2 * Copyright (C) 1984-2012 Mark Nudelman
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.
7 * For more information, see the README file.
12 * Routines which jump to a new location in the file.
18 extern int jump_sline;
20 extern int screen_trashed;
21 extern int sc_width, sc_height;
23 extern int top_scroll;
26 * Jump to the end of the file.
36 error("Cannot seek to end of file", NULL_PARG);
40 * Note; lastmark will be called later by jump_loc, but it fails
41 * because the position table has been cleared by pos_clear below.
42 * So call it here before calling pos_clear.
46 * Position the last line in the file at the last screen line.
47 * Go back one line from the end of the file
48 * to get to the beginning of the last line.
52 pos = back_line(end_pos);
53 if (pos == NULL_POSITION)
54 jump_loc((POSITION)0, sc_height-1);
57 jump_loc(pos, sc_height-1);
58 if (position(sc_height-1) != end_pos)
64 * Jump to line n in the file.
74 * Find the position of the specified line.
75 * If we can seek there, just jump to it.
76 * If we can't seek, but we're trying to go to line number 1,
77 * use ch_beg_seek() to get as close as we can.
79 pos = find_pos(linenum);
80 if (pos != NULL_POSITION && ch_seek(pos) == 0)
84 jump_loc(pos, jump_sline);
85 } else if (linenum <= 1 && ch_beg_seek() == 0)
87 jump_loc(ch_tell(), jump_sline);
88 error("Cannot seek to beginning of file", NULL_PARG);
91 parg.p_linenum = linenum;
92 error("Cannot seek to line number %n", &parg);
102 struct scrpos scrpos;
104 * Start at the line currently at the top of the screen
105 * and redisplay the screen.
109 jump_loc(scrpos.pos, scrpos.ln);
113 * Jump to a specified percentage into the file.
116 jump_percent(percent, fraction)
123 * Determine the position in the file
124 * (the specified percentage of the file's length).
126 if ((len = ch_length()) == NULL_POSITION)
128 ierror("Determining length of file", NULL_PARG);
131 if ((len = ch_length()) == NULL_POSITION)
133 error("Don't know length of file", NULL_PARG);
136 pos = percent_pos(len, percent, fraction);
140 jump_line_loc(pos, jump_sline);
144 * Jump to a specified position in the file.
145 * Like jump_loc, but the position need not be
146 * the first character in a line.
149 jump_line_loc(pos, sline)
155 if (ch_seek(pos) == 0)
158 * Back up to the beginning of the line.
160 while ((c = ch_back_get()) != '\n' && c != EOI)
163 (void) ch_forw_get();
168 jump_loc(pos, sline);
172 * Jump to a specified position in the file.
173 * The position must be the first character in a line.
174 * Place the target line on a specified line on the screen.
188 sline = adjsline(sline);
190 if ((nline = onscreen(pos)) >= 0)
193 * The line is currently displayed.
198 forw(nline, position(BOTTOM_PLUS_ONE), 1, 0, 0);
200 back(-nline, position(TOP), 1, 0);
209 * Line is not on screen.
210 * Seek to the desired location.
214 error("Cannot seek to that file position", NULL_PARG);
219 * See if the desired line is before or after
220 * the currently displayed screen.
222 tpos = position(TOP);
223 bpos = position(BOTTOM_PLUS_ONE);
224 if (tpos == NULL_POSITION || pos >= tpos)
227 * The desired line is after the current screen.
228 * Move back in the file far enough so that we can
229 * call forw() and put the desired line at the
230 * sline-th line on the screen.
232 for (nline = 0; nline < sline; nline++)
234 if (bpos != NULL_POSITION && pos <= bpos)
237 * Surprise! The desired line is
238 * close enough to the current screen
239 * that we can just scroll there after all.
241 forw(sc_height-sline+nline-1, bpos, 1, 0, 0);
248 pos = back_line(pos);
249 if (pos == NULL_POSITION)
252 * Oops. Ran into the beginning of the file.
253 * Exit the loop here and rely on forw()
254 * below to draw the required number of
255 * blank lines at the top of the screen.
263 forw(sc_height-1, pos, 1, 0, sline-nline);
267 * The desired line is before the current screen.
268 * Move forward in the file far enough so that we
269 * can call back() and put the desired line at the
270 * sline-th line on the screen.
272 for (nline = sline; nline < sc_height - 1; nline++)
274 pos = forw_line(pos);
275 if (pos == NULL_POSITION)
278 * Ran into end of file.
279 * This shouldn't normally happen,
280 * but may if there is some kind of read error.
287 * Surprise! The desired line is
288 * close enough to the current screen
289 * that we can just scroll there after all.
291 back(nline+1, tpos, 1, 0);
306 back(sc_height-1, pos, 1, 0);