public class MainActivity extends AppCompatActivity {

  private static final float mPointNum = 50f;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    init();
  }

  private void init() {
    PointF mStartPoint = new PointF(0, 0);
    PointF mEndPoint = new PointF(0, 1200);
    PointF mControlPoint = new PointF(500, 600);

    List<PointF> mPointList = new ArrayList<>();
    for (int i = 0; i <= mPointNum; i++) {
      mPointList.add(getBezierPoint(mStartPoint, mEndPoint, mControlPoint, i / mPointNum));
      Log.d("Bezier", "X:" + mPointList.get(i).x + " Y:" + mPointList.get(i).y);
    }
  }

  private PointF getBezierPoint(PointF start, PointF end, PointF control, float t) {
    PointF bezierPoint = new PointF();
    bezierPoint.x = (1 - t) * (1 - t) * start.x + 2 * t * (1 - t) * control.x + t * t * end.x;
    bezierPoint.y = (1 - t) * (1 - t) * start.y + 2 * t * (1 - t) * control.y + t * t * end.y;
    return bezierPoint;
  }
}

//用递归获取贝塞尔曲线点的x轴坐标
private float getBezierPointX(int n, int position, float t) {
    if (n == 1) {
      return (1 - t) * mPointList.get(position).x + t * mPointList.get(position + 1).x;
    }
    return (1 - t) * getBezierPointX(n - 1, position, t) + t * getBezierPointX(n - 1, position + 1, t);
  }

//用递归获取贝塞尔曲线点的x轴坐标
private float getBezierPointX(int n, int position, float t) {
    if (n == 1) {
      return (1 - t) * mPointList.get(position).x + t * mPointList.get(position + 1).x;
    }
    return (1 - t) * getBezierPointX(n - 1, position, t) + t * getBezierPointX(n - 1, position + 1, t);
  }
private ArrayList<PointF> buildBezierPoints() {
    ArrayList<PointF> points = new ArrayList<>();
    int order = mPointList.size() - 1;
    float delta = 1.0f / POINT_NUM;
    for (float t = 0; t <= 1; t += delta) {
      // Bezier点集
      points.add(new PointF(getBezierPointX(order, 0, t), getBezierPointY(order, 0, t)));
    }
    return points;
  }

canvas.drawLine(start.x,start.y,end.x,end.y);

mPath.moveTo(startPoint.x, startPoint.y);//起点
mPath.quadTo(controlPoint1.x, controlPoint1.y, endPoint.x, endPoint.y);
canvas.drawPath(mPath, mPaint);

mPath.moveTo(startPoint.x, startPoint.y);//起点
mPath.cubicTo(controlPoint1.x, controlPoint1.y, controlPoint2.x, controlPoint2.y, endPoint.x, endPoint.y);
canvas.drawPath(mPath, mPaint);

  private float[] mData = new float[8];        // 顺时针记录绘制圆形的四个数据点
  private float[] mCtrl = new float[16];       // 顺时针记录绘制圆形的八个控制点

  private float mDuration = 1000;           // 变化总时长
  private float mCurrent = 0;             // 当前已进行时长
  private float mCount = 100;             // 将时长总共划分多少份
  private float mPiece = mDuration / mCount;      // 每一份的时长

    path.reset();
    path.moveTo(mData[0], mData[1]);

    path.cubicTo(mCtrl[0], mCtrl[1], mCtrl[2], mCtrl[3], mData[2], mData[3]);
    path.cubicTo(mCtrl[4], mCtrl[5], mCtrl[6], mCtrl[7], mData[4], mData[5]);
    path.cubicTo(mCtrl[8], mCtrl[9], mCtrl[10], mCtrl[11], mData[6], mData[7]);
    path.cubicTo(mCtrl[12], mCtrl[13], mCtrl[14], mCtrl[15], mData[0], mData[1]);

    canvas.drawPath(path, mPaint);

    mCurrent += mPiece;
    if (mCurrent < mDuration) {

      mData[1] -= 120 / mCount;
      mCtrl[7] += 80 / mCount;
      mCtrl[9] += 80 / mCount;

      mCtrl[4] -= 20 / mCount;
      mCtrl[10] += 20 / mCount;

      postInvalidateDelayed((long) mPiece);
    }

public class BezierEvaluator implements TypeEvaluator<PointF> {

 private PointF mControlP1;
 private PointF mControlP2;

 public BezierEvaluator(PointF controlP1, PointF controlP2) {
   this.mControlP1 = controlP1;
   this.mControlP2 = controlP2;
 }

 @Override
 public PointF evaluate(float time, PointF start, PointF end) {

   float timeLeft = 1.0f - time;
   PointF point = new PointF();

   point.x = timeLeft * timeLeft * timeLeft * (start.x) + 3 * timeLeft * timeLeft * time *
       (mControlP1.x) + 3 * timeLeft * time *
       time * (mControlP2.x) + time * time * time * (end.x);

   point.y = timeLeft * timeLeft * timeLeft * (start.y) + 3 * timeLeft * timeLeft * time *
       (mControlP1.y) + 3 * timeLeft * time *
       time * (mControlP2.y) + time * time * time * (end.y);
   return point;
 }
}

 private void init() {

    // 初始化显示的图片
    drawables = new Drawable[3];
    drawables[0] = getResources().getDrawable(R.drawable.red);
    drawables[1] = getResources().getDrawable(R.drawable.yellow);
    drawables[2] = getResources().getDrawable(R.drawable.green);

    // 初始化插补器
    mInterpolators = new Interpolator[4];
    mInterpolators[0] = new LinearInterpolator();// 线性
    mInterpolators[1] = new AccelerateInterpolator();// 加速
    mInterpolators[2] = new DecelerateInterpolator();// 减速
    mInterpolators[3] = new AccelerateDecelerateInterpolator();// 先加速后减速

    // 底部 并且 水平居中
    dWidth = drawables[0].getIntrinsicWidth();
    dHeight = drawables[0].getIntrinsicHeight();
    lp = new LayoutParams(dWidth, dHeight);
    lp.addRule(CENTER_HORIZONTAL, TRUE);// 这里的TRUE 要注意 不是true
    lp.addRule(ALIGN_PARENT_BOTTOM, TRUE);

  }

private AnimatorSet getEnterAnimator(final View target) {
    ObjectAnimator alpha = ObjectAnimator.ofFloat(target, View.ALPHA, 0.2f, 1f);
    ObjectAnimator scaleX = ObjectAnimator.ofFloat(target, View.SCALE_X, 0.2f, 1f);
    ObjectAnimator scaleY = ObjectAnimator.ofFloat(target, View.SCALE_Y, 0.2f, 1f);
    AnimatorSet enter = new AnimatorSet();
    enter.setTarget(target);
    enter.setInterpolator(new LinearInterpolator());
    enter.setDuration(500).playTogether(alpha, scaleX, scaleY);
    return enter;
  }

  private ValueAnimator getBezierValueAnimator(final View target) {
    // 初始化贝塞尔估值器
    BezierEvaluator evaluator = new BezierEvaluator(getPointF(2), getPointF(1));
    // 起点在底部中心位置，终点在底部随机一个位置
    ValueAnimator animator = ValueAnimator.ofObject(evaluator, new PointF((mWidth - dWidth) /
        2, mHeight - dHeight), new PointF(random.nextInt(getWidth()), 0));
    animator.setTarget(target);
    animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
      @Override
      public void onAnimationUpdate(ValueAnimator valueAnimator) {
        // 这里获取到贝塞尔曲线计算出来的的x y值 赋值给view 这样就能让爱心随着曲线走啦
        PointF pointF = (PointF) valueAnimator.getAnimatedValue();
        target.setX(pointF.x);
        target.setY(pointF.y);
        // alpha动画
        target.setAlpha(1 - valueAnimator.getAnimatedFraction());
      }
    });

    animator.setDuration(3000);
    return animator;
  }

public void addHeart() {

    final ImageView imageView = new ImageView(getContext());
    // 随机选一个爱心
    imageView.setImageDrawable(drawables[random.nextInt(3)]);
    imageView.setLayoutParams(lp);
    addView(imageView);

    AnimatorSet finalSet = new AnimatorSet();

    AnimatorSet enterAnimatorSet = getEnterAnimator(imageView);//入场动画
    ValueAnimator bezierValueAnimator = getBezierValueAnimator(imageView);//贝塞尔曲线路径动画

    finalSet.playSequentially(enterAnimatorSet, bezierValueAnimator);
    finalSet.setInterpolator(mInterpolators[random.nextInt(4)]);
    finalSet.setTarget(imageView);

    finalSet.addListener(new AnimatorListenerAdapter() {
      @Override
      public void onAnimationEnd(Animator animation) {
        super.onAnimationEnd(animation);
        removeView((imageView));//删除爱心
      }
    });
    finalSet.start();

  }