Periscope点赞效果 Android项目开发 教你实现Periscope点赞效果

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());
 }
 }