KeyEditor: Do not let Next work until valid values are provided

lib/setup/key_editors.dart

@@ -1,13 +1,13 @@
 import 'package:flutter/material.dart';
 
 class PublicKeyEditor extends StatelessWidget {
-  final TextEditingController controller;
+  final Function valueChanged;
 
-  PublicKeyEditor(this.controller);
+  PublicKeyEditor(this.valueChanged);
 
   @override
   Widget build(BuildContext context) {
-    return KeyEditor(controller, _validator);
+    return KeyEditor(valueChanged, _validator);
   }
 
   String _validator(String val) {
@@ -19,13 +19,13 @@ class PublicKeyEditor extends StatelessWidget {
 }
 
 class PrivateKeyEditor extends StatelessWidget {
-  final TextEditingController controller;
+  final Function valueChanged;
 
-  PrivateKeyEditor(this.controller);
+  PrivateKeyEditor(this.valueChanged);
 
   @override
   Widget build(BuildContext context) {
-    return KeyEditor(controller, _validator);
+    return KeyEditor(valueChanged, _validator);
   }
 
   String _validator(String val) {
@@ -40,13 +40,33 @@ class PrivateKeyEditor extends StatelessWidget {
 }
 
 class KeyEditor extends StatelessWidget {
-  final TextEditingController controller;
+  final Function valueChanged;
   final Function validator;
 
-  KeyEditor(this.controller, this.validator);
+  KeyEditor(this.valueChanged, this.validator);
 
   @override
   Widget build(BuildContext context) {
+    var form = Form(
+      child: Builder(builder: (context) {
+        return TextFormField(
+          textAlign: TextAlign.left,
+          maxLines: null,
+          style: Theme.of(context).textTheme.body1,
+          autovalidate: true,
+          validator: validator,
+          onChanged: (String newVal) {
+            if (Form.of(context).validate()) {
+              valueChanged(newVal);
+            } else {
+              valueChanged("");
+            }
+          },
+        );
+      }),
+      autovalidate: true,
+    );
+
     return SizedBox(
       width: double.infinity,
       height: 80.0,
@@ -55,14 +75,7 @@ class KeyEditor extends StatelessWidget {
         child: SingleChildScrollView(
           child: Container(
             padding: const EdgeInsets.all(8.0),
-            child: TextFormField(
+            child: form,
-              controller: controller,
-              textAlign: TextAlign.left,
-              maxLines: null,
-              style: Theme.of(context).textTheme.body1,
-              autovalidate: true,
-              validator: validator,
-            ),
           ),
         ),
       ),

lib/setup/sshkey.dart

@@ -207,11 +207,14 @@ class GitHostUserProvidedKeys extends StatefulWidget {
 }
 
 class _GitHostUserProvidedKeysState extends State<GitHostUserProvidedKeys> {
+  String publicKey = "";
+  String privateKey = "";
   final _publicKeyController = TextEditingController();
   final _privateKeyController = TextEditingController();
 
   @override
   Widget build(BuildContext context) {
+    var nextEnabled = publicKey.isNotEmpty && privateKey.isNotEmpty;
     return Container(
       child: Column(
         children: <Widget>[
@@ -220,18 +223,30 @@ class _GitHostUserProvidedKeysState extends State<GitHostUserProvidedKeys> {
             style: Theme.of(context).textTheme.headline,
           ),
           const SizedBox(height: 8.0),
-          PublicKeyEditor(_publicKeyController),
+          PublicKeyEditor((String newVal) {
+            setState(() {
+              publicKey = newVal;
+            });
+          }),
           const SizedBox(height: 8.0),
           Text(
             "Private Key -",
             style: Theme.of(context).textTheme.headline,
           ),
           const SizedBox(height: 8.0),
-          PrivateKeyEditor(_privateKeyController),
+          PrivateKeyEditor((String newVal) {
+            setState(() {
+              privateKey = newVal;
+            });
+          }),
           const SizedBox(height: 16.0),
           GitHostSetupButton(
             text: "Next",
             onPressed: () {
+              if (!nextEnabled) {
+                return;
+              }
+
               var publicKey = _publicKeyController.text.trim();
               var privateKey = _privateKeyController.text.trim();
               widget.doneFunction(publicKey, privateKey);