The TodayWatchFaceService class

The TodayWatchFaceService class does all of the work, including setting the layout, reading the configuration values, and painting the UI for every tick of the second. It isn't realistic to discuss over 700 lines of code in this chapter. So, we'll look at important snippets taken from this class definition:

public class TodayWatchFaceService extends CanvasWatchFaceService { 
  @Override 
  public Engine onCreateEngine()  
  { 
    return new Engine(); 
  } 
  private class Engine extends CanvasWatchFaceService.Engine  implements DataApi.DataListener,  GoogleApiClient.ConnectionCallbacks,  GoogleApiClient.OnConnectionFailedListener  
  { 
    ... 
  } 
} 

Tip

As always, the sample source code for this chapter, and all others, is available at the GitHub link provided at the beginning of each chapter. The source code hosted at GitHub is our primary reference for a thorough understanding of how this service works.