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/* $OpenBSD: softscroll.c,v 1.1 1997/12/03 05:21:44 millert Exp $ */
/******************************************************************************
* Copyright 1997 by Thomas E. Dickey <dickey@clark.net> *
* All Rights Reserved. *
* *
* Permission to use, copy, modify, and distribute this software and its *
* documentation for any purpose and without fee is hereby granted, provided *
* that the above copyright notice appear in all copies and that both that *
* copyright notice and this permission notice appear in supporting *
* documentation, and that the name of the above listed copyright holder(s) *
* not be used in advertising or publicity pertaining to distribution of the *
* software without specific, written prior permission. *
* *
* THE ABOVE LISTED COPYRIGHT HOLDER(S) DISCLAIM ALL WARRANTIES WITH REGARD *
* TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND *
* FITNESS, IN NO EVENT SHALL THE ABOVE LISTED COPYRIGHT HOLDER(S) BE LIABLE *
* FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES *
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN *
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR *
* IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. *
******************************************************************************/
#include <curses.priv.h>
#include <term.h>
MODULE_ID("Id: softscroll.c,v 1.5 1997/10/18 18:38:47 tom Exp $")
/*
* Compute indices for the given WINDOW, preparing it for scrolling.
*
* TODO (this implementation is only for proof-of-concept)
* (a) ensure that curscr's oldindex values are cached properly so we
* don't have to recompute them on each pass.
* (b) investigate if there are gains to be made by iterating newscr's
* row indices outward from the current position, rather than by
* all rows.
*/
static void compute_curscr(void)
{
int y, x, z;
for (y = 0; y < screen_lines; y++) {
struct ldat *nline = &curscr->_line[y];
int found = y;
for (z = 0; z < y; z++) {
int same = TRUE;
struct ldat *oline = &curscr->_line[z];
for (x = 0; x < screen_columns; x++) {
if (nline->text[x] != oline->text[x]) {
same = FALSE;
break;
}
}
if (same) {
found = z;
break;
}
}
nline->oldindex = found;
}
}
static void compute_newscr(void)
{
int y, x, z;
for (y = 0; y < screen_lines; y++) {
struct ldat *nline = &newscr->_line[y];
int found = _NEWINDEX;
for (z = 0; z < screen_lines; z++) {
int same = TRUE;
struct ldat *oline = &curscr->_line[z];
for (x = 0; x < screen_columns; x++) {
if (nline->text[x] != oline->text[x]) {
same = FALSE;
break;
}
}
if (same) {
found = z;
break;
}
}
nline->oldindex = found;
}
}
void
_nc_setup_scroll(void)
{
#ifdef TRACE
if (_nc_tracing & TRACE_UPDATE) {
_tracef("_nc_setup_scroll");
_nc_linedump();
}
#endif /* TRACE */
compute_curscr();
compute_newscr();
#ifdef TRACE
if (_nc_tracing & TRACE_UPDATE) {
_tracef("..._nc_setup_scroll");
_nc_linedump();
}
#endif
}
#define MINDISP 2
#define NEWNUM(n) newscr->_line[n].oldindex
#define OLDNUM(n) curscr->_line[n].oldindex
/*
* This performs essentially the same function as _nc_scroll_optimize(), but
* uses different assumptions about the .oldindex values. More than one line
* may have the same .oldindex value. We don't assume the values are ordered.
*
* (Neither algorithm takes into account the cost of constructing the lines
* which are scrolled)
*/
void
_nc_perform_scroll(void)
{
int disp;
int row;
int top, bottom, maxdisp;
int partial;
/*
* Find the top/bottom lines that are different between curscr and
* newscr, limited by the terminal's ability to scroll portions of the
* screen.
*
* FIXME: this doesn't account for special cases of insert/delete line.
*/
if (change_scroll_region
&& (scroll_forward || parm_index)
&& (scroll_reverse || parm_rindex)) {
partial = TRUE;
for (row = 0, top = -1; row < screen_lines; row++) {
if (OLDNUM(row) != NEWNUM(row)) {
break;
}
top = row;
}
top++;
for (row = screen_lines-1, bottom = screen_lines; row >= 0; row--) {
if (OLDNUM(row) != NEWNUM(row)) {
break;
}
bottom = row;
}
bottom--;
} else {
partial = FALSE;
top = 0;
bottom = screen_lines - 1;
}
maxdisp = (bottom - top + 1) / 2;
if (maxdisp < MINDISP)
return;
T(("_nc_perform_scroll %d..%d (maxdisp=%d)", top, bottom, maxdisp));
for (disp = 1; disp < maxdisp; disp++) {
int n;
int fn, fwd = 0;
int bn, bak = 0;
int first, last;
int moved;
do {
/* check for forward-movement */
for (fn = top + disp; fn < screen_lines - disp; fn++) {
int eql = 0;
for (n = fn, fwd = 0; n < screen_lines; n++) {
if (NEWNUM(n) == _NEWINDEX
|| NEWNUM(n) != OLDNUM(n-disp))
break;
fwd++;
if (OLDNUM(n) == NEWNUM(n))
eql++;
}
if (eql == fwd)
fwd = 0;
if (fwd >= disp)
break;
fwd = 0;
}
/* check for backward-movement */
for (bn = top + disp; bn < screen_lines - disp; bn++) {
int eql = 0;
for (n = bn, bak = 0; n < screen_lines; n++) {
if (OLDNUM(n) == _NEWINDEX
|| OLDNUM(n) != NEWNUM(n-disp))
break;
bak++;
if (OLDNUM(n-disp) == NEWNUM(n-disp))
eql++;
}
if (eql == bak)
bak = 0;
if (bak >= disp)
break;
bak = 0;
}
/* choose only one, in case they overlap */
if (fwd > bak) {
first = fn - disp;
last = fn + fwd - 1;
moved = -disp;
} else if (bak) {
first = bn - disp;
last = bn + bak - 1;
moved = disp;
} else {
break;
}
TR(TRACE_UPDATE | TRACE_MOVE, ("scroll [%d, %d] by %d", first, last, moved));
if (_nc_scrolln(moved, first, last, screen_lines - 1) == ERR)
{
TR(TRACE_UPDATE | TRACE_MOVE, ("unable to scroll"));
break;
}
/* If the scrolled text was at one end of the range
* of changed lines, adjust the loop limits.
*/
if (first == top)
top = last + 1;
if (last == bottom)
bottom = first - 1;
maxdisp = (bottom - top + 1) / 2;
if (maxdisp < MINDISP)
return;
/* In any case, mark the lines so we don't try to
* use them in a subsequent scroll.
*/
for (fn = first; fn <= last; fn++) {
OLDNUM(fn) =
NEWNUM(fn) = _NEWINDEX;
}
} while (partial);
}
}
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