2 * Copyright (C) 1984-2019 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(ch_zero(), sc_height
-1);
57 jump_loc(pos
, sc_height
-1);
58 if (position(sc_height
-1) != end_pos
)
64 * Jump to the last buffered line in the file.
67 jump_forw_buffered(VOID_PARAM
)
71 if (ch_end_buffer_seek())
73 error("Cannot seek to end of buffers", NULL_PARG
);
77 if (end
!= NULL_POSITION
&& end
> 0)
78 jump_line_loc(end
-1, sc_height
-1);
82 * Jump to line n in the file.
92 * Find the position of the specified line.
93 * If we can seek there, just jump to it.
94 * If we can't seek, but we're trying to go to line number 1,
95 * use ch_beg_seek() to get as close as we can.
97 pos
= find_pos(linenum
);
98 if (pos
!= NULL_POSITION
&& ch_seek(pos
) == 0)
102 jump_loc(pos
, jump_sline
);
103 } else if (linenum
<= 1 && ch_beg_seek() == 0)
105 jump_loc(ch_tell(), jump_sline
);
106 error("Cannot seek to beginning of file", NULL_PARG
);
109 parg
.p_linenum
= linenum
;
110 error("Cannot seek to line number %n", &parg
);
115 * Repaint the screen.
120 struct scrpos scrpos
;
122 * Start at the line currently at the top of the screen
123 * and redisplay the screen.
125 get_scrpos(&scrpos
, TOP
);
127 if (scrpos
.pos
== NULL_POSITION
)
128 /* Screen hasn't been drawn yet. */
129 jump_loc(ch_zero(), 1);
131 jump_loc(scrpos
.pos
, scrpos
.ln
);
135 * Jump to a specified percentage into the file.
138 jump_percent(percent
, fraction
)
145 * Determine the position in the file
146 * (the specified percentage of the file's length).
148 if ((len
= ch_length()) == NULL_POSITION
)
150 ierror("Determining length of file", NULL_PARG
);
153 if ((len
= ch_length()) == NULL_POSITION
)
155 error("Don't know length of file", NULL_PARG
);
158 pos
= percent_pos(len
, percent
, fraction
);
162 jump_line_loc(pos
, jump_sline
);
166 * Jump to a specified position in the file.
167 * Like jump_loc, but the position need not be
168 * the first character in a line.
171 jump_line_loc(pos
, sline
)
177 if (ch_seek(pos
) == 0)
180 * Back up to the beginning of the line.
182 while ((c
= ch_back_get()) != '\n' && c
!= EOI
)
185 (void) ch_forw_get();
190 jump_loc(pos
, sline
);
194 * Jump to a specified position in the file.
195 * The position must be the first character in a line.
196 * Place the target line on a specified line on the screen.
211 sindex
= sindex_from_sline(sline
);
213 if ((nline
= onscreen(pos
)) >= 0)
216 * The line is currently displayed.
221 forw(nline
, position(BOTTOM_PLUS_ONE
), 1, 0, 0);
223 back(-nline
, position(TOP
), 1, 0);
232 * Line is not on screen.
233 * Seek to the desired location.
237 error("Cannot seek to that file position", NULL_PARG
);
242 * See if the desired line is before or after
243 * the currently displayed screen.
245 tpos
= position(TOP
);
246 bpos
= position(BOTTOM_PLUS_ONE
);
247 if (tpos
== NULL_POSITION
|| pos
>= tpos
)
250 * The desired line is after the current screen.
251 * Move back in the file far enough so that we can
252 * call forw() and put the desired line at the
253 * sline-th line on the screen.
255 for (nline
= 0; nline
< sindex
; nline
++)
257 if (bpos
!= NULL_POSITION
&& pos
<= bpos
)
260 * Surprise! The desired line is
261 * close enough to the current screen
262 * that we can just scroll there after all.
264 forw(sc_height
-sindex
+nline
-1, bpos
, 1, 0, 0);
271 pos
= back_line(pos
);
272 if (pos
== NULL_POSITION
)
275 * Oops. Ran into the beginning of the file.
276 * Exit the loop here and rely on forw()
277 * below to draw the required number of
278 * blank lines at the top of the screen.
286 forw(sc_height
-1, pos
, 1, 0, sindex
-nline
);
290 * The desired line is before the current screen.
291 * Move forward in the file far enough so that we
292 * can call back() and put the desired line at the
293 * sindex-th line on the screen.
295 for (nline
= sindex
; nline
< sc_height
- 1; nline
++)
297 pos
= forw_line(pos
);
298 if (pos
== NULL_POSITION
)
301 * Ran into end of file.
302 * This shouldn't normally happen,
303 * but may if there is some kind of read error.
308 pos
= next_unfiltered(pos
);
313 * Surprise! The desired line is
314 * close enough to the current screen
315 * that we can just scroll there after all.
317 back(nline
+1, tpos
, 1, 0);
332 back(sc_height
-1, pos
, 1, 0);