Building implicit animations using Flutter’s animations package

Now that we have learned how to leverage implicit and explicit animations, let’s refactor our code to take advantage of Flutter’s animations package, which contains pre-canned animations for common use cases from the Material motion system spec.

First, install the animations package by running flutter pub add animations in the project’s root directory in the terminal.

Next, swap out AnimatedSwitcher in excuse_page_view.dart with PageTransitionSwitcher from the package. The PageTransitionSwitcher is a variation of the AnimatedSwitcher that allows for separate transitions to be used for the entry and exit animations. Replace the build method of ExcusePageView with the following code:

final selectedExcuse = excuses[currentExcuse];
return PageTransitionSwitcher(
    duration: const Duration(milliseconds: 500),
    transitionBuilder: 
  ...