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