1 /* $OpenBSD: lib_scroll.c,v 1.5 2023/10/17 09:52:09 nicm Exp $ */
2
3 /****************************************************************************
4 * Copyright 2019,2020 Thomas E. Dickey *
5 * Copyright 1998-2010,2011 Free Software Foundation, Inc. *
6 * *
7 * Permission is hereby granted, free of charge, to any person obtaining a *
8 * copy of this software and associated documentation files (the *
9 * "Software"), to deal in the Software without restriction, including *
10 * without limitation the rights to use, copy, modify, merge, publish, *
11 * distribute, distribute with modifications, sublicense, and/or sell *
12 * copies of the Software, and to permit persons to whom the Software is *
13 * furnished to do so, subject to the following conditions: *
14 * *
15 * The above copyright notice and this permission notice shall be included *
16 * in all copies or substantial portions of the Software. *
17 * *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS *
19 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF *
20 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. *
21 * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, *
22 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR *
23 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR *
24 * THE USE OR OTHER DEALINGS IN THE SOFTWARE. *
25 * *
26 * Except as contained in this notice, the name(s) of the above copyright *
27 * holders shall not be used in advertising or otherwise to promote the *
28 * sale, use or other dealings in this Software without prior written *
29 * authorization. *
30 ****************************************************************************/
31
32 /****************************************************************************
33 * Author: Thomas E. Dickey 1996-2003 *
34 * and: Zeyd M. Ben-Halim <zmbenhal@netcom.com> 1992,1995 *
35 * and: Eric S. Raymond <esr@snark.thyrsus.com> *
36 ****************************************************************************/
37
38 /*
39 ** lib_scroll.c
40 **
41 ** The routine wscrl(win, n).
42 ** positive n scroll the window up (ie. move lines down)
43 ** negative n scroll the window down (ie. move lines up)
44 **
45 */
46
47 #include <curses.priv.h>
48
49 MODULE_ID("$Id: lib_scroll.c,v 1.5 2023/10/17 09:52:09 nicm Exp $")
50
NCURSES_EXPORT(void)51 NCURSES_EXPORT(void)
52 _nc_scroll_window(WINDOW *win,
53 int const n,
54 int const top,
55 int const bottom,
56 NCURSES_CH_T blank)
57 {
58 int limit;
59 int line;
60 int j;
61 size_t to_copy = (sizeof(NCURSES_CH_T) * (size_t) (win->_maxx + 1));
62
63 TR(TRACE_MOVE, ("_nc_scroll_window(%p, %d, %ld, %ld)",
64 (void *) win, n, (long) top, (long) bottom));
65
66 if (top < 0
67 || bottom < top
68 || bottom > win->_maxy) {
69 TR(TRACE_MOVE, ("nothing to scroll"));
70 return;
71 }
72
73 /*
74 * This used to do a line-text pointer-shuffle instead of text copies.
75 * That (a) doesn't work when the window is derived and doesn't have
76 * its own storage, (b) doesn't save you a lot on modern machines
77 * anyway. Your typical memcpy implementations are coded in
78 * assembler using a tight BLT loop; for the size of copies we're
79 * talking here, the total execution time is dominated by the one-time
80 * setup cost. So there is no point in trying to be excessively
81 * clever -- esr.
82 */
83 #define BottomLimit(n) ((n) >= 0 && (n) >= top)
84 #define TopLimit(n) ((n) <= win->_maxy && (n) <= bottom)
85
86 /* shift n lines downwards */
87 if (n < 0) {
88 limit = top - n;
89 for (line = bottom; line >= limit && BottomLimit(line); line--) {
90 TR(TRACE_MOVE, ("...copying %d to %d", line + n, line));
91 memcpy(win->_line[line].text,
92 win->_line[line + n].text,
93 to_copy);
94 if_USE_SCROLL_HINTS(win->_line[line].oldindex =
95 win->_line[line + n].oldindex);
96 }
97 for (line = top; line < limit && TopLimit(line); line++) {
98 TR(TRACE_MOVE, ("...filling %d", line));
99 for (j = 0; j <= win->_maxx; j++)
100 win->_line[line].text[j] = blank;
101 if_USE_SCROLL_HINTS(win->_line[line].oldindex = _NEWINDEX);
102 }
103 }
104
105 /* shift n lines upwards */
106 if (n > 0) {
107 limit = bottom - n;
108 for (line = top; line <= limit && TopLimit(line); line++) {
109 memcpy(win->_line[line].text,
110 win->_line[line + n].text,
111 to_copy);
112 if_USE_SCROLL_HINTS(win->_line[line].oldindex =
113 win->_line[line + n].oldindex);
114 }
115 for (line = bottom; line > limit && BottomLimit(line); line--) {
116 for (j = 0; j <= win->_maxx; j++)
117 win->_line[line].text[j] = blank;
118 if_USE_SCROLL_HINTS(win->_line[line].oldindex = _NEWINDEX);
119 }
120 }
121 touchline(win, top, bottom - top + 1);
122
123 if_WIDEC({
124 if (WINDOW_EXT(win, addch_used) != 0) {
125 int next = WINDOW_EXT(win, addch_y) + n;
126 if (next < 0 || next > win->_maxy) {
127 TR(TRACE_VIRTPUT,
128 ("Alert discarded multibyte on scroll"));
129 WINDOW_EXT(win, addch_y) = 0;
130 } else {
131 TR(TRACE_VIRTPUT, ("scrolled working position to %d,%d",
132 WINDOW_EXT(win, addch_y),
133 WINDOW_EXT(win, addch_x)));
134 WINDOW_EXT(win, addch_y) = next;
135 }
136 }
137 })
138 }
139
140 NCURSES_EXPORT(int)
wscrl(WINDOW * win,int n)141 wscrl(WINDOW *win, int n)
142 {
143 T((T_CALLED("wscrl(%p,%d)"), (void *) win, n));
144
145 if (!win || !win->_scroll) {
146 TR(TRACE_MOVE, ("...scrollok is false"));
147 returnCode(ERR);
148 }
149
150 if (n != 0) {
151 _nc_scroll_window(win, n, win->_regtop, win->_regbottom, win->_nc_bkgd);
152 _nc_synchook(win);
153 }
154 returnCode(OK);
155 }
156