#include <stdint.h>
#include <stdlib.h>
#include <stdbool.h>
#include <windows.h>
#pragma comment( lib, "user32.lib" )
#pragma comment( lib, "gdi32.lib" )

#define SCRW 640
#define SCRH 480

uint32_t scrbuf[ SCRW * SCRH ];


LRESULT window_proc( HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam ) {
    if( msg == WM_CLOSE ) {
        DestroyWindow( hwnd );
    } else if( msg == WM_DESTROY ) {
        PostQuitMessage( 0 );
    }
    return DefWindowProc( hwnd, msg, wparam, lparam );
};


int main( int argc, char* argv[] ) {
    // register window class
    WNDCLASS wc = { CS_CLASSDC, window_proc };
    wc.lpszClassName = TEXT( "MyClassName" );
    wc.hCursor = LoadCursor( NULL, IDC_ARROW );
    RegisterClass( &wc );

    // create window
    HWND hwnd = CreateWindow( wc.lpszClassName, TEXT( "Window Title" ), 
        WS_OVERLAPPED | WS_SYSMENU | WS_MINIMIZEBOX | WS_VISIBLE, 
        CW_USEDEFAULT, CW_USEDEFAULT, SCRW, SCRH, NULL, NULL, NULL, NULL );
    
    // make sure we update at least every 16ms
    SetTimer( NULL, 0, 16, NULL ); 

    bool exit = false;
    while( !exit ) {
        // windows message handling
        MSG msg;
        while( PeekMessage( &msg, 0, 0, 0, PM_REMOVE ) ) {
            if( msg.message == WM_QUIT ) exit = true;
            TranslateMessage( &msg ); 
            DispatchMessage( &msg );
        }

        // display our screenbuffer
        BITMAPINFOHEADER bmi = { sizeof( bmi ), SCRW, -SCRH, 1, 32 };
        HDC dc = GetDC( hwnd );
        SetDIBitsToDevice( dc, 0, 0, SCRW, SCRH, 0, 0, 0u, SCRH, scrbuf, 
            (BITMAPINFO*)&bmi, DIB_RGB_COLORS );
        ReleaseDC( hwnd, dc );
        
        // plot random pixels in our buffer
        int x = rand() % SCRW;
        int y = rand() % SCRH;
        uint32_t c = ( rand() << 15 ) | rand(); // random rgb color
        scrbuf[ x + y * SCRW ] = c;
    }   
    
    return 0;
}