feat: Display version number in app

lib/utils/platform_infos.dart

@@ -1,6 +1,12 @@
 import 'dart:io';
 
 import 'package:flutter/foundation.dart';
+import 'package:flutter/material.dart';
+import 'package:package_info/package_info.dart';
+import 'package:url_launcher/url_launcher.dart';
+import 'package:flutter_gen/gen_l10n/l10n.dart';
+
+import '../app_config.dart';
 
 abstract class PlatformInfos {
   static bool get isWeb => kIsWeb;
@@ -18,4 +24,32 @@ abstract class PlatformInfos {
       !kIsWeb && (Platform.isLinux || Platform.isWindows || Platform.isMacOS);
 
   static bool get usesTouchscreen => !isMobile;
+
+  static Future<String> getVersion() async {
+    var version = kIsWeb ? 'Web' : 'Unknown';
+    try {
+      version = (await PackageInfo.fromPlatform()).version;
+    } catch (_) {}
+    return version;
+  }
+
+  static void showDialog(BuildContext context) async {
+    var version = await PlatformInfos.getVersion();
+    showAboutDialog(
+      context: context,
+      children: [
+        Text('Version: $version'),
+        RaisedButton(
+          child: Text(L10n.of(context).sourceCode),
+          onPressed: () => launch(AppConfig.sourceCodeUrl),
+        ),
+        RaisedButton(
+          child: Text(L10n.of(context).help),
+          onPressed: () => launch(AppConfig.supportUrl),
+        ),
+      ],
+      applicationIcon: Image.asset('assets/logo.png', width: 100, height: 100),
+      applicationName: AppConfig.applicationName,
+    );
+  }
 }