import 'package:flutter/foundation.dart';

import 'gallery_item.dart';

/// Items the media gallery pages through. Sources that grow while the viewer
/// is open (chat history) notify; the viewer keeps the shown item in place.
abstract class GallerySource extends ChangeNotifier {
  List<GalleryItem> get items;

  bool get hasOlder => false;

  /// Called when the user nears the start (oldest end) of [items].
  Future<void> loadOlder() async {}
}

class StaticGallerySource extends GallerySource {
  @override
  final List<GalleryItem> items;

  StaticGallerySource(this.items);
}