lcdscrub.c

/* Ace_K's LCD Pixel Scrubber. Run for at least 10 minutes, screens in severe
 * condition may need several hours. Do not stare at this if you have epilepsy*/

#include <SDL/SDL.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>

#define HRES 1920
#define VRES 1080
#define FPS  60

Uint16 CreateHicolorPixel(SDL_PixelFormat * fmt, Uint8 red, Uint8 green,
              Uint8 blue)
{
    Uint16 value;
    /* This series of bit shifts uses the information from the SDL_Format
     * structure to correctly compose a 16-bit pixel value from 8-bit RGB */
    value = ((red   >> fmt->Rloss) << fmt->Rshift) +
        ((green >> fmt->Gloss) << fmt->Gshift) +
        ((blue  >> fmt->Bloss) << fmt->Bshift);

    return value;
}

int main(int argc, char **argv)
{
    (void) argc;
    (void) argv;

    SDL_Surface *screen;
    SDL_Event   event;
    Uint16  *raw_pixels;
    int x, y;
    char quit = 0;
    u_int8_t pixel_mask = 0xFF;

    /* Init SDL */
    if (SDL_Init(SDL_INIT_VIDEO) != 0) {
        fprintf(stderr, "Unable to initialize SDL: %s\n", SDL_GetError());
        return 1;
    }
    /* Make sure SDL_Quit get's called when program exits */
    atexit(SDL_Quit);
    (void) SDL_ShowCursor(SDL_DISABLE);
    screen = SDL_SetVideoMode(HRES, VRES, 16, SDL_SWSURFACE |
                          SDL_FULLSCREEN);
    if (screen == NULL) {
        fprintf(stderr, "Unable to set video mode: %s\n", SDL_GetError());
        return 1;
    }

    /* Get a pointer to the video surface's memory. */
    raw_pixels = (Uint16*) screen->pixels;

    /* create a scanline effect */
    while (!quit) {
        /*MSG PUMP*/
        if (SDL_PollEvent(&event)) {
            switch (event.type) {
                case SDL_QUIT:
                    quit = 1;
                    break;
                case SDL_KEYDOWN:
                    switch (event.key.keysym.sym) {
                        case SDLK_ESCAPE:
                        case SDLK_q:
                            quit = 1;
                            break;
                    }
                    break;
            }
        }

        SDL_LockSurface(screen);
        pixel_mask = ~pixel_mask;
        for(x = 0; x < HRES; x++) {
            for(y = 0; y < VRES; y++) {
                Uint16 pixel_color;
                int offset;
                pixel_color = CreateHicolorPixel(screen->format, 0xFF ^ pixel_mask,
                                         0xFF ^ pixel_mask,
                                         0xFF ^ pixel_mask);

                offset = ((screen->pitch >> 1) * y + x);
                raw_pixels[offset] = pixel_color;
                pixel_mask = ~pixel_mask;
            }
            pixel_mask = ~pixel_mask;
        }
        SDL_UnlockSurface(screen);

        /* Sleep for 16ms between frame draws at 60hz */
        SDL_Delay(1000 / FPS);
        SDL_UpdateRect(screen, 0, 0, 0, 0);
    }

    return 0;
}