Wallpaper介绍一个Activity如何通过Style把系统Wallpaper作为当前Activity的背景。
这是WallpaperActivity在AndroidManifest.xml中的定义：
<activity android:name=”.app.WallpaperActivity”
android:label=”@string/activity_wallpaper”
android:theme=”@style/Theme.Wallpaper”>
<intent-filter>
< action android:name=”android.intent.action.MAIN” />
<category android:name=”android.intent.category.SAMPLE_CODE” />
< /intent-filter>
< /activity>
@style/Theme.Wallpaper定义如下：继承系统android:style/Theme.Wallpaper，并将前景色设为白色（这里是文字的颜色）
<!– A theme that has a wallpaper background. Here we explicitly specify
that this theme is to inherit from the system’s wallpaper theme,
which sets up various attributes correctly. –>
<style name=”Theme.Wallpaper” parent=”android:style/Theme.Wallpaper”>
<item name=”android:colorForeground”>#fff</item>
< /style>
