Hack6 为ViewGroup添加动画效果

此例中以一个RelativeLayout作为父级容器，其中纵向设置4个TextView。由于在onCreate中设定了动画效果，所以在启动时，会产生类似瀑布流的效果。

layout文件如下：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">

<RelativeLayout
android:id="@+id/subLayout"
android:layout_centerInParent="true"
android:gravity="center"
android:layout_width="200dp"
android:layout_height="200dp">

<TextView
android:id="@+id/txt1"
android:layout_width="100dp"
android:layout_height="20dp"
android:background="#f00"/>
<TextView
android:id="@+id/txt2"
android:layout_marginTop="20dp"
android:layout_below="@+id/txt1"

b537
android:layout_width="100dp"
android:layout_height="20dp"
android:background="#0f0"/>
<TextView
android:id="@+id/txt3"
android:layout_marginTop="20dp"
android:layout_below="@+id/txt2"
android:layout_width="100dp"
android:layout_height="20dp"
android:background="#00f"/>
<TextView
android:id="@+id/txt4"
android:layout_marginTop="20dp"
android:layout_below="@+id/txt3"
android:layout_width="100dp"
android:layout_height="20dp"
android:background="#f0e000"/>

</RelativeLayout>
</RelativeLayout>

java代码如下所示：

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

RelativeLayout layout = (RelativeLayout) findViewById(R.id.subLayout);

AnimationSet animationSet = new AnimationSet(true);

TranslateAnimation animation1 = new TranslateAnimation(Animation.RELATIVE_TO_SELF,0.0f,
Animation.RELATIVE_TO_SELF,0.0f,Animation.RELATIVE_TO_SELF,-1.0f,
Animation.RELATIVE_TO_SELF,0.0f);
animation1.setDuration(4000);
AlphaAnimation animation2 = new AlphaAnimation(0.0f,1.0f);
animation2.setDuration(4000);

animationSet.addAnimation(animation1);
animationSet.addAnimation(animation2);

LayoutAnimationController layoutAnimationController = new LayoutAnimationController(
animationSet,0.5f);

layout.setLayoutAnimation(layoutAnimationController);

}