test/testgamma.c

/*
  Copyright (C) 1997-2011 Sam Lantinga <slouken@libsdl.org>

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely.
*/

/* 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"

/* Call this instead of exit(), so we can clean up SDL: atexit() is evil. */
static void
quit(int rc)
{
    SDL_Quit();
    exit(rc);
}

/* 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());
        return (1);
    }

    /* 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());
        quit(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());
        quit(1);
    }

    /* 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;
        SDL_CalculateGammaRamp(gamma, red_ramp);
        SDL_CalculateGammaRamp(1.0f / 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);

    SDL_Quit();
    return (0);
}