test/testgamma.c

   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 }