分享一个很炫的Periscope点赞效果

上次见到同学了做了一个非常炫的点赞动画，见猎心喜，查了查资料才知道是Periscope点赞效果，网上大神已经对此写过很容易集成的库了，今天迫不及待的想跟大家分享一下

分享大神git库地址

Periscope点赞效果

先看看大神做的效果吧

这里是项目结构

periscopelayout.java是动画所在布局，BezierEvaluator是贝塞尔计算器

整个项目可以看到这个动画的流程，
1.自定义动画布局
2.初始化爱心的缩放动画
3.爱心的随机出现，插值器的随机出现
4.爱心在滑动过程中透明度的渐变
5.滑动曲线的实现，实现贝塞尔曲线效果

PeriscopeLayout.java

package me.yifeiyuan.periscopelayout;

import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.animation.AnimatorSet;
import android.animation.ObjectAnimator;
import android.animation.ValueAnimator;
import android.annotation.TargetApi;
import android.content.Context;
import android.graphics.PointF;
import android.graphics.drawable.Drawable;
import android.os.Build;
import android.util.AttributeSet;
import android.view.View;
import android.view.animation.AccelerateDecelerateInterpolator;
import android.view.animation.AccelerateInterpolator;
import android.view.animation.DecelerateInterpolator;
import android.view.animation.Interpolator;
import android.view.animation.LinearInterpolator;
import android.widget.ImageView;
import android.widget.RelativeLayout;

import java.util.Random;



public class PeriscopeLayout extends RelativeLayout {

    private Interpolator line = new LinearInterpolator();//线性
    private Interpolator acc = new AccelerateInterpolator();//加速
    private Interpolator dce = new DecelerateInterpolator();//减速
    private Interpolator accdec = new AccelerateDecelerateInterpolator();//先加速后减速
    private Interpolator[] interpolators;

    private int mHeight;
    private int mWidth;
    private LayoutParams lp;
    private Drawable[] drawables;
    private Random random = new Random();

    private int dHeight;
    private int dWidth;

    public PeriscopeLayout(Context context) {
        super(context);
        init();
    }

    public PeriscopeLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public PeriscopeLayout(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
    public PeriscopeLayout(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
        init();
    }

    private void init() {

        //初始化显示的图片
        drawables = new Drawable[3];
        Drawable red = getResources().getDrawable(R.drawable.pl_red);
        Drawable yellow = getResources().getDrawable(R.drawable.pl_yellow);
        Drawable blue = getResources().getDrawable(R.drawable.pl_blue);

        drawables[0] = red;
        drawables[1] = yellow;
        drawables[2] = blue;
        //获取图的宽高 用于后面的计算
        //注意 我这里3张图片的大小都是一样的,所以我只取了一个
        dHeight = red.getIntrinsicHeight();
        dWidth = red.getIntrinsicWidth();

        //底部 并且 水平居中
        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);

        // 初始化插补器
        interpolators = new Interpolator[4];
        interpolators[0] = line;
        interpolators[1] = acc;
        interpolators[2] = dce;
        interpolators[3] = accdec;

    }


    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        mWidth = getMeasuredWidth();
        mHeight = getMeasuredHeight();
    }


    public void addHeart() {

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

        addView(imageView);

        Animator set = getAnimator(imageView);
        set.addListener(new AnimEndListener(imageView));
        set.start();

    }

    private Animator getAnimator(View target) {
        AnimatorSet set = getEnterAnimtor(target);

        ValueAnimator bezierValueAnimator = getBezierValueAnimator(target);

        AnimatorSet finalSet = new AnimatorSet();
        finalSet.playSequentially(set);
        finalSet.playSequentially(set, bezierValueAnimator);
        finalSet.setInterpolator(interpolators[random.nextInt(4)]);
        finalSet.setTarget(target);
        return finalSet;
    }

    private AnimatorSet getEnterAnimtor(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.setDuration(500);
        enter.setInterpolator(new LinearInterpolator());
        enter.playTogether(alpha, scaleX, scaleY);
        enter.setTarget(target);
        return enter;
    }

    private ValueAnimator getBezierValueAnimator(View target) {

        //初始化一个贝塞尔计算器- - 传入
       BezierEvaluator evaluator = new BezierEvaluator(getPointF(2), getPointF(1));

        //这里最好画个图 理解一下 传入了起点 和 终点
        ValueAnimator animator = ValueAnimator.ofObject(evaluator, new PointF((mWidth - dWidth) / 2, mHeight - dHeight), new PointF(random.nextInt(getWidth()), 0));
        animator.addUpdateListener(new BezierListenr(target));
        animator.setTarget(target);
        animator.setDuration(3000);
        return animator;
    }

    /** * 获取中间的两个 点 * * @param scale */
    private PointF getPointF(int scale) {

        PointF pointF = new PointF();
        pointF.x = random.nextInt((mWidth - 100));//减去100 是为了控制 x轴活动范围,看效果 随意~~
        //再Y轴上 为了确保第二个点 在第一个点之上,我把Y分成了上下两半 这样动画效果好一些 也可以用其他方法
        pointF.y = random.nextInt((mHeight - 100)) / scale;
        return pointF;
    }

    private class BezierListenr implements ValueAnimator.AnimatorUpdateListener {

        private View target;

        public BezierListenr(View target) {
            this.target = target;
        }

        @Override
        public void onAnimationUpdate(ValueAnimator animation) {
            //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) animation.getAnimatedValue();
            target.setX(pointF.x);
            target.setY(pointF.y);
            // 这里顺便做一个alpha动画
            target.setAlpha(1 - animation.getAnimatedFraction());
        }
    }


    private class AnimEndListener extends AnimatorListenerAdapter {
        private View target;

        public AnimEndListener(View target) {
            this.target = target;
        }

        @Override
        public void onAnimationEnd(Animator animation) {
            super.onAnimationEnd(animation);
            //因为不停的add 导致子view数量只增不减,所以在view动画结束后remove掉
            removeView((target));
        }
    }
}

贝塞尔曲线计算器BezierEvaluator.java

package me.yifeiyuan.periscopelayout;

import android.animation.TypeEvaluator;
import android.graphics.PointF;

public class BezierEvaluator implements TypeEvaluator<PointF> {


    private PointF pointF1;
    private PointF pointF2;
    public BezierEvaluator(PointF pointF1,PointF pointF2){
        this.pointF1 = pointF1;
        this.pointF2 = pointF2;
    }
    @Override
    public PointF evaluate(float time, PointF startValue,
                           PointF endValue) {

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

        point.x = timeLeft * timeLeft * timeLeft * (startValue.x)
                + 3 * timeLeft * timeLeft * time * (pointF1.x)
                + 3 * timeLeft * time * time * (pointF2.x)
                + time * time * time * (endValue.x);

        point.y = timeLeft * timeLeft * timeLeft * (startValue.y)
                + 3 * timeLeft * timeLeft * time * (pointF1.y)
                + 3 * timeLeft * time * time * (pointF2.y)
                + time * time * time * (endValue.y);
        return point;
    }
}

主页面是如何调用的呢？

final PeriscopeLayout periscopeLayout = (PeriscopeLayout) findViewById(R.id.periscope);
        findViewById(R.id.btn).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                periscopeLayout.addHeart();
            }
        });

这样就实现了，嗯代码不多，实现功能很简单，但原理要想搞懂就比较蛋疼了，贴上大神原文地址，

http://www.jianshu.com/p/03fdcfd3ae9c

仅供参考，源码就不上传了，就差了几张爱心的图片，大家可以稍作修改，以适应需求，谢谢大家。