test/testgamma.c
author Ryan C. Gordon <icculus@icculus.org>
Mon, 18 Feb 2019 00:26:53 -0500
changeset 69 a2c5f6a01a55
parent 0 a6cb692b8939
permissions -rw-r--r--
Fill in a default palette for 8-bit screen surfaces.
     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 }