XML

Sample:

<douglasspgyn.com.github.circularcountdown.CircularCountdown
                android:id="@+id/circularCountdown"
                android:layout_width="72dp"
                android:layout_height="72dp"
                app:countdownBackgroundColor="@color/colorAccent"
                app:countdownForegroundColor="@color/colorPrimary"
                app:countdownTextColor="@color/colorPrimaryDark"
                app:countdownTextSize="24sp" />

You have four custom attributes: countdownBackgroundColor, countdownForegroundColor, countdownTextColor and countdownTextSize.

As the name say, you can define the Background and Foreground color of the Countdown and the Color and Size of the label.