//Листинг 4.6. Тест для функции MaskBlt()


LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM
   lParam)
{
   PAINTSTRUCT ps;
   HDC hdc;
   static int x, y;
   static HDC memDC;
   static HBITMAP hSmokes, hNo;
   static BITMAP bm;
   switch (message)
   {
   case WM_CREATE:
      hNo = LoadBitmap(hInst, MAKEINTRESOURCE(IDB_NO));
      hSmokes = LoadBitmap(hInst, MAKEINTRESOURCE(IDB_SMOKES));
      GetObject(hSmokes, sizeof(bm), &bm);
      hdc = GetDC(hWnd);
      memDC = CreateCompatibleDC(hdc);

      SelectObject(memDC, hSmokes);
      ReleaseDC(hWnd, hdc);
      break;
   case WM_SIZE:
      x = (LOWORD(lParam) - bm.bmWidth)/2;
      y = (HIWORD(lParam) - bm.bmHeight)/2;
      break;
   case WM_LBUTTONDOWN:
      hdc = GetDC(hWnd);
      MaskBlt(hdc,x,y,bm.bmWidth,bm.bmHeight,memDC,0,0,hNo,0,0,SRCCOPY);
      ReleaseDC(hWnd, hdc);
      break;
   case WM_LBUTTONUP:
      InvalidateRect(hWnd, NULL, TRUE);
      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, x, y, bm.bmWidth, bm.bmHeight, memDC, 0, 0, SRCCOPY);
      EndPaint(hWnd, &ps);
      break;
   case WM_DESTROY: PostQuitMessage(0); break;
   default: return DefWindowProc(hWnd, message, wParam, lParam);
   }
   return 0;
}