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| #include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <SDL/SDL.h>
#define NBPIXELLARG 400
#define NBPIXELHAUT 200
/******************************************************************************/
/* Change la couleur du pixel de coord (x,y) sur la surface */
/******************************************************************************/
void setPixel(SDL_Surface *surface,int x,int y,int rr,int gg,int bb) {
int bpp = surface->format->BytesPerPixel;
Uint32 pixel=SDL_MapRGB(surface->format,rr,gg,bb);
Uint8 *p = (Uint8 *)surface->pixels + y * surface->pitch + x * bpp;
switch(bpp) {
case 1:
*p = pixel;
break;
case 2:
*(Uint16 *)p = pixel;
break;
case 3:
if(SDL_BYTEORDER == SDL_BIG_ENDIAN) {
p[0] = (pixel >> 16) & 0xff;
p[1] = (pixel >> 8) & 0xff;
p[2] = pixel & 0xff;
} else {
p[0] = pixel & 0xff;
p[1] = (pixel >> 8) & 0xff;
p[2] = (pixel >> 16) & 0xff;
}
break;
case 4:
*(Uint32 *)p = pixel;
break;
}
}
/******************************************************************************/
/* affiche l'image */
/******************************************************************************/
int afficherImage(unsigned char matRGB[3][NBPIXELHAUT][NBPIXELLARG]) {
SDL_Surface *ecran=NULL;
SDL_Event event;
int continuer=1, i, j;
// Demarrage de la SDL
if ( SDL_Init(SDL_INIT_VIDEO) == -1 ) {
fprintf(stderr,"erreur d'initialisation de la SDL : %s\n",SDL_GetError());
return 1;
}
// Ouverture d'une fenetre
SDL_WM_SetCaption("image generee pixel par pixel",NULL);
ecran=SDL_SetVideoMode(NBPIXELLARG,NBPIXELHAUT,32,SDL_SWSURFACE | SDL_DOUBLEBUF);
if ( ecran == NULL ) {
fprintf(stderr,"impossible de charger le mode video : %s\n",SDL_GetError());
SDL_Quit();
return 1;
}
// On vide l'image (elle devient noire) : pas obligatoire
SDL_FillRect(ecran,NULL,SDL_MapRGB(ecran->format,0,0,0));
// On fixe les pixels un par un
SDL_LockSurface(ecran);
for (i=0;i<NBPIXELHAUT;i++) {
for (j=0;j<NBPIXELLARG;j++) {
setPixel(ecran,j,i,(int)matRGB[0][i][j],(int)matRGB[1][i][j],(int)matRGB[2][i][j]);
}
}
SDL_UnlockSurface(ecran);
SDL_Flip(ecran);
// Boucle d'evenements
while (continuer) {
SDL_WaitEvent(&event);
switch(event.type) {
case SDL_QUIT:
continuer=0;
break;
}
}
// Arret de la SDL
SDL_Quit();
return 0;
}
/******************************************************************************/
/* genere un entier aleatoire entre m et M */
/******************************************************************************/
int genererEntier(int m,int M) {
return (m + (int)((double)rand() / ((double)RAND_MAX + 1) * (M-m+1)) );
}
/******************************************************************************/
/* main */
/******************************************************************************/
int main(int argc, char *argv[]) {
int i, j;
unsigned char matRGB[3][NBPIXELHAUT][NBPIXELLARG];
srand((unsigned) time(NULL));
// matrice de rouge
for (i=0;i<NBPIXELHAUT;i++) {
for (j=0;j<NBPIXELLARG;j++) {
matRGB[0][i][j] = (unsigned char)genererEntier(0,255);
}
}
// matrice de vert
for (i=0;i<NBPIXELHAUT;i++) {
for (j=0;j<NBPIXELLARG;j++) {
matRGB[1][i][j] = (unsigned char)genererEntier(0,255);
}
}
// matrice de bleu
for (i=0;i<NBPIXELHAUT;i++) {
for (j=0;j<NBPIXELLARG;j++) {
matRGB[2][i][j] = (unsigned char)genererEntier(0,255);
}
}
if ( afficherImage(matRGB) ) {
fprintf(stderr,"erreur lors de l'affichage de l'image\n");
exit(EXIT_FAILURE);
}
return EXIT_SUCCESS;
} |
