flutter-theming

Goal

Updates and manages Flutter application styling by migrating legacy Material 2 implementations to Material 3, normalizing component themes, updating deprecated button classes, and adapting UI idioms for cross-platform consistency. Assumes a Flutter environment using Dart.

Instructions

1. Analyze Current Theme State Review the existing Flutter codebase to identify legacy Material 2 components, deprecated button classes (FlatButton, RaisedButton, OutlineButton), and outdated theme properties (e.g., accentColor, color in AppBarTheme). STOP AND ASK THE USER: "What is the primary seed color for the new Material 3 ColorScheme, and which target platforms (iOS, Android, Windows, macOS, Linux, Web) should be prioritized for platform idioms?"

2. Decision Logic: Component Migration When encountering legacy widgets, use the following decision tree to determine the replacement:

   • IF BottomNavigationBar -> REPLACE WITH NavigationBar (uses NavigationDestination).
   • IF Drawer -> REPLACE WITH NavigationDrawer (uses NavigationDrawerDestination).
   • IF ToggleButtons -> REPLACE WITH SegmentedButton (uses ButtonSegment and Set for selection).
   • IF FlatButton -> REPLACE WITH TextButton.
   • IF RaisedButton -> REPLACE WITH ElevatedButton (or FilledButton for no elevation).
   • IF OutlineButton -> REPLACE WITH OutlinedButton.

3. Implement App-Wide Material 3 Theme Define the global ThemeData using ColorScheme.fromSeed. Ensure useMaterial3 is implicitly or explicitly true. Remove all references to deprecated accent properties (accentColor, accentColorBrightness, accentTextTheme, accentIconTheme).