Firebase image Provider

firebase_image.dart

// ignore_for_file: public_member_api_docs, sort_constructors_first
import 'dart:async';
import 'dart:ui' as ui;

import 'package:firebase_storage/firebase_storage.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/widgets.dart';

/// An [ImageProvider] that retrieves an image from Firebase Storage.
@immutable
class FirebaseImageProvider extends ImageProvider<FirebaseImageProvider> {
  FirebaseImageProvider(this.name, {this.bucket, this.scale = 1.0}) : _storage = FirebaseStorage.instance.ref(bucket);

  /// Firebase storage reference
  final Reference _storage;

  /// Asset name
  final String name;

  /// Bucket name
  final String? bucket;

  /// Scale of the image
  final double scale;

  @override
  Future<FirebaseImageProvider> obtainKey(ImageConfiguration configuration) {
    return SynchronousFuture<FirebaseImageProvider>(this);
  }

  @override
  ImageStreamCompleter loadImage(FirebaseImageProvider key, ImageDecoderCallback decode) {
    final chunkEvents = StreamController<ImageChunkEvent>();

    return MultiFrameImageStreamCompleter(
      codec: _loadAsync(key, chunkEvents, decode: decode),
      chunkEvents: chunkEvents.stream,
      scale: key.scale,
      debugLabel: name,
      informationCollector:
          () => <DiagnosticsNode>[
            DiagnosticsProperty<FirebaseImageProvider>('Image provider', this),
            DiagnosticsProperty<FirebaseImageProvider>('Image key', key),
          ],
    );
  }

  Future<ui.Codec> _loadAsync(
    FirebaseImageProvider key,
    StreamController<ImageChunkEvent> chunkEvents, {
    required ImageDecoderCallback decode,
  }) async {
    try {
      final image = await _storage.child(key.name).getData();

      if (image == null) {
        throw FirebasekImageLoadException(key.name);
      }

      return decode(await ui.ImmutableBuffer.fromUint8List(image));
    } on FirebaseException catch (error, stackTrace) {
      Error.throwWithStackTrace(
        FirebasekImageLoadException('Failed to load ${key.name} in bucket $bucket', error: error),
        stackTrace,
      );
    }
  }

  @override
  bool operator ==(covariant FirebaseImageProvider other) {
    if (identical(this, other)) return true;

    return other.name == name && other.scale == scale;
  }

  @override
  int get hashCode => name.hashCode ^ scale.hashCode;
}

class FirebasekImageLoadException implements Exception {
  FirebasekImageLoadException(this.name, {this.error});

  final String name;

  Object? error;

  @override
  String toString() => 'FirebaseImageLoadException: Failed to load image $name';
}