/* Bring up a window and manipulate the gamma on it */

#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#include <math.h>

#include "SDL.h"

/* Turn a normal gamma value into an appropriate gamma ramp */

void CalculateGamma(double gamma, Uint16 *ramp)

{

int i, value;

gamma = 1.0 / gamma;

for ( i=0; i<256; ++i ) {

value = (int)(pow((double)i/256.0, gamma)*65535.0 + 0.5);

if ( value > 65535 ) {

value = 65535;

}

ramp[i] = (Uint16)value;

}

}

/* This can be used as a general routine for all of the test programs */

int get_video_args(char *argv[], int *w, int *h, int *bpp, Uint32 *flags)

{

int i;

*w = 640;

*h = 480;

*bpp = 0;

*flags = SDL_SWSURFACE;

for ( i=1; argv[i]; ++i ) {

if ( strcmp(argv[i], "-width") == 0 ) {

if ( argv[i+1] ) {

*w = atoi(argv[++i]);

}

} else

if ( strcmp(argv[i], "-height") == 0 ) {

if ( argv[i+1] ) {

*h = atoi(argv[++i]);

}

} else

if ( strcmp(argv[i], "-bpp") == 0 ) {

if ( argv[i+1] ) {

*bpp = atoi(argv[++i]);

}

} else

if ( strcmp(argv[i], "-fullscreen") == 0 ) {

*flags |= SDL_FULLSCREEN;

} else

if ( strcmp(argv[i], "-hw") == 0 ) {

*flags |= SDL_HWSURFACE;

} else

if ( strcmp(argv[i], "-hwpalette") == 0 ) {

*flags |= SDL_HWPALETTE;

} else

break;

}

return i;

}

int main(int argc, char *argv[])

{

SDL_Surface *screen;

SDL_Surface *image;

float gamma;

int i;

int w, h, bpp;

Uint32 flags;

Uint16 ramp[256];

Uint16 red_ramp[256];

Uint32 then, timeout;

/* Check command line arguments */

argv += get_video_args(argv, &w, &h, &bpp, &flags);

/* Initialize SDL */

if ( SDL_Init(SDL_INIT_VIDEO) < 0 ) {

fprintf(stderr,

"Couldn't initialize SDL: %s\n", SDL_GetError());

exit(1);

}

atexit(SDL_Quit);

/* Initialize the display, always use hardware palette */

screen = SDL_SetVideoMode(w, h, bpp, flags | SDL_HWPALETTE);

if ( screen == NULL ) {

fprintf(stderr, "Couldn't set %dx%d video mode: %s\n",

w, h, SDL_GetError());

exit(1);

}

/* Set the window manager title bar */

SDL_WM_SetCaption("SDL gamma test", "testgamma");

/* Set the desired gamma, if any */

gamma = 1.0f;

if ( *argv ) {

gamma = (float)atof(*argv);

}

if ( SDL_SetGamma(gamma, gamma, gamma) < 0 ) {

fprintf(stderr, "Unable to set gamma: %s\n", SDL_GetError());

exit(1);

}

#if 0 /* This isn't supported. Integrating the gamma ramps isn't exact */

/* See what gamma was actually set */

float real[3];

if ( SDL_GetGamma(&real[0], &real[1], &real[2]) < 0 ) {

printf("Couldn't get gamma: %s\n", SDL_GetError());

} else {

printf("Set gamma values: R=%2.2f, G=%2.2f, B=%2.2f\n",

real[0], real[1], real[2]);

}

#endif

/* Do all the drawing work */

image = SDL_LoadBMP("sample.bmp");

if ( image ) {

SDL_Rect dst;

dst.x = (screen->w - image->w)/2;

dst.y = (screen->h - image->h)/2;

dst.w = image->w;

dst.h = image->h;

SDL_BlitSurface(image, NULL, screen, &dst);

SDL_UpdateRects(screen, 1, &dst);

}

/* Wait a bit, handling events */

then = SDL_GetTicks();

timeout = (5*1000);

while ( (SDL_GetTicks()-then) < timeout ) {

SDL_Event event;

while ( SDL_PollEvent(&event) ) {

switch (event.type) {

case SDL_QUIT: /* Quit now */

timeout = 0;

break;

case SDL_KEYDOWN:

switch (event.key.keysym.sym) {

case SDLK_SPACE: /* Go longer.. */

timeout += (5*1000);

break;

case SDLK_UP:

gamma += 0.2f;

SDL_SetGamma(gamma, gamma, gamma);

break;

case SDLK_DOWN:

gamma -= 0.2f;

SDL_SetGamma(gamma, gamma, gamma);

break;

case SDLK_ESCAPE:

timeout = 0;

break;

default:

break;

}

break;

}

}

}

/* Perform a gamma flash to red using color ramps */

while ( gamma < 10.0 ) {

/* Increase the red gamma and decrease everything else... */

gamma += 0.1f;

CalculateGamma(gamma, red_ramp);

CalculateGamma(1.0/gamma, ramp);

SDL_SetGammaRamp(red_ramp, ramp, ramp);

}

/* Finish completely red */

memset(red_ramp, 255, sizeof(red_ramp));

memset(ramp, 0, sizeof(ramp));

SDL_SetGammaRamp(red_ramp, ramp, ramp);

/* Now fade out to black */

for ( i=(red_ramp[0] >> 8); i >= 0; --i ) {

memset(red_ramp, i, sizeof(red_ramp));

SDL_SetGammaRamp(red_ramp, NULL, NULL);

}

SDL_Delay(1*1000);

return(0);

}