Android清空画布

public void clear()

    {

        Paint paint = new Paint();

        paint.setXfermode(new PorterDuffXfermode(Mode.CLEAR));

        canvas.drawPaint(paint);

        paint.setXfermode(new PorterDuffXfermode(Mode.SRC));

        

        invalidate();

    }

 详细请看：http://trylovecatch.iteye.com/blog/1189452