1 /* $NetBSD: jump.c,v 1.4 2013/09/04 20:02:10 tron Exp $ */
2
3 /*
4 * Copyright (C) 1984-2012 Mark Nudelman
5 *
6 * You may distribute under the terms of either the GNU General Public
7 * License or the Less License, as specified in the README file.
8 *
9 * For more information, see the README file.
10 */
11
12
13 /*
14 * Routines which jump to a new location in the file.
15 */
16
17 #include "less.h"
18 #include "position.h"
19
20 extern int jump_sline;
21 extern int squished;
22 extern int screen_trashed;
23 extern int sc_width, sc_height;
24 extern int show_attn;
25 extern int top_scroll;
26
27 /*
28 * Jump to the end of the file.
29 */
30 public void
jump_forw()31 jump_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 * Note; lastmark will be called later by jump_loc, but it fails
43 * because the position table has been cleared by pos_clear below.
44 * So call it here before calling pos_clear.
45 */
46 lastmark();
47 /*
48 * Position the last line in the file at the last screen line.
49 * Go back one line from the end of the file
50 * to get to the beginning of the last line.
51 */
52 pos_clear();
53 end_pos = ch_tell();
54 pos = back_line(end_pos);
55 if (pos == NULL_POSITION)
56 jump_loc((POSITION)0, sc_height-1);
57 else
58 {
59 jump_loc(pos, sc_height-1);
60 if (position(sc_height-1) != end_pos)
61 repaint();
62 }
63 }
64
65 /*
66 * Jump to line n in the file.
67 */
68 public void
jump_back(linenum)69 jump_back(linenum)
70 LINENUM linenum;
71 {
72 POSITION pos;
73 PARG parg;
74
75 /*
76 * Find the position of the specified line.
77 * If we can seek there, just jump to it.
78 * If we can't seek, but we're trying to go to line number 1,
79 * use ch_beg_seek() to get as close as we can.
80 */
81 pos = find_pos(linenum);
82 if (pos != NULL_POSITION && ch_seek(pos) == 0)
83 {
84 if (show_attn)
85 set_attnpos(pos);
86 jump_loc(pos, jump_sline);
87 } else if (linenum <= 1 && ch_beg_seek() == 0)
88 {
89 jump_loc(ch_tell(), jump_sline);
90 error("Cannot seek to beginning of file", NULL_PARG);
91 } else
92 {
93 parg.p_linenum = linenum;
94 error("Cannot seek to line number %n", &parg);
95 }
96 }
97
98 /*
99 * Repaint the screen.
100 */
101 public void
repaint()102 repaint()
103 {
104 struct scrpos scrpos;
105 /*
106 * Start at the line currently at the top of the screen
107 * and redisplay the screen.
108 */
109 get_scrpos(&scrpos);
110 pos_clear();
111 jump_loc(scrpos.pos, scrpos.ln);
112 }
113
114 /*
115 * Jump to a specified percentage into the file.
116 */
117 public void
jump_percent(percent,fraction)118 jump_percent(percent, fraction)
119 int percent;
120 long fraction;
121 {
122 POSITION pos, len;
123
124 /*
125 * Determine the position in the file
126 * (the specified percentage of the file's length).
127 */
128 if ((len = ch_length()) == NULL_POSITION)
129 {
130 ierror("Determining length of file", NULL_PARG);
131 ch_end_seek();
132 }
133 if ((len = ch_length()) == NULL_POSITION)
134 {
135 error("Don't know length of file", NULL_PARG);
136 return;
137 }
138 pos = percent_pos(len, percent, fraction);
139 if (pos >= len)
140 pos = len-1;
141
142 jump_line_loc(pos, jump_sline);
143 }
144
145 /*
146 * Jump to a specified position in the file.
147 * Like jump_loc, but the position need not be
148 * the first character in a line.
149 */
150 public void
jump_line_loc(pos,sline)151 jump_line_loc(pos, sline)
152 POSITION pos;
153 int sline;
154 {
155 int c;
156
157 if (ch_seek(pos) == 0)
158 {
159 /*
160 * Back up to the beginning of the line.
161 */
162 while ((c = ch_back_get()) != '\n' && c != EOI)
163 ;
164 if (c == '\n')
165 (void) ch_forw_get();
166 pos = ch_tell();
167 }
168 if (show_attn)
169 set_attnpos(pos);
170 jump_loc(pos, sline);
171 }
172
173 /*
174 * Jump to a specified position in the file.
175 * The position must be the first character in a line.
176 * Place the target line on a specified line on the screen.
177 */
178 public void
jump_loc(pos,sline)179 jump_loc(pos, sline)
180 POSITION pos;
181 int sline;
182 {
183 register int nline;
184 POSITION tpos;
185 POSITION bpos;
186
187 /*
188 * Normalize sline.
189 */
190 sline = adjsline(sline);
191
192 if ((nline = onscreen(pos)) >= 0)
193 {
194 /*
195 * The line is currently displayed.
196 * Just scroll there.
197 */
198 nline -= sline;
199 if (nline > 0)
200 forw(nline, position(BOTTOM_PLUS_ONE), 1, 0, 0);
201 else if (nline < 0)
202 back(-nline, position(TOP), 1, 0);
203 #if HILITE_SEARCH
204 if (show_attn)
205 repaint_hilite(1);
206 #endif
207 return;
208 }
209
210 /*
211 * Line is not on screen.
212 * Seek to the desired location.
213 */
214 if (ch_seek(pos))
215 {
216 error("Cannot seek to that file position", NULL_PARG);
217 return;
218 }
219
220 /*
221 * See if the desired line is before or after
222 * the currently displayed screen.
223 */
224 tpos = position(TOP);
225 bpos = position(BOTTOM_PLUS_ONE);
226 if (tpos == NULL_POSITION || pos >= tpos)
227 {
228 /*
229 * The desired line is after the current screen.
230 * Move back in the file far enough so that we can
231 * call forw() and put the desired line at the
232 * sline-th line on the screen.
233 */
234 for (nline = 0; nline < sline; nline++)
235 {
236 if (bpos != NULL_POSITION && pos <= bpos)
237 {
238 /*
239 * Surprise! The desired line is
240 * close enough to the current screen
241 * that we can just scroll there after all.
242 */
243 forw(sc_height-sline+nline-1, bpos, 1, 0, 0);
244 #if HILITE_SEARCH
245 if (show_attn)
246 repaint_hilite(1);
247 #endif
248 return;
249 }
250 pos = back_line(pos);
251 if (pos == NULL_POSITION)
252 {
253 /*
254 * Oops. Ran into the beginning of the file.
255 * Exit the loop here and rely on forw()
256 * below to draw the required number of
257 * blank lines at the top of the screen.
258 */
259 break;
260 }
261 }
262 lastmark();
263 squished = 0;
264 screen_trashed = 0;
265 forw(sc_height-1, pos, 1, 0, sline-nline);
266 } else
267 {
268 /*
269 * The desired line is before the current screen.
270 * Move forward in the file far enough so that we
271 * can call back() and put the desired line at the
272 * sline-th line on the screen.
273 */
274 for (nline = sline; nline < sc_height - 1; nline++)
275 {
276 pos = forw_line(pos);
277 if (pos == NULL_POSITION)
278 {
279 /*
280 * Ran into end of file.
281 * This shouldn't normally happen,
282 * but may if there is some kind of read error.
283 */
284 break;
285 }
286 if (pos >= tpos)
287 {
288 /*
289 * Surprise! The desired line is
290 * close enough to the current screen
291 * that we can just scroll there after all.
292 */
293 back(nline+1, tpos, 1, 0);
294 #if HILITE_SEARCH
295 if (show_attn)
296 repaint_hilite(1);
297 #endif
298 return;
299 }
300 }
301 lastmark();
302 if (!top_scroll)
303 clear();
304 else
305 home();
306 screen_trashed = 0;
307 add_back_pos(pos);
308 back(sc_height-1, pos, 1, 0);
309 }
310 }
311