Ambient mode, in contrast with interactive mode, is the energy saver mode. Depending on the watch and its configuration, an operation such as a click on a dial renders the watch faces in ambient mode:

It may not be obvious at a glance because our app is so simple, but if we compare the preceding screenshot with the screenshot of the watch face in interactive mode, we will see that the seconds don't show up and the colon symbol doesn't blink.

Here's the listener that gets called when the watch face switches from interactive mode to ambient mode:

@Override 
public void onAmbientModeChanged(boolean inAmbientMode)  
{ 
  super.onAmbientModeChanged(inAmbientMode); 
  if (Log.isLoggable(TAG, Log.DEBUG))  
  { 
    Log.d(TAG, "onAmbientModeChanged: " + inAmbientMode); 
  } 
  adjustPaintColorToCurrentMode(mBackgroundPaint, mInteractiveBackgroundColor,WatchFaceUtil.COLOR_VALUE_DEFAULT_AND_AMBIENT_BACKGROUND); 
  adjustPaintColorToCurrentMode(mHourPaint, mInteractiveHourDigitsColor,WatchFaceUtil...