Make TabBar indicator color automatic adjustment optional (#68171)

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

@@ -597,6 +597,7 @@ class TabBar extends StatefulWidget implements PreferredSizeWidget {
     this.controller,
     this.isScrollable = false,
     this.indicatorColor,
+    this.automaticIndicatorColorAdjustment = true,
     this.indicatorWeight = 2.0,
     this.indicatorPadding = EdgeInsets.zero,
     this.indicator,
@@ -685,6 +686,13 @@ class TabBar extends StatefulWidget implements PreferredSizeWidget {
   /// the tab widget itself.
   final Decoration? indicator;
 
+  /// Whether this tab bar should automatically adjust the [indicatorColor].
+  ///
+  /// If [automaticIndicatorColorAdjustment] is true,
+  /// then the [indicatorColor] will be automatically adjusted to [Colors.white]
+  /// when the [indicatorColor] is same as [Material.color] of the [Material] parent widget.
+  final bool automaticIndicatorColorAdjustment;
+
   /// Defines how the selected tab indicator's size is computed.
   ///
   /// The size of the selected tab indicator is defined relative to the
@@ -814,7 +822,11 @@ class _TabBarState extends State<TabBar> {
     //
     // The material's color might be null (if it's a transparency). In that case
     // there's no good way for us to find out what the color is so we don't.
-    if (color.value == Material.of(context)?.color?.value)
+    //
+    // TODO(xu-baolin): Remove automatic adjustment to white color indicator
+    // with a better long-term solution.
+    // https://github.com/flutter/flutter/pull/68171#pullrequestreview-517753917
+    if (widget.automaticIndicatorColorAdjustment && color.value == Material.of(context)?.color?.value)
       color = Colors.white;
 
     return UnderlineTabIndicator(

packages/flutter/test/material/tabs_test.dart

@@ -169,7 +169,7 @@ class TabControllerFrameState extends State<TabControllerFrame> with SingleTicke
   }
 }
 
-Widget buildLeftRightApp({ required List<String> tabs, required String value }) {
+Widget buildLeftRightApp({required List<String> tabs, required String value, bool automaticIndicatorColorAdjustment = true}) {
   return MaterialApp(
     theme: ThemeData(platform: TargetPlatform.android),
     home: DefaultTabController(
@@ -180,6 +180,7 @@ Widget buildLeftRightApp({ required List<String> tabs, required String value })
           title: const Text('tabs'),
           bottom: TabBar(
             tabs: tabs.map<Widget>((String tab) => Tab(text: tab)).toList(),
+            automaticIndicatorColorAdjustment: automaticIndicatorColorAdjustment,
           ),
         ),
         body: const TabBarView(
@@ -2213,7 +2214,16 @@ void main() {
     expect(tabBarBox, paints..line(
       color: Colors.white,
     ));
+  });
 
+  testWidgets('Tab indicator color should not be adjusted when disable [automaticIndicatorColorAdjustment]', (WidgetTester tester) async {
+     // Regression test for https://github.com/flutter/flutter/issues/68077
+     final List<String> tabs = <String>['LEFT', 'RIGHT'];
+     await tester.pumpWidget(buildLeftRightApp(tabs: tabs, value: 'LEFT', automaticIndicatorColorAdjustment: false));
+     final RenderBox tabBarBox = tester.firstRenderObject<RenderBox>(find.byType(TabBar));
+     expect(tabBarBox, paints..line(
+       color: const Color(0xff2196f3),
+     ));
   });
 
   testWidgets('Skipping tabs with global key does not crash', (WidgetTester tester) async {