed parts of the 6476field. The forms library allocates one buffer per field to store the data user 6477enters. Using the last parameter to new_field() we can specify it to allocate 6478some additional buffers. These can be used for any purpose you like.</P 6479><P 6480>After creating the fields, back ground attribute of both of them is set to an 6481underscore with set_field_back(). The AUTOSKIP option is turned off using 6482field_opts_off(). If this option is turned on, focus will move to the next 6483field in the form once the active field is filled up completely.</P 6484><P 6485>After attaching the fields to the form, it is posted. Here on, user inputs are 6486processed in the while loop, by making corresponding requests to form_driver. 6487The details of all the requests to the form_driver() are explained later.</P 6488></DIV 6489><DIV 6490CLASS="SECT2" 6491><HR><H3 6492CLASS="SECT2" 6493><A 6494NAME="PLAYFIELDS" 6495>18.3. Playing with Fields</A 6496></H3 6497><P 6498>Each form field is associated with a lot of attributes. They can be manipulated 6499to get the required effect and to have fun !!!. So why wait? </P 6500><DIV 6501CLASS="SECT3" 6502><HR><H4 6503CLASS="SECT3" 6504><A 6505NAME="FETCHINFO" 6506>18.3.1. Fetching Size and Location of Field</A 6507></H4 6508><P 6509>The parameters we have given at the time of creation of a field can be retrieved 6510with field_info(). It returns height, width, starty, startx, number of offscreen 6511rows, and number of additional buffers into the parameters given to it. It is a 6512sort of inverse of new_field().</P 6513><PRE 6514CLASS="PROGRAMLISTING" 6515>int field_info( FIELD *field, /* field from which to fetch */ 6516 int *height, *int width, /* field size */ 6517 int *top, int *left, /* upper left corner */ 6518 int *offscreen, /* number of offscreen rows */ 6519 int *nbuf); /* number of working buffers */</PRE 6520></DIV 6521><DIV 6522CLASS="SECT3" 6523><HR><H4 6524CLASS="SECT3" 6525><A 6526NAME="MOVEFIELD" 6527>18.3.2. Moving the field</A 6528></H4 6529><P 6530>The location of the field can be moved to a different position with 6531move_field().</P 6532><PRE 6533CLASS="PROGRAMLISTING" 6534>int move_field( FIELD *field, /* field to alter */ 6535 int top, int left); /* new upper-left corner */</PRE 6536><P 6537>As usual, the changed position can be queried with field_infor().</P 6538></DIV 6539><DIV 6540CLASS="SECT3" 6541><HR><H4 6542CLASS="SECT3" 6543><A 6544NAME="JUSTIFYFIELD" 6545>18.3.3. Field Justification</A 6546></H4 6547><P 6548>The justification to be done for the field can be fixed using the function 6549set_field_just().</P 6550><PRE 6551CLASS="PROGRAMLISTING" 6552> int set_field_just(FIELD *field, /* field to alter */ 6553 int justmode); /* mode to set */ 6554 int field_just(FIELD *field); /* fetch justify mode of field */</PRE 6555><P 6556>The justification mode valued accepted and returned by these functions are 6557NO_JUSTIFICATION, JUSTIFY_RIGHT, JUSTIFY_LEFT, or JUSTIFY_CENTER.</P 6558></DIV 6559><DIV 6560CLASS="SECT3" 6561><HR><H4 6562CLASS="SECT3" 6563><A 6564NAME="FIELDDISPATTRIB" 6565>18.3.4. Field Display Attributes</A 6566></H4 6567><P 6568>As you have seen, in the above example, display attribute for the fields can be 6569set with set_field_fore() and setfield_back(). These functions set foreground 6570and background attribute of the fields. You can also specify a pad character 6571which will be filled in the unfilled portion of the field. The pad character is 6572set with a call to set_field_pad(). Default pad value is a space. The functions 6573field_fore(), field_back, field_pad() can be used to query the present 6574foreground, background attributes and pad character for the field. The following 6575list gives the usage of functions.</P 6576><PRE 6577CLASS="PROGRAMLISTING" 6578> int set_field_fore(FIELD *field, /* field to alter */ 6579 chtype attr); /* attribute to set */ 6580 6581chtype field_fore(FIELD *field); /* field to query */ 6582 /* returns foreground attribute */ 6583 6584int set_field_back(FIELD *field, /* field to alter */ 6585 chtype attr); /* attribute to set */ 6586 6587chtype field_back(FIELD *field); /* field to query */ 6588 /* returns background attribute */ 6589 6590int set_field_pad(FIELD *field, /* field to alter */ 6591 int pad); /* pad character to set */ 6592 6593chtype field_pad(FIELD *field); /* field to query */ 6594 /* returns present pad character */ </PRE 6595><P 6596>Though above functions seem quite simple, using colors with set_field_fore() may 6597be frustrating in the beginning. Let me first explain about foreground and 6598background attributes of a field. The foreground attribute is associated with 6599the character. That means a character in the field is printed with the attribute 6600you have set with set_field_fore(). Background attribute is the attribute used 6601to fill background of field, whether any character is there or not. So what 6602about colors? Since colors are always defined in pairs, what is the right way to 6603display colored fields? Here's an example clarifying color attributes.</P 6604><DIV 6605CLASS="EXAMPLE" 6606><A 6607NAME="FFOAT" 6608></A 6609><P 6610><B 6611>Example 26. Form Attributes example </B 6612></P 6613><PRE 6614CLASS="PROGRAMLISTING" 6615><SPAN 6616CLASS="INLINEMEDIAOBJECT" 6617>#include <form.h> 6618 6619int main() 6620{ FIELD *field[3]; 6621 FORM *my_form; 6622 int ch; 6623 6624 /* Initialize curses */ 6625 initscr(); 6626 start_color(); 6627 cbreak(); 6628 noecho(); 6629 keypad(stdscr, TRUE); 6630 6631 /* Initialize few color pairs */ 6632 init_pair(1, COLOR_WHITE, COLOR_BLUE); 6633 init_pair(2, COLOR_WHITE, COLOR_BLUE); 6634 6635 /* Initialize the fields */ 6636 field[0] = new_field(1, 10, 4, 18, 0, 0); 6637 field[1] = new_field(1, 10, 6, 18, 0, 0); 6638 field[2] = NULL; 6639 6640 /* Set field options */ 6641 set_field_fore(field[0], COLOR_PAIR(1));/* Put the field with blue background */ 6642 set_field_back(field[0], COLOR_PAIR(2));/* and white foreground (characters */ 6643 /* are printed in white */ 6644 field_opts_off(field[0], O_AUTOSKIP); /* Don't go to next field when this */ 6645 /* Field is filled up */ 6646 set_field_back(field[1], A_UNDERLINE); 6647 field_opts_off(field[1], O_AUTOSKIP); 6648 6649 /* Create the form and post it */ 6650 my_form = new_form(field); 6651 post_form(my_form); 6652 refresh(); 6653 6654 set_current_field(my_form, field[0]); /* Set focus to the colored field */ 6655 mvprintw(4, 10, "Value 1:"); 6656 mvprintw(6, 10, "Value 2:"); 6657 mvprintw(LINES - 2, 0, "Use UP, DOWN arrow keys to switch between fields"); 6658 refresh(); 6659 6660 /* Loop through to get user requests */ 6661 while((ch = getch()) != KEY_F(1)) 6662 { switch(ch) 6663 { case KEY_DOWN: 6664 /* Go to next field */ 6665 form_driver(my_form, REQ_NEXT_FIELD); 6666 /* Go to the end of the present buffer */ 6667 /* Leaves nicely at the last character */ 6668 form_driver(my_form, REQ_END_LINE); 6669 break; 6670 case KEY_UP: 6671 /* Go to previous field */ 6672 form_driver(my_form, REQ_PREV_FIELD); 6673 form_driver(my_form, REQ_END_LINE); 6674 break; 6675 default: 6676 /* If this is a normal character, it gets */ 6677 /* Printed */ 6678 form_driver(my_form, ch); 6679 break; 6680 } 6681 } 6682 6683 /* Un post form and free the memory */ 6684 unpost_form(my_form); 6685 free_form(my_form); 6686 free_field(field[0]); 6687 free_field(field[1]); 6688 6689 endwin(); 6690 return 0; 6691}</SPAN 6692></PRE 6693></DIV 6694><P 6695>Play with the color pairs and try to understand the foreground and background 6696attributes. In my programs using color attributes, I usually set only the 6697background with set_field_back(). Curses simply doesn't allow defining 6698individual color attributes. </P 6699></DIV 6700><DIV 6701CLASS="SECT3" 6702><HR><H4 6703CLASS="SECT3" 6704><A 6705NAME="FIELDOPTIONBITS" 6706>18.3.5. Field Option Bits</A 6707></H4 6708><P 6709>There is also a large collection of field option bits you can set to control 6710various aspects of forms processing. You can manipulate them with these 6711functions:</P 6712><PRE 6713CLASS="PROGRAMLISTING" 6714>int set_field_opts(FIELD *field, /* field to alter */ 6715 int attr); /* attribute to set */ 6716 6717int field_opts_on(FIELD *field, /* field to alter */ 6718 int attr); /* attributes to turn on */ 6719 6720int field_opts_off(FIELD *field, /* field to alter */ 6721 int attr); /* attributes to turn off */ 6722 6723int field_opts(FIELD *field); /* field to query */ </PRE 6724><P 6725>The function set_field_opts() can be used to directly set attributes of a field 6726or you can choose to switch a few attributes on and off with field_opts_on() and 6727field_opts_off() selectively. Anytime you can query the attributes of a field 6728with field_opts(). The following is the list of available options. By default, 6729all options are on.</P 6730><P 6731></P 6732><DIV 6733CLASS="VARIABLELIST" 6734><DL 6735><DT 6736>O_VISIBLE</DT 6737><DD 6738><P 6739>Controls whether the field is visible on the screen. Can be used 6740during form processing to hide or pop up fields depending on the value 6741of parent fields.</P 6742></DD 6743><DT 6744>O_ACTIVE</DT 6745><DD 6746><P 6747>Controls whether the field is active during forms processing (i.e. 6748visited by form navigation keys). Can be used to make labels or derived 6749fields with buffer values alterable by the forms application, not the user.</P 6750></DD 6751><DT 6752>O_PUBLIC</DT 6753><DD 6754><P 6755>Controls whether data is displayed during field entry. If this option is 6756turned off on a field, the library will accept and edit data in that field, 6757but it will not be displayed and the visible field cursor will not move. 6758You can turn off the O_PUBLIC bit to define password fields.</P 6759></DD 6760><DT 6761>O_EDIT</DT 6762><DD 6763><P 6764>Controls whether the field's data can be modified. When this option is 6765off, all editing requests except <TT 6766CLASS="LITERAL" 6767>REQ_PREV_CHOICE</TT 6768> and <TT 6769CLASS="LITERAL" 6770>REQ_NEXT_CHOICE</TT 6771>will 6772fail. Such read-only fields may be useful for help messages.</P 6773></DD 6774><DT 6775>O_WRAP</DT 6776><DD 6777><P 6778>Controls word-wrapping in multi-line fields. Normally, when any 6779character of a (blank-separated) word reaches the end of the current line, the 6780entire word is wrapped to the next line (assuming there is one). When this 6781option is off, the word will be split across the line break.</P 6782></DD 6783><DT 6784>O_BLANK</DT 6785><DD 6786><P 6787>Controls field blanking. When this option is on, entering a character at 6788the first field position erases the entire field (except for the just-entered 6789character).</P 6790></DD 6791><DT 6792>O_AUTOSKIP</DT 6793><DD 6794><P 6795>Controls automatic skip to next field when this one fills. Normally, 6796when the forms user tries to type more data into a field than will fit, 6797the editing location jumps to next field. When this option is off, the 6798user's cursor will hang at the end of the field. This option is ignored 6799in dynamic fields that have not reached their size limit.</P 6800></DD 6801><DT 6802>O_NULLOK</DT 6803><DD 6804><P 6805>Controls whether validation is applied to 6806blank fields. Normally, it is not; the user can leave a field blank 6807without invoking the usual validation check on exit. If this option is 6808off on a field, exit from it will invoke a validation check.</P 6809></DD 6810><DT 6811>O_PASSOK</DT 6812><DD 6813><P 6814>Controls whether validation occurs on every exit, or only after 6815the field is modified. Normally the latter is true. Setting O_PASSOK 6816may be useful if your field's validation function may change during 6817forms processing.</P 6818></DD 6819><DT 6820>O_STATIC</DT 6821><DD 6822><P 6823>Controls whether the field is fixed to its initial dimensions. If you 6824turn this off, the field becomes dynamic and will 6825stretch to fit entered data.</P 6826></DD 6827></DL 6828></DIV 6829><P 6830>A field's options cannot be changed while the field is currently selected. 6831However, options may be changed on posted fields that are not current. </P 6832><P 6833>The option values are bit-masks and can be composed with logical-or in 6834the obvious way. You have seen the usage of switching off O_AUTOSKIP option. 6835The following example clarifies usage of some more options. Other options 6836are explained where appropriate.</P 6837><DIV 6838CLASS="EXAMPLE" 6839><A 6840NAME="FFOOP" 6841></A 6842><P 6843><B 6844>Example 27. Field Options Usage example </B 6845></P 6846><PRE 6847CLASS="PROGRAMLISTING" 6848><SPAN 6849CLASS="INLINEMEDIAOBJECT" 6850>#include <form.h> 6851 6852#define STARTX 15 6853#define STARTY 4 6854#define WIDTH 25 6855 6856#define N_FIELDS 3 6857 6858int main() 6859{ FIELD *field[N_FIELDS]; 6860 FORM *my_form; 6861 int ch, i; 6862 6863 /* Initialize curses */ 6864 initscr(); 6865 cbreak(); 6866 noecho(); 6867 keypad(stdscr, TRUE); 6868 6869 /* Initialize the fields */ 6870 for(i = 0; i < N_FIELDS - 1; ++i) 6871 field[i] = new_field(1, WIDTH, STARTY + i * 2, STARTX, 0, 0); 6872 field[N_FIELDS - 1] = NULL; 6873 6874 /* Set field options */ 6875 set_field_back(field[1], A_UNDERLINE); /* Print a line for the option */ 6876 6877 field_opts_off(field[0], O_ACTIVE); /* This field is a static label */ 6878 field_opts_off(field[1], O_PUBLIC); /* This filed is like a password field*/ 6879 field_opts_off(field[1], O_AUTOSKIP); /* To avoid entering the same field */ 6880 /* after last character is entered */ 6881 6882 /* Create the form and post it */ 6883 my_form = new_form(field); 6884 post_form(my_form); 6885 refresh(); 6886 6887 set_field_just(field[0], JUSTIFY_CENTER); /* Center Justification */ 6888 set_field_buffer(field[0], 0, "This is a static Field"); 6889 /* Initialize the field */ 6890 mvprintw(STARTY, STARTX - 10, "Field 1:"); 6891 mvprintw(STARTY + 2, STARTX - 10, "Field 2:"); 6892 refresh(); 6893 6894 /* Loop through to get user requests */ 6895 while((ch = getch()) != KEY_F(1)) 6896 { switch(ch) 6897 { case KEY_DOWN: 6898 /* Go to next field */ 6899 form_driver(my_form, REQ_NEXT_FIELD); 6900 /* Go to the end of the present buffer */ 6901 /* Leaves nicely at the last character */ 6902 form_driver(my_form, REQ_END_LINE); 6903 break; 6904 case KEY_UP: 6905 /* Go to previous field */ 6906 form_driver(my_form, REQ_PREV_FIELD); 6907 form_driver(my_form, REQ_END_LINE); 6908 break; 6909 default: 6910 /* If this is a normal character, it gets */ 6911 /* Printed */ 6912 form_driver(my_form, ch); 6913 break; 6914 } 6915 } 6916 6917 /* Un post form and free the memory */ 6918 unpost_form(my_form); 6919 free_form(my_form); 6920 free_field(field[0]); 6921 free_field(field[1]); 6922 6923 endwin(); 6924 return 0; 6925}</SPAN 6926></PRE 6927></DIV 6928><P 6929>This example, though useless, shows the usage of options. If used properly, they 6930can present information very effectively in a form. The second field being not 6931O_PUBLIC, does not show the characters you are typing.</P 6932></DIV 6933><DIV 6934CLASS="SECT3" 6935><HR><H4 6936CLASS="SECT3" 6937><A 6938NAME="FIELDSTATUS" 6939>18.3.6. Field Status</A 6940></H4 6941><P 6942>The field status specifies whether the field has got edited or not. It is 6943initially set to FALSE and when user enters something and the data buffer gets 6944modified it becomes TRUE. So a field's status can be queried to find out whether 6945it has been modified or not. The following functions can assist in those 6946operations.</P 6947><PRE 6948CLASS="PROGRAMLISTING" 6949>int set_field_status(FIELD *field, /* field to alter */ 6950 int status); /* status to set */ 6951 6952int field_status(FIELD *field); /* fetch status of field */</PRE 6953><P 6954>It's better to check the field's status only after after leaving the field, as 6955data buffer might not have been updated yet as the validation is still due. To 6956guarantee that right status is returned, call field_status() either (1) in the 6957field's exit validation check routine, (2) from the field's or form's 6958initialization or termination hooks, or (3) just after a REQ_VALIDATION request 6959has been processed by the forms driver</P 6960></DIV 6961><DIV 6962CLASS="SECT3" 6963><HR><H4 6964CLASS="SECT3" 6965><A 6966NAME="FIELDUSERPTR" 6967>18.3.7. Field User Pointer</A 6968></H4 6969><P 6970>Every field structure contains one pointer that can be used by the user for 6971various purposes. It is not touched by forms library and can be used for any 6972purpose by the user. The following functions set and fetch user pointer.</P 6973><PRE 6974CLASS="PROGRAMLISTING" 6975>int set_field_userptr(FIELD *field, 6976 char *userptr); /* the user pointer you wish to associate */ 6977 /* with the field */ 6978 6979char *field_userptr(FIELD *field); /* fetch user pointer of the field */</PRE 6980></DIV 6981><DIV 6982CLASS="SECT3" 6983><HR><H4 6984CLASS="SECT3" 6985><A 6986NAME="VARIABLESIZEFIELDS" 6987>18.3.8. Variable-Sized Fields</A 6988></H4 6989><P 6990>If you want a dynamically changing field with variable width, this is the 6991feature you want to put to full use. This will allow the user to enter more data 6992than the original size of the field and let the field grow. According to the 6993field orientation it will scroll horizontally or vertically to incorporate the 6994new data.</P 6995><P 6996>To make a field dynamically growable, the option O_STATIC should be turned off. 6997This can be done with a 6998<PRE 6999CLASS="PROGRAMLISTING" 7000> field_opts_off(field_pointer, O_STATIC);</PRE 7001></P 7002><P 7003>But it's usually not advisable to allow a field to grow infinitely. You can set 7004a maximum limit to the growth of the field with 7005<PRE 7006CLASS="PROGRAMLISTING" 7007>int set_max_field(FIELD *field, /* Field on which to operate */ 7008 int max_growth); /* maximum growth allowed for the field */</PRE 7009></P 7010><P 7011>The field info for a dynamically growable field can be retrieved by 7012<PRE 7013CLASS="PROGRAMLISTING" 7014>int dynamic_field_info( FIELD *field, /* Field on which to operate */ 7015 int *prows, /* number of rows will be filled in this */ 7016 int *pcols, /* number of columns will be filled in this*/ 7017 int *pmax) /* maximum allowable growth will be filled */ 7018 /* in this */</PRE 7019> 7020Though field_info work as usual, it is advisable to use this function to get the 7021proper attributes of a dynamically growable field.</P 7022><P 7023>Recall the library routine new_field; a new field created with height set to one 7024will be defined to be a one line field. A new field created with height greater 7025than one will be defined to be a multi line field. </P 7026><P 7027>A one line field with O_STATIC turned off (dynamically growable field) will 7028contain a single fixed row, but the number of columns can increase if the user 7029enters more data than the initial field will hold. The number of columns 7030displayed will remain fixed and the additional data will scroll horizontally. </P 7031><P 7032>A multi line field with O_STATIC turned off (dynamically growable field) will 7033contain a fixed number of columns, but the number of rows can increase if the 7034user enters more data than the initial field will hold. The number of rows 7035displayed will remain fixed and the additional data will scroll vertically.</P 7036><P 7037>The above two paragraphs pretty much describe a dynamically growable field's 7038behavior. The way other parts of forms library behaves is described below:</P 7039><P 7040></P 7041><OL 7042TYPE="1" 7043><LI 7044><P 7045>The field option O_AUTOSKIP will be ignored if the option O_STATIC is off and 7046there is no maximum growth specified for the field. Currently, O_AUTOSKIP 7047generates an automatic REQ_NEXT_FIELD form driver request when the user types in 7048the last character position of a field. On a growable field with no maximum 7049growth specified, there is no last character position. If a maximum growth is 7050specified, the O_AUTOSKIP option will work as normal if the field has grown to 7051its maximum size. </P 7052></LI 7053><LI 7054><P 7055>The field justification will be ignored if the option O_STATIC is off. 7056Currently, set_field_just can be used to JUSTIFY_LEFT, JUSTIFY_RIGHT, 7057JUSTIFY_CENTER the contents of a one line field. A growable one line field will, 7058by definition, grow and scroll horizontally and may contain more data than can 7059be justified. The return from field_just will be unchanged. </P 7060></LI 7061><LI 7062><P 7063>The overloaded form driver request REQ_NEW_LINE will operate the same way 7064regardless of the O_NL_OVERLOAD form option if the field option O_STATIC is off 7065and there is no maximum growth specified for the field. Currently, if the form 7066option O_NL_OVERLOAD is on, REQ_NEW_LINE implicitly generates a REQ_NEXT_FIELD 7067if called from the last line of a field. If a field can grow without bound, 7068there is no last line, so REQ_NEW_LINE will never implicitly generate a 7069REQ_NEXT_FIELD. If a maximum growth limit is specified and the O_NL_OVERLOAD 7070form option is on, REQ_NEW_LINE will only implicitly generate REQ_NEXT_FIELD if 7071the field has grown to its maximum size and the user is on the last line. </P 7072></LI 7073><LI 7074><P 7075>The library call dup_field will work as usual; it will duplicate the field, 7076including the current buffer size and contents of the field being duplicated. 7077Any specified maximum growth will also be duplicated. </P 7078></LI 7079><LI 7080><P 7081>The library call link_field will work as usual; it will duplicate all field 7082attributes and share buffers with the field being linked. If the O_STATIC field 7083option is subsequently changed by a field sharing buffers, how the system reacts 7084to an attempt to enter more data into the field than the buffer will currently 7085hold will depend on the setting of the option in the current field. </P 7086></LI 7087><LI 7088><P 7089>The library call field_info will work as usual; the variable nrow will contain 7090the value of the original call to new_field. The user should use 7091dynamic_field_info, described above, to query the current size of the buffer.</P 7092></LI 7093></OL 7094><P 7095>Some of the above points make sense only after explaining form driver. We will 7096be looking into that in next few sections.</P 7097></DIV 7098></DIV 7099><DIV 7100CLASS="SECT2" 7101><HR><H3 7102CLASS="SECT2" 7103><A 7104NAME="FORMWINDOWS" 7105>18.4. Form Windows</A 7106></H3 7107><P 7108>The form windows concept is pretty much similar to menu windows. Every form is 7109associated with a main window and a sub window. The form main window displays 7110any title or border associated or whatever the user wishes. Then the sub window 7111contains all the fields and displays them according to their position. This 7112gives the flexibility of manipulating fancy form displaying very easily. </P 7113><P 7114>Since this is pretty much similar to menu windows, I am providing an example 7115with out much explanation. The functions are similar and they work the same way.</P 7116><DIV 7117CLASS="EXAMPLE" 7118><A 7119NAME="FFOWI" 7120></A 7121><P 7122><B 7123>Example 28. Form Windows Example </B 7124></P 7125><PRE 7126CLASS="PROGRAMLISTING" 7127><SPAN 7128CLASS="INLINEMEDIAOBJECT" 7129>#include <form.h> 7130 7131void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color); 7132 7133int main() 7134{ 7135 FIELD *field[3]; 7136 FORM *my_form; 7137 WINDOW *my_form_win; 7138 int ch, rows, cols; 7139 7140 /* Initialize curses */ 7141 initscr(); 7142 start_color(); 7143 cbreak(); 7144 noecho(); 7145 keypad(stdscr, TRUE); 7146 7147 /* Initialize few color pairs */ 7148 init_pair(1, COLOR_RED, COLOR_BLACK); 7149 7150 /* Initialize the fields */ 7151 field[0] = new_field(1, 10, 6, 1, 0, 0); 7152 field[1] = new_field(1, 10, 8, 1, 0, 0); 7153 field[2] = NULL; 7154 7155 /* Set field options */ 7156 set_field_back(field[0], A_UNDERLINE); 7157 field_opts_off(field[0], O_AUTOSKIP); /* Don't go to next field when this */ 7158 /* Field is filled up */ 7159 set_field_back(field[1], A_UNDERLINE); 7160 field_opts_off(field[1], O_AUTOSKIP); 7161 7162 /* Create the form and post it */ 7163 my_form = new_form(field); 7164 7165 /* Calculate the area required for the form */ 7166 scale_form(my_form, &rows, &cols); 7167 7168 /* Create the window to be associated with the form */ 7169 my_form_win = newwin(rows + 4, cols + 4, 4, 4); 7170 keypad(my_form_win, TRUE); 7171 7172 /* Set main window and sub window */ 7173 set_form_win(my_form, my_form_win); 7174 set_form_sub(my_form, derwin(my_form_win, rows, cols, 2, 2)); 7175 7176 /* Print a border around the main window and print a title */ 7177 box(my_form_win, 0, 0); 7178 print_in_middle(my_form_win, 1, 0, cols + 4, "My Form", COLOR_PAIR(1)); 7179 7180 post_form(my_form); 7181 wrefresh(my_form_win); 7182 7183 mvprintw(LINES - 2, 0, "Use UP, DOWN arrow keys to switch between fields"); 7184 refresh(); 7185 7186 /* Loop through to get user requests */ 7187 while((ch = wgetch(my_form_win)) != KEY_F(1)) 7188 { switch(ch) 7189 { case KEY_DOWN: 7190 /* Go to next field */ 7191 form_driver(my_form, REQ_NEXT_FIELD); 7192 /* Go to the end of the present buffer */ 7193 /* Leaves nicely at the last character */ 7194 form_driver(my_form, REQ_END_LINE); 7195 break; 7196 case KEY_UP: 7197 /* Go to previous field */ 7198 form_driver(my_form, REQ_PREV_FIELD); 7199 form_driver(my_form, REQ_END_LINE); 7200 break; 7201 default: 7202 /* If this is a normal character, it gets */ 7203 /* Printed */ 7204 form_driver(my_form, ch); 7205 break; 7206 } 7207 } 7208 7209 /* Un post form and free the memory */ 7210 unpost_form(my_form); 7211 free_form(my_form); 7212 free_field(field[0]); 7213 free_field(field[1]); 7214 7215 endwin(); 7216 return 0; 7217} 7218 7219void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color) 7220{ int length, x, y; 7221 float temp; 7222 7223 if(win == NULL) 7224 win = stdscr; 7225 getyx(win, y, x); 7226 if(startx != 0) 7227 x = startx; 7228 if(starty != 0) 7229 y = starty; 7230 if(width == 0) 7231 width = 80; 7232 7233 length = strlen(string); 7234 temp = (width - length)/ 2; 7235 x = startx + (int)temp; 7236 wattron(win, color); 7237 mvwprintw(win, y, x, "%s", string); 7238 wattroff(win, color); 7239 refresh(); 7240}</SPAN 7241></PRE 7242></DIV 7243></DIV 7244><DIV 7245CLASS="SECT2" 7246><HR><H3 7247CLASS="SECT2" 7248><A 7249NAME="FILEDVALIDATE" 7250>18.5. Field Validation</A 7251></H3 7252><P 7253>By default, a field will accept any data input by the user. It is possible to 7254attach validation to the field. Then any attempt by the user to leave the field, 7255while it contains data that doesn't match the validation type will fail. Some 7256validation types also have a character-validity check for each time a character 7257is entered in the field.</P 7258><P 7259>Validation can be attached to a field with the following function. 7260<PRE 7261CLASS="PROGRAMLISTING" 7262>int set_field_type(FIELD *field, /* field to alter */ 7263 FIELDTYPE *ftype, /* type to associate */ 7264 ...); /* additional arguments*/</PRE 7265> 7266Once set, the validation type for a field can be queried with 7267<PRE 7268CLASS="PROGRAMLISTING" 7269>FIELDTYPE *field_type(FIELD *field); /* field to query */</PRE 7270></P 7271><P 7272>The form driver validates the data in a field only when data is entered by the 7273end-user. Validation does not occur when </P 7274><P 7275></P 7276><UL 7277><LI 7278><P 7279>the application program changes the field value by calling set_field_buffer. </P 7280></LI 7281><LI 7282><P 7283>linked field values are changed indirectly -- by changing the field to which 7284they are linked</P 7285></LI 7286></UL 7287><P 7288>The following are the pre-defined validation types. You can also specify custom 7289validation, though it's a bit tricky and cumbersome.</P 7290><H1 7291CLASS="BRIDGEHEAD" 7292><A 7293NAME="AEN1069" 7294></A 7295>TYPE_ALPHA</H1 7296><P 7297>This field type accepts alphabetic data; no blanks, no digits, no special 7298characters (this is checked at character-entry time). It is set up with: </P 7299><PRE 7300CLASS="PROGRAMLISTING" 7301>int set_field_type(FIELD *field, /* field to alter */ 7302 TYPE_ALPHA, /* type to associate */ 7303 int width); /* maximum width of field */</PRE 7304><P 7305>The width argument sets a minimum width of data. The user has to enter at-least 7306width number of characters before he can leave the field. Typically 7307you'll want to set this to the field width; if it's greater than the 7308field width, the validation check will always fail. A minimum width 7309of zero makes field completion optional. </P 7310><H1 7311CLASS="BRIDGEHEAD" 7312><A 7313NAME="AEN1073" 7314></A 7315>TYPE_ALNUM</H1 7316><P 7317>This field type accepts alphabetic data and digits; no blanks, no special 7318characters (this is checked at character-entry time). It is set up with: </P 7319><PRE 7320CLASS="PROGRAMLISTING" 7321>int set_field_type(FIELD *field, /* field to alter */ 7322 TYPE_ALNUM, /* type to associate */ 7323 int width); /* maximum width of field */</PRE 7324><P 7325>The width argument sets a minimum width of data. As with 7326TYPE_ALPHA, typically you'll want to set this to the field width; if it's 7327greater than the field width, the validation check will always fail. A 7328minimum width of zero makes field completion optional. </P 7329><H1 7330CLASS="BRIDGEHEAD" 7331><A 7332NAME="AEN1077" 7333></A 7334>TYPE_ENUM</H1 7335><P 7336>This type allows you to restrict a field's values to be among a specified 7337set of string values (for example, the two-letter postal codes for U.S. 7338states). It is set up with: </P 7339><PRE 7340CLASS="PROGRAMLISTING" 7341>int set_field_type(FIELD *field, /* field to alter */ 7342 TYPE_ENUM, /* type to associate */ 7343 char **valuelist; /* list of possible values */ 7344 int checkcase; /* case-sensitive? */ 7345 int checkunique); /* must specify uniquely? */</PRE 7346><P 7347>The valuelist parameter must point at a NULL-terminated list of 7348valid strings. The checkcase argument, if true, makes comparison 7349with the string case-sensitive. </P 7350><P 7351>When the user exits a TYPE_ENUM field, the validation procedure tries to 7352complete the data in the buffer to a valid entry. If a complete choice string 7353has been entered, it is of course valid. But it is also possible to enter a 7354prefix of a valid string and have it completed for you. </P 7355><P 7356>By default, if you enter such a prefix and it matches more than one value 7357in the string list, the prefix will be completed to the first matching 7358value. But the checkunique argument, if true, requires prefix 7359matches to be unique in order to be valid. </P 7360><P 7361>The REQ_NEXT_CHOICE and REQ_PREV_CHOICE input requests can be particularly 7362useful with these fields. </P 7363><H1 7364CLASS="BRIDGEHEAD" 7365><A 7366NAME="AEN1084" 7367></A 7368>TYPE_INTEGER</H1 7369><P 7370>This field type accepts an integer. It is set up as follows: </P 7371><PRE 7372CLASS="PROGRAMLISTING" 7373>int set_field_type(FIELD *field, /* field to alter */ 7374 TYPE_INTEGER, /* type to associate */ 7375 int padding, /* # places to zero-pad to */ 7376 int vmin, int vmax); /* valid range */</PRE 7377><P 7378>Valid characters consist of an optional leading minus and digits. 7379The range check is performed on exit. If the range maximum is less 7380than or equal to the minimum, the range is ignored. </P 7381><P 7382>If the value passes its range check, it is padded with as many leading 7383zero digits as necessary to meet the padding argument. </P 7384><P 7385>A TYPE_INTEGER value buffer can conveniently be interpreted with the C library 7386function atoi(3).</P 7387><H1 7388CLASS="BRIDGEHEAD" 7389><A 7390NAME="AEN1090" 7391></A 7392>TYPE_NUMERIC</H1 7393><P 7394>This field type accepts a decimal number. It is set up as follows: </P 7395><PRE 7396CLASS="PROGRAMLISTING" 7397>int set_field_type(FIELD *field, /* field to alter */ 7398 TYPE_NUMERIC, /* type to associate */ 7399 int padding, /* # places of precision */ 7400 int vmin, int vmax); /* valid range */</PRE 7401><P 7402>Valid characters consist of an optional leading minus and digits. possibly 7403including a decimal point. The range check is performed on exit. If the 7404range maximum is less than or equal to the minimum, the range is 7405ignored. </P 7406><P 7407>If the value passes its range check, it is padded with as many trailing 7408zero digits as necessary to meet the padding argument. </P 7409><P 7410>A TYPE_NUMERIC value buffer can conveniently be interpreted with the C library 7411function atof(3).</P 7412><H1 7413CLASS="BRIDGEHEAD" 7414><A 7415NAME="AEN1096" 7416></A 7417>TYPE_REGEXP</H1 7418><P 7419>This field type accepts data matching a regular expression. It is set up 7420as follows: </P 7421><PRE 7422CLASS="PROGRAMLISTING" 7423>int set_field_type(FIELD *field, /* field to alter */ 7424 TYPE_REGEXP, /* type to associate */ 7425 char *regexp); /* expression to match */</PRE 7426><P 7427>The syntax for regular expressions is that of regcomp(3). 7428The check for regular-expression match is performed on exit.</P 7429></DIV 7430><DIV 7431CLASS="SECT2" 7432><HR><H3 7433CLASS="SECT2" 7434><A 7435NAME="FORMDRIVER" 7436>18.6. Form Driver: The work horse of the forms system</A 7437></H3 7438><P 7439>As in the menu system, form_driver() plays a very important role in forms 7440system. All types of requests to forms system should be funneled through 7441form_driver().</P 7442><PRE 7443CLASS="PROGRAMLISTING" 7444>int form_driver(FORM *form, /* form on which to operate */ 7445 int request) /* form request code */</PRE 7446><P 7447>As you have seen some of the examples above, you have to be in a loop looking 7448for user input and then decide whether it's a field data or a form request. The 7449form requests are then passed to form_driver() to do the work.</P 7450><P 7451>The requests roughly can be divided into following categories. Different 7452requests and their usage is explained below:</P 7453><DIV 7454CLASS="SECT3" 7455><HR><H4 7456CLASS="SECT3" 7457><A 7458NAME="PAGENAVREQ" 7459>18.6.1. Page Navigation Requests</A 7460></H4 7461><P 7462>These requests cause page-level moves through the form, triggering display of a 7463new form screen. A form can be made of multiple pages. If you have a big form 7464with lot of fields and logical sections, then you can divide the form into 7465pages. The function set_new_page() to set a new page at the field specified.</P 7466><PRE 7467CLASS="PROGRAMLISTING" 7468>int set_new_page(FIELD *field,/* Field at which page break to be set or unset */ 7469 bool new_page_flag); /* should be TRUE to put a break */</PRE 7470><P 7471>The following requests allow you to move to different pages</P 7472><P 7473></P 7474><UL 7475><LI 7476><P 7477><SPAN 7478CLASS="emphasis" 7479><I 7480CLASS="EMPHASIS" 7481>REQ_NEXT_PAGE</I 7482></SPAN 7483> Move to the next form page.</P 7484></LI 7485><LI 7486><P 7487><SPAN 7488CLASS="emphasis" 7489><I 7490CLASS="EMPHASIS" 7491>REQ_PREV_PAGE</I 7492></SPAN 7493> Move to the previous 7494form page.</P 7495></LI 7496><LI 7497><P 7498><SPAN 7499CLASS="emphasis" 7500><I 7501CLASS="EMPHASIS" 7502>REQ_FIRST_PAGE</I 7503></SPAN 7504> Move to the first form page.</P 7505></LI 7506><LI 7507><P 7508><SPAN 7509CLASS="emphasis" 7510><I 7511CLASS="EMPHASIS" 7512>REQ_LAST_PAGE</I 7513></SPAN 7514> Move to the last form page. </P 7515></LI 7516></UL 7517><P 7518>These requests treat the list as cyclic; that is, REQ_NEXT_PAGE from the 7519last page goes to the first, and REQ_PREV_PAGE from the first page goes to 7520the last.</P 7521></DIV 7522><DIV 7523CLASS="SECT3" 7524><HR><H4 7525CLASS="SECT3" 7526><A 7527NAME="INTERFIELDNAVREQ" 7528>18.6.2. Inter-Field Navigation Requests</A 7529></H4 7530><P 7531>These requests handle navigation between fields on the same page.</P 7532><P 7533></P 7534><UL 7535><LI 7536><P 7537><SPAN 7538CLASS="emphasis" 7539><I 7540CLASS="EMPHASIS" 7541>REQ_NEXT_FIELD</I 7542></SPAN 7543> 7544 Move to next field. </P 7545></LI 7546><LI 7547><P 7548><SPAN 7549CLASS="emphasis" 7550><I 7551CLASS="EMPHASIS" 7552>REQ_PREV_FIELD</I 7553></SPAN 7554> 7555 Move to previous field. </P 7556></LI 7557><LI 7558><P 7559><SPAN 7560CLASS="emphasis" 7561><I 7562CLASS="EMPHASIS" 7563>REQ_FIRST_FIELD</I 7564></SPAN 7565> 7566 Move to the first field. </P 7567></LI 7568><LI 7569><P 7570><SPAN 7571CLASS="emphasis" 7572><I 7573CLASS="EMPHASIS" 7574>REQ_LAST_FIELD</I 7575></SPAN 7576> 7577 Move to the last field. </P 7578></LI 7579><LI 7580><P 7581><SPAN 7582CLASS="emphasis" 7583><I 7584CLASS="EMPHASIS" 7585>REQ_SNEXT_FIELD</I 7586></SPAN 7587> 7588 Move to sorted next field. </P 7589></LI 7590><LI 7591><P 7592><SPAN 7593CLASS="emphasis" 7594><I 7595CLASS="EMPHASIS" 7596>REQ_SPREV_FIELD</I 7597></SPAN 7598> 7599 Move to sorted previous field. </P 7600></LI 7601><LI 7602><P 7603><SPAN 7604CLASS="emphasis" 7605><I 7606CLASS="EMPHASIS" 7607>REQ_SFIRST_FIELD</I 7608></SPAN 7609> 7610 Move to the sorted first field. </P 7611></LI 7612><LI 7613><P 7614><SPAN 7615CLASS="emphasis" 7616><I 7617CLASS="EMPHASIS" 7618>REQ_SLAST_FIELD</I 7619></SPAN 7620> 7621 Move to the sorted last field. </P 7622></LI 7623><LI 7624><P 7625><SPAN 7626CLASS="emphasis" 7627><I 7628CLASS="EMPHASIS" 7629>REQ_LEFT_FIELD</I 7630></SPAN 7631> 7632 Move left to field. </P 7633></LI 7634><LI 7635><P 7636><SPAN 7637CLASS="emphasis" 7638><I 7639CLASS="EMPHASIS" 7640>REQ_RIGHT_FIELD</I 7641></SPAN 7642> 7643 Move right to field. </P 7644></LI 7645><LI 7646><P 7647><SPAN 7648CLASS="emphasis" 7649><I 7650CLASS="EMPHASIS" 7651>REQ_UP_FIELD</I 7652></SPAN 7653> 7654 Move up to field. </P 7655></LI 7656><LI 7657><P 7658><SPAN 7659CLASS="emphasis" 7660><I 7661CLASS="EMPHASIS" 7662>REQ_DOWN_FIELD</I 7663></SPAN 7664> 7665 Move down to field. </P 7666></LI 7667></UL 7668><P 7669>These requests treat the list of fields on a page as cyclic; that is, 7670REQ_NEXT_FIELD from the last field goes to the first, and REQ_PREV_FIELD 7671from the first field goes to the last. The order of the fields for these 7672(and the REQ_FIRST_FIELD and REQ_LAST_FIELD requests) is simply the order of 7673the field pointers in the form array (as set up by new_form() or 7674set_form_fields()</P 7675><P 7676>It is also possible to traverse the fields as if they had been sorted in 7677screen-position order, so the sequence goes left-to-right and top-to-bottom. 7678To do this, use the second group of four sorted-movement requests.</P 7679><P 7680>Finally, it is possible to move between fields using visual directions up, 7681down, right, and left. To accomplish this, use the third group of four 7682requests. Note, however, that the position of a form for purposes of these 7683requests is its upper-left corner.</P 7684><P 7685>For example, suppose you have a multi-line field B, and two single-line 7686fields A and C on the same line with B, with A to the left of B and C to the 7687right of B. A REQ_MOVE_RIGHT from A will go to B only if A, B, and C all 7688share the same first line; otherwise it will skip over B to C.</P 7689></DIV 7690><DIV 7691CLASS="SECT3" 7692><HR><H4 7693CLASS="SECT3" 7694><A 7695NAME="INTRAFIELDNAVREQ" 7696>18.6.3. Intra-Field Navigation Requests</A 7697></H4 7698><P 7699>These requests drive movement of the edit cursor within the currently 7700selected field.</P 7701><P 7702></P 7703><UL 7704><LI 7705><P 7706><SPAN 7707CLASS="emphasis" 7708><I 7709CLASS="EMPHASIS" 7710>REQ_NEXT_CHAR</I 7711></SPAN 7712> 7713 Move to next character. </P 7714></LI 7715><LI 7716><P 7717><SPAN 7718CLASS="emphasis" 7719><I 7720CLASS="EMPHASIS" 7721>REQ_PREV_CHAR</I 7722></SPAN 7723> 7724 Move to previous character. </P 7725></LI 7726><LI 7727><P 7728><SPAN 7729CLASS="emphasis" 7730><I 7731CLASS="EMPHASIS" 7732>REQ_NEXT_LINE</I 7733></SPAN 7734> 7735 Move to next line. </P 7736></LI 7737><LI 7738><P 7739><SPAN 7740CLASS="emphasis" 7741><I 7742CLASS="EMPHASIS" 7743>REQ_PREV_LINE</I 7744></SPAN 7745> 7746 Move to previous line. </P 7747></LI 7748><LI 7749><P 7750><SPAN 7751CLASS="emphasis" 7752><I 7753CLASS="EMPHASIS" 7754>REQ_NEXT_WORD</I 7755></SPAN 7756> 7757 Move to next word. </P 7758></LI 7759><LI 7760><P 7761><SPAN 7762CLASS="emphasis" 7763><I 7764CLASS="EMPHASIS" 7765>REQ_PREV_WORD</I 7766></SPAN 7767> 7768 Move to previous word. </P 7769></LI 7770><LI 7771><P 7772><SPAN 7773CLASS="emphasis" 7774><I 7775CLASS="EMPHASIS" 7776>REQ_BEG_FIELD</I 7777></SPAN 7778> 7779 Move to beginning of field. </P 7780></LI 7781><LI 7782><P 7783><SPAN 7784CLASS="emphasis" 7785><I 7786CLASS="EMPHASIS" 7787>REQ_END_FIELD</I 7788></SPAN 7789> 7790 Move to end of field. </P 7791></LI 7792><LI 7793><P 7794><SPAN 7795CLASS="emphasis" 7796><I 7797CLASS="EMPHASIS" 7798>REQ_BEG_LINE</I 7799></SPAN 7800> 7801 Move to beginning of line. </P 7802></LI 7803><LI 7804><P 7805><SPAN 7806CLASS="emphasis" 7807><I 7808CLASS="EMPHASIS" 7809>REQ_END_LINE</I 7810></SPAN 7811> 7812 Move to end of line. </P 7813></LI 7814><LI 7815><P 7816><SPAN 7817CLASS="emphasis" 7818><I 7819CLASS="EMPHASIS" 7820>REQ_LEFT_CHAR</I 7821></SPAN 7822> 7823 Move left in field. </P 7824></LI 7825><LI 7826><P 7827><SPAN 7828CLASS="emphasis" 7829><I 7830CLASS="EMPHASIS" 7831>REQ_RIGHT_CHAR</I 7832></SPAN 7833> 7834 Move right in field. </P 7835></LI 7836><LI 7837><P 7838><SPAN 7839CLASS="emphasis" 7840><I 7841CLASS="EMPHASIS" 7842>REQ_UP_CHAR</I 7843></SPAN 7844> 7845 Move up in field. </P 7846></LI 7847><LI 7848><P 7849><SPAN 7850CLASS="emphasis" 7851><I 7852CLASS="EMPHASIS" 7853>REQ_DOWN_CHAR</I 7854></SPAN 7855> 7856 Move down in field. </P 7857></LI 7858></UL 7859><P 7860>Each word is separated from the previous and next characters by whitespace. 7861The commands to move to beginning and end of line or field look for the 7862first or last non-pad character in their ranges.</P 7863></DIV 7864><DIV 7865CLASS="SECT3" 7866><HR><H4 7867CLASS="SECT3" 7868><A 7869NAME="SCROLLREQ" 7870>18.6.4. Scrolling Requests</A 7871></H4 7872><P 7873>Fields that are dynamic and have grown and fields explicitly created with 7874offscreen rows are scrollable. One-line fields scroll horizontally; 7875multi-line fields scroll vertically. Most scrolling is triggered by editing 7876and intra-field movement (the library scrolls the field to keep the cursor 7877visible). It is possible to explicitly request scrolling with the following 7878requests:</P 7879><P 7880></P 7881><UL 7882><LI 7883><P 7884><SPAN 7885CLASS="emphasis" 7886><I 7887CLASS="EMPHASIS" 7888>REQ_SCR_FLINE</I 7889></SPAN 7890> 7891 Scroll vertically forward a line. </P 7892></LI 7893><LI 7894><P 7895><SPAN 7896CLASS="emphasis" 7897><I 7898CLASS="EMPHASIS" 7899>REQ_SCR_BLINE</I 7900></SPAN 7901> 7902 Scroll vertically backward a line. </P 7903></LI 7904><LI 7905><P 7906><SPAN 7907CLASS="emphasis" 7908><I 7909CLASS="EMPHASIS" 7910>REQ_SCR_FPAGE</I 7911></SPAN 7912> 7913 Scroll vertically forward a page. </P 7914></LI 7915><LI 7916><P 7917><SPAN 7918CLASS="emphasis" 7919><I 7920CLASS="EMPHASIS" 7921>REQ_SCR_BPAGE</I 7922></SPAN 7923> 7924 Scroll vertically backward a page. </P 7925></LI 7926><LI 7927><P 7928><SPAN 7929CLASS="emphasis" 7930><I 7931CLASS="EMPHASIS" 7932>REQ_SCR_FHPAGE</I 7933></SPAN 7934> 7935 Scroll vertically forward half a page. </P 7936></LI 7937><LI 7938><P 7939><SPAN 7940CLASS="emphasis" 7941><I 7942CLASS="EMPHASIS" 7943>REQ_SCR_BHPAGE</I 7944></SPAN 7945> 7946 Scroll vertically backward half a page. </P 7947></LI 7948><LI 7949><P 7950><SPAN 7951CLASS="emphasis" 7952><I 7953CLASS="EMPHASIS" 7954>REQ_SCR_FCHAR</I 7955></SPAN 7956> 7957 Scroll horizontally forward a character. </P 7958></LI 7959><LI 7960><P 7961><SPAN 7962CLASS="emphasis" 7963><I 7964CLASS="EMPHASIS" 7965>REQ_SCR_BCHAR</I 7966></SPAN 7967> 7968 Scroll horizontally backward a character. </P 7969></LI 7970><LI 7971><P 7972><SPAN 7973CLASS="emphasis" 7974><I 7975CLASS="EMPHASIS" 7976>REQ_SCR_HFLINE</I 7977></SPAN 7978> 7979 Scroll horizontally one field width forward. </P 7980></LI 7981><LI 7982><P 7983><SPAN 7984CLASS="emphasis" 7985><I 7986CLASS="EMPHASIS" 7987>REQ_SCR_HBLINE</I 7988></SPAN 7989> 7990 Scroll horizontally one field width backward. </P 7991></LI 7992><LI 7993><P 7994><SPAN 7995CLASS="emphasis" 7996><I 7997CLASS="EMPHASIS" 7998>REQ_SCR_HFHALF</I 7999></SPAN 8000> 8001 Scroll horizontally one half field width forward. </P 8002></LI 8003><LI 8004><P 8005><SPAN 8006CLASS="emphasis" 8007><I 8008CLASS="EMPHASIS" 8009>REQ_SCR_HBHALF</I 8010></SPAN 8011> 8012 Scroll horizontally one half field width backward. </P 8013></LI 8014></UL 8015><P 8016>For scrolling purposes, a page of a field is the height of its visible part.</P 8017></DIV 8018><DIV 8019CLASS="SECT3" 8020><HR><H4 8021CLASS="SECT3" 8022><A 8023NAME="EDITREQ" 8024>18.6.5. Editing Requests</A 8025></H4 8026><P 8027>When you pass the forms driver an ASCII character, it is treated as a 8028request to add the character to the field's data buffer. Whether this is an 8029insertion or a replacement depends on the field's edit mode (insertion is 8030the default.</P 8031><P 8032>The following requests support editing the field and changing the edit mode:</P 8033><P 8034></P 8035><UL 8036><LI 8037><P 8038><SPAN 8039CLASS="emphasis" 8040><I 8041CLASS="EMPHASIS" 8042>REQ_INS_MODE</I 8043></SPAN 8044> 8045 Set insertion mode. </P 8046></LI 8047><LI 8048><P 8049><SPAN 8050CLASS="emphasis" 8051><I 8052CLASS="EMPHASIS" 8053>REQ_OVL_MODE</I 8054></SPAN 8055> 8056 Set overlay mode. </P 8057></LI 8058><LI 8059><P 8060><SPAN 8061CLASS="emphasis" 8062><I 8063CLASS="EMPHASIS" 8064>REQ_NEW_LINE</I 8065></SPAN 8066> 8067 New line request (see below for explanation). </P 8068></LI 8069><LI 8070><P 8071><SPAN 8072CLASS="emphasis" 8073><I 8074CLASS="EMPHASIS" 8075>REQ_INS_CHAR</I 8076></SPAN 8077> 8078 Insert space at character location. </P 8079></LI 8080><LI 8081><P 8082><SPAN 8083CLASS="emphasis" 8084><I 8085CLASS="EMPHASIS" 8086>REQ_INS_LINE</I 8087></SPAN 8088> 8089 Insert blank line at character location. </P 8090></LI 8091><LI 8092><P 8093><SPAN 8094CLASS="emphasis" 8095><I 8096CLASS="EMPHASIS" 8097>REQ_DEL_CHAR</I 8098></SPAN 8099> 8100 Delete character at cursor. </P 8101></LI 8102><LI 8103><P 8104><SPAN 8105CLASS="emphasis" 8106><I 8107CLASS="EMPHASIS" 8108>REQ_DEL_PREV</I 8109></SPAN 8110> 8111 Delete previous word at cursor. </P 8112></LI 8113><LI 8114><P 8115><SPAN 8116CLASS="emphasis" 8117><I 8118CLASS="EMPHASIS" 8119>REQ_DEL_LINE</I 8120></SPAN 8121> 8122 Delete line at cursor. </P 8123></LI 8124><LI 8125><P 8126><SPAN 8127CLASS="emphasis" 8128><I 8129CLASS="EMPHASIS" 8130>REQ_DEL_WORD</I 8131></SPAN 8132> 8133 Delete word at cursor. </P 8134></LI 8135><LI 8136><P 8137><SPAN 8138CLASS="emphasis" 8139><I 8140CLASS="EMPHASIS" 8141>REQ_CLR_EOL</I 8142></SPAN 8143> 8144 Clear to end of line. </P 8145></LI 8146><LI 8147><P 8148><SPAN 8149CLASS="emphasis" 8150><I 8151CLASS="EMPHASIS" 8152>REQ_CLR_EOF</I 8153></SPAN 8154> 8155 Clear to end of field. </P 8156></LI 8157><LI 8158><P 8159><SPAN 8160CLASS="emphasis" 8161><I 8162CLASS="EMPHASIS" 8163>REQ_CLR_FIELD</I 8164></SPAN 8165> 8166 Clear entire field. </P 8167></LI 8168></UL 8169><P 8170>The behavior of the REQ_NEW_LINE and REQ_DEL_PREV requests is complicated 8171and partly controlled by a pair of forms options. The special cases are 8172triggered when the cursor is at the beginning of a field, or on the last 8173line of the field.</P 8174><P 8175>First, we consider REQ_NEW_LINE:</P 8176><P 8177>The normal behavior of REQ_NEW_LINE in insert mode is to break the current 8178line at the position of the edit cursor, inserting the portion of the 8179current line after the cursor as a new line following the current and moving 8180the cursor to the beginning of that new line (you may think of this as 8181inserting a newline in the field buffer).</P 8182><P 8183>The normal behavior of REQ_NEW_LINE in overlay mode is to clear the current 8184line from the position of the edit cursor to end of line. The cursor is then 8185moved to the beginning of the next line.</P 8186><P 8187>However, REQ_NEW_LINE at the beginning of a field, or on the last line of a 8188field, instead does a REQ_NEXT_FIELD. O_NL_OVERLOAD option is off, this 8189special action is disabled.</P 8190><P 8191>Now, let us consider REQ_DEL_PREV:</P 8192><P 8193>The normal behavior of REQ_DEL_PREV is to delete the previous character. If 8194insert mode is on, and the cursor is at the start of a line, and the text on 8195that line will fit on the previous one, it instead appends the contents of 8196the current line to the previous one and deletes the current line (you may 8197think of this as deleting a newline from the field buffer).</P 8198><P 8199>However, REQ_DEL_PREV at the beginning of a field is instead treated as a 8200REQ_PREV_FIELD.</P 8201><P 8202>If the O_BS_OVERLOAD option is off, this special action is disabled and the 8203forms driver just returns E_REQUEST_DENIED.</P 8204></DIV 8205><DIV 8206CLASS="SECT3" 8207><HR><H4 8208CLASS="SECT3" 8209><A 8210NAME="ORDERREQ" 8211>18.6.6. Order Requests</A 8212></H4 8213><P 8214>If the type of your field is ordered, and has associated functions for 8215getting the next and previous values of the type from a given value, there 8216are requests that can fetch that value into the field buffer:</P 8217><P 8218></P 8219><UL 8220><LI 8221><P 8222><SPAN 8223CLASS="emphasis" 8224><I 8225CLASS="EMPHASIS" 8226>REQ_NEXT_CHOICE</I 8227></SPAN 8228> 8229 Place the successor value of the current value in the buffer. 8230 </P 8231></LI 8232><LI 8233><P 8234><SPAN 8235CLASS="emphasis" 8236><I 8237CLASS="EMPHASIS" 8238>REQ_PREV_CHOICE</I 8239></SPAN 8240> 8241 Place the predecessor value of the current value in the buffer. 8242 </P 8243></LI 8244></UL 8245><P 8246>Of the built-in field types, only TYPE_ENUM has built-in successor and 8247predecessor functions. When you define a field type of your own (see Custom 8248Validation Types), you can associate our own ordering functions.</P 8249></DIV 8250><DIV 8251CLASS="SECT3" 8252><HR><H4 8253CLASS="SECT3" 8254><A 8255NAME="APPLICCOMMANDS" 8256>18.6.7. Application Commands</A 8257></H4 8258><P 8259>Form requests are represented as integers above the curses value greater than 8260KEY_MAX and less than or equal to the constant MAX_COMMAND. A value within this 8261range gets ignored by form_driver(). So this can be used for any purpose by the 8262application. It can be treated as an application specific action and take 8263corresponding action.</P 8264></DIV 8265></DIV 8266></DIV 8267><DIV 8268CLASS="SECT1" 8269><HR><H2 8270CLASS="SECT1" 8271><A 8272NAME="TOOLS" 8273>19. Tools and Widget Libraries</A 8274></H2 8275><P 8276> 8277Now that you have seen the capabilities of ncurses and its sister libraries, you 8278are rolling your sleeves up and gearing for a project that heavily manipulates 8279screen. But wait.. It can be pretty difficult to write and maintain complex GUI 8280widgets in plain ncurses or even with the additional libraries. There are some 8281ready-to-use tools and widget libraries that can be used instead of writing your 8282own widgets. You can use some of them, get ideas from the code, or even extend 8283them.</P 8284><DIV 8285CLASS="SECT2" 8286><HR><H3 8287CLASS="SECT2" 8288><A 8289NAME="CDK" 8290>19.1. CDK (Curses Development Kit)</A 8291></H3 8292><P 8293>In the author's words </P 8294><P 8295><SPAN 8296CLASS="emphasis" 8297><I 8298CLASS="EMPHASIS" 8299> 8300CDK stands for 'Curses Development Kit' and it currently contains 21 ready 8301to use widgets which facilitate the speedy development of full screen 8302curses programs. </I 8303></SPAN 8304></P 8305><P 8306>The kit provides some useful widgets, which can be used in your programs 8307directly. It's pretty well written and the documentation is very good. The 8308examples in the examples directory can be a good place to start for beginners. 8309The CDK can be downloaded from <A 8310HREF="http://invisible-island.net/cdk/" 8311TARGET="_top" 8312>http://invisible-island.net/cdk/</A 8313> 8314. Follow the instructions in 8315README file to install it.</P 8316><DIV 8317CLASS="SECT3" 8318><HR><H4 8319CLASS="SECT3" 8320><A 8321NAME="WIDGETLIST" 8322>19.1.1. Widget List</A 8323></H4 8324><P 8325>The following is the list of widgets provided with cdk and their description.</P 8326><PRE 8327CLASS="PROGRAMLISTING" 8328>Widget Type Quick Description 8329=========================================================================== 8330Alphalist Allows a user to select from a list of words, with 8331 the ability to narrow the search list by typing in a 8332 few characters of the desired word. 8333Buttonbox This creates a multiple button widget. 8334Calendar Creates a little simple calendar widget. 8335Dialog Prompts the user with a message, and the user 8336 can pick an answer from the buttons provided. 8337Entry Allows the user to enter various types of information. 8338File Selector A file selector built from Cdk base widgets. This 8339 example shows how to create more complicated widgets 8340 using the Cdk widget library. 8341Graph Draws a graph. 8342Histogram Draws a histogram. 8343Item List Creates a pop up field which allows the user to select 8344 one of several choices in a small field. Very useful 8345 for things like days of the week or month names. 8346Label Displays messages in a pop up box, or the label can be 8347 considered part of the screen. 8348Marquee Displays a message in a scrolling marquee. 8349Matrix Creates a complex matrix with lots of options. 8350Menu Creates a pull-down menu interface. 8351Multiple Line Entry A multiple line entry field. Very useful 8352 for long fields. (like a description 8353 field) 8354Radio List Creates a radio button list. 8355Scale Creates a numeric scale. Used for allowing a user to 8356 pick a numeric value and restrict them to a range of 8357 values. 8358Scrolling List Creates a scrolling list/menu list. 8359Scrolling Window Creates a scrolling log file viewer. Can add 8360 information into the window while its running. 8361 A good widget for displaying the progress of 8362 something. (akin to a console window) 8363Selection List Creates a multiple option selection list. 8364Slider Akin to the scale widget, this widget provides a 8365 visual slide bar to represent the numeric value. 8366Template Creates a entry field with character sensitive 8367 positions. Used for pre-formatted fields like 8368 dates and phone numbers. 8369Viewer This is a file/information viewer. Very useful 8370 when you need to display loads of information. 8371===========================================================================</PRE 8372><P 8373>A few of the widgets are modified by Thomas Dickey in recent versions.</P 8374></DIV 8375><DIV 8376CLASS="SECT3" 8377><HR><H4 8378CLASS="SECT3" 8379><A 8380NAME="CDKATTRACT" 8381>19.1.2. Some Attractive Features</A 8382></H4 8383><P 8384>Apart from making our life easier with readily usable widgets, cdk solves one 8385frustrating problem with printing multi colored strings, justified strings 8386elegantly. Special formatting tags can be embedded in the strings which are 8387passed to CDK functions. For Example</P 8388><P 8389>If the string</P 8390><PRE 8391CLASS="PROGRAMLISTING" 8392>"</B/1>This line should have a yellow foreground and a blue 8393background.<!1>"</PRE 8394><P 8395>given as a parameter to newCDKLabel(), it prints the line with yellow foreground 8396and blue background. There are other tags available for justifying string, 8397embedding special drawing characters etc.. Please refer to the man page 8398cdk_display(3X) for details. The man page explains the usage with nice examples.</P 8399></DIV 8400><DIV 8401CLASS="SECT3" 8402><HR><H4 8403CLASS="SECT3" 8404><A 8405NAME="CDKCONCLUSION" 8406>19.1.3. Conclusion</A 8407></H4 8408><P 8409>All in all, CDK is a well-written package of widgets, which if used properly can 8410form a strong frame work for developing complex GUI.</P 8411></DIV 8412></DIV 8413><DIV 8414CLASS="SECT2" 8415><HR><H3 8416CLASS="SECT2" 8417><A 8418NAME="DIALOG" 8419>19.2. The dialog</A 8420></H3 8421><P 8422>Long long ago, in September 1994, when few people knew linux, Jeff Tranter wrote 8423an <A 8424HREF="http://www2.linuxjournal.com/lj-issues/issue5/2807.html" 8425TARGET="_top" 8426>article</A 8427> on dialog in Linux Journal. He starts the article with these words..</P 8428><P 8429><SPAN 8430CLASS="emphasis" 8431><I 8432CLASS="EMPHASIS" 8433>Linux is based on the Unix operating system, but also features a number of 8434unique and useful kernel features and application programs that often go beyond 8435what is available under Unix. One little-known gem is "dialog", a utility for 8436creating professional-looking dialog boxes from within shell scripts. This 8437article presents a tutorial introduction to the dialog utility, and shows 8438examples of how and where it can be used</I 8439></SPAN 8440></P 8441><P 8442> 8443As he explains, dialog is a real gem in making professional-looking dialog boxes 8444with ease. It creates a variety of dialog boxes, menus, check lists etc.. It is 8445usually installed by default. If not, you can download it from <A 8446HREF="http://invisible-island.net/dialog/" 8447TARGET="_top" 8448>Thomas Dickey</A 8449>'s site. </P 8450><P 8451>The above-mentioned article gives a very good overview of its uses and 8452capabilites. The man page has more details. It can be used in variety of 8453situations. One good example is building of linux kernel in text mode. Linux 8454kernel uses a modified version of dialog tailored for its needs. </P 8455><P 8456>dialog was initially designed to be used with shell scripts. If you want to use 8457its functionality in a c program, then you can use libdialog. The documentation 8458regarding this is sparse. Definitive reference is the dialog.h header file which 8459comes with the library. You may need to hack here and there to get the required 8460output. The source is easily customizable. I have used it on a number of 8461occasions by modifying the code.</P 8462></DIV 8463><DIV 8464CLASS="SECT2" 8465><HR><H3 8466CLASS="SECT2" 8467><A 8468NAME="PERLCURSES" 8469>19.3. Perl Curses Modules CURSES::FORM and CURSES::WIDGETS</A 8470></H3 8471><P 8472>The perl module Curses, Curses::Form and Curses::Widgets give access to curses 8473from perl. If you have curses and basic perl is installed, you can get these 8474modules from <A 8475HREF="http://www.cpan.org/modules/01modules.index.html" 8476TARGET="_top" 8477> CPAN 8478All Modules page</A 8479>. Get the three zipped modules in the Curses category. 8480Once installed you can use these modules from perl scripts like any other 8481module. For more information on perl modules see perlmod man page. The above 8482modules come with good documentation and they have some demo scripts to test the 8483functionality. Though the widgets provided are very rudimentary, these modules 8484provide good access to curses library from perl.</P 8485><P 8486>Some of my code examples are converted to perl by Anuradha Ratnaweera and they 8487are available in the <TT 8488CLASS="LITERAL" 8489>perl</TT 8490> directory.</P 8491><P 8492> 8493For more information see man pages Curses(3) , Curses::Form(3) and 8494Curses::Widgets(3). These pages are installed only when the above modules are 8495acquired and installed.</P 8496></DIV 8497></DIV 8498><DIV 8499CLASS="SECT1" 8500><HR><H2 8501CLASS="SECT1" 8502><A 8503NAME="JUSTFORFUN" 8504>20. Just For Fun !!!</A 8505></H2 8506><P 8507>This section contains few programs written by me just for fun. They don't 8508signify a better programming practice or the best way of using ncurses. They are 8509provided here so as to allow beginners to get ideas and add more programs to 8510this section. If you have written a couple of nice, simple programs in curses 8511and want them to included here, contact <A 8512HREF="mailto:ppadala@gmail.com" 8513TARGET="_top" 8514>me</A 8515>.</P 8516><DIV 8517CLASS="SECT2" 8518><HR><H3 8519CLASS="SECT2" 8520><A 8521NAME="GAMEOFLIFE" 8522>20.1. The Game of Life</A 8523></H3 8524><P 8525>Game of life is a wonder of math. In 8526<A 8527HREF="http://www.math.com/students/wonders/life/life.html" 8528TARGET="_top" 8529>Paul Callahan</A 8530>'s words</P 8531><PRE 8532CLASS="PROGRAMLISTING" 8533><SPAN 8534CLASS="emphasis" 8535><I 8536CLASS="EMPHASIS" 8537>The Game of Life (or simply Life) is not a game in the conventional sense. There 8538are no players, and no winning or losing. Once the "pieces" are placed in the 8539starting position, the rules determine everything that happens later. 8540Nevertheless, Life is full of surprises! In most cases, it is impossible to look 8541at a starting position (or pattern) and see what will happen in the future. The 8542only way to find out is to follow the rules of the game.</I 8543></SPAN 8544></PRE 8545><P 8546>This program starts with a simple inverted U pattern and shows how wonderful 8547life works. There is a lot of room for improvement in the program. You can let 8548the user enter pattern of his choice or even take input from a file. You can 8549also change rules and play with a lot of variations. Search on <A 8550HREF="http://www.google.com" 8551TARGET="_top" 8552>google</A 8553> for interesting information on game 8554of life.</P 8555><P 8556><SPAN 8557CLASS="emphasis" 8558><I 8559CLASS="EMPHASIS" 8560>File Path: JustForFun/life.c</I 8561></SPAN 8562></P 8563></DIV 8564><DIV 8565CLASS="SECT2" 8566><HR><H3 8567CLASS="SECT2" 8568><A 8569NAME="MAGIC" 8570>20.2. Magic Square</A 8571></H3 8572><P 8573>Magic Square, another wonder of math, is very simple to understand but very 8574difficult to make. In a magic square sum of the numbers in each row, each column 8575is equal. Even diagnol sum can be equal. There are many variations which have 8576special properties.</P 8577><P 8578>This program creates a simple magic square of odd order.</P 8579><P 8580><SPAN 8581CLASS="emphasis" 8582><I 8583CLASS="EMPHASIS" 8584>File Path: JustForFun/magic.c</I 8585></SPAN 8586></P 8587></DIV 8588><DIV 8589CLASS="SECT2" 8590><HR><H3 8591CLASS="SECT2" 8592><A 8593NAME="HANOI" 8594>20.3. Towers of Hanoi</A 8595></H3 8596><P 8597>The famous towers of hanoi solver. The aim of the game is to move the disks on 8598the first peg to last peg, using middle peg as a temporary stay. The catch is 8599not to place a larger disk over a small disk at any time.</P 8600><P 8601><SPAN 8602CLASS="emphasis" 8603><I 8604CLASS="EMPHASIS" 8605>File Path: JustForFun/hanoi.c</I 8606></SPAN 8607></P 8608></DIV 8609><DIV 8610CLASS="SECT2" 8611><HR><H3 8612CLASS="SECT2" 8613><A 8614NAME="QUEENS" 8615>20.4. Queens Puzzle</A 8616></H3 8617><P 8618>The objective of the famous N-Queen puzzle is to put N queens on a N X N chess 8619board without attacking each other. </P 8620><P 8621>This program solves it with a simple backtracking technique.</P 8622><P 8623><SPAN 8624CLASS="emphasis" 8625><I 8626CLASS="EMPHASIS" 8627>File Path: JustForFun/queens.c</I 8628></SPAN 8629></P 8630></DIV 8631><DIV 8632CLASS="SECT2" 8633><HR><H3 8634CLASS="SECT2" 8635><A 8636NAME="SHUFFLE" 8637>20.5. Shuffle</A 8638></H3 8639><P 8640>A fun game, if you have time to kill. </P 8641><P 8642><SPAN 8643CLASS="emphasis" 8644><I 8645CLASS="EMPHASIS" 8646>File Path: JustForFun/shuffle.c</I 8647></SPAN 8648></P 8649></DIV 8650><DIV 8651CLASS="SECT2" 8652><HR><H3 8653CLASS="SECT2" 8654><A 8655NAME="TT" 8656>20.6. Typing Tutor</A 8657></H3 8658><P 8659>A simple typing tutor, I created more out of need than for ease of use. If you 8660know how to put your fingers correctly on the keyboard, but lack practice, this 8661can be helpful. </P 8662><P 8663><SPAN 8664CLASS="emphasis" 8665><I 8666CLASS="EMPHASIS" 8667>File Path: JustForFun/tt.c</I 8668></SPAN 8669></P 8670></DIV 8671></DIV 8672><DIV 8673CLASS="SECT1" 8674><HR><H2 8675CLASS="SECT1" 8676><A 8677NAME="REF" 8678>21. References</A 8679></H2 8680><P 8681></P 8682><UL 8683><LI 8684><P 8685>NCURSES man pages </P 8686></LI 8687><LI 8688><P 8689>NCURSES FAQ at <A 8690HREF="http://invisible-island.net/ncurses/ncurses.faq.html" 8691TARGET="_top" 8692>http://invisible-island.net/ncurses/ncurses.faq.html</A 8693> 8694 </P 8695></LI 8696><LI 8697><P 8698>Writing programs with NCURSES by Eric Raymond and Zeyd M. 8699Ben-Halim at 8700<A 8701HREF="http://invisible-island.net/ncurses/ncurses-intro.html" 8702TARGET="_top" 8703>http://invisible-island.net/ncurses/ncurses-intro.html</A 8704> - somewhat 8705obsolete. I was inspired by this document and the structure of this HOWTO 8706follows from the original document</P 8707></LI 8708></UL 8709></DIV 8710></DIV 8711></BODY 8712></HTML 8713>