Android(安卓)SDK示例代码学习（1）----BouncingBalls

最近在学习android的开发，打算把sdk的示例代码研究一下，一直以来都没有做笔记的习惯，以至于看过的东西记住的少遗忘的多，因此试试记下笔记，以备以后查询。

-----------------------------以上是首博呢喃------------------------------------------------------

BouncingBalls主要使用的是ValueAnimator及其子类ObjectAnimator

首先是采用了ValueAnimator及其子类ObjectAnimator来设置背景颜色渐变的动画效果

//创建一个值渐变动画，其中backgroundColor是View中的属性，即View类中有setBackgroundColor方法ValueAnimatorcolorAnim=ObjectAnimator.ofInt(this,"backgroundColor",RED,BLUE);colorAnim.setDuration(3000);colorAnim.setEvaluator(newArgbEvaluator());//设置颜色插值器colorAnim.setRepeatCount(ValueAnimator.INFINITE);colorAnim.setRepeatMode(ValueAnimator.REVERSE);colorAnim.start();

自定义了ShapHolder类保存用于绘制ball的属性

publicclassShapeHolder{privatefloatx=0,y=0;//ball的中心点坐标privateShapeDrawableshape;//ball的图形privateintcolor;privateRadialGradientgradient;//ball的环形渲染器，没有用到，渲染器已经设置到paint里边了privatefloatalpha=1f;privatePaintpaint;.....}

ball的动画效果通过一组ValueAnimator叠加来完成

//ball加速下落，还没有碰到下边框的动画ValueAnimatorbounceAnim=ObjectAnimator.ofFloat(newBall,"y",startY,endY);bounceAnim.setDuration(duration);bounceAnim.setInterpolator(newAccelerateInterpolator());//设置加速//ball碰到下边框后压扁的效果，宽度拉长一倍，所以中心点要相应调整ValueAnimatorsquashAnim1=ObjectAnimator.ofFloat(newBall,"x",newBall.getX(),newBall.getX()-25f);squashAnim1.setDuration(duration/4);squashAnim1.setRepeatCount(1);//压扁和回弹是逆向过程，所以这里需要重复一次squashAnim1.setRepeatMode(ValueAnimator.REVERSE);//设置重复的那次动画是逆向过程squashAnim1.setInterpolator(newDecelerateInterpolator());//设置减速//ball碰到下边框后压扁的效果，宽度拉长一倍ValueAnimatorsquashAnim2=ObjectAnimator.ofFloat(newBall,"width",newBall.getWidth(),newBall.getWidth()+50);squashAnim2.setDuration(duration/4);squashAnim2.setRepeatCount(1);squashAnim2.setRepeatMode(ValueAnimator.REVERSE);squashAnim2.setInterpolator(newDecelerateInterpolator());//ball碰到下边框后压扁的效果，高度变为原来的一半，中心点相应调整ValueAnimatorstretchAnim1=ObjectAnimator.ofFloat(newBall,"y",endY,endY+25f);stretchAnim1.setDuration(duration/4);stretchAnim1.setRepeatCount(1);stretchAnim1.setInterpolator(newDecelerateInterpolator());stretchAnim1.setRepeatMode(ValueAnimator.REVERSE);//ball碰到下边框后压扁的效果，高度变为原来的一半ValueAnimatorstretchAnim2=ObjectAnimator.ofFloat(newBall,"height",newBall.getHeight(),newBall.getHeight()-25);stretchAnim2.setDuration(duration/4);stretchAnim2.setRepeatCount(1);stretchAnim2.setInterpolator(newDecelerateInterpolator());stretchAnim2.setRepeatMode(ValueAnimator.REVERSE);//ball回弹的效果ValueAnimatorbounceBackAnim=ObjectAnimator.ofFloat(newBall,"y",endY,startY);bounceBackAnim.setDuration(duration);bounceBackAnim.setInterpolator(newDecelerateInterpolator());

ball回弹完成之后，有一个逐渐消失的过程动画

ValueAnimatorfadeAnim=ObjectAnimator.ofFloat(newBall,"alpha",1f,0f);fadeAnim.setDuration(250);fadeAnim.addListener(newAnimatorListenerAdapter(){@OverridepublicvoidonAnimationEnd(Animatoranimation){//消失动画完成后删除ballballs.remove(((ObjectAnimator)animation).getTarget());}});

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