ExcludeClipRect

 

  hdc = BeginPaint(hWnd, &ps);
  
  RECT rtClient;
  ::GetClientRect(hWnd, &rtClient);
 
  // 不包含的剪切区域(也就是说, 从(0, 0)到(400, 400)的矩形, 不会被绘制)
  ::ExcludeClipRect(hdc, 0, 0, 400, 400);

  ::MoveToEx(hdc, 0, 0, NULL);
  ::LineTo(hdc, rtClient.right, rtClient.bottom);

  EndPaint(hWnd, &ps);