自定义view电子签名

public class DrawClear extends View {
    private Paint myPaint;  //自定义的画笔
    private Bitmap myBitmap;// 实现双缓存绘图的 Bitmap
    private Canvas myCanvas;
    private List<Point> points;
    int i;
    private float x;
    private float y;

    public DrawClear(Context context) {
        this(context,null);
    }

    public DrawClear(Context context, AttributeSet attrs) {
        this(context, attrs,0);

    }


    public DrawClear(Context context,AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        initPaint();
        points = new ArrayList<>();

    }

    //初始化画笔
    private void initPaint() {
        if (myPaint == null) {
            myPaint = new Paint(Paint.ANTI_ALIAS_FLAG | Paint.DITHER_FLAG);
            myPaint.setStyle(Paint.Style.FILL);
            myPaint.setColor(Color.BLACK);
            //设置画笔的粗细
            myPaint.setStrokeWidth(10);
            //设置划线是线的圆角
            myPaint.setStrokeJoin(Paint.Join.ROUND);// 圆角
            myPaint.setStrokeCap(Paint.Cap.ROUND);

            myPaint.setPathEffect(new CornerPathEffect(50));
            // PahtEfect指笔迹的风格，CornerPathEffect在拐角处添加弧度，弧度半径50像素点     linePaint.setStyle(Style.STROKE);// 设置画笔风格

            //设置画笔
           // myPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OUT));
        }
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        int width = getMeasuredWidth();
        int height = getMeasuredHeight();
        if (width == 0) {
            width = getWidth();
        }
        if (height == 0) {
            height = getHeight();
        }
        Log.e(TAG, "onMeasure: DrawClear" + width + "  ==" + height);
        //初始化 自己用来缓存的Bitmap  与画布
        if (myBitmap == null) {

            myBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);

            myCanvas = new Canvas(myBitmap);
            myCanvas.drawColor(Color.BLUE);
        }
        //设置被刮去的图片
//        Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher);
//        //在被刮去图片上在画上显示的字
//        Paint paint = new Paint();
//        myCanvas.drawBitmap(bitmap, 0, 0, paint);
//        paint.setColor(Color.BLACK);
//        paint.setStrokeWidth(20);
//        paint.setTextSize(50);
//        myCanvas.drawText("刮一刮", 50, 100, paint);
    }

    /**
     * 滑动事件 判断
     *
     * @param
     * @return
     */
    int size = 0;
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        int action = event.getAction();
        Log.e("rrr","走进了点击"+action);
        switch (action) {
               case MotionEvent.ACTION_DOWN:
                   Path path = new Path();
                   x = event.getX();
                   y = event.getY();
                   Log.e("rrr","走进了点击1");
                   break;
            case MotionEvent.ACTION_MOVE:
                Log.e("rrr","滑动");
                int a = (int) event.getX();
                int b = (int) event.getY();
                Point point = new Point(a, b);
                points.add(point);
                //记录最后的点
                size = points.size() - 1;
                if (size > 0) {
                    //只画出最后的两个点之间的线
                    myCanvas.drawLine(points.get(size - 1).x, points.get(size - 1).y, points.get(size).x, points.get(size).y, myPaint);
                 //   myCanvas.drawLine(x,y, points.get(size).x, points.get(size).y, myPaint);
                }
                invalidate();
                break;
            case MotionEvent.ACTION_UP:
                Log.e("rrr","走进了点击33");
                //清理所有记录的点
                points.clear();
                break;
        }
        return true;
    }

    public Bitmap getB(){

        return myBitmap;
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        if (myBitmap == null) {
            Log.e("rrr","kong");
            return;
        }
        Log.e("rrr",""+(i++));
        canvas.drawBitmap(myBitmap, 0, 0, null);
    }
}