view test/testgamma.c @ 4590:1ad70fb49fcb

Fix so many things that there is little place in this column to list them all but the result is that blending modes just work now for drawing primitives. Fixes involved: 1. Fix handling of alpha channel when SDL_BLENDMODE_NONE is set. 2. Make xrendercolor use floating-point values for color channels and then convert to 16 bit ints. 3. Fix handling of visuals in SDL_x11modes.c so that a 32 bit ARGB visual is used. 4. Fix the background pixel value in SDL_x11window.c so that the window background has an alpha value of 0xFF and not 0.
author Sunny Sachanandani <sunnysachanandani@gmail.com>
date Fri, 09 Jul 2010 21:36:41 +0530
parents c121d94672cb
children
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/* 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);
}

/* 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());
        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);
    }
#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);

    SDL_Quit();
    return (0);
}