[AndroidDev] Live Wallpaper

• Very similar to a Service.
• The only difference is the addition of a new method, onCreateEngine(), whose goal is to create a WallpaperService.Engine.

WallpaperService.Engine

• The engine is responsible for handling the lifecycle and drawing of a wallpaper.
• The system provides a surface on which you can draw, just like you would with a SurfaceView.
• The engine can also implement several methods to interact with the user or the home application.

Performance

• The most important part of the lifecycle of a wallpaper is when it becomes visible, as indicated by a call to onVisibilityChanged().
• When invisible, such as when the user launches an application that covers the home screen, a wallpaper must stop all activity.
• 所以必須優化繪圖的內容及管理好 wallpaper 的 lifecycle，以達到以下改善:
• To avoid using too much CPU.
• Survive the battery life.
• To avoid slowing down the rest of the system.

Configurations

• <uses-sdk android:minSdkVersion="7" />, 
• which indicates to Android Market and the platform that your application requires Android 2.1 or higher.
• <uses-feature android:name="android.software.live_wallpaper" />

Pending Study

• Draw content for wallpaper. 

* Reference 
- Live Wallpapers | Android Developers