daddf7ab8e
Fixes https://github.com/flutter/flutter/issues/178856 Fixes https://github.com/flutter/flutter/issues/178271 Fixes https://github.com/flutter/flutter/issues/178238 ### Description - Fixes an issue in `lineHeightScaleFactorOverride` calculation, causing it to have abnormal values. - Integrates text scale factor update into recently added `_addTypographySettingsObserver`. The `ResizeObserver` on the typography probe element is getting notified each time the font size changes, because it leads to the element's size change. - Removes `DomMutationObserver` previously used for font size observations. - Adds/Updates tests to verify the fixes. | BEFORE | AFTER | | - | - | | <video src="https://github.com/user-attachments/assets/f62fb3c6-63e1-447f-b4ef-8f22ad944a0a"/> | <video src="https://github.com/user-attachments/assets/c220dd30-89d9-4f76-a43f-b908a940fafb"/> | ### Demo https://flutter-text-scale-factor.web.app <details closed><summary>Code sample</summary> ```dart import 'package:flutter/material.dart'; void main() { runApp(const App()); } class App extends StatelessWidget { const App({super.key}); @override Widget build(BuildContext context) { return const MaterialApp( debugShowCheckedModeBanner: false, home: Screen(), ); } } class Screen extends StatefulWidget { const Screen({super.key}); @override State<Screen> createState() => _ScreenState(); } class _ScreenState extends State<Screen> with SingleTickerProviderStateMixin { @override Widget build(BuildContext context) { return Scaffold( body: Center( child: Padding( padding: const EdgeInsets.all(8), child: Column( mainAxisAlignment: MainAxisAlignment.center, spacing: 10, children: [ Builder( builder: (context) { print( 'lineHeightScaleFactorOverride: ${MediaQuery.maybeLineHeightScaleFactorOverrideOf(context)}', ); final scale = MediaQuery.textScalerOf(context).scale(1); return Text( 'Scale ${scale.toStringAsFixed(3)}', style: TextStyle( fontSize: 30, backgroundColor: Colors.grey.shade200, ), textAlign: TextAlign.center, ); }, ), ], ), ), ), ); } } ``` </details> ## Pre-launch Checklist - [X] I read the [Contributor Guide] and followed the process outlined there for submitting PRs. - [X] I read the [Tree Hygiene] wiki page, which explains my responsibilities. - [X] I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement]. - [X] I signed the [CLA]. - [X] I listed at least one issue that this PR fixes in the description above. - [X] I updated/added relevant documentation (doc comments with `///`). - [X] I added new tests to check the change I am making, or this PR is [test-exempt]. - [X] I followed the [breaking change policy] and added [Data Driven Fixes] where supported. - [X] All existing and new tests are passing. <!-- Links --> [Contributor Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview [Tree Hygiene]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md [test-exempt]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests [Flutter Style Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md [Features we expect every widget to implement]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement [CLA]: https://cla.developers.google.com/ [flutter/tests]: https://github.com/flutter/tests [breaking change policy]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes [Discord]: https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md [Data Driven Fixes]: https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md
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