delphi之模拟按键

网上有很多的关于模拟按键的例子，经过实验，我选如下一组函数

procedure SendShift(H: HWnd; Down: Boolean);

var

   vKey, ScanCode: Word;

   lParam: longint;

begin

    vKey:= $10;

    ScanCode:= MapVirtualKey(vKey, 0);

    lParam:= longint(ScanCode) shl 16 or 1;

    if not(Down) then

       lParam:= lParam or $C0000000;

    SendMessage(H,WM_KEYDOWN, vKey, lParam);

end;