Format seperated into seperate file,

worked on MultiFormatTextBox,
added SendData to SendReceiveViewModel

MultiTerm.Core/Model/MultiFormatString.cs

@@ -0,0 +1,35 @@
+using MultiTerm.Core.Types;
+
+namespace MultiTerm.Core.Model;
+
+public class MultiFormatString
+{
+    public List<Tuple<FormatType, string>> FormatValuePairs { get; private set; } = new();
+
+    public void Add(FormatType format, string value)
+    {
+        // TODO check if value is valid
+        this.FormatValuePairs.Add(Tuple.Create(format, value));
+    }
+
+    public void Remove(int amount)
+    {
+        // guard amount <= 0
+        if (amount <= 0) throw new ArgumentException($"{nameof(amount)} cannot be <= 0");
+
+        // limit amount to maximum
+        int listCount = this.FormatValuePairs.Count;
+        if (amount > listCount)
+        {
+            amount = listCount;
+        }
+
+        // remove range
+        this.FormatValuePairs.RemoveRange( (listCount - amount) , amount);
+    }
+
+    public override string ToString()
+    {
+        throw new NotImplementedException();
+    }
+}

MultiTerm.Core/Types/FormatType.cs

@@ -0,0 +1,19 @@
+namespace MultiTerm.Core.Types;
+
+public enum FormatType
+{
+    /// <summary>
+    /// UTF-16 encoded character
+    /// </summary>
+    Character,
+
+    /// <summary>
+    /// Hex type
+    /// </summary>
+    Hexadecimal,
+
+    /// <summary>
+    /// Binary type
+    /// </summary>
+    Binary
+}

MultiTerm.Core/ViewModel/SendReceiveViewModel.cs

@@ -1,4 +1,6 @@
-using MultiTerm.Core.Types;
+using CommunityToolkit.Mvvm.ComponentModel;
+using MultiTerm.Core.Model;
+using MultiTerm.Core.Types;
 
 namespace MultiTerm.Core.ViewModel;
 
@@ -13,5 +15,9 @@ public partial class SendReceiveViewModel : TerminalViewModel
     }
     public override TerminalViewType ViewType => TerminalViewType.SendReceive;
 
-
+    /// <summary>
+    /// Send data model.
+    /// </summary>
+    [ObservableProperty]
+    private MultiFormatString sendData = new();
 }

MultiTerm.Wpf.CustomControl/MultiFormatTextBox/Format.cs

@@ -0,0 +1,55 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Windows.Input;
+using System.Windows.Media;
+using System.Windows;
+using MultiTerm.Core.Types;
+
+namespace MultiTerm.Wpf.CustomControl;
+
+internal class Format
+{
+    private readonly string? backgroundColorResourceName;
+
+    public string Name { get; set; }
+    public Brush BackgroundBrush { get; set; }
+    public FormatType AssociatedFormatType { get; set; }
+    public Predicate<Key> IsKeyValid { get; set; }
+    public Format(string name, Brush backgroundBrush, FormatType associatedFormatType, Predicate<Key> keyValidator)
+    {
+        this.Name = name;
+        this.BackgroundBrush = backgroundBrush;
+        this.AssociatedFormatType = associatedFormatType;
+        this.IsKeyValid = keyValidator;
+    }
+    public Format(string name, string backgroundColorResourceName, FormatType associatedFormatType, Predicate<Key> keyValidator)
+    {
+        this.Name = name;
+        this.backgroundColorResourceName = backgroundColorResourceName;
+        this.BackgroundBrush = Brushes.White;  // set background brush to white
+        this.AssociatedFormatType = associatedFormatType;
+        this.IsKeyValid = keyValidator;
+    }
+    public static List<string> GetListOfNames(IEnumerable<Format> formats)
+    {
+        return formats.Select(item => item.Name).ToList();
+    }
+    public static void UpdateBackgroundBrushesFromResources(FrameworkElement fwElement, IEnumerable<Format> formats)
+    {
+        if (fwElement == null) throw new ArgumentNullException(nameof(fwElement));
+
+        foreach (var format in formats)
+        {
+            // if resource name not set => skip
+            if (format.backgroundColorResourceName == null) continue;
+
+            // get background brush color from resources
+            try
+            {
+                format.BackgroundBrush = (SolidColorBrush)fwElement.FindResource(format.backgroundColorResourceName);
+            }
+            catch (Exception) { continue; } // ignore 
+        }
+    }
+}

MultiTerm.Wpf.CustomControl/MultiFormatTextBox/MultiFormatTextBox.cs

@@ -1,6 +1,9 @@
-using System;
+using MultiTerm.Core.Model;
+using MultiTerm.Core.Types;
+using System;
 using System.Collections.Generic;
-using System.Drawing;
+using System.ComponentModel;
+using System.Diagnostics;
 using System.Linq;
 using System.Runtime.CompilerServices;
 using System.Windows;
@@ -40,69 +43,55 @@ namespace MultiTerm.Wpf.CustomControl;
 ///     <MyNamespace:MultiFormatTextBox/>
 ///
 /// </summary>
-internal class Format
-{
-    private readonly string? backgroundColorResourceName;
 
-    public string Name { get; set; }
-    public Brush BackgroundBrush { get; set; }
-    public Predicate<Key> IsKeyValid { get; set; }
-    public Format(string name, Brush backgroundBrush, Predicate<Key> keyValidator)
-    {
-        this.Name = name;
-        this.BackgroundBrush = backgroundBrush;
-        this.IsKeyValid = keyValidator;
-    }
-    public Format(string name, string backgroundColorResourceName, Predicate<Key> keyValidator)
-    {
-        this.Name = name;
-        this.backgroundColorResourceName = backgroundColorResourceName;
-        this.BackgroundBrush = Brushes.White;  // set background brush to white
-        this.IsKeyValid = keyValidator;
-    }
-    public static List<string> GetListOfNames(IEnumerable<Format> formats)
-    {
-        return formats.Select(item => item.Name).ToList();
-    }
-    public static void UpdateBackgroundBrushesFromResources(FrameworkElement fwElement, IEnumerable<Format> formats)
-    {
-        if (fwElement == null) throw new ArgumentNullException(nameof(fwElement));
-
-        foreach (var format in formats)
-        {
-            // if resource name not set => skip
-            if (format.backgroundColorResourceName == null) continue;
-
-            // get background brush color from resources
-            try
-            {
-                format.BackgroundBrush = (SolidColorBrush)fwElement.FindResource(format.backgroundColorResourceName);
-            }
-            catch (Exception) { continue; } // ignore 
-        }
-    }
-}
 
 public class MultiFormatTextBox : Control
 {
+    #region static content
     private static readonly Brush defaultBackgroundBrush = Brushes.White;
     private static readonly List<Format> formats = new()
     {
-        // character input, accepts all keys except space
+        // character input, accepts all keys 
-        //new Format("CHAR", Brushes.LightSkyBlue, delegate(Key k) { return (k != Key.Space); }),
+        new Format("CHAR", "MultiFormatTextBox.CHAR.Background", Core.Types.FormatType.Character,
-        new Format("CHAR", "MultiFormatTextBox.CHAR.Background", delegate(Key k) { return (k != Key.Space); }),
+            delegate(Key k) { return true; }),
         // hex input, ignores all keys that are not inbetween 0 and F
-        //new Format("HEX", Brushes.LightGreen, delegate(Key k) { return (k >= Key.D0 && k <= Key.F); }),
+        new Format("HEX", "MultiFormatTextBox.HEX.Background", Core.Types.FormatType.Hexadecimal,
-        new Format("HEX", "MultiFormatTextBox.HEX.Background", delegate(Key k) { return (k >= Key.D0 && k <= Key.F); }),
+            delegate(Key k) { return (k >= Key.D0 && k <= Key.F); }),
         // binary input, ignores all keys except 0 and 1
-        //new Format("BIN", Brushes.LightPink, delegate(Key k) { return (k == Key.D0 || k == Key.D1); })
+        new Format("BIN", "MultiFormatTextBox.BIN.Background", Core.Types.FormatType.Binary,
-        new Format("BIN", "MultiFormatTextBox.BIN.Background", delegate(Key k) { return (k == Key.D0 || k == Key.D1); })
+            delegate(Key k) { return (k == Key.D0 || k == Key.D1); })
     };
 
-    private ComboBox comboBox;
+    #endregion
-    private RichTextBox richTextBox;
+
-    private Format currentlySelectedFormat;
+    #region private content
+    private const string comboBoxTemplateKey = "comboBox";
+    private const string richTextBoxTemplateKey = "richTextBox";
+
+    private ComboBox? comboBox;
+    private RichTextBox? richTextBox;
+    private Format? currentlySelectedFormat;
     private int offsetContentStartToFormatStart;
+    private object lockObj = new();
+
+    #endregion
+
+    #region Dependency Properties
+    public static readonly DependencyProperty CurrentMultiFormatStringProperty =
+        DependencyProperty.Register("CurrentMultiFormatString",
+        typeof(MultiFormatString), typeof(MultiFormatTextBox),
+        new PropertyMetadata(null, OnCurrentMultiFormatStringChanged));
+
+    /// <summary>
+    /// .NET Property for CurrentMultiFormatString.
+    /// </summary>
+    [Bindable(true)]
+    public MultiFormatString CurrentMultiFormatString
+    {
+        get { return (MultiFormatString)GetValue(CurrentMultiFormatStringProperty); }
+        set { SetValue(CurrentMultiFormatStringProperty, value); }
+    }
+    #endregion
 
     static MultiFormatTextBox()
     {
@@ -116,36 +105,53 @@ public class MultiFormatTextBox : Control
         // initialize format background brushes
         Format.UpdateBackgroundBrushesFromResources(this, formats);
         // set initially selected format
-        this.currentlySelectedFormat = formats!.First();
+        this.currentlySelectedFormat = formats.First();
 
 
         // get comboBox from template
-        var comboBox = GetTemplateChild("comboBox") as ComboBox;
+        if (GetTemplateChild(comboBoxTemplateKey) is ComboBox comboBox)
-        if (comboBox != null)
         {
             this.comboBox = comboBox;
             this.comboBox.ItemsSource = Format.GetListOfNames(formats);
             this.comboBox.SelectedItem = currentlySelectedFormat.Name;
             this.comboBox.SelectionChanged += ComboBox_SelectionChanged;
         }
+        else
+        {
+            throw new Exception($"Implementation fault, {comboBoxTemplateKey} not found in template.");
+        }
 
         // get richTextBox from template
-        var richTextBox = GetTemplateChild("richTextBox") as RichTextBox;
+        if (GetTemplateChild(richTextBoxTemplateKey) is RichTextBox richTextBox)
-        if (richTextBox != null)
         {
             this.richTextBox = richTextBox;
+            this.richTextBox.AcceptsReturn = false;
             this.richTextBox.KeyDown += RichTextBox_KeyDown;
             this.richTextBox.TextChanged += RichTextBox_TextChanged;
             this.offsetContentStartToFormatStart = 0;
         }
+        else
+        {
+            throw new Exception($"Implementation fault, {richTextBoxTemplateKey} not found in template.");
+        }
+    }
 
+    private static void OnCurrentMultiFormatStringChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
+    {
+        // extract instance and guard null
+        if (d is not MultiFormatTextBox mftb) { return; }
+
+        // nothing to do
     }
 
 
     private void ComboBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
+    {
+        lock (lockObj) // lock so no richtextbox textchanged event can happen
         {
             // match all formats with the name selected in the combobox
             var matchingFormats = formats.Where(format => format.Name == (string)this.comboBox!.SelectedItem);
+
             // check if exactly one format was matched
             if (matchingFormats.Count() != 1)
             {
@@ -157,49 +163,46 @@ public class MultiFormatTextBox : Control
             // insert space to separate formats
             this.InsertSeparation();
 
-        // set new start position
-        this.StoreCaretPosition();
-
             // focus textbox
-        this.richTextBox.Focus();
+            this.richTextBox!.Focus();
+        }
     }
 
     private void InsertSeparation()
     {
         // disable event handler
-        this.richTextBox.TextChanged -= RichTextBox_TextChanged;
+        this.richTextBox!.TextChanged -= RichTextBox_TextChanged;
-
-        // store caret position before
-        this.StoreCaretPosition();
 
-        // insert
+        // insert separator, manually updating caret position because wpf somehow does not do it....
+        int caretIndexBefore = this.richTextBox.Document.ContentStart.GetOffsetToPosition(this.richTextBox.CaretPosition);
+        Debug.WriteLine($"caret position before inserting separator: offset={this.richTextBox.Document.ContentStart.GetOffsetToPosition(this.richTextBox.CaretPosition)}");
         this.richTextBox.AppendText(" ");
+        this.richTextBox.CaretPosition = this.richTextBox.Document.ContentStart.GetPositionAtOffset(caretIndexBefore + 1);
+        Debug.WriteLine($"caret position after inserting separator: offset={this.richTextBox.Document.ContentStart.GetOffsetToPosition(this.richTextBox.CaretPosition)}");
 
-        // change background
+        // change background of last one character
         RtbChangeTextBackground(this.richTextBox,
-           start: this.richTextBox.Document.ContentStart.GetPositionAtOffset(-this.offsetContentStartToFormatStart),
+           start: this.richTextBox!.Document.ContentStart.GetPositionAtOffset(caretIndexBefore),
-           end: this.richTextBox.Document.ContentEnd,
+           end: this.richTextBox.CaretPosition,
            color: defaultBackgroundBrush);
 
-        // store new caret position after
-        this.StoreCaretPosition();
-
         // reenable
         this.richTextBox.TextChanged += RichTextBox_TextChanged;
     }
 
-    private void StoreCaretPosition()
-    {
-        this.offsetContentStartToFormatStart = this.richTextBox.CaretPosition.GetOffsetToPosition(this.richTextBox.Document.ContentStart);
-    }
-
     private void RichTextBox_KeyDown(object sender, KeyEventArgs e)
     {
         // guard combobox null
         if (this.comboBox == null) throw new Exception($"{nameof(this.comboBox)} cannot be null");
 
         // if key is invalid for this format => ignore it (handled = true)
-        if(this.currentlySelectedFormat.IsKeyValid(e.Key) == false)
+        if (this.currentlySelectedFormat!.IsKeyValid(e.Key) == false)
+        {
+            e.Handled = true;
+        }
+
+        // ignore enter
+        if(e.Key == Key.Enter) 
         { 
             e.Handled = true; 
         }
@@ -207,34 +210,105 @@ public class MultiFormatTextBox : Control
 
     private void RichTextBox_TextChanged(object sender, TextChangedEventArgs e)
     {
-        if (e.Changes.Count > 1 || e.Changes.Count == 0) { return; }
+        // no changes => exit
+        if (e.Changes.Count == 0) return;
+
+        lock (lockObj)  // lock so no concurrent combobox change can happen
+        {
+            foreach (var change in e.Changes)
+            {
+                // print new text
+                Debug.WriteLine($"{nameof(RichTextBox_TextChanged)} changed to '{new TextRange(this.richTextBox!.Document.ContentStart, this.richTextBox.Document.ContentEnd).Text}'");
+                Debug.WriteLine($"{nameof(RichTextBox_TextChanged)} caret position '{this.richTextBox!.Document.ContentStart.GetOffsetToPosition(this.richTextBox.CaretPosition)}'");
+
+                // ignore changes that replace something
+                if (change.RemovedLength == change.AddedLength) continue;
 
                 // if something was added => change background color
-        if (e.Changes.First().AddedLength > 0)
+                if (change.AddedLength > 0)
                 {
-            RtbChangeTextBackground(this.richTextBox,
+                    Debug.WriteLine($"{nameof(RichTextBox_TextChanged)} offset of change = {change.Offset}");
-                start: this.richTextBox.Document.ContentStart.GetPositionAtOffset(-this.offsetContentStartToFormatStart),
+
-                end: this.richTextBox.Document.ContentEnd,
+                    // disable event handler so the update does not trigger any TextChanged events (which it does, interestingly)
-                color: this.currentlySelectedFormat.BackgroundBrush);
+                    this.richTextBox!.TextChanged -= RichTextBox_TextChanged;
+
+                    // update color
+                    RtbChangeTextBackground(this.richTextBox!,
+                        start: this.richTextBox!.Document.ContentStart.GetPositionAtOffset(change.Offset),
+                        end: this.richTextBox!.Document.ContentStart.GetPositionAtOffset(change.Offset + change.AddedLength),
+                        color: this.currentlySelectedFormat!.BackgroundBrush);
+
+                    // reenable event handler
+                    this.richTextBox.TextChanged += RichTextBox_TextChanged;
                 }
-        // if something was removed => update start of content to current location
+            }
-        else if(e.Changes.First().RemovedLength > 0)
+
-        {
+            // update CurrentMultiFormatString
-            this.StoreCaretPosition();
+            this.CurrentMultiFormatString = this.ConvertRtbContentToMultiFormatString(this.richTextBox!);
         }
     }
 
     private static void RtbChangeTextBackground(RichTextBox rtb, TextPointer start, TextPointer end, Brush color)
     {
-        // Get text selection
+        // print offsets to start and end position
-        TextSelection textRange = rtb.Selection;
+        Debug.WriteLine($"Changing background of textbox offset {rtb.Document.ContentStart.GetOffsetToPosition(start)} until {rtb.Document.ContentStart.GetOffsetToPosition(end)} to {color}");
+        
+        // get editable selection
+        var textRange = rtb.Selection;
         textRange.Select(start, end);
 
         // Apply property to the selection:
         textRange.ApplyPropertyValue(TextElement.BackgroundProperty, color);
 
-        // deselect
+        // deselect everything (set to end)
-        rtb.Selection.Select(rtb.Document.ContentEnd, rtb.Document.ContentEnd);
+        rtb.Selection.Select(end, end);
     }
 
+    private MultiFormatString ConvertRtbContentToMultiFormatString(RichTextBox rtb)
+    {
+        MultiFormatString multiFormatString = new();
+        // store current caret position
+        int offsetToCaretPosition = rtb.Document.ContentStart.GetOffsetToPosition(rtb.CaretPosition);
+
+        // get number of symbols
+        var textLength = rtb.Document.ContentStart.GetOffsetToPosition(rtb.Document.ContentEnd);
+        // get full content as TextSelection object
+        var textRange = rtb.Selection;
+
+        // loop through every character
+        for (int offset = 0; offset < textLength; offset++)
+        {
+            // select one character
+            textRange.Select(rtb.Document.ContentStart.GetPositionAtOffset(offset), rtb.Document.ContentStart.GetPositionAtOffset(offset + 1));
+
+            //skip empty textRange
+            if (textRange.IsEmpty)
+            { continue; }
+
+            // extract background brush
+            var brush = (Brush)textRange.GetPropertyValue(TextElement.BackgroundProperty);
+
+            // ignore this symbol, since its a separator
+            if (brush == defaultBackgroundBrush)
+            { continue; } 
+
+            // search if it is a brush of a format
+            foreach (var format in formats)
+            {
+                // format has this background brush => add to string with format and text
+                if (brush == format.BackgroundBrush)
+                {
+                    multiFormatString.Add(format.AssociatedFormatType, textRange.Text);
+                    break;  // end loop
+                }
+            }
+        }
+
+        // deselect everything (set to end)
+        textRange.Select(
+            rtb.Document.ContentStart.GetPositionAtOffset(offsetToCaretPosition),
+            rtb.Document.ContentStart.GetPositionAtOffset(offsetToCaretPosition));
+
+        return multiFormatString;
+    }
 }

MultiTerm.Wpf.CustomControl/MultiTerm.Wpf.CustomControl.csproj

@@ -6,4 +6,8 @@
     <UseWPF>true</UseWPF>
   </PropertyGroup>
 
+  <ItemGroup>
+    <ProjectReference Include="..\MultiTerm.Core\MultiTerm.Core.csproj" />
+  </ItemGroup>
+
 </Project>

MultiTerm.Wpf/View/SendReceiveView.xaml

@@ -39,7 +39,7 @@
                 <DockPanel DockPanel.Dock="Top" LastChildFill="True">
                     <!--<TextBox Width="700"></TextBox>-->
                     <Button DockPanel.Dock="Right" Content="Send"/>
-                    <custom_controls:MultiFormatTextBox DockPanel.Dock="Left"></custom_controls:MultiFormatTextBox>
+                    <custom_controls:MultiFormatTextBox DockPanel.Dock="Left" CurrentMultiFormatString="{Binding SendData}"></custom_controls:MultiFormatTextBox>
                 </DockPanel>
                 <Separator/>
                 <RichTextBox DockPanel.Dock="Bottom">