130 lines
2.6 KiB
C
130 lines
2.6 KiB
C
/*
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alpha2.c
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--------
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Various transparency operations, aka "alpha channel ops"
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "tthimage.h"
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/*::------------------------------------------------------------------::*/
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int Image_alpha_setvalue(Image_Desc *dst, int v_alpha)
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{
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int y;
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#if DEBUG_LEVEL
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fprintf(stderr, "%s : %d -> %p\n", __func__, v_alpha, dst);
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#endif
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if (dst->type != IMAGE_RGBA)
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{
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fprintf(stderr, "%s : picz %p haz no alpha\n", __func__, dst);
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#if MUST_ABORT
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abort();
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#endif
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return NO_ALPHA_CHANNEL;
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}
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for (y=0; y<dst->height; y++)
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{
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memset(dst->Apix[y], v_alpha, dst->width);
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}
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dst->modified = 1;
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return OLL_KORRECT;
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}
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/*::------------------------------------------------------------------::*/
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/*
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* values of r,g,b pixels are scaled by alpha value.
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*/
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int
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Image_alpha_reduce(Image_Desc *src, Image_Desc *dst, int yo)
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{
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int foo, x, y;
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int r, g, b, a;
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#if DEBUG_LEVEL
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fprintf(stderr, "Image: alpha reduce: %p -> %p (yo=%d)\n", src, dst, yo);
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#endif
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if (src->type != IMAGE_RGBA)
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{
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fprintf(stderr, "Image: alpha reduce: %p is not RGBA", src);
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return NO_ALPHA_CHANNEL;
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}
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if ( (foo=Image_compare_desc(src, dst)) )
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{
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fprintf(stderr, "Image: alpha reduce: images are differents %d\n", foo);
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return foo;
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}
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for (y=0; y<src->height; y++)
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{
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for (x=0; x<src->width; x++)
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{
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Image_getRGBA(src, x, y, &r, &g, &b, &a);
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r = (r * a) / 256;
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g = (g * a) / 256;
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b = (b * a) / 256;
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Image_plotRGB(dst, x, y, r, g, b);
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}
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}
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dst->modified = 1;
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return FUNC_IS_BETA;
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}
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/*::------------------------------------------------------------------::*/
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/*
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* this fonction need more explanations :(
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*/
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int
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Image_poke_alpha_from_rgb(Image_Desc *src, Image_Desc *dst,
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int fr, int fg, int fb, int flag)
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{
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int foo, x, y, r, g, b, a0, a1, a;
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a = 0; /* warning shutdown */
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if ( (foo=Image_compare_desc(src, dst)) )
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{
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fprintf(stderr, "Poke alpha from rgb: images are differents %d\n", foo);
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return foo;
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}
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if ( dst->Apix == NULL )
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{
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fprintf(stderr, "poke alpha from rgb: dest image have NO alpha channel\n");
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return NO_ALPHA_CHANNEL;
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}
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a0 = flag ? 0 : 255;
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a1 = flag ? 255 : 0;
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#if DEBUG_LEVEL
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fprintf(stderr, "For rgb = %d,%d,%d alpha wil be %d\n", fr, fg, fb, a);
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#endif
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for (y=0; y<src->height; y++)
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{
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for (x=0; x<src->width; x++)
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{
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Image_getRGB(src, x, y, &r, &g, &b);
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if (r==fr && g==fg && b==fb) a = a0;
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else a = a1;
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Image_plotRGBA(dst, x, y, r, g, b, a);
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}
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}
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dst->modified = 1;
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return FUNC_NOT_FINISH;
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}
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/*::------------------------------------------------------------------::*/
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