[Gallery] Add version number to About dialog (#260)

* Add version number to About dialog

* Update about.dart

* Address feedback

gallery/gallery/ios/Podfile.lock

@@ -1,5 +1,7 @@
 PODS:
   - Flutter (1.0.0)
+  - package_info (0.0.1):
+    - Flutter
   - shared_preferences (0.0.1):
     - Flutter
   - shared_preferences_macos (0.0.1):
@@ -15,6 +17,7 @@ PODS:
 
 DEPENDENCIES:
   - Flutter (from `Flutter`)
+  - package_info (from `.symlinks/plugins/package_info/ios`)
   - shared_preferences (from `.symlinks/plugins/shared_preferences/ios`)
   - shared_preferences_macos (from `.symlinks/plugins/shared_preferences_macos/ios`)
   - shared_preferences_web (from `.symlinks/plugins/shared_preferences_web/ios`)
@@ -25,6 +28,8 @@ DEPENDENCIES:
 EXTERNAL SOURCES:
   Flutter:
     :path: Flutter
+  package_info:
+    :path: ".symlinks/plugins/package_info/ios"
   shared_preferences:
     :path: ".symlinks/plugins/shared_preferences/ios"
   shared_preferences_macos:
@@ -40,6 +45,7 @@ EXTERNAL SOURCES:
 
 SPEC CHECKSUMS:
   Flutter: 0e3d915762c693b495b44d77113d4970485de6ec
+  package_info: 48b108e75b8802c2d5e126f208ef540561c98aef
   shared_preferences: 430726339841afefe5142b9c1f50cb6bd7793e01
   shared_preferences_macos: f3f29b71ccbb56bf40c9dd6396c9acf15e214087
   shared_preferences_web: 141cce0c3ed1a1c5bf2a0e44f52d31eeb66e5ea9

gallery/gallery/lib/pages/about.dart

@@ -4,6 +4,7 @@
 
 import 'package:flutter/gestures.dart';
 import 'package:flutter/material.dart';
+import 'package:package_info/package_info.dart';
 import 'package:url_launcher/url_launcher.dart';
 
 import 'package:gallery/l10n/gallery_localizations.dart';
@@ -20,6 +21,11 @@ void showAboutDialog({
   );
 }
 
+Future<String> getVersionNumber() async {
+  PackageInfo packageInfo = await PackageInfo.fromPlatform();
+  return packageInfo.version;
+}
+
 class _AboutDialog extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
@@ -47,9 +53,10 @@ class _AboutDialog extends StatelessWidget {
           crossAxisAlignment: CrossAxisAlignment.start,
           mainAxisSize: MainAxisSize.min,
           children: [
-            Center(
-              child: Text(
-                '$name',
+            FutureBuilder(
+              future: getVersionNumber(),
+              builder: (context, snapshot) => Text(
+                snapshot.hasData ? '$name ${snapshot.data}' : '$name',
                 style: textTheme.display1.apply(color: colorScheme.onPrimary),
               ),
             ),

gallery/gallery/pubspec.lock

@@ -238,6 +238,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.1.0"
+  package_info:
+    dependency: "direct main"
+    description:
+      name: package_info
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.4.0+13"
   path:
     dependency: transitive
     description:

gallery/gallery/pubspec.yaml

@@ -25,6 +25,7 @@ dependencies:
   shared_preferences: ^0.5.4+8
   collection: ^1.14.0
   flutter_gallery_assets: 0.1.9+2
+  package_info: ^0.4.0+13
 
 dev_dependencies:
   flutter_test: