Fix `SliverAppBar.large` and `SliverAppBar.medium` do not use `foregroundColor` (#118322)

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

@@ -1652,6 +1652,7 @@ class SliverAppBar extends StatefulWidget {
       actions: actions,
       flexibleSpace: flexibleSpace ?? _ScrollUnderFlexibleSpace(
         title: title,
+        foregroundColor: foregroundColor,
         variant: _ScrollUnderFlexibleVariant.medium,
         centerCollapsedTitle: centerTitle,
         primary: primary,
@@ -1753,6 +1754,7 @@ class SliverAppBar extends StatefulWidget {
       actions: actions,
       flexibleSpace: flexibleSpace ?? _ScrollUnderFlexibleSpace(
         title: title,
+        foregroundColor: foregroundColor,
         variant: _ScrollUnderFlexibleVariant.large,
         centerCollapsedTitle: centerTitle,
         primary: primary,
@@ -2227,12 +2229,14 @@ enum _ScrollUnderFlexibleVariant { medium, large }
 class _ScrollUnderFlexibleSpace extends StatelessWidget {
   const _ScrollUnderFlexibleSpace({
     this.title,
+    this.foregroundColor,
     required this.variant,
     this.centerCollapsedTitle,
     this.primary = true,
   });
 
   final Widget? title;
+  final Color? foregroundColor;
   final _ScrollUnderFlexibleVariant variant;
   final bool? centerCollapsedTitle;
   final bool primary;
@@ -2240,6 +2244,7 @@ class _ScrollUnderFlexibleSpace extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     late final ThemeData theme = Theme.of(context);
+    late final AppBarTheme appBarTheme = AppBarTheme.of(context);
     final FlexibleSpaceBarSettings settings = context.dependOnInheritedWidgetOfExactType<FlexibleSpaceBarSettings>()!;
     final double topPadding = primary ? MediaQuery.viewPaddingOf(context).top : 0;
     final double collapsedHeight = settings.minExtent - topPadding;
@@ -2259,13 +2264,13 @@ class _ScrollUnderFlexibleSpace extends StatelessWidget {
     if (title != null) {
       collapsedTitle = config.collapsedTextStyle != null
         ? DefaultTextStyle(
-            style: config.collapsedTextStyle!,
+            style: config.collapsedTextStyle!.copyWith(color: foregroundColor ?? appBarTheme.foregroundColor),
             child: title!,
           )
         : title;
       expandedTitle = config.expandedTextStyle != null
         ? DefaultTextStyle(
-            style: config.expandedTextStyle!,
+            style: config.expandedTextStyle!.copyWith(color: foregroundColor ?? appBarTheme.foregroundColor),
             child: title!,
           )
         : title;
@@ -2286,9 +2291,7 @@ class _ScrollUnderFlexibleSpace extends StatelessWidget {
             return true;
         }
       }
-      centerTitle = centerCollapsedTitle
-        ?? theme.appBarTheme.centerTitle
-        ?? platformCenter();
+      centerTitle = centerCollapsedTitle ?? appBarTheme.centerTitle ?? platformCenter();
     }
 
     final bool isCollapsed = settings.isScrolledUnder ?? false;
@@ -2307,7 +2310,7 @@ class _ScrollUnderFlexibleSpace extends StatelessWidget {
                 alignment: centerTitle
                   ? Alignment.center
                   : AlignmentDirectional.centerStart,
-                child: collapsedTitle
+                child: collapsedTitle,
               ),
             ),
           ),

packages/flutter/test/material/app_bar_theme_test.dart

@@ -574,6 +574,78 @@ void main() {
     expect(navToolbar.middleSpacing, 40);
   });
 
+  testWidgets("SliverAppBar.medium's title uses AppBarTheme.foregroundColor", (WidgetTester tester) async {
+    const Color foregroundColor = Color(0xff00ff00);
+    await tester.pumpWidget(MaterialApp(
+      theme: ThemeData(appBarTheme: const AppBarTheme(foregroundColor: foregroundColor)),
+      home: CustomScrollView(
+        slivers: <Widget>[
+          SliverAppBar.medium(
+            title: const Text('Medium Title'),
+          ),
+        ],
+      ),
+    ));
+
+    final RichText text = tester.firstWidget(find.byType(RichText));
+    expect(text.text.style!.color, foregroundColor);
+  });
+
+  testWidgets(
+    "SliverAppBar.medium's foregroundColor takes priority over AppBarTheme.foregroundColor", (WidgetTester tester) async {
+      const Color foregroundColor = Color(0xff00ff00);
+      await tester.pumpWidget(MaterialApp(
+        theme: ThemeData(appBarTheme: const AppBarTheme(foregroundColor: Color(0xffff0000))),
+        home: CustomScrollView(
+          slivers: <Widget>[
+            SliverAppBar.medium(
+              foregroundColor: foregroundColor,
+              title: const Text('Medium Title'),
+            ),
+          ],
+        ),
+      ));
+
+      final RichText text = tester.firstWidget(find.byType(RichText));
+      expect(text.text.style!.color, foregroundColor);
+  });
+
+  testWidgets("SliverAppBar.large's title uses AppBarTheme.foregroundColor", (WidgetTester tester) async {
+    const Color foregroundColor = Color(0xff00ff00);
+    await tester.pumpWidget(MaterialApp(
+      theme: ThemeData(appBarTheme: const AppBarTheme(foregroundColor: foregroundColor)),
+      home: CustomScrollView(
+        slivers: <Widget>[
+          SliverAppBar.large(
+            title: const Text('Large Title'),
+          ),
+        ],
+      ),
+    ));
+
+    final RichText text = tester.firstWidget(find.byType(RichText));
+    expect(text.text.style!.color, foregroundColor);
+  });
+
+  testWidgets(
+    "SliverAppBar.large's foregroundColor takes priority over AppBarTheme.foregroundColor", (WidgetTester tester) async {
+      const Color foregroundColor = Color(0xff00ff00);
+      await tester.pumpWidget(MaterialApp(
+        theme: ThemeData(appBarTheme: const AppBarTheme(foregroundColor: Color(0xffff0000))),
+        home: CustomScrollView(
+          slivers: <Widget>[
+            SliverAppBar.large(
+              foregroundColor: foregroundColor,
+              title: const Text('Large Title'),
+            ),
+          ],
+        ),
+      ));
+
+      final RichText text = tester.firstWidget(find.byType(RichText));
+      expect(text.text.style!.color, foregroundColor);
+  });
+
   testWidgets('Default AppBarTheme debugFillProperties', (WidgetTester tester) async {
     final DiagnosticPropertiesBuilder builder = DiagnosticPropertiesBuilder();
     const AppBarTheme().debugFillProperties(builder);