unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.Button1Click(Sender: TObject);
begin
  Canvas.Pen.Color:=clBlue;
  //多边形
  Canvas.PolyGon([Point(10,10),Point(30,10),
  Point(120,30),Point(230,120)]);
  //圆角矩形
  Canvas.RoundRect(200,200,300,250,20,20);
  //圆形
  Canvas.Ellipse(50,50,100,100);
end;

end.