//Листинг 4.8. 

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM
	lParam)
{
   PAINTSTRUCT ps;
   HDC hdc;
   int r, g, b, maxX, maxY;
   static int sx, sy;
   static HDC memBit;
   HBRUSH hBrush;
   RECT rt;
   HBITMAP hBitmap;
   SYSTEMTIME tm;
   switch (message)
   {
   case WM_CREATE:
      SetTimer(hWnd, 1, 100, NULL);
      maxX = GetSystemMetrics(SM_CXSCREEN);
      maxY = GetSystemMetrics(SM_CYSCREEN);
      hdc = GetDC(hWnd);
      memBit = CreateCompatibleDC(hdc);

      hBitmap = CreateCompatibleBitmap(hdc, maxX, maxY);
      SelectObject(memBit, hBitmap);
      PatBlt(memBit, 0, 0, maxX, maxY, WHITENESS);
      ReleaseDC(hWnd, hdc);
      GetSystemTime(&tm);
      srand(tm.wMilliseconds);
      break;
   case WM_SIZE:
      sx = LOWORD(lParam);
      sy = HIWORD(lParam);
      break;
   case WM_TIMER:
      rt.right = (rt.left = rand()*sx/RAND_MAX) + rand()*sx/RAND_MAX/2;
      rt.top = (rt.bottom = rand()*sy/RAND_MAX) - rand()*sy/RAND_MAX/2;
      r = rand()*255/RAND_MAX;
      g = rand()*255/RAND_MAX;
      b = rand()*255/RAND_MAX;
      hBrush = CreateSolidBrush(RGB(r,g,b));
      FillRect(memBit, &rt, hBrush);
      DeleteObject(hBrush);
      InvalidateRect(hWnd, NULL, 0);
      break;
   case WM_COMMAND:
      switch (LOWORD(wParam))
      {
      case IDM_EXIT: DestroyWindow(hWnd); break;
      default: return DefWindowProc(hWnd, message, wParam, lParam);
      }
      break;
   case WM_PAINT:
      hdc = BeginPaint(hWnd, &ps);
      BitBlt(hdc, 0, 0, sx, sy, memBit, 0, 0, SRCCOPY);
      EndPaint(hWnd, &ps);
      break;
   case WM_DESTROY:
      DeleteObject(memBit);
      PostQuitMessage(0);
      break;
   default: return DefWindowProc(hWnd, message, wParam, lParam);
   }
   return 0;
}