获取矩形局域的方法，Rect、Bounds、Point

var
  R: TRect;

procedure TForm5.FormCreate(Sender: TObject);
begin
  RadioGroup1.Items.CommaText := ‘Undo,Rect,RectPoint,Bounds‘;
  R := Button1.BoundsRect;
end;

procedure TForm5.RadioGroup1Click(Sender: TObject);
begin
  case RadioGroup1.ItemIndex of
    0: Button1.BoundsRect := R;

    //function Rect(ALeft, ATop, ARight, ABottom: Integer): TRect;
    1: Button1.BoundsRect := Rect(50, 50, 100, 80);  {50与50是矩形左上角点，100与80是矩形 右下角这个点}

    //function Rect(const ATopLeft, ABottomRight: TPoint): TRect;
    2: Button1.BoundsRect := Rect(Point(50, 50), Point(100,80)); //不发生变化，可见上面10与80就是矩形 右下角这个点

    //function Bounds(ALeft, ATop, AWidth, AHeight: Integer): TRect;
    3: Button1.BoundsRect := Bounds(50, 50, 100, 80);{50和50是矩形左上角点，100从这个点向右延伸宽度，80是从这个点向下延伸高度}
  end;
end;