[ADDITION] Added databinding to the chatbox function.

Tried to broadcast the message, doesn't work yet.

Client/Client.cs

@@ -65,7 +65,6 @@ namespace Client
             }
 
             stream.BeginRead(buffer, 0, buffer.Length, new AsyncCallback(OnReadComplete), null);
-
         }
 
         private void handleData(byte[] message)
@@ -84,16 +83,18 @@ namespace Client
                     string textUsername = combo.Item1;
                     string textMsg = combo.Item2;
                     //TODO display username and message in chat window
-
+                    Debug.WriteLine("Message username: {0}\t Message: {1}", textUsername, textMsg);
                     break;
 
                 case JSONConvert.LOBBY:
                     // lobby data
                     //TODO fill lobby with the data received
                     break;
+
                 case JSONConvert.CANVAS:
                     // canvas data
                     break;
+
                 default:
                     Debug.WriteLine("[CLIENT] Received weird identifier: " + id);
                     break;

Client/ViewModels/ViewModelGame.cs

@@ -1,10 +1,69 @@
-using System.Collections.ObjectModel;
+using GalaSoft.MvvmLight.Command;
+using SharedClientServer;
+using System.Collections.ObjectModel;
 using System.ComponentModel;
+using System.Diagnostics;
+using System.Windows.Input;
 
 namespace Client.ViewModels
 {
     class ViewModelGame : INotifyPropertyChanged
     {
+        ClientData data = ClientData.Instance;
         public event PropertyChangedEventHandler PropertyChanged;
+        public ObservableCollection<string> Messages { get; } = new ObservableCollection<string>();
+
+        private dynamic _payload;
+
+        private string _username;
+
+        private string _message;
+        public string Message
+        {
+            get
+            {
+                return _message;
+            }
+            set
+            {
+                _message = value;
+            }
+        }
+        public ICommand OnKeyDown { get; set; }
+
+        public ViewModelGame()
+        {
+            if (_payload == null)
+            {
+                _message = "";
+            }
+            else
+            {
+                _message = _payload.message;
+                _username = _payload.username;
+            }
+            OnKeyDown = new RelayCommand(ChatBox_KeyDown);
+        }
+
+        private void ChatBox_KeyDown()
+        {
+            //if enter then clear textbox and send message.
+            if (Message != string.Empty) AddMessage(Message);
+            Message = string.Empty;
+        }
+
+        internal void AddMessage(string message)
+        {
+            Messages.Add($"{data.User.Username}: {message}");
+
+            _payload = new
+            {
+                username = data.User.Username,
+                message = message
+            };
+
+            //Broadcast the message after adding it to the list!
+            data.Client.SendMessage(JSONConvert.GetMessageToSend(JSONConvert.MESSAGE, _payload));
+        }
     }
 }

Client/Views/GameWindow.xaml

@@ -48,8 +48,13 @@
         </Border>
 
         <Grid Grid.Column="2" Grid.Row="1">
-            <TextBox Name="SentMessage" IsReadOnly="True" Margin="0,0,0,50"/>
-            <TextBox x:Name="ChatBox" Keyboard.KeyDown="ChatBox_KeyDown" Width="200" Height="50" ToolTip="Message goes here" ToolTipService.IsEnabled="True" VerticalAlignment="Bottom" HorizontalAlignment="Left"/>
+            <ListBox Name ="TextBox" ItemsSource="{Binding Path=Messages}" Margin="0,0,0,69"/>
+
+            <TextBox Name="ChatBox" Text="{Binding Message, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Margin="0,465,0,0">
+                <TextBox.InputBindings>
+                    <KeyBinding Key="Return" Command="{Binding OnKeyDown}"/>
+                </TextBox.InputBindings>
+            </TextBox>
         </Grid>
 
     </Grid>

Client/Views/GameWindow.xaml.cs

@@ -18,7 +18,7 @@ namespace Client.Views
     /// </summary>
     public partial class GameWindow : Window
     {
-        ClientData data = ClientData.Instance;
+       
         public GameWindow()
         {
             DataContext = new ViewModelGame();
@@ -82,7 +82,6 @@ namespace Client.Views
             //    var deepCopy = System.Windows.Markup.XamlReader.Parse(xaml) as UIElement;
             //    TEST.Children.Add(deepCopy);
             //}
-
         }
 
         private void ClrPcker_Background_SelectedColorChanged_1(object sender, RoutedPropertyChangedEventArgs<Color?> e)
@@ -95,23 +94,14 @@ namespace Client.Views
             color = colorSelected;
         }
 
-        private void ChatBox_KeyDown(object sender, KeyEventArgs e)
-        {
-            //if enter then clear textbox and send message.
-            if (e.Key.Equals(Key.Enter))
-            {
-                WriteToChat(ChatBox.Text);
-                ChatBox.Clear();
-            }
-        }
-
-        /*
-         * Writes the current client's message to the chatbox.
-         */
-        private void WriteToChat(string message)
-        {
-            string user = data.User.Username; 
-            SentMessage.AppendText($"{user}: {message}\n");
-        }
+        ///*
+        // * Writes the current client's message to the chatbox.
+        // */
+        //private void WriteToChat(string message)
+        //{
+        //    string user = data.User.Username;
+        //    SentMessage.AppendText($"{user}: {message}\n");
+        //    data.User.Message = message;
+        //}
     }
 }

Client/Views/MainWindow.xaml.cs

@@ -32,7 +32,6 @@ namespace Client
 
         private void Button_Click(object sender, RoutedEventArgs e)
         {
-
             Lobby lobbySelected = LobbyList.SelectedItem as Lobby;
             if(lobbySelected != null)
             {

SharedClientServer/ClientServerUtil.cs

@@ -18,6 +18,5 @@ namespace SharedClientServer
             Array.Copy(stringAsBytes, 0, res, 1, stringAsBytes.Length);
             return res;
         }
-
     }
 }

SharedClientServer/User.cs

@@ -9,6 +9,7 @@ namespace SharedClientServer
         private string _username;
         private int _score;
         private bool _host;
+        private string _message;
 
         public User(string username, int score, bool host)
         {