// main.cpp

#include <stdio.h>
#include <SDL.h>

#define WIDTH 640
#define HEIGHT 480
#define BPP 4
#define DEPTH 32

void SetPixel(SDL_Surface *screen, int x, int y, Uint8 r, Uint8 g, Uint8 b)
{
    int ytimesw = y*screen->pitch/BPP;
    Uint32 *pixmem32 = (Uint32*) screen->pixels + ytimesw + x;
    *pixmem32 = SDL_MapRGB( screen->format, r, g, b );
}

void ClearSurface(SDL_Surface* surf, Uint8 r, Uint8 g, Uint8 b)
{
    int w = surf->w;
    int h = surf->h;
    for(int y=0 ; y < h ; y++)
    {
        for(int x=0 ; x < w ; x++)
        {
            SetPixel(surf, x, y, r, g ,b);
        }
    }
}

void DrawScreen(SDL_Surface* screen)
{
    for(int y=0 ; y < HEIGHT ; y++)
    {
        for(int x=0 ; x < WIDTH ; x++)
        {
            float fr = 255.0f * float(x) / float(WIDTH-1);
            float fg = 255.0f * float(y) / float(HEIGHT-1);
            SetPixel(screen, x, y, (Uint8)fr, (Uint8)fg, 0x00);
        }
    }
}


int main(int argc, char* argv[])
{
    SDL_Surface *screen;
    SDL_Event evt;

    int keypress = 0;
    int h=0;

    if (SDL_Init(SDL_INIT_VIDEO) < 0 ) return 1;

    if (!(screen = SDL_SetVideoMode(WIDTH, HEIGHT, DEPTH, SDL_HWSURFACE)))
    {
        SDL_Quit();
        return 1;
    }

    while(!keypress)
    {
        bool bSkip = false;
        if(SDL_MUSTLOCK(screen))
            if(SDL_LockSurface(screen) < 0)
                bSkip = true;
        if(!bSkip)
        {
            DrawScreen(screen);

            if(SDL_MUSTLOCK(screen))
                SDL_UnlockSurface(screen);

            SDL_Flip(screen);
        }

        while(SDL_PollEvent(&evt))
        {
            switch (evt.type)
            {
            case SDL_QUIT:
                keypress = 1;
                break;
            //case SDL_KEYDOWN:
            //  keypress = 1;
            //  break;
            default:
                break;
            }
        }
    }

    SDL_Quit();

    return 0;
}