如何清理或刷新ImageView bitMap画布？

Question

源代码：

//The drawing of the circle on the canvas
imageView = new ImageView(this);
bitmap = Bitmap.createBitmap(200 ,200 , Bitmap.Config.ARGB_8888);
imageView.setBackgroundDrawable(new BitmapDrawable(bitmap));
Canvas canvas = new Canvas (bitmap);
canvas.drawCircle (50 , 50 , 20 , paint );

.....

现在我要刷新或清理画布

我该怎么做？

Answer 1

为什么不简单地做：

canvas = new Canvas(bitmap);