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Fixed alpha blending textures with the GDI renderer
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Original file line number | Diff line number | Diff line change |
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/* | ||
SDL - Simple DirectMedia Layer | ||
Copyright (C) 1997-2009 Sam Lantinga | ||
This library is free software; you can redistribute it and/or | ||
modify it under the terms of the GNU Lesser General Public | ||
License as published by the Free Software Foundation; either | ||
version 2.1 of the License, or (at your option) any later version. | ||
This library is distributed in the hope that it will be useful, | ||
but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | ||
Lesser General Public License for more details. | ||
You should have received a copy of the GNU Lesser General Public | ||
License along with this library; if not, write to the Free Software | ||
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA | ||
Sam Lantinga | ||
slouken@libsdl.org | ||
*/ | ||
#include "SDL_config.h" | ||
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#include "SDL_blit.h" | ||
#include "SDL_alphamult.h" | ||
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/* Functions to pre-multiply the alpha channel into the color channels */ | ||
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#define DEFINE_PREMULTIPLY_FUNC(fmt) \ | ||
void \ | ||
SDL_PreMultiplyAlpha##fmt(int w, int h, Uint32 *pixels, int pitch) \ | ||
{ \ | ||
pitch /= 4; \ | ||
while (h--) { \ | ||
int n; \ | ||
Uint32 *row = pixels; \ | ||
Uint32 pixel; \ | ||
unsigned r, g, b, a; \ | ||
\ | ||
for (n = w; n--; ) { \ | ||
pixel = *row; \ | ||
RGBA_FROM_##fmt(pixel, r, g, b, a); \ | ||
r = (r * a) / 255; \ | ||
g = (g * a) / 255; \ | ||
b = (b * a) / 255; \ | ||
fmt##_FROM_RGBA(*row, r, g, b, a); \ | ||
++row; \ | ||
} \ | ||
pixels += pitch; \ | ||
} \ | ||
} | ||
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DEFINE_PREMULTIPLY_FUNC(ARGB8888) | ||
DEFINE_PREMULTIPLY_FUNC(RGBA8888) | ||
DEFINE_PREMULTIPLY_FUNC(ABGR8888) | ||
DEFINE_PREMULTIPLY_FUNC(BGRA8888) | ||
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/* vi: set ts=4 sw=4 expandtab: */ |
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Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,36 @@ | ||
/* | ||
SDL - Simple DirectMedia Layer | ||
Copyright (C) 1997-2009 Sam Lantinga | ||
This library is free software; you can redistribute it and/or | ||
modify it under the terms of the GNU Lesser General Public | ||
License as published by the Free Software Foundation; either | ||
version 2.1 of the License, or (at your option) any later version. | ||
This library is distributed in the hope that it will be useful, | ||
but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | ||
Lesser General Public License for more details. | ||
You should have received a copy of the GNU Lesser General Public | ||
License along with this library; if not, write to the Free Software | ||
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA | ||
Sam Lantinga | ||
slouken@libsdl.org | ||
*/ | ||
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/* Functions to pre-multiply the alpha channel into the color channels */ | ||
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#define DEFINE_PREMULTIPLY_FUNC(fmt) \ | ||
void \ | ||
SDL_PreMultiplyAlpha##fmt(int w, int h, Uint32 *pixels, int pitch); | ||
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DEFINE_PREMULTIPLY_FUNC(ARGB8888) | ||
DEFINE_PREMULTIPLY_FUNC(RGBA8888) | ||
DEFINE_PREMULTIPLY_FUNC(ABGR8888) | ||
DEFINE_PREMULTIPLY_FUNC(BGRA8888) | ||
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#undef DEFINE_PREMULTIPLY_FUNC | ||
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/* vi: set ts=4 sw=4 expandtab: */ |
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