106 lines
2.4 KiB
C
106 lines
2.4 KiB
C
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/*
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halfsize.c
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------------------
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see also: scale.c doublesz.c
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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#include "../tthimage.h"
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/*::------------------------------------------------------------------::*/
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/*
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* Fabrication d'une image moiti<EFBFBD> de l'image source.
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*
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* cette fonction alloue une _nouvelle_ image
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* ==========
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* m<EFBFBD>thodes:
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* 0: primitive.
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* 1: semblant d'interpolation.
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*
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*/
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Image_Desc *
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Image_MakeHalfSize(Image_Desc *image, int methode)
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{
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int largeur, hauteur, x, y, xx, yy;
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Image_Desc *demi;
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largeur = image->width / 2; hauteur = image->height / 2;
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if (image->type != IMAGE_RGB)
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{
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fprintf(stderr, "Image HalfSize: bad image type %d\n", image->type);
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return NULL;
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}
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#if DEBUG_LEVEL
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fprintf(stderr, "MakeHalfSize: from %dx%d, method %d -> %d x %d\n",
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image->width, image->height, methode, largeur, hauteur);
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#endif
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demi = Image_alloc(largeur, hauteur, image->type);
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if ( demi == NULL )
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{
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fprintf(stderr, "Image make half size: no memory\n");
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exit(5);
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}
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/*
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* ne faudrait-il pas transmettre certains des attributs de
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* l'image originale <EFBFBD> la nouvelle image ?
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*/
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demi->modified = 0;
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demi->errmsg = image->errmsg;
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for (y=0; y<hauteur; y++)
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{
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yy = y * 2;
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for (x=0; x<largeur; x++)
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{
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xx = x * 2;
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switch(methode)
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{
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case 0:
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(demi->Rpix[y])[x] = (image->Rpix[yy])[xx];
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(demi->Gpix[y])[x] = (image->Gpix[yy])[xx];
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(demi->Bpix[y])[x] = (image->Bpix[yy])[xx];
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break;
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case 1:
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(demi->Rpix[y])[x] = ( (image->Rpix[yy])[xx] +
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(image->Rpix[yy+1])[xx] +
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(image->Rpix[yy])[xx+1] +
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(image->Rpix[yy+1])[xx+1] ) / 4;
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(demi->Gpix[y])[x] = ( (image->Gpix[yy])[xx] +
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(image->Gpix[yy+1])[xx] +
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(image->Gpix[yy])[xx+1] +
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(image->Gpix[yy+1])[xx+1] ) / 4;
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(demi->Bpix[y])[x] = ( (image->Bpix[yy])[xx] +
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(image->Bpix[yy+1])[xx] +
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(image->Bpix[yy])[xx+1] +
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(image->Bpix[yy+1])[xx+1] ) / 4;
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break;
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default:
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/*
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* et ici, un message d'erreur ?
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*/
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break;
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}
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}
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}
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demi->modified = 1;
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return demi; /* demi is a pointer to an Image_Desc ! */
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}
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/*::------------------------------------------------------------------::*/
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