Delphi Canvas填充区域图形

procedure TForm1.FormCreate(Sender: TObject);
begin
  pb := TPaintBox.Create(Self); pb.Parent := Self;
end;

procedure TForm1.Button1Click(Sender: TObject); begin
  pb.Canvas.Pen.Color := clBlue;
  pb.Canvas.Brush.Color := clRed;
  pb.Canvas.Rectangle(0,0,50,50);
end;