2 * Copyright (C) 1984-2005 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)
111 * Determine the position in the file
112 * (the specified percentage of the file's length).
114 if ((len = ch_length()) == NULL_POSITION)
116 ierror("Determining length of file", NULL_PARG);
119 if ((len = ch_length()) == NULL_POSITION)
121 error("Don't know length of file", NULL_PARG);
124 pos = percent_pos(len, percent);
128 jump_line_loc(pos, jump_sline);
132 * Jump to a specified position in the file.
133 * Like jump_loc, but the position need not be
134 * the first character in a line.
137 jump_line_loc(pos, sline)
143 if (ch_seek(pos) == 0)
146 * Back up to the beginning of the line.
148 while ((c = ch_back_get()) != '\n' && c != EOI)
151 (void) ch_forw_get();
156 jump_loc(pos, sline);
160 * Jump to a specified position in the file.
161 * The position must be the first character in a line.
162 * Place the target line on a specified line on the screen.
176 sline = adjsline(sline);
178 if ((nline = onscreen(pos)) >= 0)
181 * The line is currently displayed.
186 forw(nline, position(BOTTOM_PLUS_ONE), 1, 0, 0);
188 back(-nline, position(TOP), 1, 0);
195 * Line is not on screen.
196 * Seek to the desired location.
200 error("Cannot seek to that file position", NULL_PARG);
205 * See if the desired line is before or after
206 * the currently displayed screen.
208 tpos = position(TOP);
209 bpos = position(BOTTOM_PLUS_ONE);
210 if (tpos == NULL_POSITION || pos >= tpos)
213 * The desired line is after the current screen.
214 * Move back in the file far enough so that we can
215 * call forw() and put the desired line at the
216 * sline-th line on the screen.
218 for (nline = 0; nline < sline; nline++)
220 if (bpos != NULL_POSITION && pos <= bpos)
223 * Surprise! The desired line is
224 * close enough to the current screen
225 * that we can just scroll there after all.
227 forw(sc_height-sline+nline-1, bpos, 1, 0, 0);
232 pos = back_line(pos);
233 if (pos == NULL_POSITION)
236 * Oops. Ran into the beginning of the file.
237 * Exit the loop here and rely on forw()
238 * below to draw the required number of
239 * blank lines at the top of the screen.
248 forw(sc_height-1, pos, 1, 0, sline-nline);
252 * The desired line is before the current screen.
253 * Move forward in the file far enough so that we
254 * can call back() and put the desired line at the
255 * sline-th line on the screen.
257 for (nline = sline; nline < sc_height - 1; nline++)
259 pos = forw_line(pos);
260 if (pos == NULL_POSITION)
263 * Ran into end of file.
264 * This shouldn't normally happen,
265 * but may if there is some kind of read error.
272 * Surprise! The desired line is
273 * close enough to the current screen
274 * that we can just scroll there after all.
276 back(nline+1, tpos, 1, 0);
283 if (top_scroll != OPT_ON)
289 back(sc_height-1, pos, 1, 0);