Mercurial > sdl-ios-xcode
view src/video/SDL_alphamult.c @ 4446:8b03a20b320f
Much improved multi-display support for iPad.
Fixes most issues and limitations, I think.
author | Ryan C. Gordon <icculus@icculus.org> |
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date | Sun, 02 May 2010 05:08:12 -0400 |
parents | f7b03b6838cb |
children |
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/* SDL - Simple DirectMedia Layer Copyright (C) 1997-2010 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" #include "SDL_blit.h" #include "SDL_alphamult.h" /* Functions to pre-multiply the alpha channel into the color channels */ #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; \ } \ } /* *INDENT-OFF* */ DEFINE_PREMULTIPLY_FUNC(ARGB8888) DEFINE_PREMULTIPLY_FUNC(RGBA8888) DEFINE_PREMULTIPLY_FUNC(ABGR8888) DEFINE_PREMULTIPLY_FUNC(BGRA8888) /* *INDENT-ON* */ /* vi: set ts=4 sw=4 expandtab: */