清空画布的内容

Question

Image1.Canvas.TextOut(0, 0,  'aaaaa');
以后，如何把画布内容清空

Answer 1

Image1.Canvas.TextOut(0, 0,  'aaaaa');清空:
  Image1.Canvas.Font.Color := Image1.Canvas.Brush.Color;
  Image1.Canvas.TextOut(0,0,'aaaaa');

Answer 2

image1.Canvas.Brush.Color:=clBlack;
  image1.Canvas.Rectangle(x1,y1,x2,y2);
  image1.Canvas.Pen.Color:=clRed;
  image1.Canvas.TextOut(x3,y3,'1');

Answer 3

那么我来抢几分:在
  image1.Canvas.Brush.Color:=clBlack;
  image1.Canvas.Rectangle(x1,y1,x2,y2);
  image1.Canvas.Pen.Color:=clRed;
  image1.Canvas.TextOut(x3,y3,'1');之前,必须设定  image1.Canvas.Brush.style:=bsSolid;否则不能肯定是填充或均匀填充.

Answer 4

用透明色擦掉原来的（设计时Image的brush的颜色即透明色）即可 
 with Image1 do
    begin
      Canvas.Brush.Color := TransColor;
      Canvas.FillRect( Rect( 0, 0, Width, Height ) ); //用透明色擦掉原来的
      ...
   end;

Answer 5

画布内容全清
必须Image1.Canvas.Brush.Style := bsSolid;var
  RC: TRect;
begin
  GetClipBox(Image1.Canvas.Handle, RC);
  InvalidateRect(Image1.Canvas.Handle, @RC, True);
  Image1.Canvas.FillRect(RC);如果只请局部
RC的Top、Left、Bottom、Right就要赋值，并且不要 GetClipBox(Image1.Canvas.Handle, RC); 这句

Answer 6

画布内容全清
必须Image1.Canvas.Brush.Style := bsSolid;var
  RC: TRect;
begin
  GetClipBox(Image1.Canvas.Handle, RC);
  InvalidateRect(Image1.Canvas.Handle, @RC, True);
  Image1.Canvas.FillRect(RC);如果只请局部
RC的Top、Left、Bottom、Right就要赋值，并且不要 GetClipBox(Image1.Canvas.Handle, RC); 这句不错，高手。

Answer 7

清空只需要这一句即可：
Canvas.FillRect(Image1.ClientRect);