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。