【 tulaoshi.com - 编程语言 】
                             
                              unsigned char bybits[16]={0x55,0x0,0xaa,0x0,0x55,0x0,0xaa,0x0,
                            0x55,0x0,0xaa,0x0,0x55,0x0,0xaa,0x0};
  HANDLE hBitmap,hBrush;  
  //---------------------------------------------------------------------------
  void __fastcall TForm1::Button1Click(TObject *Sender)
  {
      /使屏幕暗下来
      HANDLE hdc5;
      hBitmap=CreateBitmap(8,8,1,1,&bybits[0]);
      hBrush=CreatePatternBrush(hBitmap);
      hdc5=GetDC(0);
      SelectObject(hdc5,hBrush);
      PatBlt(hdc5,0,0,Screen-Width,Screen-Height,0xa000c9);
      DeleteObject(hBrush);
      DeleteObject(hBitmap);
      ReleaseDC(0,hdc5);
  }
  //---------------------------------------------------------------------------
  void __fastcall TForm1::Button2Click(TObject *Sender)
  {
      //复原屏幕
      InvalidateRect(0,0,1);
  }
  //---------------------------------------------------------------------------