32fde139bc
fix https://github.com/flutter/flutter/issues/117722 ### Description 1. Fix the divider doesn't stretch to take all the available width in the scrollable tab bar in M3 2. Add `dividerHeight` property. 3. Update the default tab alignment for the scrollable tab bar to match the specs (this is backward compatible for M2 with the new `tabAlignment` property). ### Bug (default tab alignment)  ### Fix (default tab alignment)  ### Code sample <details> <summary>code sample</summary> ```dart import 'package:flutter/material.dart'; /// Flutter code sample for [TabBar]. void main() => runApp(const TabBarApp()); class TabBarApp extends StatelessWidget { const TabBarApp({super.key}); @override Widget build(BuildContext context) { return MaterialApp( theme: ThemeData( // tabBarTheme: const TabBarTheme(tabAlignment: TabAlignment.start), useMaterial3: true, ), home: const TabBarExample(), ); } } class TabBarExample extends StatefulWidget { const TabBarExample({super.key}); @override State<TabBarExample> createState() => _TabBarExampleState(); } class _TabBarExampleState extends State<TabBarExample> { bool rtl = false; @override Widget build(BuildContext context) { return DefaultTabController( initialIndex: 1, length: 3, child: Directionality( textDirection: rtl ? TextDirection.rtl : TextDirection.ltr, child: Scaffold( appBar: AppBar( title: const Text('TabBar Sample'), ), body: const Column( children: <Widget>[ Text('Scrollable-TabAlignment.start'), TabBar( isScrollable: true, tabAlignment: TabAlignment.start, tabs: <Widget>[ Tab( icon: Icon(Icons.cloud_outlined), ), Tab( icon: Icon(Icons.beach_access_sharp), ), Tab( icon: Icon(Icons.brightness_5_sharp), ), ], ), Text('Scrollable-TabAlignment.startOffset'), TabBar( isScrollable: true, tabAlignment: TabAlignment.startOffset, tabs: <Widget>[ Tab( icon: Icon(Icons.cloud_outlined), ), Tab( icon: Icon(Icons.beach_access_sharp), ), Tab( icon: Icon(Icons.brightness_5_sharp), ), ], ), Text('Scrollable-TabAlignment.center'), TabBar( isScrollable: true, tabAlignment: TabAlignment.center, tabs: <Widget>[ Tab( icon: Icon(Icons.cloud_outlined), ), Tab( icon: Icon(Icons.beach_access_sharp), ), Tab( icon: Icon(Icons.brightness_5_sharp), ), ], ), Spacer(), Text('Non-scrollable-TabAlignment.fill'), TabBar( tabAlignment: TabAlignment.fill, tabs: <Widget>[ Tab( icon: Icon(Icons.cloud_outlined), ), Tab( icon: Icon(Icons.beach_access_sharp), ), Tab( icon: Icon(Icons.brightness_5_sharp), ), ], ), Text('Non-scrollable-TabAlignment.center'), TabBar( tabAlignment: TabAlignment.center, tabs: <Widget>[ Tab( icon: Icon(Icons.cloud_outlined), ), Tab( icon: Icon(Icons.beach_access_sharp), ), Tab( icon: Icon(Icons.brightness_5_sharp), ), ], ), Spacer(), ], ), floatingActionButton: FloatingActionButton.extended( onPressed: () { setState(() { rtl = !rtl; }); }, label: const Text('Switch Direction'), icon: const Icon(Icons.swap_horiz), ), ), ), ); } } ``` </details> 
Token Defaults Generator
Script that generates component theme data defaults based on token data.
Usage
Run this program from the root of the git repository:
dart dev/tools/gen_defaults/bin/gen_defaults.dart [-v]
This updates generated/used_tokens.csv and the various component theme files.
Templates
There is a template file for every component that needs defaults from
the token database. These templates are implemented as subclasses of
TokenTemplate. This base class provides some utilities and a structure
for adding a new block of generated code to the bottom of a given file.
Templates need to override the generate method to provide the generated
code block as a string.
See lib/fab_template.dart for an example that generates defaults for the
Floating Action Button.
Tokens
Tokens are stored in JSON files in data/, and are sourced from
an internal Google database.
template.dart should provide nearly all useful token resolvers
(e.g. color, shape, etc.). For special cases in which one shouldn't
be defined, use getToken to get the raw token value. The script, through
the various revolvers and getToken, validates tokens, keeps track of
which tokens are used, and generates generated/used_tokens.csv.