libtthimage/Lib/drawalpha.c

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/*
primitives graphiques deuxieme module (circa 2002)
--------------------------------------------------
*/
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include "../tthimage.h"
/*::------------------------------------------------------------------::*/
#ifndef min
#define min(a,b) ((a)<(b)?(a):(b))
#define max(a,b) ((a)>(b)?(a):(b))
#endif
/*::------------------------------------------------------------------::*/
/*
* the easy one.
*/
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int Image_paint_A_rect(Image_Desc *img, Image_Rect *rect, RGBA *rgba)
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{
int xd, yd, xf, yf, x, y;
int r, g, b, a0, a1, nbre;
xd = max(0, rect->x);
yd = max(0, rect->y);
xf = min((img->width-1), (rect->x+rect->w));
yf = min((img->height-1), (rect->y+rect->h));
#if DEBUG_LEVEL
fprintf(stderr, "Paint Alpha Rect: %d <X< %d %d <Y< %d\n", xd, xf, yd, yf);
Image_print_rgba("encre alpha", rgba, 0);
#endif
a0 = 255 - rgba->a;
a1 = rgba->a;
/* printf("a0 = %d a1 = %d\n", a0, a1); */
nbre = 0;
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for (x=xd; x<xf; x++) {
for (y=yd; y<yf; y++) {
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Image_getRGB(img, x, y, &r, &g, &b);
/*
* ok, compute now...
*/
r = ( r*a0 + rgba->r*a1 ) / 255;
g = ( g*a0 + rgba->g*a1 ) / 255;
b = ( b*a0 + rgba->b*a1 ) / 255;
Image_plotRGB(img, x, y, r, g, b);
nbre++;
}
}
return FUNC_IS_BETA;
}
/*::------------------------------------------------------------------::*/
/*
* new 15 Janvier 2003.
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* premiere utilisation: l'ecriture des titres des
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* image de l'expovsition.
*/
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int Image_fade_A_rect(Image_Desc *img, Image_Rect *rect, int alpha)
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{
int xd, yd, xf, yf, x, y;
int r, g, b ;
xd = max(0, rect->x);
yd = max(0, rect->y);
xf = min((img->width-1), (rect->x+rect->w));
yf = min((img->height-1), (rect->y+rect->h));
#if DEBUG_LEVEL
fprintf(stderr, "Fade Alpha Rect: %d < X < %d %d < Y < %d\n",
xd, xf, yd, yf);
fprintf(stderr, " coefficient alpha = %d\n", alpha);
#endif
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for (x=xd; x<xf; x++) {
for (y=yd; y<yf; y++) {
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Image_getRGB(img, x, y, &r, &g, &b);
/*
* ok, compute now...
*/
r = ( r*alpha ) / 255;
g = ( g*alpha ) / 255;
b = ( b*alpha ) / 255;
Image_plotRGB(img, x, y, r, g, b);
}
}
return FUNC_IS_BETA; /* need unit testing */
}
/*::------------------------------------------------------------------::*/
/* nouveau vacances de fevrier 2010 */
/*
* bon, une fonction pour tamponner une image quelconque avec une
* image alpha, il serait temps de la mettre en place, nom ?
*/
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int Image_tampon_alpha_0(Image_Desc *src, Image_Desc *tampon, Image_Desc *dst)
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{
int x, y, rs, gs, bs, rt, gt, bt;
int rd, gd, bd, clean_tampon;
clean_tampon = 0;
/* if the 'tampon' is not defined, we have to imagine one */
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if (NULL==tampon) {
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tampon = Image_clone(src, 0);
fprintf(stderr, "fake tampon @ %p\n", tampon);
Image_mirror(src, tampon, 0);
clean_tampon = 1;
}
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for (y=0; y<src->height; y++) {
for (x=0; x<src->width; x++) {
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Image_getRGB(src, x, y, &rs, &gs, &bs);
Image_getRGB(tampon, x, y, &rt, &gt, &bt);
rd = (rs * rt) / 256;
}
}
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if (clean_tampon) {
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fprintf(stderr, "clean %p in %s\n", tampon, __func__);
Image_DeAllocate(tampon); free(tampon);
}
return FUNC_IS_ALPHA;
}
/*::------------------------------------------------------------------::*/