buildDefaultDragHandles property

If true: on desktop platforms, a drag handle is stacked over the center of each item's trailing edge; on mobile platforms, a long press anywhere on the item starts a drag.

The default desktop drag handle is just an Icons.drag_handle wrapped by a ReorderableDragStartListener. On mobile platforms, the entire item is wrapped with a ReorderableDelayedDragStartListener.

To change the appearance or the layout of the drag handles, make this parameter false and wrap each list item, or a widget within each list item, with ReorderableDragStartListener or ReorderableDelayedDragStartListener, or a custom subclass of ReorderableDragStartListener.

The following sample specifies buildDefaultDragHandles: false, and uses a Card at the leading edge of each item for the item's drag handle.

{@tool dartpad --template=stateful_widget_scaffold}

final List<int> _items = List<int>.generate(50, (int index) => index);

@override
Widget build(BuildContext context){
  final ColorScheme colorScheme = Theme.of(context).colorScheme;
  final Color oddItemColor = colorScheme.primary.withOpacity(0.05);
  final Color evenItemColor = colorScheme.primary.withOpacity(0.15);

  return KnownExtentsReorderableListView(
    buildDefaultDragHandles: false,
    children: <Widget>[
      for (int index = 0; index < _items.length; index++)
        Container(
          key: Key('$index'),
          color: _items[index].isOdd ? oddItemColor : evenItemColor,
          child: Row(
            children: <Widget>[
              Container(
                width: 64,
                height: 64,
                padding: const EdgeInsets.all(8),
                child: ReorderableDragStartListener(
                  index: index,
                  child: Card(
                    color: colorScheme.primary,
                    elevation: 2,
                  ),
                ),
              ),
              Text('Item ${_items[index]}'),
            ],
          ),
        ),
    ],
    onReorder: (int oldIndex, int newIndex) {
      setState(() {
        if (oldIndex < newIndex) {
          newIndex -= 1;
        }
        final int item = _items.removeAt(oldIndex);
        _items.insert(newIndex, item);
      });
    },
  );
}

{@end-tool}

Implementation

KnownExtentsReorderableListView class