Improved login page

lib/ui/routes/login_route.dart

@@ -19,6 +19,7 @@ class _LoginRouteState extends State<LoginRoute> {
   String _currEmail;
   String _currPassword;
   AuthResult _authResult;
+  bool _loading = false;
 
   @override
   void initState() {
@@ -41,6 +42,10 @@ class _LoginRouteState extends State<LoginRoute> {
 
   /// Call this whenever the user request to perform login
   Future<void> _submitForm(BuildContext context) async {
+    setState(() {
+      _loading = true;
+    });
+
     final loginResult = await AccountHelper().signIn(
         AuthenticationDetails(email: _currEmail, password: _currPassword));
 
@@ -50,19 +55,21 @@ class _LoginRouteState extends State<LoginRoute> {
     else
       setState(() {
         _authResult = loginResult;
+        _loading = false;
       });
   }
 
   // Build error card
   Widget _buildErrorCard() {
-    if (_authResult == null)
-      return null;
+    if (_authResult == null) return null;
 
     //Determine the right message
-    final message = (_authResult == AuthResult.INVALID_CREDENTIALS ? tr(
-        "Invalid credentials!") : (_authResult == AuthResult.TOO_MANY_ATTEMPTS
-        ? tr("Too many unsuccessfull login attempts! Please try again later...")
-        : tr("A network error occured!")));
+    final message = (_authResult == AuthResult.INVALID_CREDENTIALS
+        ? tr("Invalid credentials!")
+        : (_authResult == AuthResult.TOO_MANY_ATTEMPTS
+            ? tr(
+                "Too many unsuccessfull login attempts! Please try again later...")
+            : tr("A network error occured!")));
 
     return buildErrorCard(message);
   }
@@ -100,11 +107,14 @@ class _LoginRouteState extends State<LoginRoute> {
               onChanged: _passwordChanged,
             ),
 
-            RaisedButton(
-              child: Text(tr("Sign in")),
-              onPressed: !validateEmail(_currEmail) || _currPassword.length < 3
-                  ? null
-                  : () => _submitForm(context),
+            Container(
+              padding: EdgeInsets.all(8.0),
+              child: _loading ? CircularProgressIndicator() : RaisedButton(
+                child: Text(tr("Sign in")),
+                onPressed: !validateEmail(_currEmail) || _currPassword.length < 3
+                    ? null
+                    : () => _submitForm(context),
+              ),
             )
           ],
         ),

lib/utils/ui_utils.dart

@@ -2,12 +2,18 @@ import 'package:flutter/material.dart';
 
 /// User interface utilities
 
+/// Build centered progress bar
+Widget buildCenteredProgressBar() {
+  return Center(
+    child: CircularProgressIndicator(),
+  );
+}
+
+
 /// Build and return a full loading page
 Widget buildLoadingPage() {
   return Scaffold(
-    body: Center(
-      child: CircularProgressIndicator(),
-    ),
+    body: buildCenteredProgressBar(),
   );
 }