/*
* Copyright (C) 1984-2023 Mark Nudelman
*
* You may distribute under the terms of either the GNU General Public
* License or the Less License, as specified in the README file.
*
* For more information, see the README file.
*/
/*
* Routines which jump to a new location in the file.
*/
#include "less.h"
#include "position.h"
extern int jump_sline;
extern int squished;
extern int screen_trashed;
extern int sc_width, sc_height;
extern int show_attn;
extern int top_scroll;
/*
* Jump to the end of the file.
*/
public void jump_forw(void)
{
POSITION pos;
POSITION end_pos;
if (ch_end_seek())
{
error("Cannot seek to end of file", NULL_PARG);
return;
}
end_pos = ch_tell();
if (position(sc_height-1) == end_pos)
{
eof_bell();
return;
}
/*
* Note; lastmark will be called later by jump_loc, but it fails
* because the position table has been cleared by pos_clear below.
* So call it here before calling pos_clear.
*/
lastmark();
/*
* Position the last line in the file at the last screen line.
* Go back one line from the end of the file
* to get to the beginning of the last line.
*/
pos_clear();
pos = back_line(end_pos);
if (pos == NULL_POSITION)
jump_loc(ch_zero(), sc_height-1);
else
{
jump_loc(pos, sc_height-1);
if (position(sc_height-1) != end_pos)
repaint();
}
}
/*
* Jump to the last buffered line in the file.
*/
public void jump_forw_buffered(void)
{
POSITION end;
if (ch_end_buffer_seek())
{
error("Cannot seek to end of buffers", NULL_PARG);
return;
}
end = ch_tell();
if (end != NULL_POSITION && end > 0)
jump_line_loc(end-1, sc_height-1);
}
/*
* Jump to line n in the file.
*/
public void jump_back(LINENUM linenum)
{
POSITION pos;
PARG parg;
/*
* Find the position of the specified line.
* If we can seek there, just jump to it.
* If we can't seek, but we're trying to go to line number 1,
* use ch_beg_seek() to get as close as we can.
*/
pos = find_pos(linenum);
if (pos != NULL_POSITION && ch_seek(pos) == 0)
{
if (show_attn)
set_attnpos(pos);
jump_loc(pos, jump_sline);
} else if (linenum <= 1 && ch_beg_seek() == 0)
{
jump_loc(ch_tell(), jump_sline);
error("Cannot seek to beginning of file", NULL_PARG);
} else
{
parg.p_linenum = linenum;
error("Cannot seek to line number %n", &parg);
}
}
/*
* Repaint the screen.
*/
public void repaint(void)
{
struct scrpos scrpos;
/*
* Start at the line currently at the top of the screen
* and redisplay the screen.
*/
get_scrpos(&scrpos, TOP);
pos_clear();
if (scrpos.pos == NULL_POSITION)
/* Screen hasn't been drawn yet. */
jump_loc(ch_zero(), 1);
else
jump_loc(scrpos.pos, scrpos.ln);
}
/*
* Jump to a specified percentage into the file.
*/
public void jump_percent(int percent, long fraction)
{
POSITION pos, len;
/*
* Determine the position in the file
* (the specified percentage of the file's length).
*/
if ((len = ch_length()) == NULL_POSITION)
{
ierror("Determining length of file", NULL_PARG);
ch_end_seek();
}
if ((len = ch_length()) == NULL_POSITION)
{
error("Don't know length of file", NULL_PARG);
return;
}
pos = percent_pos(len, percent, fraction);
if (pos >= len)
pos = len-1;
jump_line_loc(pos, jump_sline);
}
/*
* Jump to a specified position in the file.
* Like jump_loc, but the position need not be
* the first character in a line.
*/
public void jump_line_loc(POSITION pos, int sline)
{
int c;
if (ch_seek(pos) == 0)
{
/*
* Back up to the beginning of the line.
*/
while ((c = ch_back_get()) != '\n' && c != EOI)
;
if (c == '\n')
(void) ch_forw_get();
pos = ch_tell();
}
if (show_attn)
set_attnpos(pos);
jump_loc(pos, sline);
}
/*
* Jump to a specified position in the file.
* The position must be the first character in a line.
* Place the target line on a specified line on the screen.
*/
public void jump_loc(POSITION pos, int sline)
{
int nline;
int sindex;
POSITION tpos;
POSITION bpos;
if ((nline = onscreen(pos)) >= 0)
{
/*
* The line is currently displayed.
* Just scroll there.
*/
nline -= sindex;
if (nline > 0)
forw(nline, position(BOTTOM_PLUS_ONE), 1, 0, 0);
else if (nline < 0)
back(-nline, position(TOP), 1, 0);
#if HILITE_SEARCH
if (show_attn)
repaint_hilite(1);
#endif
return;
}
/*
* Line is not on screen.
* Seek to the desired location.
*/
if (ch_seek(pos))
{
error("Cannot seek to that file position", NULL_PARG);
return;
}
/*
* See if the desired line is before or after
* the currently displayed screen.
*/
tpos = position(TOP);
bpos = position(BOTTOM_PLUS_ONE);
if (tpos == NULL_POSITION || pos >= tpos)
{
/*
* The desired line is after the current screen.
* Move back in the file far enough so that we can
* call forw() and put the desired line at the
* sline-th line on the screen.
*/
for (nline = 0; nline < sindex; nline++)
{
if (bpos != NULL_POSITION && pos <= bpos)
{
/*
* Surprise! The desired line is
* close enough to the current screen
* that we can just scroll there after all.
*/
forw(sc_height-sindex+nline-1, bpos, 1, 0, 0);
#if HILITE_SEARCH
if (show_attn)
repaint_hilite(1);
#endif
return;
}
pos = back_line(pos);
if (pos == NULL_POSITION)
{
/*
* Oops. Ran into the beginning of the file.
* Exit the loop here and rely on forw()
* below to draw the required number of
* blank lines at the top of the screen.
*/
break;
}
}
lastmark();
squished = 0;
screen_trashed = 0;
forw(sc_height-1, pos, 1, 0, sindex-nline);
} else
{
/*
* The desired line is before the current screen.
* Move forward in the file far enough so that we
* can call back() and put the desired line at the
* sindex-th line on the screen.
*/
for (nline = sindex; nline < sc_height - 1; nline++)
{
pos = forw_line(pos);
if (pos == NULL_POSITION)
{
/*
* Ran into end of file.
* This shouldn't normally happen,
* but may if there is some kind of read error.
*/
break;
}
#if HILITE_SEARCH
pos = next_unfiltered(pos);
#endif
if (pos >= tpos)
{
/*
* Surprise! The desired line is
* close enough to the current screen
* that we can just scroll there after all.
*/
back(nline+1, tpos, 1, 0);
#if HILITE_SEARCH
if (show_attn)
repaint_hilite(1);
#endif
return;
}
}
lastmark();
if (!top_scroll)
clear();
else
home();
screen_trashed = 0;
add_back_pos(pos);
back(sc_height-1, pos, 1, 0);
}
}
