What is the equivalent of onExpansionChanged for Flutter ExpandablePanel

Question

I would like to call a fonction when my ExpandablePanel is expanded, with ExpansionTile I do this with onExpansionChanged but here I don't want to use ExpansionTile,

Doesn't anyone have a solution?

Thanks.

Answer 1

Use an ExpandableController and an ExpandableNotifier :

class MyWidget extends StatefulWidget {
  const MyWidget({Key? key}) : super(key: key);

  @override
  State<StatefulWidget> createState() => _MyWidget();
}

class _MyWidget extends State<MyWidget> {
  final ExpandableController expandableController = ExpandableController();

  void onExpandableControllerStateChanged() {
    if (expandableController.expanded) {
      // Do your stuff when panel got expanded here
    } else {
      // Do your stuff when panel got collapsed here
    }
  }

  @override
  void initState() {
    super.initState();
    expandableController.addListener(onExpandableControllerStateChanged);
  }

  @override
  void dispose() {
    expandableController.removeListener(onExpandableControllerStateChanged);
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return ExpandableNotifier(
      controller: expandableController,
      child: ExpandablePanel(
        header: HeaderWidget(),
        collapsed: CollapsedWidget(),
        expanded: ExpandedWidget(),
      ),
    );
  }
}

Answer 2

You can put the ExpansionPanel inside an ExpansionPanelList and inside it will have a property called expansionCallback

Answer 3

You can wrap ExpansionPanel with ExpansionPanelList, so that you can access to a callback function named expansionCallback . Take a look at the snippet below:

ExpansionPanelList(
        animationDuration: const Duration(milliseconds:1000),
        children: [
          ExpansionPanel(), //..your expansionPanel here
        ],
        expansionCallback: (int item, bool status) {
            //status is what you're looking for
        },
      ),