introduce localized text geometry in MaterialLocalizations (#11829)

* introduce localized text geometry in MaterialLocalizations

* remove geometry from color text themes

* fix merge conflict

* optional Localizations

* fix fallback; test; docs

packages/flutter/lib/src/material/i18n/localizations.dart

@@ -12,6 +12,7 @@
 /// This variable is used by [MaterialLocalizations].
 const Map<String, Map<String, String>> localizations = const <String, Map<String, String>> {
   "ar": const <String, String>{
+    "scriptCategory": r"tall",
     "timeOfDayFormat": r"h:mm a",
     "openAppDrawerTooltip": r"افتح قائمة التنقل",
     "backButtonTooltip": r"الى الخلف",
@@ -40,6 +41,7 @@ const Map<String, Map<String, String>> localizations = const <String, Map<String
     "postMeridiemAbbreviation": r"م",
   },
   "de": const <String, String>{
+    "scriptCategory": r"English-like",
     "timeOfDayFormat": r"HH:mm",
     "openAppDrawerTooltip": r"Navigationsmenü öffnen",
     "backButtonTooltip": r"Zurück",
@@ -68,6 +70,7 @@ const Map<String, Map<String, String>> localizations = const <String, Map<String
     "viewLicensesButtonLabel": r"LIZENZEN ANZEIGEN",
   },
   "en": const <String, String>{
+    "scriptCategory": r"English-like",
     "timeOfDayFormat": r"h:mm a",
     "openAppDrawerTooltip": r"Open navigation menu",
     "backButtonTooltip": r"Back",
@@ -107,6 +110,7 @@ const Map<String, Map<String, String>> localizations = const <String, Map<String
     "timeOfDayFormat": r"HH:mm",
   },
   "es": const <String, String>{
+    "scriptCategory": r"English-like",
     "timeOfDayFormat": r"H:mm",
     "openAppDrawerTooltip": r"Abrir el menú de navegación",
     "backButtonTooltip": r"Espalda",
@@ -140,6 +144,7 @@ const Map<String, Map<String, String>> localizations = const <String, Map<String
     "postMeridiemAbbreviation": r"PM",
   },
   "fa": const <String, String>{
+    "scriptCategory": r"tall",
     "timeOfDayFormat": r"H:mm",
     "openAppDrawerTooltip": r"منوی ناوبری را باز کنید",
     "backButtonTooltip": r"بازگشت",
@@ -166,6 +171,7 @@ const Map<String, Map<String, String>> localizations = const <String, Map<String
     "viewLicensesButtonLabel": r"مشاهده مجوز",
   },
   "fr": const <String, String>{
+    "scriptCategory": r"English-like",
     "timeOfDayFormat": r"HH:mm",
     "openAppDrawerTooltip": r"Ouvrir le menu de navigation",
     "backButtonTooltip": r"Retour",
@@ -197,6 +203,7 @@ const Map<String, Map<String, String>> localizations = const <String, Map<String
     "timeOfDayFormat": r"HH 'h' mm",
   },
   "he": const <String, String>{
+    "scriptCategory": r"English-like",
     "timeOfDayFormat": r"H:mm",
     "openAppDrawerTooltip": r"פתח תפריט ניווט",
     "backButtonTooltip": r"אחורה",
@@ -223,6 +230,7 @@ const Map<String, Map<String, String>> localizations = const <String, Map<String
     "viewLicensesButtonLabel": r"ראה רישיונות",
   },
   "it": const <String, String>{
+    "scriptCategory": r"English-like",
     "timeOfDayFormat": r"HH:mm",
     "openAppDrawerTooltip": r"Apri il menu di navigazione",
     "backButtonTooltip": r"Indietro",
@@ -249,6 +257,7 @@ const Map<String, Map<String, String>> localizations = const <String, Map<String
     "viewLicensesButtonLabel": r"VEDI LE LICENZE",
   },
   "ja": const <String, String>{
+    "scriptCategory": r"dense",
     "timeOfDayFormat": r"H:mm",
     "openAppDrawerTooltip": r"ナビゲーションメニューを開く",
     "backButtonTooltip": r"戻る",
@@ -275,6 +284,7 @@ const Map<String, Map<String, String>> localizations = const <String, Map<String
     "viewLicensesButtonLabel": r"ライセンス表記",
   },
   "ps": const <String, String>{
+    "scriptCategory": r"tall",
     "timeOfDayFormat": r"HH:mm",
     "openAppDrawerTooltip": r"د پرانیستی نیینګ مینو",
     "backButtonTooltip": r"شاته",
@@ -301,6 +311,7 @@ const Map<String, Map<String, String>> localizations = const <String, Map<String
     "viewLicensesButtonLabel": r"لیدلس وګورئ",
   },
   "pt": const <String, String>{
+    "scriptCategory": r"English-like",
     "timeOfDayFormat": r"HH:mm",
     "openAppDrawerTooltip": r"Abrir menu de navegação",
     "backButtonTooltip": r"Costas",
@@ -327,6 +338,7 @@ const Map<String, Map<String, String>> localizations = const <String, Map<String
     "viewLicensesButtonLabel": r"VER LICENÇAS",
   },
   "ru": const <String, String>{
+    "scriptCategory": r"English-like",
     "timeOfDayFormat": r"H:mm",
     "openAppDrawerTooltip": r"Открыть меню навигации",
     "backButtonTooltip": r"Назад",
@@ -355,6 +367,7 @@ const Map<String, Map<String, String>> localizations = const <String, Map<String
     "viewLicensesButtonLabel": r"ПРОСМОТРЕТЬ ЛИЦЕНЗИИ",
   },
   "sd": const <String, String>{
+    "scriptCategory": r"tall",
     "timeOfDayFormat": r"HH:mm",
     "openAppDrawerTooltip": r"اوپن جي مينڊيٽ مينيو",
     "backButtonTooltip": r"پوئتي",
@@ -381,6 +394,7 @@ const Map<String, Map<String, String>> localizations = const <String, Map<String
     "viewLicensesButtonLabel": r"لائسنس ڏسو",
   },
   "ur": const <String, String>{
+    "scriptCategory": r"tall",
     "timeOfDayFormat": r"h:mm a",
     "openAppDrawerTooltip": r"کھولیں نیویگیشن مینو",
     "backButtonTooltip": r"واپس",
@@ -409,6 +423,7 @@ const Map<String, Map<String, String>> localizations = const <String, Map<String
     "postMeridiemAbbreviation": r"PM",
   },
   "zh": const <String, String>{
+    "scriptCategory": r"dense",
     "timeOfDayFormat": r"ah:mm",
     "openAppDrawerTooltip": r"打开导航菜单",
     "backButtonTooltip": r"返回",

packages/flutter/lib/src/material/i18n/material_ar.arb

 {
+  "scriptCategory": "tall",
   "timeOfDayFormat": "h:mm a",
   "openAppDrawerTooltip": "افتح قائمة التنقل",
   "backButtonTooltip": "الى الخلف",

packages/flutter/lib/src/material/i18n/material_de.arb

 {
+  "scriptCategory": "English-like",
   "timeOfDayFormat": "HH:mm",
   "@anteMeridiemAbbreviation": { "notUsed": "German time format does not use a.m. indicator" },
   "@postMeridiemAbbreviation": { "notUsed": "German time format does not use p.m. indicator" },

packages/flutter/lib/src/material/i18n/material_en.arb

 {
+  "scriptCategory": "English-like",
+  "@scriptCategory": {
+    "description": "The name of the language's script category (see https://material.io/guidelines/style/typography.html#typography-language-categories-reference)",
+    "type": "text"
+  },
+
   "timeOfDayFormat": "h:mm a",
   "@timeOfDayFormat": {
     "description": "The ICU 'Short Time' pattern, such as 'HH:mm', 'h:mm a', 'H:mm'. See: http://demo.icu-project.org/icu-bin/locexp?d_=en&_=en_US",

packages/flutter/lib/src/material/i18n/material_es.arb

 {
+  "scriptCategory": "English-like",
   "timeOfDayFormat": "H:mm",
   "@anteMeridiemAbbreviation": { "notUsed": "Standard Spanish time format does not use a.m. indicator" },
   "@postMeridiemAbbreviation": { "notUsed": "Standard Spanish time format does not use p.m. indicator" },

packages/flutter/lib/src/material/i18n/material_fa.arb

 {
+  "scriptCategory": "tall",
   "timeOfDayFormat": "H:mm",
   "@anteMeridiemAbbreviation": { "notUsed": "Farsi time format does not use a.m. indicator" },
   "@postMeridiemAbbreviation": { "notUsed": "Farsi time format does not use p.m. indicator" },

packages/flutter/lib/src/material/i18n/material_fr.arb

 {
+  "scriptCategory": "English-like",
   "timeOfDayFormat": "HH:mm",
   "@anteMeridiemAbbreviation": { "notUsed": "French time format does not use a.m. indicator" },
   "@postMeridiemAbbreviation": { "notUsed": "French time format does not use p.m. indicator" },

packages/flutter/lib/src/material/i18n/material_he.arb

 {
+  "scriptCategory": "English-like",
   "timeOfDayFormat": "H:mm",
   "@anteMeridiemAbbreviation": { "notUsed": "Hebrew time format does not use a.m. indicator" },
   "@postMeridiemAbbreviation": { "notUsed": "Hebrew time format does not use p.m. indicator" },

packages/flutter/lib/src/material/i18n/material_it.arb

 {
+  "scriptCategory": "English-like",
   "timeOfDayFormat": "HH:mm",
   "@anteMeridiemAbbreviation": { "notUsed": "Italian time format does not use a.m. indicator" },
   "@postMeridiemAbbreviation": { "notUsed": "Italian time format does not use p.m. indicator" },

packages/flutter/lib/src/material/i18n/material_ja.arb

 {
+  "scriptCategory": "dense",
   "timeOfDayFormat": "H:mm",
   "@anteMeridiemAbbreviation": { "notUsed": "Japanese time format does not use a.m. indicator" },
   "@postMeridiemAbbreviation": { "notUsed": "Japanese time format does not use p.m. indicator" },

packages/flutter/lib/src/material/i18n/material_ps.arb

 {
+  "scriptCategory": "tall",
   "timeOfDayFormat": "HH:mm",
   "@anteMeridiemAbbreviation": { "notUsed": "Pashto time format does not use a.m. indicator" },
   "@postMeridiemAbbreviation": { "notUsed": "Pashto time format does not use p.m. indicator" },

packages/flutter/lib/src/material/i18n/material_pt.arb

 {
+  "scriptCategory": "English-like",
   "timeOfDayFormat": "HH:mm",
   "@anteMeridiemAbbreviation": { "notUsed": "Portuguese time format does not use a.m. indicator" },
   "@postMeridiemAbbreviation": { "notUsed": "Portuguese time format does not use p.m. indicator" },

packages/flutter/lib/src/material/i18n/material_ru.arb

 {
+  "scriptCategory": "English-like",
   "timeOfDayFormat": "H:mm",
   "@anteMeridiemAbbreviation": { "notUsed": "Russian time format does not use a.m. indicator" },
   "@postMeridiemAbbreviation": { "notUsed": "Russian time format does not use p.m. indicator" },

packages/flutter/lib/src/material/i18n/material_sd.arb

 {
+  "scriptCategory": "tall",
   "timeOfDayFormat": "HH:mm",
   "@anteMeridiemAbbreviation": { "notUsed": "Sindhi time format does not use a.m. indicator" },
   "@postMeridiemAbbreviation": { "notUsed": "Sindhi time format does not use p.m. indicator" },

packages/flutter/lib/src/material/i18n/material_ur.arb

 {
+  "scriptCategory": "tall",
   "timeOfDayFormat": "h:mm a",
   "openAppDrawerTooltip": "کھولیں نیویگیشن مینو",
   "backButtonTooltip": "واپس",

packages/flutter/lib/src/material/i18n/material_zh.arb

 {
+  "scriptCategory": "dense",
   "timeOfDayFormat": "ah:mm",
   "openAppDrawerTooltip": "打开导航菜单",
   "backButtonTooltip": "返回",

packages/flutter/lib/src/material/material_localizations.dart

@@ -9,6 +9,7 @@ import 'package:flutter/widgets.dart';
 import 'package:intl/intl.dart' as intl;
 
 import 'i18n/localizations.dart';
+import 'typography.dart';
 
 /// Defines the localized resource values used by the Material widgets.
 ///
@@ -95,6 +96,19 @@ abstract class MaterialLocalizations {
   /// each supported layout.
   TimeOfDayFormat get timeOfDayFormat;
 
+  /// Provides geometric text preferences for the current locale.
+  ///
+  /// This text theme is incomplete. For example, it lacks text color
+  /// information. This theme must be merged with another text theme that
+  /// provides the missing values. The text styles provided by this theme have
+  /// their [TextStyle.inherit] property set to `true`.
+  ///
+  /// Typically a complete theme is obtained via [Theme.of], which can be
+  /// localized using the [Localizations] widget.
+  ///
+  /// See also: https://material.io/guidelines/style/typography.html
+  TextTheme get localTextGeometry;
+
   /// The `MaterialLocalizations` from the closest [Localizations] instance
   /// that encloses the given context.
   ///
@@ -287,6 +301,10 @@ class DefaultMaterialLocalizations implements MaterialLocalizations {
     return _icuTimeOfDayToEnum[icuShortTimePattern];
   }
 
+  /// Looks up text geometry defined in [MaterialTextGeometry].
+  @override
+  TextTheme get localTextGeometry => MaterialTextGeometry.forScriptCategory(_nameToValue["scriptCategory"]);
+
   /// Creates an object that provides localized resource values for the
   /// for the widgets of the material library.
   ///

packages/flutter/lib/src/material/theme.dart

@@ -5,7 +5,9 @@
 import 'package:flutter/foundation.dart';
 import 'package:flutter/widgets.dart';
 
+import 'material_localizations.dart';
 import 'theme_data.dart';
+import 'typography.dart';
 
 export 'theme_data.dart' show Brightness, ThemeData;
 
@@ -65,6 +67,10 @@ class Theme extends StatelessWidget {
   /// The data from the closest [Theme] instance that encloses the given
   /// context.
   ///
+  /// If the given context is enclosed in a [Localizations] widget providing
+  /// [MaterialLocalizations], the returned data is localized according to the
+  /// nearest available [MaterialLocalizations].
+  ///
   /// Defaults to [new ThemeData.fallback] if there is no [Theme] in the given
   /// build context.
   ///
@@ -123,7 +129,11 @@ class Theme extends StatelessWidget {
         return null;
       return inheritedTheme.theme.data;
     }
-    return (inheritedTheme != null) ? inheritedTheme.theme.data : _kFallbackTheme;
+
+    final ThemeData colorTheme = (inheritedTheme != null) ? inheritedTheme.theme.data : _kFallbackTheme;
+    final MaterialLocalizations localizations = MaterialLocalizations.of(context);
+    final TextTheme geometryTheme = localizations?.localTextGeometry ?? MaterialTextGeometry.englishLike;
+    return ThemeData.localize(colorTheme, geometryTheme);
   }
 
   @override

packages/flutter/lib/src/widgets/localizations.dart

@@ -401,10 +401,13 @@ class Localizations extends StatefulWidget {
     return new List<LocalizationsDelegate<dynamic>>.from(scope.localizationsState.widget.delegates);
   }
 
-  /// Returns the 'type' localized resources for the widget tree that
-  /// corresponds to [BuildContext] `context`.
+  /// Returns the localized resources object of the given `type` for the widget
+  /// tree that corresponds to the given `context`.
+  ///
+  /// Returns `null` if no resources object of the given `type` exists within
+  /// the given `context`.
   ///
-  /// This method is typically used by a static factory method on the 'type'
+  /// This method is typically used by a static factory method on the `type`
   /// class. For example Flutter's MaterialLocalizations class looks up Material
   /// resources with a method defined like this:
   ///
@@ -417,8 +420,7 @@ class Localizations extends StatefulWidget {
     assert(context != null);
     assert(type != null);
     final _LocalizationsScope scope = context.inheritFromWidgetOfExactType(_LocalizationsScope);
-    assert(scope != null, 'a Localizations ancestor was not found');
-    return scope.localizationsState.resourcesFor<T>(type);
+    return scope?.localizationsState?.resourcesFor<T>(type);
   }
 
   @override

packages/flutter/test/material/material_localizations_test.dart

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/foundation.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:flutter/widgets.dart';
+
+void main() {
+  testWidgets('$MaterialLocalizations localizes text inside the tree', (WidgetTester tester) async {
+    await tester.pumpWidget(new MaterialApp(
+      home: new ListView(
+        children: <Widget>[
+          new LocalizationTracker(key: const ValueKey<String>('outer')),
+          new Localizations(
+            locale: const Locale('zh', 'CN'),
+            delegates: <LocalizationsDelegate<dynamic>>[
+              new _MaterialLocalizationsDelegate(
+                new DefaultMaterialLocalizations(const Locale('zh', 'CN')),
+              ),
+              const DefaultWidgetsLocalizationsDelegate(),
+            ],
+            child: new LocalizationTracker(key: const ValueKey<String>('inner')),
+          ),
+        ],
+      ),
+    ));
+
+    final LocalizationTrackerState outerTracker = tester.state(find.byKey(const ValueKey<String>('outer')));
+    expect(outerTracker.captionFontSize, 12.0);
+    final LocalizationTrackerState innerTracker = tester.state(find.byKey(const ValueKey<String>('inner')));
+    expect(innerTracker.captionFontSize, 13.0);
+  });
+}
+
+class LocalizationTracker extends StatefulWidget {
+  LocalizationTracker({Key key}) : super(key: key);
+
+  @override
+  State<StatefulWidget> createState() => new LocalizationTrackerState();
+}
+
+class LocalizationTrackerState extends State<LocalizationTracker> {
+  double captionFontSize;
+
+  @override
+  Widget build(BuildContext context) {
+    captionFontSize = Theme.of(context).textTheme.caption.fontSize;
+    return new Container();
+  }
+}
+
+// Same as _MaterialLocalizationsDelegate in widgets/app.dart
+class _MaterialLocalizationsDelegate extends LocalizationsDelegate<MaterialLocalizations> {
+  const _MaterialLocalizationsDelegate(this.localizations);
+
+  final MaterialLocalizations localizations;
+
+  @override
+  Future<MaterialLocalizations> load(Locale locale) {
+    return new SynchronousFuture<MaterialLocalizations>(localizations);
+  }
+
+  @override
+  bool shouldReload(_MaterialLocalizationsDelegate old) => false;
+}
+
+// Same as _WidgetsLocalizationsDelegate in widgets/app.dart
+class DefaultWidgetsLocalizationsDelegate extends LocalizationsDelegate<WidgetsLocalizations> {
+  const DefaultWidgetsLocalizationsDelegate();
+
+  @override
+  Future<WidgetsLocalizations> load(Locale locale) {
+    return new SynchronousFuture<WidgetsLocalizations>(new DefaultWidgetsLocalizations(locale));
+  }
+
+  @override
+  bool shouldReload(DefaultWidgetsLocalizationsDelegate old) => false;
+}

packages/flutter/test/material/text_field_test.dart

@@ -4,8 +4,8 @@
 
 import 'dart:async';
 
-import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/services.dart';
 
@@ -789,8 +789,11 @@ void main() {
   });
 
   testWidgets('TextField with default helperStyle', (WidgetTester tester) async {
-    final ThemeData themeData = new ThemeData(
-      hintColor: Colors.blue[500],
+    final ThemeData themeData = ThemeData.localize(
+      new ThemeData(
+        hintColor: Colors.blue[500],
+      ),
+      MaterialTextGeometry.forScriptCategory(MaterialTextGeometry.englishLikeCategory),
     );
 
     await tester.pumpWidget(

packages/flutter/test/material/theme_test.dart

@@ -53,7 +53,9 @@ void main() {
       )
     );
 
-    expect(Theme.of(capturedContext), equals(new ThemeData.fallback()));
+    final dynamic localizedTheme = Theme.of(capturedContext);
+    expect('${localizedTheme.runtimeType}', '_LocalizedThemeData');
+    expect(localizedTheme.delegate, equals(new ThemeData.fallback()));
     expect(Theme.of(capturedContext, shadowThemeOnly: true), isNull);
   });
 

packages/flutter/test/material/typography_test.dart

@@ -30,23 +30,27 @@ void main() {
 
   test('Typography on iOS defaults to the correct SF font family based on size', () {
     // Ref: https://developer.apple.com/ios/human-interface-guidelines/visual-design/typography/
-    final Matcher hasCorrectFont = predicate((TextStyle s) {
-      return s.fontFamily == (s.fontSize <= 19.0 ? '.SF UI Text' : '.SF UI Display');
-    }, 'Uses SF Display font for font sizes over 19.0, otherwise SF Text font');
+    final Matcher isDisplayFont = predicate((TextStyle s) {
+      return s.fontFamily == '.SF UI Display';
+    }, 'Uses SF Display font');
+
+    final Matcher isTextFont = predicate((TextStyle s) {
+      return s.fontFamily == '.SF UI Text';
+    }, 'Uses SF Text font');
 
     final Typography typography = new Typography(platform: TargetPlatform.iOS);
     for (TextTheme textTheme in <TextTheme>[typography.black, typography.white]) {
-      expect(textTheme.display4, hasCorrectFont);
-      expect(textTheme.display3, hasCorrectFont);
-      expect(textTheme.display2, hasCorrectFont);
-      expect(textTheme.display1, hasCorrectFont);
-      expect(textTheme.headline, hasCorrectFont);
-      expect(textTheme.title, hasCorrectFont);
-      expect(textTheme.subhead, hasCorrectFont);
-      expect(textTheme.body2, hasCorrectFont);
-      expect(textTheme.body1, hasCorrectFont);
-      expect(textTheme.caption, hasCorrectFont);
-      expect(textTheme.button, hasCorrectFont);
+      expect(textTheme.display4, isDisplayFont);
+      expect(textTheme.display3, isDisplayFont);
+      expect(textTheme.display2, isDisplayFont);
+      expect(textTheme.display1, isDisplayFont);
+      expect(textTheme.headline, isDisplayFont);
+      expect(textTheme.title, isDisplayFont);
+      expect(textTheme.subhead, isTextFont);
+      expect(textTheme.body2, isTextFont);
+      expect(textTheme.body1, isTextFont);
+      expect(textTheme.caption, isTextFont);
+      expect(textTheme.button, isTextFont);
     }
   });
 }