android动画例子大全

# HelloAnimations Sample project for Android Animations. ## Property Animation [Property Animation](https://developer.android.com/guide/topics/graphics/prop-animation.html) Property Animation相关的类: - [ValueAnimator](https://developer.android.com/reference/android/animation/ValueAnimator.html) - [ObjectAnimator](https://developer.android.com/reference/android/animation/ObjectAnimator.html) - [AnimatorSet](https://developer.android.com/reference/android/animation/AnimatorSet.html) 对应的xml中元素: - `ValueAnimator` -> `<animator>` - `ObjectAnimator` -> `<objectAnimator>` - `AnimatorSet` -> `<set>` Property Animation相关的类都处在包`android.animation`中, 除了用到的Interpolater都在`android.view.animation`包中. Property Animation的xml文件在`res/animator`文件夹中. ### Listeners [Animator.AnimatorListener](https://developer.android.com/reference/android/animation/Animator.AnimatorListener.html) 动画的开始, 结束, 重复, 和取消事件. (常用). [ValueAnimator.AnimatorUpdateListener](https://developer.android.com/reference/android/animation/ValueAnimator.AnimatorUpdateListener.html) 和`ValueAnimator`配合使用, 接收每一帧的回调和计算出来的值. (因为通常只配合`ValueAnimator`, 不常用). - `onAnimationUpdate()`动画的每一帧都调用, 可以通过`getAnimatedValue()`得到当前动画值. 根据你当前动画的对象和属性, 你可能需要自己调用`invalidate()`方法来强制View重绘. 不过所有View的set方法都已经自己做了`invalidate()`的工作, 所以在调用这些方法的时候不需要手动invalidate. ### Layout Animation ViewGroup默认的layout动画可以在xml中通过`android:animateLayoutChanges="true"`开启. 当ViewGroup中的成员发生增加/减少, 显示/隐藏, 就会出现该动画效果. 如果需要指定自定义的layout动画, 可以通过`setLayoutTransition()`给ViewGroup指定一个`LayoutTransition`. `LayoutTransition.setAnimator(int transitionType, Animator animator)`方法可用于指定五种具体类型的动画: - CHANGE_APPEARING - CHANGE_DISAPPEARING - APPEARING - DISAPPEARING - CHANGING ## Interpolators 整个动画过程中, 涉及的计算分三步: - 1.`ValueAnimator`对象根据动画的总时间和已经流逝的时间计算出一个0到1之间的elapsed fraction值. 这个elapsed fraction值就代表了时间完成的程度. - 2.计算出elapsed fraction之后, `ValueAnimator`对象会调用`TimeInterpolator`来计算一个interpolated fraction, 即, 根据所设置的时间插值方法将elapsed fraction映射到interpolated fraction. (如果是线性插值的话elapsed fraction和interpolated fraction会是一直相等的, 但是非线性变换就不是了). - 3.interpolated fraction计算出来后, `ValueAnimator`会调用`TypeEvaluator`, 计算动画属性值. 这时候用的输入参数就是interpolated fraction的值, 以及属性值的起始值和终止值. 整个过程如下图所示：  所有的Interpolater都是整个接口的子类: [Interpolator](https://developer.android.com/reference/android/view/animation/Interpolator.html) ## View Animation [View Animation](https://developer.android.com/guide/topics/graphics/view-animation.html) View Animation相关的类都在`android.view.animation`包中. View Animation相关的xml文件在`res/anim`文件夹中. - [AlphaAnimation](https://developer.android.com/reference/android/view/animation/AlphaAnimation.html) - [RotateAnimation](https://developer.android.com/reference/android/view/animation/RotateAnimation.html) - [ScaleAnimation](https://developer.android.com/reference/android/view/animation/ScaleAnimation.html) - [TranslateAnimation](https://developer.android.com/reference/android/view/animation/TranslateAnimation.html) - [AnimationSet](https://developer.android.com/reference/android/view/animation/AnimationSet.html) 对应的xml中元素: - `AlphaAnimation` -> `<alpha>` - `RotateAnimation` -> `<rotate>` - `ScaleAnimation` -> `<scale>` - `TranslateAnimation` -> `<translate>` - `AnimationSet` -> `<set>` View Animation有一个缺点就是当View被移动到另一个位置以后, 其真实的位置仍在原来的位置. 即: 点击当前所看到的View并不会触发点击事件, 但点击它初始的位置会触发. ## Transitions 在Android 5.0 (API 21)之前, Activity的转场动画是靠`overridePendingTransition()`指定(指定anim), Fragment是`setCustomAnimations()`指定(v4指定anim, 非v4指定animator). 它们只能把整个屏幕作为整体做转换. 从Android 5.0开始, Lollipop APIs让我们可以独立地动画场景中的View元素, 并且可以在两个Activity/Fragment转换的过程中移动共享元素. ### Shared Element Transition 注意实际进行动画的元素是第二屏的View, 所以如果shared view中的内容并不一致, 动画效果并不理想. ## Reference Demos - [AnimationApiDemos](https://github.com/mengdd/AnimationApiDemos) (Old demo in Eclipse time). - [Material-Animations](https://github.com/lgvalle/Material-Animations) ## References - [官方文档Training Adding Animations](https://developer.android.com/training/animation/index.html) - [官方文档Training Defining Custom Animations](https://developer.android.com/training/material/animations.html) - [官方文档Guides Animation and Graphics Overview](https://developer.android.com/guide/topics/graphics/overview.html) - [CodePath Animations](https://guides.codepath.com/android/Animations) Transitions: - [官方文档Training Transitions](https://developer.android.com/training/transitions/overview.html) - [Activity & Fragment Transitions](http://www.androiddesignpatterns.com/2014/12/activity-fragment-transitions-in-android-lollipop-part1.html) 早年的博客系列文章: [Android Animation](http://www.cnblogs.com/mengdd/category/514665.html)