drag_and_drop_lists

dependencies:
  drag_and_drop_lists: ^0.2.1

  // Outer list
  List<DragAndDropList> _contents;

  @override
  void initState() {
    super.initState();

    // Generate a list
    _contents = List.generate(10, (index) {
      return DragAndDropList(
        header: Text('Header $index'),
        children: <DragAndDropItem>[
          DragAndDropItem(
            child: Text('$index.1'),
          ),
          DragAndDropItem(
            child: Text('$index.2'),
          ),
          DragAndDropItem(
            child: Text('$index.3'),
          ),
        ],
      );
    });
  }

  @override
  Widget build(BuildContext context) {
    // Add a DragAndDropLists. The only required parameters are children,
    // onItemReorder, and onListReorder. All other parameters are used for
    // styling the lists and changing its behaviour. See the samples in the
    // example app for many more ways to configure this.
    return DragAndDropLists(
      children: _contents,
      onItemReorder: _onItemReorder,
      onListReorder: _onListReorder,
    );
  }

  _onItemReorder(int oldItemIndex, int oldListIndex, int newItemIndex, int newListIndex) {
    setState(() {
      var movedItem = _contents[oldListIndex].children.removeAt(oldItemIndex);
      _contents[newListIndex].children.insert(newItemIndex, movedItem);
    });
  }

  _onListReorder(int oldListIndex, int newListIndex) {
    setState(() {
      var movedList = _contents.removeAt(oldListIndex);
      _contents.insert(newListIndex, movedList);
    });
  }