1. 在delphi根据TshiftState值来判断用户按下Ctrl,shift,alt等键的方法

procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton;
    Shift: TShiftState; X, Y: Integer);
begin
if ssCtrl in shift then
    ShowMessage('ssCtrl');

shift 是一个集合变量。type TShiftState = set of (ssShift, ssAlt, ssCtrl, ssLeft, ssRight, ssMiddle, ssDouble);

Value Meaning

ssShift              The Shift key is held down.
ssAlt                 The Alt key is held down.
ssCtrl               The Ctrl key is held down.
ssLeft               The left mouse button is held down.
ssRight            The right mouse button is held down.
ssMiddle           The middle mouse button is held down.
ssDouble         The mouse was double-clicked.