The Flutter team has also pushed this feature to the framework, https://github.com/flutter/flutter/blob/master/packages/flutter/lib/src/material/reorderable_list.dart

A new Flutter package which handles all aspects of drag and drop inside a listView.

In your pubspec.yaml

dependencies:
  flutter_list_drag_and_drop: "^0.1.3"

• When dragging an item to the top/ bottom the list scroll accordingly
• Works with different sized items
• material like behaviour

If you encounter feel free to open an issue. Pull request are also welcome.