1/****************************************************************************
2 * Copyright (c) 1998-2010,2011 Free Software Foundation, Inc.              *
3 *                                                                          *
4 * Permission is hereby granted, free of charge, to any person obtaining a  *
5 * copy of this software and associated documentation files (the            *
6 * "Software"), to deal in the Software without restriction, including      *
7 * without limitation the rights to use, copy, modify, merge, publish,      *
8 * distribute, distribute with modifications, sublicense, and/or sell       *
9 * copies of the Software, and to permit persons to whom the Software is    *
10 * furnished to do so, subject to the following conditions:                 *
11 *                                                                          *
12 * The above copyright notice and this permission notice shall be included  *
13 * in all copies or substantial portions of the Software.                   *
14 *                                                                          *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS  *
16 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF               *
17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.   *
18 * IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,   *
19 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR    *
20 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR    *
21 * THE USE OR OTHER DEALINGS IN THE SOFTWARE.                               *
22 *                                                                          *
23 * Except as contained in this notice, the name(s) of the above copyright   *
24 * holders shall not be used in advertising or otherwise to promote the     *
25 * sale, use or other dealings in this Software without prior written       *
26 * authorization.                                                           *
27 ****************************************************************************/
28
29/****************************************************************************
30 *  Author: Thomas E. Dickey 1996-2003                                      *
31 *     and: Zeyd M. Ben-Halim <zmbenhal@netcom.com> 1992,1995               *
32 *     and: Eric S. Raymond <esr@snark.thyrsus.com>                         *
33 ****************************************************************************/
34
35/*
36**	lib_scroll.c
37**
38**	The routine wscrl(win, n).
39**  positive n scroll the window up (ie. move lines down)
40**  negative n scroll the window down (ie. move lines up)
41**
42*/
43
44#include <curses.priv.h>
45
46MODULE_ID("$Id: lib_scroll.c,v 1.29 2011/10/22 16:34:50 tom Exp $")
47
48NCURSES_EXPORT(void)
49_nc_scroll_window(WINDOW *win,
50		  int const n,
51		  int const top,
52		  int const bottom,
53		  NCURSES_CH_T blank)
54{
55    int limit;
56    int line;
57    int j;
58    size_t to_copy = (sizeof(NCURSES_CH_T) * (size_t) (win->_maxx + 1));
59
60    TR(TRACE_MOVE, ("_nc_scroll_window(%p, %d, %ld, %ld)",
61		    (void *) win, n, (long) top, (long) bottom));
62
63    if (top < 0
64	|| bottom < top
65	|| bottom > win->_maxy) {
66	TR(TRACE_MOVE, ("nothing to scroll"));
67	return;
68    }
69
70    /*
71     * This used to do a line-text pointer-shuffle instead of text copies.
72     * That (a) doesn't work when the window is derived and doesn't have
73     * its own storage, (b) doesn't save you a lot on modern machines
74     * anyway.  Your typical memcpy implementations are coded in
75     * assembler using a tight BLT loop; for the size of copies we're
76     * talking here, the total execution time is dominated by the one-time
77     * setup cost.  So there is no point in trying to be excessively
78     * clever -- esr.
79     */
80
81    /* shift n lines downwards */
82    if (n < 0) {
83	limit = top - n;
84	for (line = bottom; line >= limit && line >= 0; line--) {
85	    TR(TRACE_MOVE, ("...copying %d to %d", line + n, line));
86	    memcpy(win->_line[line].text,
87		   win->_line[line + n].text,
88		   to_copy);
89	    if_USE_SCROLL_HINTS(win->_line[line].oldindex =
90				win->_line[line + n].oldindex);
91	}
92	for (line = top; line < limit && line <= win->_maxy; line++) {
93	    TR(TRACE_MOVE, ("...filling %d", line));
94	    for (j = 0; j <= win->_maxx; j++)
95		win->_line[line].text[j] = blank;
96	    if_USE_SCROLL_HINTS(win->_line[line].oldindex = _NEWINDEX);
97	}
98    }
99
100    /* shift n lines upwards */
101    if (n > 0) {
102	limit = bottom - n;
103	for (line = top; line <= limit && line <= win->_maxy; line++) {
104	    memcpy(win->_line[line].text,
105		   win->_line[line + n].text,
106		   to_copy);
107	    if_USE_SCROLL_HINTS(win->_line[line].oldindex =
108				win->_line[line + n].oldindex);
109	}
110	for (line = bottom; line > limit && line >= 0; line--) {
111	    for (j = 0; j <= win->_maxx; j++)
112		win->_line[line].text[j] = blank;
113	    if_USE_SCROLL_HINTS(win->_line[line].oldindex = _NEWINDEX);
114	}
115    }
116    touchline(win, top, bottom - top + 1);
117
118    if_WIDEC({
119	if (WINDOW_EXT(win, addch_used) != 0) {
120	    int next = WINDOW_EXT(win, addch_y) + n;
121	    if (next < 0 || next > win->_maxy) {
122		TR(TRACE_VIRTPUT,
123		   ("Alert discarded multibyte on scroll"));
124		WINDOW_EXT(win, addch_y) = 0;
125	    } else {
126		TR(TRACE_VIRTPUT, ("scrolled working position to %d,%d",
127				   WINDOW_EXT(win, addch_y),
128				   WINDOW_EXT(win, addch_x)));
129		WINDOW_EXT(win, addch_y) = next;
130	    }
131	}
132    })
133}
134
135NCURSES_EXPORT(int)
136wscrl(WINDOW *win, int n)
137{
138    T((T_CALLED("wscrl(%p,%d)"), (void *) win, n));
139
140    if (!win || !win->_scroll) {
141	TR(TRACE_MOVE, ("...scrollok is false"));
142	returnCode(ERR);
143    }
144
145    if (n != 0) {
146	_nc_scroll_window(win, n, win->_regtop, win->_regbottom, win->_nc_bkgd);
147	_nc_synchook(win);
148    }
149    returnCode(OK);
150}
151