@Override
    public void onDraw (Canvas canvas)
    {
        //super.onDraw(canvas);
        
        //创建画笔
        p = new Paint();
        //设置画笔的颜色
        p.setColor(Color.GRAY);
         /**画笔的类型**/
        p.setStyle(Paint.Style.STROKE);
        /**设置画笔变为圆滑状**/
        p.setStrokeCap(Paint.Cap.ROUND);
        /**设置线的宽度**/
        p.setStrokeWidth(Integer.parseInt(m_width));
        
        mPath.moveTo(currentX, currentY);
        canvas.drawPath(mPath , p);        
        m_canvas=canvas;
        DrawBitmap(canvas);
    }
    @Override
    public boolean onTouchEvent(MotionEvent event)
    {
        //当前组件的currentX、currentY两个属性
        this.currentX = event.getX();
        this.currentY = event.getY();    
        //返回true表明处理方法已经处理该事件
        switch (event.getAction()) {
        case MotionEvent.ACTION_UP:
            upX = event.getX();
            upY = event.getY();
            p=null;
            break;
        case MotionEvent.ACTION_DOWN:
            downX = event.getX();
            downY = event.getY();
            mPath.moveTo(downX, downY);
            break;
        case MotionEvent.ACTION_MOVE:
            upX = event.getX();
            upY = event.getY();
            mPath.quadTo(downX, downY,upX, upY );
            //m_canvas.drawPath(mPath, paint);            
            downX = upX;
            downY = upY;
            break;
        case MotionEvent.ACTION_CANCEL:
            break;

        }
        //通知改组件重绘
        this.invalidate();
        return true;
    }