| /* |
| 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: */ |