2 * Copyright (C) 1984-2007 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 about less, or for information on how to
8 * contact the author, see the README file.
13 * Routines which jump to a new location in the file.
20 extern int jump_sline;
22 extern int screen_trashed;
23 extern int sc_width, sc_height;
25 extern int top_scroll;
28 * Jump to the end of the file.
37 error("Cannot seek to end of file", NULL_PARG);
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.
45 pos = back_line(ch_tell());
46 if (pos == NULL_POSITION)
47 jump_loc((POSITION)0, sc_height-1);
49 jump_loc(pos, sc_height-1);
53 * Jump to line n in the file.
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.
68 pos = find_pos(linenum);
69 if (pos != NULL_POSITION && ch_seek(pos) == 0)
73 jump_loc(pos, jump_sline);
74 } else if (linenum <= 1 && ch_beg_seek() == 0)
76 jump_loc(ch_tell(), jump_sline);
77 error("Cannot seek to beginning of file", NULL_PARG);
80 parg.p_linenum = linenum;
81 error("Cannot seek to line number %n", &parg);
93 * Start at the line currently at the top of the screen
94 * and redisplay the screen.
98 jump_loc(scrpos.pos, scrpos.ln);
102 * Jump to a specified percentage into the file.
105 jump_percent(percent, fraction)
112 * Determine the position in the file
113 * (the specified percentage of the file's length).
115 if ((len = ch_length()) == NULL_POSITION)
117 ierror("Determining length of file", NULL_PARG);
120 if ((len = ch_length()) == NULL_POSITION)
122 error("Don't know length of file", NULL_PARG);
125 pos = percent_pos(len, percent, fraction);
129 jump_line_loc(pos, jump_sline);
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.
138 jump_line_loc(pos, sline)
144 if (ch_seek(pos) == 0)
147 * Back up to the beginning of the line.
149 while ((c = ch_back_get()) != '\n' && c != EOI)
152 (void) ch_forw_get();
157 jump_loc(pos, sline);
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.
177 sline = adjsline(sline);
179 if ((nline = onscreen(pos)) >= 0)
182 * The line is currently displayed.
187 forw(nline, position(BOTTOM_PLUS_ONE), 1, 0, 0);
189 back(-nline, position(TOP), 1, 0);
196 * Line is not on screen.
197 * Seek to the desired location.
201 error("Cannot seek to that file position", NULL_PARG);
206 * See if the desired line is before or after
207 * the currently displayed screen.
209 tpos = position(TOP);
210 bpos = position(BOTTOM_PLUS_ONE);
211 if (tpos == NULL_POSITION || pos >= tpos)
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.
219 for (nline = 0; nline < sline; nline++)
221 if (bpos != NULL_POSITION && pos <= bpos)
224 * Surprise! The desired line is
225 * close enough to the current screen
226 * that we can just scroll there after all.
228 forw(sc_height-sline+nline-1, bpos, 1, 0, 0);
233 pos = back_line(pos);
234 if (pos == NULL_POSITION)
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.
249 forw(sc_height-1, pos, 1, 0, sline-nline);
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.
258 for (nline = sline; nline < sc_height - 1; nline++)
260 pos = forw_line(pos);
261 if (pos == NULL_POSITION)
264 * Ran into end of file.
265 * This shouldn't normally happen,
266 * but may if there is some kind of read error.
273 * Surprise! The desired line is
274 * close enough to the current screen
275 * that we can just scroll there after all.
277 back(nline+1, tpos, 1, 0);
290 back(sc_height-1, pos, 1, 0);