Guide Book

A reference you can read front to back or dip into. Every chapter explains the syntax, and most topics have a 🔍 Behind the scenes section you can open to see what Python is actually doing, the details classes usually skip. Look for 🧭 Scenario cards for real-world uses, and press Try it on any example, then open the Inspect tab to look inside.

1. Chapter 1How Flutter rendersThree trees — widgets, elements and render objects — and why rebuilding a widget is cheap.
2. Chapter 2Widgets & compositionStateless versus stateful, the constructor-and-final-fields pattern, and why composition replaces inheritance and configuration.
3. Chapter 3LayoutConstraints go down, sizes go up, the parent sets the position — one sentence that explains every layout in Flutter.
4. Chapter 4State`setState` and what it really does, where state should live, lifting it up, and the controllers that must be disposed.
5. Chapter 5Input, gestures & formsButtons and gesture detectors, text input and controllers, and the `Form` machinery for validation.
6. Chapter 6NavigationThe navigator stack, pushing and popping with results, named and declarative routing, and passing data between screens.
7. Chapter 7Theming & Material`ThemeData` and colour schemes, reading the theme instead of hard-coding, dark mode, and where component themes belong.
8. Chapter 8Async UI`FutureBuilder` and `StreamBuilder`, handling loading and error states properly, and the mistakes that make them refetch forever.
9. Chapter 9State managementBeyond `setState` — `InheritedWidget`, `ChangeNotifier` and `ValueNotifier`, and how to choose an approach that fits the app.
10. Chapter 10AnimationImplicit animations for almost everything, explicit controllers when you need control, and the transitions that come for free.
11. Chapter 11Performance & testingWhat actually costs a frame, the structural fixes that beat micro-optimisation, and the three kinds of Flutter test.