procedure TForm1.Button1Click(Sender: TObject);
var
c: TCanvas;
begin { TODO : 动态创建画布 }
c := TControlCanvas.Create;
TControlCanvas(c).Control := SElf.TabSheet1;
c.Brush.Style := bsClear;
c.Pen.Color := clBlue;
// c.Rectangle(5, 5, 15, 15);
c.Draw(0, 0, image1.Picture.Bitmap);
c.Free;
end;