List of Listings

Chapter 1. Meet Flutter

Listing 1.1. Example build method for the custom QuantityCounter stateful widget

Chapter 2. A brief intro to Dart

Listing 2.1. Dart for-in loops

Listing 2.2. I/O in Dart

Chapter 3. Breaking into Flutter

Listing 3.1. An example button widget

Listing 3.2. A widget with configuration

Listing 3.3. Adding a raised button to _MyHomePageState.build

Listing 3.4. Column widget in the counter app

Listing 3.5. Wrapping widgets in a Row

Listing 3.6. Adding a second button to the Row

Listing 3.7. Adding an image to your Flutter pubspec.yaml file

Listing 3.8. Adding an image to your Flutter app

Listing 3.9. Adding a Container widget

Listing 3.10. _MyHomePageState configuration

Listing 3.11. The FancyButton custom widget

Listing 3.12. Updated app to use the FancyButton class

Chapter 4. Flutter UI: Important widgets, themes, and layout

Listing 4.1. Weather app file structure

Listing 4.2. pubspec.yaml configuration for the weather app

Listing 4.3. The weather app main function

Listing 4.4. setPreferredOrientations in the weather app

Listing 4.5. The top-level widget in main.dart

Listing 4.6. The build method of the MyApp widget

Listing 4.7. Scaffold full property list

Listing 4.8. Using PreferredSize in a scaffold

Listing 4.9. ThemeData in the weather app

Listing 4.10. Screen-aware sizing methods

Listing 4.11. Stack code in the forecast page

Listing 4.12. Example of non-animated Stack code

Listing 4.13. The API for the Table widget

Listing 4.14. Using FixedColumnWidth on rows 0, 2, and 3 makes row 1 flexed

Listing 4.15. Table code from the weather app

Listing 4.16. Table cell examples from the weather app

Listing 4.17. A portion of the ForecastPageState.build method

Listing 4.18. TabController and TabBar widget setup

Listing 4.19. Implementing Flutter tabs in the weather app

Listing 4.20. TabBar widget in the build method

Listing 4.21. ListView builder code in the settings page

Chapter 5. User interaction: Forms and gestures

Listing 5.1. Using the drag gesture

Listing 5.2. Handling the end of a drag gesture

Listing 5.3. Using Dismissible in a collection

Listing 5.4. add_city_page.dart outline

Listing 5.5. Initial form setup in the weather app

Listing 5.6. TextFormField example

Listing 5.7. TextFormField example

Listing 5.8. DropdownButtonFormField example

Listing 5.9. Creating CountryDropdownField in the AddNewCity widget

Listing 5.10. Implementing the check box form field

Listing 5.11. InputDecoration example

Listing 5.12. Form methods

Listing 5.13. Conditional auto-validation

Listing 5.14. Saving the form state from a button

Listing 5.15. Methods called when the form is saved

Listing 5.16. Using onWillPop on a form page

Chapter 6. Pushing pixels: Flutter animations and using the canvas

Listing 6.1. Animation controller example

Listing 6.2. The complete animated Sun widget

Listing 6.3. Passing an animation into an animated widget

Listing 6.4. Setting up the State object for animation use

Listing 6.5. _ForecastPageState._render method

Listing 6.6. Creating the TimePickerRow widget

Listing 6.7. The _ForecastPageState._handleStateChange method

Listing 6.8. _ForecastPageState animation helper methods

Listing 6.9. The Clouds class

Listing 6.10. The bare minimum for a custom painter

Listing 6.11. Half of the CloudPainter.paint method

Listing 6.12. The CloudPainter.paint method

Listing 6.13. ForecastPageState.handleStateChange method

Listing 6.14. ForecastPageState._buildTweens method

Listing 6.15. Passing animation values into widgets

Listing 6.16. The ForecastPageState._buildTweens method

Listing 6.17. The OffsetSequence class

Chapter 7. Flutter routing in depth

Listing 7.1. Important files for the e-commerce Farmers Market app

Listing 7.2. AngularDart Router route definitions

Listing 7.3. Define routes in the MaterialApp widget

Listing 7.4. AppMenu widget’s build method, condensed to widgets only

Listing 7.5. Flutter’s AboutListTile Material widget

Listing 7.6. Menu drawer item in a ListTile widget

Listing 7.7. Navigating from the AppMenu widget

Listing 7.8. UserAccountsDrawerHeader usage in AppMenu widget

Listing 7.9. Pass route observers into the MaterialApp widget

Listing 7.10. Listen to the route observer

Listing 7.11. Example code showing routing on the fly

Listing 7.12. Navigate to a new route on the fly

Listing 7.13. Choice code from the AddToCartBottomSheet widget

Listing 7.14. _showQuickAddToCart method revisited

Listing 7.15. Writing a custom page transition

Chapter 8. Flutter state management

Listing 8.1. StatefulWidget example

Listing 8.2. Custom of method

Listing 8.3. Handle a state object with the inherited widget

Listing 8.4. AppState.build method

Listing 8.5. Functionality to control quantity with InheritedWidget

Listing 8.6. Override the didChangeDependencies method

Listing 8.7. Call method from the inherited widget from the bottom sheet

Listing 8.8. Blocs work with stream builders (their outputs are all streams)

Listing 8.9. The BlocProvider class (for cleaner code)

Listing 8.10. AppStateContainer stateful widget

Listing 8.11. Relevant pieces of the AppState class

Listing 8.12. The Flutter stream builder example

Chapter 9. Async Dart and Flutter and infinite scrolling

Listing 9.1. Example Dart code using streams and sinks

Listing 9.2. A Future example

Listing 9.3. async and await example

Listing 9.4. Get data asynchronously

Listing 9.5. The catchError method

Listing 9.6. try/catch with async calls

Listing 9.7. Stream using the hamburger restaurant example

Listing 9.8. Broadcast stream controller example

Listing 9.9. GoodBurgerRestaurant class

Listing 9.10. Custom stream transformer class

Listing 9.11. Custom stream transformer class, continued

Listing 9.12. Multiple streams for each category

Listing 9.13. A longer way to create a list of controllers

Listing 9.14. Stream as input to work with state outside the widget

Listing 9.15. StreamBuilder displays data that constantly changes

Listing 9.16. StreamBuilder widget

Listing 9.17. Catalog bloc output for products, by category

Listing 9.18. A header sliver for the current category

Listing 9.19. Display the products for a category

Listing 9.20. SliverChildBuilderDelegate usage

Listing 9.21. The setup for the custom header

Listing 9.22. Custom slivers

Chapter 10. Working with data: HTTP, Firestore, and JSON

Listing 10.1. Adding the HTTP dependency to your Flutter app

Listing 10.2. An HTTP GET request

Listing 10.3. JSON object from getPosts call

Listing 10.4. Using todos in the UI

Listing 10.5. Example of a todo from the Typicode JSONPlaceholder service

Listing 10.6. Todo class

Listing 10.7. fromJson factory methods

Listing 10.8. Parsing data out of an HTTP response

Listing 10.9. Creating a serializable model

Listing 10.10. Code generated by the json_serialization package

Listing 10.11. Todo controller

Listing 10.12. The root of the Flutter app

Listing 10.13. The Todo list page

Listing 10.14. The _TodoPageState build method

Listing 10.15. The finished pubspec file

Listing 10.16. Implement Firebase services

Listing 10.17. Convert a Firestore QuerySnapshot into a Dart object

Listing 10.18. Use abstract classes for dependency injection

Listing 10.19. Using dependency injection

Listing 10.20. Starting up the Flutter app

Chapter 11. Testing Flutter apps

Listing 11.1. Todo app pubspec dependencies

Listing 11.2. Testable code from the todos completed counter

Listing 11.3. Basic unit test in Dart

Listing 11.4. Multiple expect calls in a test

Listing 11.5. Full unit test example

Listing 11.6. Mock services class

Listing 11.7. getTodos makes an HTTP request

Listing 11.8. Using mockito to stub an HTTP call

Listing 11.9. Basic widget test function

Listing 11.10. Basic widget test function

Listing 11.11. Finding and tapping on a button

Listing 11.12. Finding widgets by keys in tests

Listing 11.13. Todo app pubspec dependencies

Listing 11.14. Set up the flutter_driver extension

Listing 11.15. Writing flutter_driver integration tests

Listing 11.16. Profiling you app with flutter_driver

Appendix C. Flutter for web developers

Listing 3.1. The Column widget in the counter app