Android贝塞尔曲线实现直播点赞效果

//1、继承RelativeLayout
public class ChristmasView extends RelativeLayout implements View.OnClickListener {

 private Context context;
 //2、准备几张点赞图片
 private int[] christmas_drawable = {R.drawable.christmas01, R.drawable.christmas02, R.drawable.christmas03
 , R.drawable.christmas04, R.drawable.christmas05, R.drawable.christmas06};
 //随机数种子
 private Random random = new Random();
 //View的宽高
 private int width, height;
 //图片的宽高
 private int drawableWidth, drawableHeight;

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

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

 public ChristmasView(Context context, AttributeSet attrs, int defStyleAttr) {
 super(context, attrs, defStyleAttr);

 this.context = context;
 //3、设置点击事件
 setOnClickListener(this);
 //4、获取点赞图片的宽高
 Drawable drawable = ContextCompat.getDrawable(context, R.drawable.christmas01);
 drawableWidth = drawable.getIntrinsicWidth();
 drawableHeight = drawable.getIntrinsicHeight();
 }
}

@Override
public void onClick(View v) {
 //5、点击增加点赞图片
 addChristmas(context);
}

private void addChristmas(Context context) {
 /**
 * 1、点击一次增加一张图片在底部
 */
 final ImageView imageView = new ImageView(context);
 imageView.setBackgroundResource(christmas_drawable[random.nextInt(christmas_drawable.length - 1)]);
 RelativeLayout.LayoutParams params = new LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT,
 ViewGroup.LayoutParams.WRAP_CONTENT);
 params.addRule(ALIGN_PARENT_BOTTOM);
 params.addRule(CENTER_HORIZONTAL);
 imageView.setLayoutParams(params);
 addView(imageView);

 //2、开始执行点赞效果
 AnimatorSet animatorSet = getAnimatorSet(imageView);
 animatorSet.addListener(new AnimatorListenerAdapter() {
 @Override
 public void onAnimationEnd(Animator animation) {
 //3、动画执行后移除View
 removeView(imageView);
 }
 });
 animatorSet.start();
}

private AnimatorSet getAnimatorSet(ImageView imageView) {
 AnimatorSet enter = new AnimatorSet();

 //1、缩放动画
 AnimatorSet scaleAnimator = new AnimatorSet();
 ObjectAnimator alpha = ObjectAnimator.ofFloat(imageView, "alpha", 0.3f, 1f);
 ObjectAnimator scaleX = ObjectAnimator.ofFloat(imageView, "scaleX", 0.3f, 1f);
 ObjectAnimator scaleY = ObjectAnimator.ofFloat(imageView, "scaleY", 0.3f, 1f);
 scaleAnimator.setDuration(300);
 scaleAnimator.playTogether(alpha, scaleX, scaleY);

 //2、贝塞尔动画
 ValueAnimator bezierAnimator = getBezierAnimator(imageView);

 //3、两个动画按顺序播放
 enter.playSequentially(scaleAnimator, bezierAnimator);
 return enter;
}

/**
 * 贝塞尔曲线估值器：计算动画的执行轨迹
 *
 * @params 传入贝塞尔曲线需要的四个点
 * @return 通过计算返回贝塞尔曲线的坐标
 */
public class BezierEvaluator implements TypeEvaluator<PointF> {

 private PointF point1;
 private PointF point2;

 public BezierEvaluator(PointF point1, PointF point2) {
 this.point1 = point1;
 this.point2 = point2;
 }

 @Override
 public PointF evaluate(float t, PointF point0, PointF point3) {
 PointF point = new PointF();
 //t 取值为 [0,1]

 /**
 * 三阶贝塞尔公式
 *
 * B(t)=(1 - t)^3 P0
 * + 3 t (1 - t)^2 P1
 * + 3 t^2 (1 - t) P2
 * + t^3 P3
 */
 point.x = point0.x * (1 - t) * (1 - t) * (1 - t)
 + 3 * point1.x * t * (1 - t) * (1 - t)
 + 3 * point2.x * t * t * (1 - t)
 + point3.x * t * t * t;

 /**
 * 三阶贝塞尔公式
 *
 * B(t)=(1 - t)^3 P0
 * + 3 t (1 - t)^2 P1
 * + 3 t^2 (1 - t) P2
 * + t^3 P3
 */
 point.y = point0.y * (1 - t) * (1 - t) * (1 - t)
 + 3 * point1.y * t * (1 - t) * (1 - t)
 + 3 * point2.y * t * t * (1 - t)
 + point3.y * t * t * t;

 return point;
 }
}

/**
 * 贝塞尔动画
 *
 * @return
 */
private ValueAnimator getBezierAnimator(final ImageView imageView) {
 //1、构建贝塞尔曲线的四个点
 PointF point0 = new PointF((width - drawableWidth) / 2, height - drawableHeight);
 PointF point1 = new PointF(random.nextInt(width), random.nextInt(height / 2));
 PointF point2 = new PointF(random.nextInt(width), random.nextInt(height / 2) + height / 2);
 PointF point3 = new PointF(random.nextInt(width - drawableWidth), 0);

 //2、创建贝塞尔属性动画
 BezierEvaluator evaluator = new BezierEvaluator(point1, point2);
 final ValueAnimator valueAnimator = ObjectAnimator.ofObject(evaluator, point0, point3);
 valueAnimator.setInterpolator(new LinearInterpolator());
 valueAnimator.setDuration(3000);
 //3、监听贝塞尔曲线估值器返回值
 valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
 @Override
 public void onAnimationUpdate(ValueAnimator animation) {
 //4、获取BezierEvaluator中evaluate()返回的运行轨迹坐标点，设置点赞图片路线
 PointF pointF = (PointF) animation.getAnimatedValue();
 imageView.setX(pointF.x);
 imageView.setY(pointF.y);
 //6、获取BezierEvaluator中evaluate()返回的参数t，设置消失动画
 float t = animation.getAnimatedFraction();
 imageView.setAlpha(1 - t + 0.2f);
 }
 });
 return valueAnimator;
}

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="match_parent"
 android:layout_height="match_parent">

 <com.handsome.boke2.CustomView.ChristmasView
 android:layout_width="100dp"
 android:layout_height="200dp"
 android:layout_alignParentBottom="true"
 android:layout_alignParentRight="true" />
</RelativeLayout>