Android 动画分三种，其中属性动画为我们最常用动画，且能满足项目中开发几乎全部需求，google官方包支持3.0+，我们可以引用三方包nineoldandroids来失陪到低版本。本例子中就是用属性动画实现效果。
对普通的View做动画，我们只要定义好要的动画ObjectAnimator或AnimatorSet，然后设置属性启动及可。但是，对ListView做动画应该如何、什么时候、在什么地方、对哪个View做动画属性呢？
github上有成熟的listview动画包 https://github.com/nhaarman/ListViewAnimations.git , 基本可以满足比较炫的效果，比如google+动态list加载，各种动态list显示及删除。问题是，如果不能满足我们的需求，如何实现自己想要的ListView动画效果呢？研究github上项目实现原理发现并不复杂，下面我们就参考开源项目实现自己的ListView动画效果。
要想对ListView的Item做动画，首先想到的是Adapter的getView（）方法。在getView方面里可以获得每个Item view,然后定义好动画效果，结合动画需求对contentView做动画。
如需要做一个删除item时的动画，可以在getView时把View和position传给做的动画或动画集，这个比较简单见代码：
public static AnimatorSet buildListRemoveAnimator(final View view, final List list,
final MyAnimListAdapter adapter, final int index) {
AnimatorListener al = new AnimatorListener() {
@Override
public void onAnimationStart(Animator animation) {
// TODO Auto-generated method stub
}
@Override
public void onAnimationRepeat(Animator animation) {
// TODO Auto-generated method stub
}
@Override
public void onAnimationEnd(Animator animation) {
// TODO Auto-generated method stub
list.remove(index);
ViewHolder vh = (ViewHolder) view.getTag();
vh.needInflate = true;
adapter.notifyDataSetChanged();
}
@Override
public void onAnimationCancel(Animator animation) {
// TODO Auto-generated method stub
}
};
AnimatorSet animatorSet = new AnimatorSet();
Animator anim = ObjectAnimator.ofFloat(view, "rotationX", 0, 90);
Animator animb = ObjectAnimator.ofFloat(view, "alpha", 1, 0);
ValueAnimator valueAnimator = ValueAnimator.ofFloat(0, 1);
final int height = view.getMeasuredHeight();
valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
@Override
public void onAnimationUpdate(ValueAnimator animation) {
// TODO Auto-generated method stub
if (animation.getAnimatedFraction() >= 1) {
view.setVisibility(View.GONE);
}
else {
view.getLayoutParams().height = height
- (int) (height * animation.getAnimatedFraction());
view.requestLayout();
}
}
});
anim.setDuration(ANIMATION_DURATION);
animb.setDuration(ANIMATION_DURATION);
valueAnimator.setDuration(ANIMATION_DURATION + ANIMATION_DURATION + 100);
animatorSet.playTogether(anim, animb, valueAnimator);
animatorSet.addListener(al);
return animatorSet;
}
如何做一个listview动态现实每个Item的显示效果。这个教删除复杂，需要计算每个item动画的开始时间，及判断是否动画现实，还有就是显示动画要按照什么样的规则或是顺序, 计算动画现实的时间等因素。并且不好优化list的性能，及显示效果。下面的例子只是实现了基本动画效果，性能优化欠缺。
public static AnimatorSet buildShowAnimatorList(ViewGroup parent, ListView list, View view, long mAnimationStartMillis,
int mLastAnimatedPosition, int mFirstAnimatedPosition) {
if (mAnimationStartMillis == -1) {
mAnimationStartMillis = System.currentTimeMillis();
}
ViewHelper.setAlpha(view, 0);
Animator alphaAnimator = ObjectAnimator.ofFloat(view, "alpha", 0, 1);
Animator rx = ObjectAnimator.ofFloat(view, "rotationX", -90, 0);
AnimatorSet set = new AnimatorSet();
set.playTogether(alphaAnimator, rx);
set.setStartDelay(calculateAnimationDelay(list, mLastAnimatedPosition, mFirstAnimatedPosition,mAnimationStartMillis));
set.setDuration(DEFAULTANIMATIONDELAYMILLIS);
set.start();
return set;
}
private static long calculateAnimationDelay(ListView list, int last, int first,long starmill) {
long delay;
int lastVisiblePosition = list.getLastVisiblePosition();
int firstVisiblePosition = list.getFirstVisiblePosition();
int numberOfItemsOnScreen = lastVisiblePosition - firstVisiblePosition;
int numberOfAnimatedItems = last - first;
if (numberOfItemsOnScreen + 1 < numberOfAnimatedItems) {
delay = DEFAULTANIMATIONDELAYMILLIS;
} else {
long delaySinceStart = (last - first + 1)
* DEFAULTANIMATIONDELAYMILLIS;
delay = starmill + DEFAULTANIMATIONDELAYMILLIS + delaySinceStart
- System.currentTimeMillis();
}
return Math.max(0, delay);
}
参照上面的方法可以实现自己想要的ListView Item动画，并且可以去自定义想要的效果。
本例源码地址：
https://github.com/CankingApp/ListAnimator
多多提建议，多多交流~
Android ListView动画特效实现原理及源码,布布扣,bubuko.com