1 2 /* Bring up a window and manipulate the gamma on it */ 3 4 #include <stdlib.h> 5 #include <stdio.h> 6 #include <string.h> 7 #include <math.h> 8 9 #include "SDL.h" 10 11 /* Call this instead of exit(), so we can clean up SDL: atexit() is evil. */ 12 static void quit(int rc) 13 { 14 SDL_Quit(); 15 exit(rc); 16 } 17 18 /* Turn a normal gamma value into an appropriate gamma ramp */ 19 void CalculateGamma(double gamma, Uint16 *ramp) 20 { 21 int i, value; 22 23 gamma = 1.0 / gamma; 24 for ( i=0; i<256; ++i ) { 25 value = (int)(pow((double)i/256.0, gamma)*65535.0 + 0.5); 26 if ( value > 65535 ) { 27 value = 65535; 28 } 29 ramp[i] = (Uint16)value; 30 } 31 } 32 33 /* This can be used as a general routine for all of the test programs */ 34 int get_video_args(char *argv[], int *w, int *h, int *bpp, Uint32 *flags) 35 { 36 int i; 37 38 *w = 640; 39 *h = 480; 40 *bpp = 0; 41 *flags = SDL_SWSURFACE; 42 43 for ( i=1; argv[i]; ++i ) { 44 if ( strcmp(argv[i], "-width") == 0 ) { 45 if ( argv[i+1] ) { 46 *w = atoi(argv[++i]); 47 } 48 } else 49 if ( strcmp(argv[i], "-height") == 0 ) { 50 if ( argv[i+1] ) { 51 *h = atoi(argv[++i]); 52 } 53 } else 54 if ( strcmp(argv[i], "-bpp") == 0 ) { 55 if ( argv[i+1] ) { 56 *bpp = atoi(argv[++i]); 57 } 58 } else 59 if ( strcmp(argv[i], "-fullscreen") == 0 ) { 60 *flags |= SDL_FULLSCREEN; 61 } else 62 if ( strcmp(argv[i], "-hw") == 0 ) { 63 *flags |= SDL_HWSURFACE; 64 } else 65 if ( strcmp(argv[i], "-hwpalette") == 0 ) { 66 *flags |= SDL_HWPALETTE; 67 } else 68 break; 69 } 70 return i; 71 } 72 73 int main(int argc, char *argv[]) 74 { 75 SDL_Surface *screen; 76 SDL_Surface *image; 77 float gamma; 78 int i; 79 int w, h, bpp; 80 Uint32 flags; 81 Uint16 ramp[256]; 82 Uint16 red_ramp[256]; 83 Uint32 then, timeout; 84 85 /* Check command line arguments */ 86 argv += get_video_args(argv, &w, &h, &bpp, &flags); 87 88 /* Initialize SDL */ 89 if ( SDL_Init(SDL_INIT_VIDEO) < 0 ) { 90 fprintf(stderr, 91 "Couldn't initialize SDL: %s\n", SDL_GetError()); 92 return(1); 93 } 94 95 /* Initialize the display, always use hardware palette */ 96 screen = SDL_SetVideoMode(w, h, bpp, flags | SDL_HWPALETTE); 97 if ( screen == NULL ) { 98 fprintf(stderr, "Couldn't set %dx%d video mode: %s\n", 99 w, h, SDL_GetError()); 100 quit(1); 101 } 102 103 /* Set the window manager title bar */ 104 SDL_WM_SetCaption("SDL gamma test", "testgamma"); 105 106 /* Set the desired gamma, if any */ 107 gamma = 1.0f; 108 if ( *argv ) { 109 gamma = (float)atof(*argv); 110 } 111 if ( SDL_SetGamma(gamma, gamma, gamma) < 0 ) { 112 fprintf(stderr, "Unable to set gamma: %s\n", SDL_GetError()); 113 quit(1); 114 } 115 116 #if 0 /* This isn't supported. Integrating the gamma ramps isn't exact */ 117 /* See what gamma was actually set */ 118 float real[3]; 119 if ( SDL_GetGamma(&real[0], &real[1], &real[2]) < 0 ) { 120 printf("Couldn't get gamma: %s\n", SDL_GetError()); 121 } else { 122 printf("Set gamma values: R=%2.2f, G=%2.2f, B=%2.2f\n", 123 real[0], real[1], real[2]); 124 } 125 #endif 126 127 /* Do all the drawing work */ 128 image = SDL_LoadBMP("sample.bmp"); 129 if ( image ) { 130 SDL_Rect dst; 131 132 dst.x = (screen->w - image->w)/2; 133 dst.y = (screen->h - image->h)/2; 134 dst.w = image->w; 135 dst.h = image->h; 136 SDL_BlitSurface(image, NULL, screen, &dst); 137 SDL_UpdateRects(screen, 1, &dst); 138 } 139 140 /* Wait a bit, handling events */ 141 then = SDL_GetTicks(); 142 timeout = (5*1000); 143 while ( (SDL_GetTicks()-then) < timeout ) { 144 SDL_Event event; 145 146 while ( SDL_PollEvent(&event) ) { 147 switch (event.type) { 148 case SDL_QUIT: /* Quit now */ 149 timeout = 0; 150 break; 151 case SDL_KEYDOWN: 152 switch (event.key.keysym.sym) { 153 case SDLK_SPACE: /* Go longer.. */ 154 timeout += (5*1000); 155 break; 156 case SDLK_UP: 157 gamma += 0.2f; 158 SDL_SetGamma(gamma, gamma, gamma); 159 break; 160 case SDLK_DOWN: 161 gamma -= 0.2f; 162 SDL_SetGamma(gamma, gamma, gamma); 163 break; 164 case SDLK_ESCAPE: 165 timeout = 0; 166 break; 167 default: 168 break; 169 } 170 break; 171 } 172 } 173 } 174 175 /* Perform a gamma flash to red using color ramps */ 176 while ( gamma < 10.0 ) { 177 /* Increase the red gamma and decrease everything else... */ 178 gamma += 0.1f; 179 CalculateGamma(gamma, red_ramp); 180 CalculateGamma(1.0/gamma, ramp); 181 SDL_SetGammaRamp(red_ramp, ramp, ramp); 182 } 183 /* Finish completely red */ 184 memset(red_ramp, 255, sizeof(red_ramp)); 185 memset(ramp, 0, sizeof(ramp)); 186 SDL_SetGammaRamp(red_ramp, ramp, ramp); 187 188 /* Now fade out to black */ 189 for ( i=(red_ramp[0] >> 8); i >= 0; --i ) { 190 memset(red_ramp, i, sizeof(red_ramp)); 191 SDL_SetGammaRamp(red_ramp, NULL, NULL); 192 } 193 SDL_Delay(1*1000); 194 195 SDL_Quit(); 196 return(0); 197 } 198
