42 lines
1.3 KiB
C
42 lines
1.3 KiB
C
/*******************************************************************************
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Copyright(C) Jonas 'Sortie' Termansen 2014, 2015.
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This program is free software: you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by the Free
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Software Foundation, either version 3 of the License, or (at your option)
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any later version.
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This program is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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more details.
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You should have received a copy of the GNU General Public License along with
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this program. If not, see <http://www.gnu.org/licenses/>.
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pixel.c
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Pixel utilities.
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*******************************************************************************/
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#include <stdint.h>
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#include "pixel.h"
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uint32_t blend_pixel(uint32_t bg_value, uint32_t fg_value)
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{
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union color_rgba8 fg; fg.value = fg_value;
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union color_rgba8 bg; bg.value = bg_value;
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if ( fg.a == 255 )
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return fg.value;
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if ( fg.a == 0 )
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return bg.value;
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union color_rgba8 ret;
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ret.a = 255;
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ret.r = ((255-fg.a)*bg.r + fg.a*fg.r) / 256;
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ret.g = ((255-fg.a)*bg.g + fg.a*fg.g) / 256;
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ret.b = ((255-fg.a)*bg.b + fg.a*fg.b) / 256;
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return ret.value;
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}
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