Merge remote-tracking branch 'remotes/kraxel/tags/pull-vga-20170103-1' into staging
[qemu.git] / ui / sdl_zoom.c
1 /*
2 * SDL_zoom - surface scaling
3 *
4 * Copyright (c) 2009 Citrix Systems, Inc.
5 *
6 * Derived from: SDL_rotozoom, LGPL (c) A. Schiffler from the SDL_gfx library.
7 * Modifications by Stefano Stabellini.
8 *
9 * This work is licensed under the terms of the GNU GPL version 2.
10 * See the COPYING file in the top-level directory.
11 *
12 */
13
14 #include "qemu/osdep.h"
15 #include "sdl_zoom.h"
16
17 static void sdl_zoom_rgb16(SDL_Surface *src, SDL_Surface *dst, int smooth,
18 SDL_Rect *dst_rect);
19 static void sdl_zoom_rgb32(SDL_Surface *src, SDL_Surface *dst, int smooth,
20 SDL_Rect *dst_rect);
21
22 #define BPP 32
23 #include "sdl_zoom_template.h"
24 #undef BPP
25 #define BPP 16
26 #include "sdl_zoom_template.h"
27 #undef BPP
28
29 int sdl_zoom_blit(SDL_Surface *src_sfc, SDL_Surface *dst_sfc, int smooth,
30 SDL_Rect *in_rect)
31 {
32 SDL_Rect zoom, src_rect;
33 int extra;
34
35 /* Grow the size of the modified rectangle to avoid edge artefacts */
36 src_rect.x = (in_rect->x > 0) ? (in_rect->x - 1) : 0;
37 src_rect.y = (in_rect->y > 0) ? (in_rect->y - 1) : 0;
38
39 src_rect.w = in_rect->w + 1;
40 if (src_rect.x + src_rect.w > src_sfc->w)
41 src_rect.w = src_sfc->w - src_rect.x;
42
43 src_rect.h = in_rect->h + 1;
44 if (src_rect.y + src_rect.h > src_sfc->h)
45 src_rect.h = src_sfc->h - src_rect.y;
46
47 /* (x,y) : round down */
48 zoom.x = (int)(((float)(src_rect.x * dst_sfc->w)) / (float)(src_sfc->w));
49 zoom.y = (int)(((float)(src_rect.y * dst_sfc->h)) / (float)(src_sfc->h));
50
51 /* (w,h) : round up */
52 zoom.w = (int)( ((double)((src_rect.w * dst_sfc->w) + (src_sfc->w - 1))) /
53 (double)(src_sfc->w));
54
55 zoom.h = (int)( ((double)((src_rect.h * dst_sfc->h) + (src_sfc->h - 1))) /
56 (double)(src_sfc->h));
57
58 /* Account for any (x,y) rounding by adding one-source-pixel's worth
59 * of destination pixels and then edge checking.
60 */
61
62 extra = ((dst_sfc->w-1) / src_sfc->w) + 1;
63
64 if ((zoom.x + zoom.w) < (dst_sfc->w - extra))
65 zoom.w += extra;
66 else
67 zoom.w = dst_sfc->w - zoom.x;
68
69 extra = ((dst_sfc->h-1) / src_sfc->h) + 1;
70
71 if ((zoom.y + zoom.h) < (dst_sfc->h - extra))
72 zoom.h += extra;
73 else
74 zoom.h = dst_sfc->h - zoom.y;
75
76 /* The rectangle (zoom.x, zoom.y, zoom.w, zoom.h) is the area on the
77 * destination surface that needs to be updated.
78 */
79 if (src_sfc->format->BitsPerPixel == 32)
80 sdl_zoom_rgb32(src_sfc, dst_sfc, smooth, &zoom);
81 else if (src_sfc->format->BitsPerPixel == 16)
82 sdl_zoom_rgb16(src_sfc, dst_sfc, smooth, &zoom);
83 else {
84 fprintf(stderr, "pixel format not supported\n");
85 return -1;
86 }
87
88 /* Return the rectangle of the update to the caller */
89 *in_rect = zoom;
90
91 return 0;
92 }
93