Android 如何跟随手指画一条平滑的线条

如何在Android中跟随手指画一条平滑的线条

java
public class SmoothLineView extends View {
    private Path path;
    private Paint paint;
    public SmoothLineView(Context context) {
        super(context);
        init();
    }
    public SmoothLineView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }
    private void init() {
        path = new Path();
        paint = new Paint();
        paint.setColor(Color.BLACK);
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeWidth(5f);
        paint.setAntiAlias(true);
        paint.setDither(true);
    }
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawPath(path, paint);
    }
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        float x = event.getX();
        float y = event.getY();
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                path.moveTo(x, y);
                break;
            case MotionEvent.ACTION_MOVE:
                path.lineTo(x, y);
                break;
            case MotionEvent.ACTION_UP:
                // Do something when finger is lifted
                break;
        }
        invalidate();
        return true;
    }
}

xml
    android:layout_width="match_parent"
    android:layout_height="match_parent" />