1/* 2 * Copyright (C) 1984-2007 Mark Nudelman 3 * 4 * You may distribute under the terms of either the GNU General Public 5 * License or the Less License, as specified in the README file. 6 * 7 * For more information about less, or for information on how to 8 * contact the author, see the README file. 9 */ 10 11 12/* 13 * Routines which jump to a new location in the file. 14 */ 15 16#include "less.h" 17#include "position.h" 18 19extern int hit_eof; 20extern int jump_sline; 21extern int squished; 22extern int screen_trashed; 23extern int sc_width, sc_height; 24extern int show_attn; 25extern int top_scroll; 26 27/* 28 * Jump to the end of the file. 29 */ 30 public void 31jump_forw() 32{ 33 POSITION pos; 34 POSITION end_pos; 35 36 if (ch_end_seek()) 37 { 38 error("Cannot seek to end of file", NULL_PARG); 39 return; 40 } 41 /* 42 * Position the last line in the file at the last screen line. 43 * Go back one line from the end of the file 44 * to get to the beginning of the last line. 45 */ 46 lastmark(); 47 pos_clear(); 48 end_pos = ch_tell(); 49 pos = back_line(end_pos); 50 if (pos == NULL_POSITION) 51 jump_loc((POSITION)0, sc_height-1); 52 else 53 { 54 jump_loc(pos, sc_height-1); 55 if (position(sc_height-1) != end_pos) 56 repaint(); 57 } 58} 59 60/* 61 * Jump to line n in the file. 62 */ 63 public void 64jump_back(linenum) 65 LINENUM linenum; 66{ 67 POSITION pos; 68 PARG parg; 69 70 /* 71 * Find the position of the specified line. 72 * If we can seek there, just jump to it. 73 * If we can't seek, but we're trying to go to line number 1, 74 * use ch_beg_seek() to get as close as we can. 75 */ 76 pos = find_pos(linenum); 77 if (pos != NULL_POSITION && ch_seek(pos) == 0) 78 { 79 if (show_attn) 80 set_attnpos(pos); 81 jump_loc(pos, jump_sline); 82 } else if (linenum <= 1 && ch_beg_seek() == 0) 83 { 84 jump_loc(ch_tell(), jump_sline); 85 error("Cannot seek to beginning of file", NULL_PARG); 86 } else 87 { 88 parg.p_linenum = linenum; 89 error("Cannot seek to line number %n", &parg); 90 } 91} 92 93/* 94 * Repaint the screen. 95 */ 96 public void 97repaint() 98{ 99 struct scrpos scrpos; 100 /* 101 * Start at the line currently at the top of the screen 102 * and redisplay the screen. 103 */ 104 get_scrpos(&scrpos); 105 pos_clear(); 106 jump_loc(scrpos.pos, scrpos.ln); 107} 108 109/* 110 * Jump to a specified percentage into the file. 111 */ 112 public void 113jump_percent(percent, fraction) 114 int percent; 115 long fraction; 116{ 117 POSITION pos, len; 118 119 /* 120 * Determine the position in the file 121 * (the specified percentage of the file's length). 122 */ 123 if ((len = ch_length()) == NULL_POSITION) 124 { 125 ierror("Determining length of file", NULL_PARG); 126 ch_end_seek(); 127 } 128 if ((len = ch_length()) == NULL_POSITION) 129 { 130 error("Don't know length of file", NULL_PARG); 131 return; 132 } 133 pos = percent_pos(len, percent, fraction); 134 if (pos >= len) 135 pos = len-1; 136 137 jump_line_loc(pos, jump_sline); 138} 139 140/* 141 * Jump to a specified position in the file. 142 * Like jump_loc, but the position need not be 143 * the first character in a line. 144 */ 145 public void 146jump_line_loc(pos, sline) 147 POSITION pos; 148 int sline; 149{ 150 int c; 151 152 if (ch_seek(pos) == 0) 153 { 154 /* 155 * Back up to the beginning of the line. 156 */ 157 while ((c = ch_back_get()) != '\n' && c != EOI) 158 ; 159 if (c == '\n') 160 (void) ch_forw_get(); 161 pos = ch_tell(); 162 } 163 if (show_attn) 164 set_attnpos(pos); 165 jump_loc(pos, sline); 166} 167 168/* 169 * Jump to a specified position in the file. 170 * The position must be the first character in a line. 171 * Place the target line on a specified line on the screen. 172 */ 173 public void 174jump_loc(pos, sline) 175 POSITION pos; 176 int sline; 177{ 178 register int nline; 179 POSITION tpos; 180 POSITION bpos; 181 182 /* 183 * Normalize sline. 184 */ 185 sline = adjsline(sline); 186 187 if ((nline = onscreen(pos)) >= 0) 188 { 189 /* 190 * The line is currently displayed. 191 * Just scroll there. 192 */ 193 nline -= sline; 194 if (nline > 0) 195 forw(nline, position(BOTTOM_PLUS_ONE), 1, 0, 0); 196 else 197 back(-nline, position(TOP), 1, 0); 198 if (show_attn) 199 repaint_hilite(1); 200 return; 201 } 202 203 /* 204 * Line is not on screen. 205 * Seek to the desired location. 206 */ 207 if (ch_seek(pos)) 208 { 209 error("Cannot seek to that file position", NULL_PARG); 210 return; 211 } 212 213 /* 214 * See if the desired line is before or after 215 * the currently displayed screen. 216 */ 217 tpos = position(TOP); 218 bpos = position(BOTTOM_PLUS_ONE); 219 if (tpos == NULL_POSITION || pos >= tpos) 220 { 221 /* 222 * The desired line is after the current screen. 223 * Move back in the file far enough so that we can 224 * call forw() and put the desired line at the 225 * sline-th line on the screen. 226 */ 227 for (nline = 0; nline < sline; nline++) 228 { 229 if (bpos != NULL_POSITION && pos <= bpos) 230 { 231 /* 232 * Surprise! The desired line is 233 * close enough to the current screen 234 * that we can just scroll there after all. 235 */ 236 forw(sc_height-sline+nline-1, bpos, 1, 0, 0); 237 if (show_attn) 238 repaint_hilite(1); 239 return; 240 } 241 pos = back_line(pos); 242 if (pos == NULL_POSITION) 243 { 244 /* 245 * Oops. Ran into the beginning of the file. 246 * Exit the loop here and rely on forw() 247 * below to draw the required number of 248 * blank lines at the top of the screen. 249 */ 250 break; 251 } 252 } 253 lastmark(); 254 hit_eof = 0; 255 squished = 0; 256 screen_trashed = 0; 257 forw(sc_height-1, pos, 1, 0, sline-nline); 258 } else 259 { 260 /* 261 * The desired line is before the current screen. 262 * Move forward in the file far enough so that we 263 * can call back() and put the desired line at the 264 * sline-th line on the screen. 265 */ 266 for (nline = sline; nline < sc_height - 1; nline++) 267 { 268 pos = forw_line(pos); 269 if (pos == NULL_POSITION) 270 { 271 /* 272 * Ran into end of file. 273 * This shouldn't normally happen, 274 * but may if there is some kind of read error. 275 */ 276 break; 277 } 278 if (pos >= tpos) 279 { 280 /* 281 * Surprise! The desired line is 282 * close enough to the current screen 283 * that we can just scroll there after all. 284 */ 285 back(nline+1, tpos, 1, 0); 286 if (show_attn) 287 repaint_hilite(1); 288 return; 289 } 290 } 291 lastmark(); 292 if (!top_scroll) 293 clear(); 294 else 295 home(); 296 screen_trashed = 0; 297 add_back_pos(pos); 298 back(sc_height-1, pos, 1, 0); 299 } 300} 301