2 Simple DirectMedia Layer
3 Copyright (C) 1997-2016 Sam Lantinga <slouken@libsdl.org>
5 This software is provided 'as-is', without any express or implied
6 warranty. In no event will the authors be held liable for any damages
7 arising from the use of this software.
9 Permission is granted to anyone to use this software for any purpose,
10 including commercial applications, and to alter it and redistribute it
11 freely, subject to the following restrictions:
13 1. The origin of this software must not be misrepresented; you must not
14 claim that you wrote the original software. If you use this software
15 in a product, an acknowledgment in the product documentation would be
16 appreciated but is not required.
17 2. Altered source versions must be plainly marked as such, and must not be
18 misrepresented as being the original software.
19 3. This notice may not be removed or altered from any source distribution.
21 #include "../SDL_internal.h"
23 #include "SDL_video.h"
25 #include "SDL_blit_slow.h"
27 /* The ONE TRUE BLITTER
28 * This puppy has to handle all the unoptimized cases - yes, it's slow.
31 SDL_Blit_Slow(SDL_BlitInfo * info)
33 const int flags = info->flags;
34 const Uint32 modulateR = info->r;
35 const Uint32 modulateG = info->g;
36 const Uint32 modulateB = info->b;
37 const Uint32 modulateA = info->a;
39 Uint32 srcR, srcG, srcB, srcA;
41 Uint32 dstR, dstG, dstB, dstA;
45 SDL_PixelFormat *src_fmt = info->src_fmt;
46 SDL_PixelFormat *dst_fmt = info->dst_fmt;
47 int srcbpp = src_fmt->BytesPerPixel;
48 int dstbpp = dst_fmt->BytesPerPixel;
52 incy = (info->src_h << 16) / info->dst_h;
53 incx = (info->src_w << 16) / info->dst_w;
55 while (info->dst_h--) {
57 Uint8 *dst = (Uint8 *) info->dst;
61 while (posy >= 0x10000L) {
66 if (posx >= 0x10000L) {
67 while (posx >= 0x10000L) {
72 (info->src + (srcy * info->src_pitch) + (srcx * srcbpp));
75 DISEMBLE_RGBA(src, srcbpp, src_fmt, srcpixel, srcR, srcG,
78 DISEMBLE_RGB(src, srcbpp, src_fmt, srcpixel, srcR, srcG,
82 if (flags & SDL_COPY_COLORKEY) {
83 /* srcpixel isn't set for 24 bpp */
85 srcpixel = (srcR << src_fmt->Rshift) |
86 (srcG << src_fmt->Gshift) | (srcB << src_fmt->Bshift);
88 if (srcpixel == info->colorkey) {
95 DISEMBLE_RGBA(dst, dstbpp, dst_fmt, dstpixel, dstR, dstG,
98 DISEMBLE_RGB(dst, dstbpp, dst_fmt, dstpixel, dstR, dstG,
103 if (flags & SDL_COPY_MODULATE_COLOR) {
104 srcR = (srcR * modulateR) / 255;
105 srcG = (srcG * modulateG) / 255;
106 srcB = (srcB * modulateB) / 255;
108 if (flags & SDL_COPY_MODULATE_ALPHA) {
109 srcA = (srcA * modulateA) / 255;
111 if (flags & (SDL_COPY_BLEND | SDL_COPY_ADD)) {
112 /* This goes away if we ever use premultiplied alpha */
114 srcR = (srcR * srcA) / 255;
115 srcG = (srcG * srcA) / 255;
116 srcB = (srcB * srcA) / 255;
119 switch (flags & (SDL_COPY_BLEND | SDL_COPY_ADD | SDL_COPY_MOD)) {
127 dstR = srcR + ((255 - srcA) * dstR) / 255;
128 dstG = srcG + ((255 - srcA) * dstG) / 255;
129 dstB = srcB + ((255 - srcA) * dstB) / 255;
143 dstR = (srcR * dstR) / 255;
144 dstG = (srcG * dstG) / 255;
145 dstB = (srcB * dstB) / 255;
148 if (dst_fmt->Amask) {
149 ASSEMBLE_RGBA(dst, dstbpp, dst_fmt, dstR, dstG, dstB, dstA);
151 ASSEMBLE_RGB(dst, dstbpp, dst_fmt, dstR, dstG, dstB);
157 info->dst += info->dst_pitch;
161 /* vi: set ts=4 sw=4 expandtab: */