Finished the media view and the gallery for the event screen

lib/src/App.dart

@@ -16,6 +16,9 @@ class App extends StatelessWidget {
       theme: ThemeData(
         // Accent color is set to be used by the floating action button.
         accentColor: Color(0xFF707070),
+        iconTheme: IconThemeData(
+          color: Colors.white,
+        ),
         canvasColor: Color.fromRGBO(23, 25, 29, 1.0),
         cardColor: Color.fromRGBO(36, 39, 44, 1.0),
         cursorColor: Color.fromRGBO(112, 112, 112, 1),
@@ -55,9 +58,15 @@ class App extends StatelessWidget {
         },
       );
     } else if (routeTokens.first == 'newImage') {
+      String eventName;
+      if (routeTokens.length > 1) {
+        eventName = routeTokens[1];
+      }
       return MaterialPageRoute(
         builder: (BuildContext context) {
-          return NewImageScreen();
+          return NewImageScreen(
+            defaultEventName: eventName,
+          );
         },
       );
     } else if (routeTokens.first == 'event') {

lib/src/blocs/event_bloc.dart

@@ -103,6 +103,7 @@ class EventBloc {
       if (isThumbnail) {
         path = getImageThumbnailPath(path);
       }
+      // Do not re-fetch the image if it resolved already.
       if (cache.containsKey(path)) {
         return cache;
       }

lib/src/blocs/new_image_bloc.dart

@@ -29,7 +29,13 @@ class NewImageBloc {
   /// A subject of the current media event name.
   final _eventName = BehaviorSubject<String>();
 
-  NewImageBloc() {
+  /// Default event name.
+  final String defaultEventName;
+
+  NewImageBloc({this.defaultEventName}) {
+    if (defaultEventName != null && defaultEventName != '') {
+      _eventName.sink.add(defaultEventName);
+    }
     setCurrentUser();
   }
 

lib/src/resources/firebase_storage_provider.dart

@@ -1,5 +1,6 @@
 import 'dart:async';
 import 'dart:io';
+import 'dart:typed_data';
 
 import 'package:firebase_storage/firebase_storage.dart';
 import 'package:path_provider/path_provider.dart';
@@ -47,17 +48,47 @@ class FirebaseStorageProvider {
 
   // TODO: Add tests for this method.
   // TODO: Delete the tmp file when the app closes.
+  // TODO: Add support for requests taking too long not only errors.
   /// Returns a future of the file from the path.
   ///
   /// Downloads the raw bytes from the sotrage buckets and converts it to a file.
-  Future<File> getFile(String path) async {
-    final fileName = path.split('/').last;
-    final fileReference = _storage.child(path);
-    final metadata = await fileReference.getMetadata();
-    final bytes = await fileReference.getData(metadata.sizeBytes);
-
+  /// The fetching process is repeated up to [retries] times with a [retryDelay]
+  /// delay in between tries.
+  Future<File> getFile(
+    String path, {
+    int retries = 3,
+    Duration retryDelay = const Duration(seconds: 2),
+  }) async {
     final Directory tmp = await getTemporaryDirectory();
+    final fileName = path.split('/').last;
     final file = File('${tmp.path}/$fileName');
+
+    // Don't re-fetch if the file is already in the temp directory.
+    if (await file.exists()) {
+      return file;
+    }
+    Uint8List bytes;
+    // Repeat until the fetching process is successful or the number of retries
+    // is excceded.
+    while (bytes == null && retries > 0) {
+      final fileReference = _storage.child(path);
+      // Assing null to metadata if there's an error during the fetching process.
+      // aka the file potentially doesn't exist.
+      final metadata =
+          await fileReference.getMetadata().catchError((error) => null);
+      // Restart the fetching process if there was an error.
+      if (metadata == null) {
+        print('retrying');
+        await Future.delayed(retryDelay);
+        retries -= 1;
+        continue;
+      }
+      bytes = await fileReference.getData(metadata.sizeBytes);
+      print('done getting data');
+    }
+    if (bytes == null) {
+      return null;
+    }
     return file.writeAsBytes(bytes);
   }
 }

lib/src/screens/event_screen.dart

@@ -1,16 +1,16 @@
 import 'dart:async';
-import 'dart:io';
 
 import 'package:flutter/material.dart';
 
 import '../utils.dart' show getImageThumbnailPath;
 import '../blocs/event_bloc.dart';
+import '../screens/gallery_screen.dart';
 import '../models/task_model.dart';
+import '../widgets/async_thumbnail.dart';
 import '../widgets/custom_app_bar.dart';
 import '../widgets/gradient_touchable_container.dart';
 import '../widgets/loading_indicator.dart';
 import '../widgets/task_list_tile.dart';
-import '../widgets/async_thumbnail.dart';
 
 /// A screen that shows all the items linked to an event.
 class EventScreen extends StatefulWidget {
@@ -128,9 +128,12 @@ class _EventScreenState extends State<EventScreen>
             final imagePath = listSnap.data[index - 1];
             bloc.fetchThumbnail(imagePath);
 
-            return AsyncThumbnail(
+            return GestureDetector(
+              onTap: () => openGallery(imageIndex: index - 1),
+              child: AsyncThumbnail(
                 cacheStream: bloc.thumbnails,
                 cacheId: getImageThumbnailPath(imagePath),
+              ),
             );
           },
           gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
@@ -143,9 +146,12 @@ class _EventScreenState extends State<EventScreen>
     );
   }
 
+  // TODO: Change the navigation call whent the new package is ready.
   Widget buildAddPictureButton() {
     return GradientTouchableContainer(
       radius: 8,
+      onTap: () =>
+          Navigator.of(context).pushNamed('newImage/${bloc.eventName}'),
       child: Icon(
         Icons.camera_alt,
         color: Colors.white,
@@ -154,6 +160,22 @@ class _EventScreenState extends State<EventScreen>
     );
   }
 
+  /// Pushes a new screen that shows the pictures in full size.
+  void openGallery({int imageIndex}) {
+    Navigator.of(context).push(
+      MaterialPageRoute(
+        builder: (BuildContext context) {
+          return GalleryScreen(
+            fetchImage: bloc.fetchImage,
+            cacheStream: bloc.images,
+            pathsStream: bloc.imagesPaths,
+            initialScreen: imageIndex,
+          );
+        },
+      ),
+    );
+  }
+
   void dispose() {
     bloc.dispose();
     super.dispose();

lib/src/screens/gallery_screen.dart

@@ -0,0 +1,169 @@
+import 'dart:async';
+import 'dart:io';
+
+import 'package:flutter/material.dart';
+import 'package:font_awesome_flutter/font_awesome_flutter.dart';
+import 'package:rxdart/rxdart.dart';
+
+import '../widgets/async_image.dart';
+import '../widgets/fractionally_screen_sized_box.dart';
+import '../widgets/loading_indicator.dart';
+
+/// A screen that shows a series of puctures in full resolution with zoom
+/// capability and navigation controls.
+class GalleryScreen extends StatelessWidget {
+  /// An observable that emits a list of all the paths of the images the gallery
+  /// will show.
+  final Observable<List<String>> pathsStream;
+
+  /// An observable that emits a map that caches the files corresponding to the
+  /// images to be shown.
+  final Observable<Map<String, Future<File>>> cacheStream;
+
+  /// A function to be called when an image needs to be fetched.
+  final Function(String) fetchImage;
+
+  /// The initial screen (picture) to be shown.
+  ///
+  /// If provided, the gallery will automatically show this image upon opening.
+  final int initialScreen;
+
+  /// A controller for the underlaying [PageView].
+  final PageController _controller;
+
+  /// Creates a screen that shows a series of puctures in full resolution with zoom
+  /// capability and navigation controls
+  ///
+  /// [patshStream], [cacheStream] and [fetchImage] must not be null.
+  GalleryScreen({
+    @required this.pathsStream,
+    @required this.cacheStream,
+    this.initialScreen = 0,
+    @required this.fetchImage,
+  })  : assert(pathsStream != null),
+        assert(cacheStream != null),
+        assert(fetchImage != null),
+        _controller = PageController(
+          initialPage: initialScreen,
+          keepPage: false,
+        );
+
+  Widget build(BuildContext context) {
+    return Scaffold(
+      body: Stack(
+        children: <Widget>[
+          StreamBuilder(
+            stream: pathsStream,
+            builder:
+                (BuildContext context, AsyncSnapshot<List<String>> listSnap) {
+              // Wait until the images paths have been fetched.
+              if (!listSnap.hasData) {
+                return buildImagePlaceholder();
+              }
+
+              return PageView.builder(
+                // Do not allow page changes on swipe. User manual controls,
+                // the [PageView] gestures interfere with zooming otherwhise.
+                physics: new NeverScrollableScrollPhysics(),
+                controller: _controller,
+                itemCount: listSnap.data.length,
+                itemBuilder: (BuildContext context, int index) {
+                  final imagePath = listSnap.data[index];
+                  fetchImage(imagePath);
+
+                  return AsyncImage(
+                    cacheId: imagePath,
+                    cacheMap: cacheStream,
+                  );
+                },
+              );
+            },
+          ),
+          buildCloseButton(context),
+          buildPageNavigation(),
+        ],
+      ),
+    );
+  }
+
+  /// Jumps to the specified page.
+  void animateToPage(Page page) {
+    final curve = Curves.easeInOut;
+    final duration = Duration(milliseconds: 300);
+    switch (page) {
+      case Page.previous:
+        _controller.previousPage(
+          curve: curve,
+          duration: duration,
+        );
+        break;
+      case Page.next:
+        _controller.nextPage(
+          curve: curve,
+          duration: duration,
+        );
+    }
+  }
+
+  /// Builds the button that closes this screen.
+  Widget buildCloseButton(BuildContext context) {
+    return Positioned(
+      left: 20,
+      top: 60,
+      child: IconButton(
+        onPressed: () => Navigator.of(context).pop(),
+        icon: Icon(
+          Icons.close,
+          size: 40,
+        ),
+      ),
+    );
+  }
+
+  /// Builds the navigation controls.
+  ///
+  /// Two icon buttons allow the user to navigate to the next or previous page.
+  Widget buildPageNavigation() {
+    return Positioned(
+      bottom: 50,
+      child: FractionallyScreenSizedBox(
+        widthFactor: 1,
+        child: Row(
+          children: <Widget>[
+            Spacer(),
+            IconButton(
+              onPressed: () => animateToPage(Page.previous),
+              icon: Icon(
+                FontAwesomeIcons.caretLeft,
+                size: 40,
+              ),
+            ),
+            Spacer(
+              flex: 8,
+            ),
+            IconButton(
+              onPressed: () => animateToPage(Page.next),
+              icon: Icon(
+                FontAwesomeIcons.caretRight,
+                size: 40,
+              ),
+            ),
+            Spacer(),
+          ],
+        ),
+      ),
+    );
+  }
+
+  /// Builds a placeholder for an image.
+  Widget buildImagePlaceholder() {
+    return Container(
+      color: Colors.black,
+      child: Center(
+        child: LoadingIndicator(),
+      ),
+    );
+  }
+}
+
+enum Page { previous, next }

lib/src/screens/new_image_screen.dart

@@ -12,13 +12,31 @@ import '../widgets/custom_dropdown.dart';
 import '../widgets/fractionally_screen_sized_box.dart';
 import '../widgets/gradient_touchable_container.dart';
 
+/// A screen that prompts the user for an image and uploads it to
+/// firebase storage.
 class NewImageScreen extends StatefulWidget {
+  /// The name of the event to be preselected in the dropdown menu.
+  final String defaultEventName;
+
+  /// Creates a new screen that prompts the user for an image and uploads it to
+  /// firevase storage.
+  NewImageScreen({
+    this.defaultEventName,
+  });
+
   _NewImageScreenState createState() => _NewImageScreenState();
 }
 
 class _NewImageScreenState extends State<NewImageScreen> {
   /// An instance of the bloc for this scree.
-  final NewImageBloc bloc = NewImageBloc();
+  NewImageBloc bloc;
+
+  initState() {
+    bloc = NewImageBloc(
+      defaultEventName: widget.defaultEventName,
+    );
+    super.initState();
+  }
 
   Widget build(BuildContext context) {
     return Scaffold(

lib/src/widgets/async_image.dart

@@ -0,0 +1,66 @@
+import 'dart:async';
+import 'dart:io';
+
+import 'package:flutter/material.dart';
+import 'package:photo_view/photo_view.dart';
+import 'package:rxdart/rxdart.dart';
+
+import './loading_indicator.dart';
+
+/// A widget that shows an image given a cache map and its cache id.
+///
+/// A placeholder is shown while it loads.
+class AsyncImage extends StatelessWidget {
+  /// The id of the image inside the [cacheMap].
+  final String cacheId;
+
+  /// A cache that maps an image path to its file.
+  final Observable<Map<String, Future<File>>> cacheMap;
+
+  /// Creates a widget that shows an image given a cache map and its cache id.
+  ///
+  /// A placeholder is shown while the image loads.
+  AsyncImage({
+    @required this.cacheId,
+    @required this.cacheMap,
+  })  : assert(cacheId != null),
+        assert(cacheMap != null);
+
+  Widget build(BuildContext context) {
+    return StreamBuilder(
+      stream: cacheMap,
+      builder: (BuildContext context,
+          AsyncSnapshot<Map<String, Future<File>>> imagesCacheSnap) {
+        // Wait until the images cache has data.
+        if (!imagesCacheSnap.hasData) {
+          return buildImagePlaceholder();
+        }
+
+        return FutureBuilder(
+          future: imagesCacheSnap.data[cacheId],
+          builder: (BuildContext context, AsyncSnapshot<File> imageFileSnap) {
+            // Wait until the future of the file for this image resolves.
+            if (!imageFileSnap.hasData) {
+              return buildImagePlaceholder();
+            }
+
+            return PhotoView(
+              imageProvider: FileImage(imageFileSnap.data),
+              minScale: .2,
+              maxScale: 2.0,
+            );
+          },
+        );
+      },
+    );
+  }
+
+  Widget buildImagePlaceholder() {
+    return Container(
+      color: Colors.black,
+      child: Center(
+        child: LoadingIndicator(),
+      ),
+    );
+  }
+}

pubspec.yaml

@@ -32,6 +32,7 @@ dependencies:
   image_picker: ^0.5.0+3
   mockito: ^4.0.0
   path_provider: ^0.5.0+1
+  photo_view: 0.2.3
   rxdart: ^0.20.0
   sqflite: ^1.1.0
   uuid: ^2.0.0