属性动画(Property Animation)

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1. 概述
   1. 2D和3D图形
2. 属性动画
   1. 属性动画特点
   2. 属性动画如何工作
   3. 属性动画与视图动画区别
   4. 应用属性动画有两个步骤
   5. ValueAnimator
   6. ObjectAnimator
   7. AnimatorSet
   8. Animation Listeners
   9. 为viewGroup的layout改变设置动画
   10. KeyFrams
   11. Animation Views
   12. ViewPropertyAnimator
   13. 在XMl中声明animation

转载请注明出处：http://blog.youkuaiyun.com/ZhouLi_优快云/article/details/45968639

概述

andorid系统提供了两种动画系统，属性动画和视图动画。属性动画更灵活并且功能也更强。此外，android还提供了帧动画（drawable animation）.

1. 属性动画：andorid3.0引入，允许绘制任何对象，包括没有显示在屏幕上的，并且系统允许自定义类型。属性动画改变对象的一个field值实现动画。指定你想要的属性，多长时间，动画的值就可以实现了。
2. 只能使用在views上面
3. 帧动画，连续播放图形资源

2D和3D图形

1. canvas和drawables 
   android系统提供了一些用户控件，你可以扩展这些类更改它们的样子和行为.
2. open gl 
   系统提供了框架api和native api，使用它们可以做一些canvas不支持的api。

属性动画

属性动画特点

• Duration：可以指定时间长度，默认为300ms。
• Time interpolation：属性的计算方式，如先快后慢
• Repeat count and behavior：重复次数与方式，如1次，3次或者循环或者播完在反向回放。
• Repeat count and behavior：指定多个动画。可以一起播放或者顺序播放或者指定的延迟时间。
• Frame refresh delay：多长时间刷新一次,默认为10ms，最终刷新时间受系统负载程度和硬件性能的影响。

属性动画如何工作

1. 首先一个线性插值例子： 
   下图描述了一个X属性变化的动画。duration ：40ms，距离为40px，每10ms，刷新一次，移动10px，在40ms的时候停止，对象停止在40px的地方。 
   
2. 非线性插值例子： 
   这个对象仍然在40ms内移动40px，但是在前半程加速，后半程减速。 
   
3. 相关的类： 
    
   ValueAnimation跟踪动画，例如动画开始多久了和动画属性当前的值。 
   ValueAnimation封装了一个TimeInterpolator定义时间插值，TypeEvaluator怎么计算属性的值。例如：例子2中TimeInterpolator使用AccelerateDecelerateInterpolator ，TypeEvaluator使用IntEvaluator. 
   要开始一个动画，需要创建一个ValueAnimator，给定属性的开始和结束值，和动画时间长度，并调用 start()方法开始。在动画期间，计算一个动画以进行时间的百分比（0-1）。 
   TypeEvaluator：根据属性的开始、结束值与TimeInterpolation计算出的因子计算出当前时间的属性值。 
   ValueAnimation计算运行时间后，调用当前设定的TimeInterpolator ，计算出一个interpolated fraction，最后TypeAnimator通过这个因子计算出属性值，如上例中10ms时： 
   经插值计算(inteplator)后的插值因子:大约为0.15，上述例子中用了AccelerateDecelerateInterpolator，计算公式为（input即为时间因子）：

(Math.cos((input + 1) * Math.PI) / 2.0f) + 0.5f;

最后根据TypeEvaluator计算出在10ms时的属性值：0.15*（40-0）=6pixel。上例中TypeEvaluator为FloatEvaluator，计算方法为 ：

public Float evaluate(float fraction, Number startValue, Number endValue) { 
float startFloat = startValue.floatValue(); 
return startFloat + fraction * (endValue.floatValue() - startFloat); 
}

属性动画与视图动画区别

1. 视图动画只允许对views对象设置动画，例如对view做放大和旋转，但是不能对view的背景颜色做改变 。
2. 属性动画的另一个缺点是它只是改变了view在什么地方draw ，并不是实际的view。例如，当你把一个button移动到另一个地方，但是button可以相应点击事件的位置并没有改变。
3. 属性动画没有这些问题，你可以改变任何对象，的属性，例如颜色，位置，大小。

应用属性动画有两个步骤：

1. 计算属性值

2. 根据属性值执行相应的动作，如改变对象的某一属性。

   1. ValueAnimation:只进行了第一步；需要实现ValueAnimator.onUpdateListener接口
   2. ObjectAnimation:两步都做，但是需要设置属性的get和set方法。
   3. 根据应用动画的对象或属性的不同，可能需要在onAnimationUpdate函数中调用invalidate()函数刷新视图。 
      AnimationSet：动画集合。

3. 计算器(Evaluators):根据属性的开始、结束值与TimeInterpolation计算出的因子计算出当前时间的属性值。

   1. IntEvaluator:整型属性
   2. FloatEvalluator:浮点型
   3. ArgbEvaluator：颜色属性
   4. TypeEvaluator:自定义计算方法
4. 插值器：（ TimeInterpolator） 
   
   1. AccelerateInterpolator 加速插值器
   2. AccelerateDecelerateInterpolator 加速减速插值器
   3. LinearInterpolator 线性插值器
   4. BounceInterpolator 弹跳插值器
   5. AnticipateInterpolator 回荡秋千插值器
   6. AnticipateOvershootInterpolator
   7. CycleInterpolator 正弦周期变化插值器
   8. OvershootInterpolator 
      关于插值器可以参考这篇文章：插值器详细介绍

ValueAnimator:

通过ValueAnimator的ofInt(),ofFloat,ofObeact()方法获得， 
需要实现监听器更改要改变的对象的属性值。

ObjectAnimator

初始化需要指定对象和对象的属性以及值区间。 
有些改变需要调用invalidate()方法，重绘。可以在onAnimationUpdate()方法中做。

AnimatorSet

包含动画的集合，也可以自嵌套，例如：

<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;">AnimatorSet bouncer = new AnimatorSet()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
bouncer<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.play</span>(bounceAnim)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.before</span>(squashAnim1)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
bouncer<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.play</span>(squashAnim1)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.with</span>(squashAnim2)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
bouncer<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.play</span>(squashAnim1)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.with</span>(stretchAnim1)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
bouncer<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.play</span>(squashAnim1)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.with</span>(stretchAnim2)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
bouncer<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.play</span>(bounceBackAnim)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.after</span>(stretchAnim2)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
ValueAnimator fadeAnim = ObjectAnimator<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.ofFloat</span>(newBall, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"alpha"</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>f, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>f)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
fadeAnim<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.setDuration</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">250</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
AnimatorSet animatorSet = new AnimatorSet()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
animatorSet<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.play</span>(bouncer)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.before</span>(fadeAnim)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
animatorSet<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.start</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li></ul>

Animation Listeners

• Animator.AnimatorListener:
• ValueAnimator.AnimatorUpdateListener:
• AnimatorListenerAdapter:

为viewGroup的layout改变设置动画

ViewGroup中的子元素可以通过setVisibility使其Visible、Invisible或Gone，当有子元素可见性改变时(VISIBLE、GONE)，可以向其应用动画，通过LayoutTransition类应用此类动画： 
通过setAnimator应用动画，第一个参数表示应用的情境，可以以下4种类型：

• APPEARING： 当一个元素在其父元素中变为Visible时对这个元素应用动画
• CHANGE_APPEARING： 当一个元素在其父元素中变为Visible时，因系统要重新布局有一些元素需要移动，对这些要移动的元素应用动画
• DISAPPEARING： 当一个元素在其父元素中变为GONE时对其应用动画
• CHANGE_DISAPPEARING： 当一个元素在其父元素中变为GONE时，因系统要重新布局有一些元素需要移动，这些要移动的元素应用动画.

可以使用自定义动画也可以使用默认的；默认可以在xml设置：

<code class="hljs xml has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">LinearLayout
</span>    <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:orientation</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"vertical"</span>
    <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_width</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"wrap_content"</span>
    <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:layout_height</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"match_parent"</span>
    <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:id</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"@+id/verticalContainer"</span>
    <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:animateLayoutChanges</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"true"</span> /></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li></ul>

使用TypeEvalutor

<code class="hljs java has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">FloatEvaluator</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">implements</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">TypeEvaluator</span> {</span>

    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> Object <span class="hljs-title" style="box-sizing: border-box;">evaluate</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> fraction, Object startValue, Object endValue) {
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> startFloat = ((Number) startValue).floatValue();
        <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> startFloat + fraction * (((Number) endValue).floatValue() - startFloat);
    }
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li></ul>

KeyFrams:

keyFrame是一个 时间/值 对，通过它可以定义一个在特定时间的特定状态，即关键帧，而且在两个keyFrame之间可以定义不同的Interpolator，就好像多个动画的拼接，第一个动画的结束点是第二个动画的开始点。KeyFrame是抽象类，要通过ofInt(),ofFloat(),ofObject()获得适当的KeyFrame，然后通过PropertyValuesHolder.ofKeyframe获得PropertyValuesHolder对象，如以下例子：

<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;">Keyframe kf0 = Keyframe<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.ofFloat</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>f, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>f)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
Keyframe kf1 = Keyframe<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.ofFloat</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">.5</span>f, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">360</span>f)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
Keyframe kf2 = Keyframe<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.ofFloat</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>f, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>f)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
PropertyValuesHolder pvhRotation = PropertyValuesHolder<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.ofKeyframe</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"rotation"</span>, kf0, kf1, kf2)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
ObjectAnimator rotationAnim = ObjectAnimator<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.ofPropertyValuesHolder</span>(target, pvhRotation)
rotationAnim<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.setDuration</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">5000</span>ms)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li></ul>

Animation Views:

在View Animation中，对View应用Animation并没有改变View的属性，动画的实现是通过其Parent View实现的，在View被drawn时Parents View改变它的绘制参数，draw后再改变参数invalidate，这样虽然View的大小或旋转角度等改变了，但View的实际属性没变，所以有效区域还是应用动画之前的区域，比如你把一按钮放大两倍，但还是放大这前的区域可以触发点击事件。为了改变这一点，在Android 3.0中给View增加了一些参数并对这些参数增加了相应的getter/setter函数（ObjectAnimator要用这些函数改变这些属性）：

translationX,translationY: View相对于原始位置的偏移量 
rotation,rotationX,rotationY: 旋转，rotation用于2D旋转角度，3D中用到后两个 
scaleX,scaleY: 缩放比 
x,y: View的最终坐标，是View的left，top位置加上translationX，translationY 
alpha: 透明度 
跟位置有关的参数有3个，以X坐标为例，可以通过getLeft(),getX(),getTranslateX()获得，若有一Button btn2，布局时其坐标为（40,0）：

<code class="hljs fsharp has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//应用动画之前</span>
btn2.getLeft();    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//40</span>
btn2.getX();    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//40</span>
btn2.getTranslationX();    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//0</span>
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//应用translationX动画</span>
ObjectAnimator oa=ObjectAnimator.ofFloat(btn2,<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"translationX"</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">200</span>);
oa.setDuration(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2000</span>);
oa.start();
/*应用translationX动画后
btn2.getLeft();    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//40</span>
btn2.getX();    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//240</span>
btn2.getTranslationX();    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//200</span>
*/
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//应用X动画，假设没有应用之前的translationX动画</span>
ObjectAnimator oa=ObjectAnimator.ofFloat(btn2, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"x"</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">200</span>);
oa.setDuration(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2000</span>);
oa.start();
/*应用X动画后
btn2.getLeft();    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//40</span>
btn2.getX();    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//200</span>
btn2.getTranslationX();    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//160</span>
*/</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li></ul>

无论怎样应用动画，原来的布局时的位置通过getLeft()获得，保持不变； 
　　X是View最终的位置； 
　　translationX为最终位置与布局时初始位置这差。 
　　所以若就用translationX即为在原来基础上移动多少，X为最终多少 
　　getX()的值为getLeft()与getTranslationX()的和 
　　对于X动画，源代码是这样的：　

<code class="hljs cs has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">case</span> X:
       info.mTranslationX = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">value</span> - mView.mLeft;
       <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">break</span>;</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li></ul>

Property Animation也可以在XML中定义

• - AnimatorSet
• - ValueAnimator
• - ObjectAnimator 
  XML文件应放大/res/animator/中，通过以下方式应用动画：

<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;">AnimatorSet <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">set</span> = (AnimatorSet) AnimatorInflater<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.loadAnimator</span>(myContext, R<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.anim</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.property</span>_animator)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">set</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.setTarget</span>(myObject)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">set</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.start</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li></ul>

ViewPropertyAnimator:

如果需要对一个View的多个属性进行动画可以用ViewPropertyAnimator类，该类对多属性动画进行了优化，会合并一些invalidate()来减少刷新视图，该类在3.1中引入。

以下三段代码实现同样的效果：

• Multiple ObjectAnimator objects

<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;">ObjectAnimator animX = ObjectAnimator<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.ofFloat</span>(myView, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"x"</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">50</span>f)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
ObjectAnimator animY = ObjectAnimator<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.ofFloat</span>(myView, <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"y"</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">100</span>f)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
AnimatorSet animSetXY = new AnimatorSet()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
animSetXY<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.playTogether</span>(animX, animY)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
animSetXY<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.start</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li></ul>

• One ObjectAnimator

<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;">PropertyValuesHolder pvhX = PropertyValuesHolder<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.ofFloat</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"x"</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">50</span>f)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
PropertyValuesHolder pvhY = PropertyValuesHolder<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.ofFloat</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"y"</span>, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">100</span>f)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
ObjectAnimator<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.ofPropertyValuesHolder</span>(myView, pvhX, pvyY)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.start</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li></ul>

• ViewPropertyAnimator

<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;">myView<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.animate</span>()<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.x</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">50</span>f)<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.y</span>(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">100</span>f)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>

在XMl中声明animation

在3.1以后，声明属性动画必须在res/animator/路径下。例如：

<code class="hljs xml has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">set</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:ordering</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"sequentially"</span>></span>
    <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">set</span>></span>
        <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">objectAnimator
</span>            <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:propertyName</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"x"</span>
            <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:duration</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"500"</span>
            <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:valueTo</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"400"</span>
            <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:valueType</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"intType"</span>/></span>
        <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">objectAnimator
</span>            <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:propertyName</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"y"</span>
            <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:duration</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"500"</span>
            <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:valueTo</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"300"</span>
            <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:valueType</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"intType"</span>/></span>
    <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">set</span>></span>
    <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">objectAnimator
</span>        <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:propertyName</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"alpha"</span>
        <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:duration</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"500"</span>
        <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">android:valueTo</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"1f"</span>/></span>
<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">set</span>></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li></ul>

运行：

<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;">AnimatorSet <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">set</span> = (AnimatorSet) AnimatorInflater<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.loadAnimator</span>(myContext,
    R<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.anim</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.property</span>_animator)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">set</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.setTarget</span>(myObject)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">set</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.start</span>()<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span></code>