Sheet that snaps between open and dismissed

draggable_yeetable_sheet.dart

class DraggableYeetableSheet extends StatefulWidget {
  const DraggableYeetableSheet({super.key});

  @override
  State<DraggableYeetableSheet> createState() => _DraggableYeetableSheetState();
}

class _DraggableYeetableSheetState extends State<DraggableYeetableSheet> {
  final DraggableScrollableController sheetController =
      DraggableScrollableController();

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Stack(
          children: [
            Container(
              color: Colors.black,
            ),
            // You probably want to not include this in the tree when it's min
            // size is at zero.
            // You can get the current size of the sheet by listening to the
            // sheet controller.
            // This is left as an exercise to the reader.
            DraggableScrollableSheet(
              snap: true,
              controller: sheetController,
              maxChildSize: 1,
              initialChildSize: 0,
              // This + the controller is the secret sauce.
              minChildSize: 0,
              builder: (context, scrollController) {
                return ListView.builder(
                  controller: scrollController,
                  itemCount: 20,
                  itemBuilder: (context, index) {
                    return Container(
                      height: 100,
                      color: index.isEven ? Colors.green : Colors.grey,
                    );
                  },
                );
              },
            ),
          ],
        ),
        floatingActionButton: FloatingActionButton(
          child: const Icon(Icons.add),
          onPressed: () async {
            return sheetController.animateTo(
              // If we're not visible, animate us to the top. Else, animate us
              // to the bottom.
              // You can customize this logic fairly arbitrarily to meet your
              // needs.
              // Note that if the sheet is not in the tree animate to will
              // throw. Make sure it's only called while the sheet is in the
              // tree.
              sheetController.size == 0 ? 1 : 0,
              duration: const Duration(milliseconds: 300),
              curve: Curves.easeInOut,
            );
          },
        ),
      ),
    );
  }
}