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/* $OpenBSD: lib_scroll.c,v 1.5 2023/10/17 09:52:09 nicm Exp $ */
/****************************************************************************
* Copyright 2019,2020 Thomas E. Dickey *
* Copyright 1998-2010,2011 Free Software Foundation, Inc. *
* *
* Permission is hereby granted, free of charge, to any person obtaining a *
* copy of this software and associated documentation files (the *
* "Software"), to deal in the Software without restriction, including *
* without limitation the rights to use, copy, modify, merge, publish, *
* distribute, distribute with modifications, sublicense, and/or sell *
* copies of the Software, and to permit persons to whom the Software is *
* furnished to do so, subject to the following conditions: *
* *
* The above copyright notice and this permission notice shall be included *
* in all copies or substantial portions of the Software. *
* *
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS *
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF *
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. *
* IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, *
* DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR *
* OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR *
* THE USE OR OTHER DEALINGS IN THE SOFTWARE. *
* *
* Except as contained in this notice, the name(s) of the above copyright *
* holders shall not be used in advertising or otherwise to promote the *
* sale, use or other dealings in this Software without prior written *
* authorization. *
****************************************************************************/
/****************************************************************************
* Author: Thomas E. Dickey 1996-2003 *
* and: Zeyd M. Ben-Halim <zmbenhal@netcom.com> 1992,1995 *
* and: Eric S. Raymond <esr@snark.thyrsus.com> *
****************************************************************************/
/*
** lib_scroll.c
**
** The routine wscrl(win, n).
** positive n scroll the window up (ie. move lines down)
** negative n scroll the window down (ie. move lines up)
**
*/
#include <curses.priv.h>
MODULE_ID("$Id: lib_scroll.c,v 1.5 2023/10/17 09:52:09 nicm Exp $")
NCURSES_EXPORT(void)
_nc_scroll_window(WINDOW *win,
int const n,
int const top,
int const bottom,
NCURSES_CH_T blank)
{
int limit;
int line;
int j;
size_t to_copy = (sizeof(NCURSES_CH_T) * (size_t) (win->_maxx + 1));
TR(TRACE_MOVE, ("_nc_scroll_window(%p, %d, %ld, %ld)",
(void *) win, n, (long) top, (long) bottom));
if (top < 0
|| bottom < top
|| bottom > win->_maxy) {
TR(TRACE_MOVE, ("nothing to scroll"));
return;
}
/*
* This used to do a line-text pointer-shuffle instead of text copies.
* That (a) doesn't work when the window is derived and doesn't have
* its own storage, (b) doesn't save you a lot on modern machines
* anyway. Your typical memcpy implementations are coded in
* assembler using a tight BLT loop; for the size of copies we're
* talking here, the total execution time is dominated by the one-time
* setup cost. So there is no point in trying to be excessively
* clever -- esr.
*/
#define BottomLimit(n) ((n) >= 0 && (n) >= top)
#define TopLimit(n) ((n) <= win->_maxy && (n) <= bottom)
/* shift n lines downwards */
if (n < 0) {
limit = top - n;
for (line = bottom; line >= limit && BottomLimit(line); line--) {
TR(TRACE_MOVE, ("...copying %d to %d", line + n, line));
memcpy(win->_line[line].text,
win->_line[line + n].text,
to_copy);
if_USE_SCROLL_HINTS(win->_line[line].oldindex =
win->_line[line + n].oldindex);
}
for (line = top; line < limit && TopLimit(line); line++) {
TR(TRACE_MOVE, ("...filling %d", line));
for (j = 0; j <= win->_maxx; j++)
win->_line[line].text[j] = blank;
if_USE_SCROLL_HINTS(win->_line[line].oldindex = _NEWINDEX);
}
}
/* shift n lines upwards */
if (n > 0) {
limit = bottom - n;
for (line = top; line <= limit && TopLimit(line); line++) {
memcpy(win->_line[line].text,
win->_line[line + n].text,
to_copy);
if_USE_SCROLL_HINTS(win->_line[line].oldindex =
win->_line[line + n].oldindex);
}
for (line = bottom; line > limit && BottomLimit(line); line--) {
for (j = 0; j <= win->_maxx; j++)
win->_line[line].text[j] = blank;
if_USE_SCROLL_HINTS(win->_line[line].oldindex = _NEWINDEX);
}
}
touchline(win, top, bottom - top + 1);
if_WIDEC({
if (WINDOW_EXT(win, addch_used) != 0) {
int next = WINDOW_EXT(win, addch_y) + n;
if (next < 0 || next > win->_maxy) {
TR(TRACE_VIRTPUT,
("Alert discarded multibyte on scroll"));
WINDOW_EXT(win, addch_y) = 0;
} else {
TR(TRACE_VIRTPUT, ("scrolled working position to %d,%d",
WINDOW_EXT(win, addch_y),
WINDOW_EXT(win, addch_x)));
WINDOW_EXT(win, addch_y) = next;
}
}
})
}
NCURSES_EXPORT(int)
wscrl(WINDOW *win, int n)
{
T((T_CALLED("wscrl(%p,%d)"), (void *) win, n));
if (!win || !win->_scroll) {
TR(TRACE_MOVE, ("...scrollok is false"));
returnCode(ERR);
}
if (n != 0) {
_nc_scroll_window(win, n, win->_regtop, win->_regbottom, win->_nc_bkgd);
_nc_synchook(win);
}
returnCode(OK);
}
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