如何清除在image.canvas上画的东西?
我在image的canvas上作如下工作:在任意鼠标点击处(posx,posy)画圆
var
r1:TRect;
begin
r1.left:=posx-1;
r1.top:=posy-1;
r1.right:=posx+1;
r1.bottom:=posy+1;
image1.Canvas.Pen.Color:=clred;
image1.Canvas.Brush.Color:=clred;
image1.Canvas.Ellipse(r1);
现在想清除这些圆点,试了canvas.repaint canvas.refresh都不管用,该如何解决?