实现关机时的效果的一段代码[VC/C++编程]

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)
{
　//答复屏幕
　InvalidateRect(0,0,1);
}
//---------------------------------------------------------------------------