The CanvasWatchFaceService class and registering your watch face

Watch faces are services with and visual rendering ability; all watch faces will extend the CanvasWatchFaceService class. The CanvasWatchFaceService class extracts its functionalities from the WallpaperSevice and WallpaperService.Engine classes. The Engine class, with its methods, helps the watch face with its lifecycle. If you have to make a watch face for an Android Wear, you should use the CanvasWatchfaceService class instead of plain old vanilla WallpaperService. A watch face service, like a wallpaper service, must implement only the onCreateEngine() method. Watch face engines need to implement the method onTimeTick() to refresh the time and refresh the view and onAmbientModeChanged(boolean) to switch between different version of watch faces, such as the grey mode and colorful watch face. Watch face engines in a like manner implement onInterruptionFilterChanged(int) to update the view dependent upon how much information...