public class FavorLayout extends RelativeLayout{

private Random random = new Random();//用于实现随机功能

  private int dHeight;//爱心的高度
  private int dWidth;//爱心的宽度
private int mHeight;//FavorLayout的高度
  private int mWidth;//FavorLayout的宽度
public FavorLayout(Context context) {
    super(context);
  }
public FavorLayout(Context context, AttributeSet attrs) {

 super(context, attrs);
 //为了显示区域,我设置了一个背景颜色,随意
 setBackgroundColor(getResources().getColor(R.color.bg));
//init里做一些初始化变量的操作
 init();
}


//重写onMeasure 获取控件宽高
@Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    //注意!! 获取本身的宽高 需要在测量之后才有宽高
    mWidth = getMeasuredWidth();
    mHeight = getMeasuredHeight();
  }

}
//定义完毕后我们来实现底部,水平居中:

//定义一个LayoutParams 用它来控制子view的位置
    private LayoutParams lp;

    //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);
    //好了,之后只要给子view设置LayoutParams就可以实现了

//首先定义 3个代表不同爱心的drawable,以及他们的和drawables
  private Drawable red ;
  private Drawable yellow ;
  private Drawable blue ;
  private Drawable[] drawables ;

    //接下去我们初始化:
    //初始化显示的图片
    drawables = new Drawable[3];
    red = getResources().getDrawable(R.mipmap.red);
    yellow = getResources().getDrawable(R.mipmap.yellow);
    blue = getResources().getDrawable(R.mipmap.blue);
    //赋值给drawables
    drawables[0]=red;
    drawables[1]=yellow;
    drawables[2]=blue;

drawables[random.nextInt(3)]//表示0-2的随机数,注意,3是取不到的,是个开区间

//我封装了一个方法 利用ObjectAnimator AnimatorSet来实现 alpha以及x,y轴的缩放功能
//target就是爱心
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;
  }

mBtnStartAnim.setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
        mFavorLayout.addFavor();
      }
    });

public void addFavor() {

    ImageView imageView = new ImageView(getContext());
    //随机选一个
    imageView.setImageDrawable(drawables[random.nextInt(3)]);
    // 设置底部 水平居中
    imageView.setLayoutParams(lp);

    addView(imageView);
    Log.v(TAG, "add后子view数:"+getChildCount());

    Animator set = getEnterAnimtor(imageView);
    set.start();

}

//我们自定义一个BezierEvaluator 实现 TypeEvaluator
//由于我们view的移动需要控制x y 所以就传入PointF 作为参数,是不是感觉完全契合??
public class BezierEvaluator implements TypeEvaluator<PointF> {


  private PointF pointF1;//途径的两个点 
  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

    PointF point0 = (PointF)startValue;//起点

    PointF point3 = (PointF)endValue;//终点
    //代入公式 
    point.x = timeLeft * timeLeft * timeLeft * (point0.x)
        + 3 * timeLeft * timeLeft * time * (pointF1.x)
        + 3 * timeLeft * time * time * (pointF2.x)
        + time * time * time * (point3.x);

    point.y = timeLeft * timeLeft * timeLeft * (point0.y)
        + 3 * timeLeft * timeLeft * time * (pointF1.y)
        + 3 * timeLeft * time * time * (pointF2.y)
        + time * time * time * (point3.y);
    return point;
  }
}

private ValueAnimator getBezierValueAnimator(View target) {

    //初始化一个BezierEvaluator
    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));//随机
    animator.addUpdateListener(new BezierListenr(target));
    animator.setTarget(target);
    animator.setDuration(3000);
    return animator;
  }

//这里涉及到另外一个方法:getPointF(),这个是我用来获取途径的两个点
// 这里的取值可以随意调整,调整到你希望的样子就好
/**
   * 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);
      // 这里偷个懒,顺便做一个alpha动画,这样alpha渐变也完成啦
      target.setAlpha(1-animation.getAnimatedFraction());
    }
  }

public void addFavor() {

    ImageView imageView = new ImageView(getContext());
    //随机选一个
    imageView.setImageDrawable(drawables[random.nextInt(3)]);
    imageView.setLayoutParams(lp);
    addView(imageView);
    Log.v(TAG, "add后子view数:"+getChildCount());
    getBezierValueAnimator(imageView).start();
  }

// 我为了实现 变速效果 挑选了几种插补器
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
   // 在init中初始化
  private Interpolator[] interpolators ;

// 最终 init方法长这样:
private void init() {

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

  }

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)]);//实现随机变速
    finalSet.setTarget(target);
    return finalSet;
  }

public void addFavor() {

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

    addView(imageView);
    Log.v(TAG, "add后子view数:"+getChildCount());

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

  }

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));
      Log.v(TAG, "removeView后子view数:"+getChildCount());
    }
  }