自定义view，用来测试屏幕

public class BezierGestureTrackView extends View {

    private Bitmap mBufferBitmap;
    private Canvas mBufferCanvas;

    public BezierGestureTrackView(Context context) {
        super(context);
    }
    PointF pointF;

    Paint paint;
    Paint paint2;

    Path p,path ;

    @ColorInt public static final int YELLOW      = 0xFFFFFF00;
    @ColorInt
    public static final int CYAN        = 0xFF00FFFF;
    public static final int c1        = 0xEF8A97;
    public static final int c2        = 0xFBD2A8;

    public BezierGestureTrackView(Context context, AttributeSet attrs) {
        super(context, attrs);
        paint = new Paint();
        paint.setStyle(Paint.Style.STROKE);//设置画笔的填充模式
        paint.setStrokeJoin(Paint.Join.ROUND);//设置画笔图形接触时笔迹的形状
        paint.setStrokeCap(Paint.Cap.ROUND);//设置画笔离开画板时笔迹的形状
        paint.setStrokeWidth(8);//设置画笔粗细  6
        paint.setAntiAlias(true);//设置抗锯齿
        paint.setColor(Color.WHITE);
        initPaint();
       // BitmapFactory.decodeResource(getResources(), R.drawable.hbbg);
    }

    //新建两个SparseArray<Path>用来保存我们画出的Path对象,具体为什么之后会解释
    //mActivePointers用来保存当前正在画的Path
    SparseArray<Path> mActivePointers = new SparseArray<>();
    //truePointers用来保存所有的Path，在onDraw()方法里面我们也是绘制这里的所有Path
    SparseArray<Path> truePointers = new SparseArray<>();

    //保存单个点
    private int i=0;
    private float[] a= new float[1000];

//重写onTouchEvent()方法
    @Override
    public boolean onTouchEvent(MotionEvent event) {

        //获取当前DOWN或者UP的是手指的index
        int curPointerIndex = event.getActionIndex();
        //通过index获得当前手指的id
        int curPointerId = event.getPointerId(curPointerIndex);
      //获取当前正在发生的事件
        int actionMasked = event.getActionMasked();

        switch (actionMasked) {
        //不管是第一个还是第N个手指落下，都执行以下方法：
            case MotionEvent.ACTION_DOWN:

            case MotionEvent.ACTION_POINTER_DOWN:
            //新建一个PointF对象用来保存点的坐标
                pointF = new PointF();
                pointF.x = event.getX(curPointerIndex);
                pointF.y = event.getY(curPointerIndex);
                //每当有手指下落时，都新建一个Path，并移动到手指落下的点
                Path p = new Path();
                p.moveTo(pointF.x, pointF.y);
                //将新建的path添加到mActivePointers中
                mActivePointers.append(curPointerId, p);

                //保存单个点位置

                if (i<998){
                    a[i++]=event.getX(curPointerIndex);
                    a[i++]=event.getY(curPointerIndex);
                }

                break;

            case MotionEvent.ACTION_MOVE:
            //当有手指移动时，遍历mActivePointers，注意这里遍历的条件并不是mActivePointers.size(),而是event.getPointerCount()
            //也就是只监控当前所有正在滑动的手指数，另外在MotionEvent.ACTION_UP事件中，抬起的手指已经从mActivePointers中删除了
                for (int size = event.getPointerCount(), i = 0; i < size; i++) {
                //获取mActivePointers中的每一个Path
                    path = mActivePointers.get(event.getPointerId(i));
                    if (path != null) {
                    //更新每一个Path将得到的点连线
                        path.lineTo(event.getX(i), event.getY(i));
                   
                    }
                }

                break;
            case MotionEvent.ACTION_UP:

            case MotionEvent.ACTION_POINTER_UP:
            //当手指抬起时，代表已经绘制完毕，取得抬起的手指绘制图线实例，传入truePointers让Drow()绘制
             path = mActivePointers.get(curPointerId);
                truePointers.append(truePointers.size(), path);
            //从mActivePointers中将抬起的手指删除
                mActivePointers.remove(curPointerId);
                break;

        }
        //重绘
        invalidate();
        return true;
    }

    private void initBuffer(){
        mBufferBitmap = Bitmap.createBitmap(getWidth(), getHeight(), Bitmap.Config.ARGB_8888);
        mBufferCanvas = new Canvas(mBufferBitmap);
    }

    @Override
    protected void onDraw(Canvas canvas) {
         //canvas.drawColor(Color.BLACK);

//            Bitmap srcBitmap= BitmapFactory.decodeResource(getResources(), R.drawable.hbbg);
//            canvas.drawBitmap(srcBitmap,0f,0f,null);

        //遍历mActivePointers，因为只有当手指抬起时Path才被加入truePointers,此时truePointers里面还没有保存当前正在绘制的图线
        //如果没有遍历mActivePointers，则图线不会即时显示，只有在抬起手指的瞬间，图线才会一起显示
                for (int size = mActivePointers.size(), i = 0; i < size; i++) {
                  Path path = mActivePointers.valueAt(i);
                  canvas.drawPath(path, paint);
        }
        //遍历truePointers，这里保存的是当前正在画的图线
        for (int size = truePointers.size(), i = 0; i < size; i++) {
             path = truePointers.valueAt(i);
            //绘制truePointers里的所有Path
            canvas.drawPath(path, paint);
        }

        if (pointF!=null){
            //canvas.drawPoint(pointF.x, pointF.y,paint2);
            canvas.drawPoints(a, paint2);

            for (int j = 0; j < a.length; j++) {
                Log.e("TAG","a:"+a[i]+"a的长度："+a.length);
            }
        }

    }
//    public void clean(){
////        Canvas canvas = sh.lockCanvas();
////
////
////        if(canvas!=null){
////            Paint paint = new Paint();
////            paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
////            canvas.drawPaint(paint);
//////canvas.drawColor(Color.BLUE);
////        }
//        Log.e("BezierGestureTrackView","CLEAN");
//    }

    public void clear() {

        if (mBufferBitmap != null) {
            if (mActivePointers!=null){
                mActivePointers.clear();
            }
            if (truePointers != null) {
                truePointers.clear();
            }

            mBufferBitmap.eraseColor(Color.TRANSPARENT);
            invalidate();

        }

    }

    private void initPaint() {
        paint2 = new Paint();
        //LinearGradient lg=new LinearGradient(0,0,100,100,Color.RED,Color.BLUE, Shader.TileMode.MIRROR); //参数一为渐变起初点坐标x位
        LinearGradient lg=new LinearGradient(0,0,100,100,CYAN,YELLOW, Shader.TileMode.MIRROR); //参数一为渐变起初点坐标x位
        paint2.setStyle(Paint.Style.STROKE);//设置画笔的填充模式
        paint2.setStrokeJoin(Paint.Join.ROUND);//设置画笔图形接触时笔迹的形状
        paint2.setStrokeCap(Paint.Cap.ROUND);//设置画笔离开画板时笔迹的形状
        paint2.setStrokeWidth(45);//设置画笔粗细 50
        paint2.setAntiAlias(true);//设置抗锯齿
        paint2.setColor(Color.WHITE);//设置抗锯齿
        paint2.setShader(lg);
    }
}