Created the upload status service to keep track of currently being uploaded files

lib/src/blocs/event_bloc.dart

@@ -10,6 +10,7 @@ import '../models/user_model.dart';
 import '../resources/firestore_provider.dart';
 import '../resources/firebase_storage_provider.dart';
 import '../services/auth_service.dart';
+import '../services/upload_status_service.dart';
 import '../utils.dart'
     show kTaskListPriorityTransforemer, getImageThumbnailPath;
 

lib/src/blocs/home_bloc.dart

@@ -107,8 +107,10 @@ class HomeBloc {
     _searchBoxText.add(newText);
   }
 
-  void dispose() {
+  void dispose() async {
+    await _searchBoxText.drain();
     _searchBoxText.close();
+    await _tasks.drain();
     _tasks.close();
   }
 }

lib/src/screens/event_screen.dart

@@ -1,3 +1,5 @@
+import 'dart:async';
+
 import 'package:flutter/material.dart';
 
 import '../utils.dart' show getImageThumbnailPath;
@@ -165,8 +167,7 @@ class _EventScreenState extends State<EventScreen>
   Widget buildAddPictureButton() {
     return GradientTouchableContainer(
       radius: 8,
-      onTap: () =>
-          Navigator.of(context).pushNamed('newImage/${bloc.eventName}'),
+      onTap: onAddPicturePressed,
       child: Icon(
         Icons.camera_alt,
         color: Colors.white,
@@ -191,6 +192,11 @@ class _EventScreenState extends State<EventScreen>
     );
   }
 
+  Future<void> onAddPicturePressed() async {
+    await Navigator.of(context).pushNamed('newImage/${bloc.eventName}');
+    print('popped the pictures');
+  }
+
   void dispose() {
     bloc.dispose();
     super.dispose();

lib/src/services/upload_status_service.dart

@@ -0,0 +1,86 @@
+import 'dart:async';
+
+import 'package:firebase_storage/firebase_storage.dart';
+import 'package:rxdart/rxdart.dart';
+
+/// A service that maintains a record of the upload operations made to
+/// the firebase storage bucket.
+class _UploadStatusService {
+  /// A subject of the current status of uploads.
+  final _status = BehaviorSubject<UploadStatus>();
+
+  /// A map that contains the information about all the current upload tasks.
+  Map<StorageUploadTask, List<int>> tasksData =
+      <StorageUploadTask, List<int>>{};
+
+  /// An observable of the status for all current upload tasks.
+  Observable<UploadStatus> get status => _status.stream;
+
+  /// Adds a new upload task to be tracked.
+  ///
+  /// The task gets automatically removed when done.
+  void addNewUpload(StorageUploadTask task) async {
+    final initialSnap = task.lastSnapshot;
+    // Initialize the map entry with the initial values.
+    tasksData[task] = [
+      initialSnap.bytesTransferred,
+      initialSnap.totalByteCount,
+    ];
+    task.events.listen(
+      (StorageTaskEvent event) {
+        // Update the map with the current values.
+        final snap = event.snapshot;
+        tasksData[task] = [
+          snap.bytesTransferred,
+          snap.totalByteCount,
+        ];
+        _sendUpdate();
+      },
+    );
+    await task.onComplete;
+    tasksData.remove(task);
+  }
+
+  /// Updates the _status subject with the most current data.
+  void _sendUpdate() {
+    int totalBytes = 0, bytestTransferred = 0;
+    double percentage = 0.0;
+    tasksData.forEach(
+      (_, data) {
+        bytestTransferred += data[0];
+        totalBytes += data[1];
+      },
+    );
+    if (bytestTransferred != 0) {
+      percentage = totalBytes / bytestTransferred;
+    }
+    _status.sink.add(UploadStatus(
+      percentage: percentage,
+      numberOfFiles: tasksData.length,
+    ));
+  }
+
+  dispose() async {
+    await _status.drain();
+    _status.close();
+  }
+}
+
+/// The status of an upload.
+class UploadStatus {
+  /// Percentage of the upload.
+  final double percentage;
+
+  /// Number of files being uploaded.
+  ///
+  /// It can be 0 if nothing is currently being uploaded.
+  final int numberOfFiles;
+
+  /// Creates an [UploadStatus] instance.
+  UploadStatus({
+    this.percentage,
+    this.numberOfFiles,
+  });
+}
+
+final uploadStatusService = _UploadStatusService();