Draw Something To Screen

[srelu]

Here's a sample that uses a thread.

Put the following function in any Win32 application:

DWORD WINAPI MyThread(LPVOID lpParameter)
{
  HDC hdc;
  SIZE s;
  s.cx = ::GetSystemMetrics(SM_CXSCREEN);
  s.cy = ::GetSystemMetrics(SM_CYSCREEN);
  int x, y, z, r, g, b;
  HBRUSH hbr, hbrOld;
  while(TRUE)
  {
    x = s.cx * rand() / RAND_MAX; // position x
    y = s.cy * rand() / RAND_MAX; // position y
    z = 100 * rand() / RAND_MAX; // radius
    r = 255 * rand() / RAND_MAX; // red color componennt
    g = 255 * rand() / RAND_MAX;// green color component
    b = 255 * rand() / RAND_MAX;// blue color component
    hbr = ::CreateSolidBrush(RGB(r,g,b));
    hdc = ::GetDCEx(NULL, 0, 0);
    hbrOld = (HBRUSH) ::SelectObject(hdc, hbr);
    ::Ellipse(hdc, x - z, y - z, x + z, y + z);
    ::SelectObject(hdc, hbrOld);
    ::DeleteObject(hbr);
    ::ReleaseDC(NULL, hdc);
    ::Sleep(20);
  }
}

You start the thread using the following code:

::CreateThread(0, 0, MyThread, 0, 0, 0);

This line can be antwhere in the Win32 application, just make sure it's in a place where it will be excuted exactly once (you can place it in the InitInstance function).

It will fill the whole screen with colorfull circles.