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TabController indexIsChanging always return false when swiping TabBarView #28298
Description
Steps to Reproduce
class MyTabbedPage extends StatefulWidget {
const MyTabbedPage({ Key key }) : super(key: key);
@override
_MyTabbedPageState createState() => _MyTabbedPageState();
}
class _MyTabbedPageState extends State<MyTabbedPage> with SingleTickerProviderStateMixin {
final List<Tab> myTabs = <Tab>[
Tab(text: 'LEFT'),
Tab(text: 'RIGHT'),
];
TabController _tabController;
@override
void initState() {
super.initState();
_tabController = TabController(vsync: this, length: myTabs.length);
_tabController.addListener(() {
print('indexIsChanging: ${_tabController.indexIsChanging}'); // always false
});
}
@override
void dispose() {
_tabController.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
bottom: TabBar(
controller: _tabController,
tabs: myTabs,
),
),
body: TabBarView(
controller: _tabController,
children: myTabs.map((Tab tab) {
return Center(child: Text(tab.text));
}).toList(),
),
);
}
}- Tap
TabBar,indexIsChangingreturntrue - Swipe
TabBarView,indexIsChangingreturn false
Logs
[✓] Flutter (Channel stable, v1.0.0, on Mac OS X 10.14.2 18C54, locale en-ID)
• Flutter version 1.0.0 at /Users/yuda/flutter
• Framework revision 5391447fae (3 months ago), 2018-11-29 19:41:26 -0800
• Engine revision 7375a0f414
• Dart version 2.1.0 (build 2.1.0-dev.9.4 f9ebf21297)
[✓] Android toolchain - develop for Android devices (Android SDK 28.0.3)
• Android SDK at /Users/yuda/Library/Android/sdk
• Android NDK location not configured (optional; useful for native profiling support)
• Platform android-28, build-tools 28.0.3
• ANDROID_HOME = /Users/yuda/Library/Android/sdk
• Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
• Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1248-b01)
• All Android licenses accepted.
[✓] iOS toolchain - develop for iOS devices (Xcode 10.1)
• Xcode at /Applications/Xcode.app/Contents/Developer
• Xcode 10.1, Build version 10B61
• ios-deploy 1.9.4
• CocoaPods version 1.5.3
[✓] Android Studio (version 3.3)
• Android Studio at /Applications/Android Studio.app/Contents
• Flutter plugin version 33.1.1
• Dart plugin version 182.5215
• Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1248-b01)
[✓] Connected device (1 available)
• iPhone X • A29A6A52-4245-4904-8ED4-D10AE01FBD8D • ios • iOS 12.1 (simulator)
Activity
HansMuller commentedon Feb 28, 2019
The
indexIsChangingproperty is a bit of a misnomer. Its value is true when the controller animation's value is changing from one value to another because the user tapped a tab, but not when the animation's value is changing because the user is dragging the TabBarView.Here's a version of your example that demos the difference: https://gist.github.com/HansMuller/ba3f841296bacc6522b99b8d474286b5
The documentation could be clearer about this; will fix it.
sultanmyrza commentedon Apr 27, 2020
If you want change bottom bar selected icon after swipe you can try this
here is the full gist
https://gist.github.com/sultanmyrza/36f6726e563f9c6bacf9ad0e4a47b807
github-actions commentedon Aug 14, 2021
This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of
flutter doctor -vand a minimal reproduction of the issue.