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 }