WPF TextBlock binding to a ViewModel using TextBlock extension not working - wpf

Question

I am binding a view model to a TextBlock. The Inlines property is not a DependencyProperty so I made a TextBlockExtensions class and created an attached DependencyProperty called BindableInlines.
Here below is my View Model.
public class MainWindowModel: INotifyPropertyChanged
{
private buttonAddNewTextCommand _btnAddNewTextCommand;
public ObservableCollection<Inline> ProcessTrackerInlines { get; set; }
public ICommand btnAddNewTextCommand
{
get
{
return _btnAddNewTextCommand;
}
}
public event PropertyChangedEventHandler PropertyChanged;
public MainWindowModel()
{
_btnAddNewTextCommand = new buttonAddNewTextCommand(this);
loadProcessTracker();
}
public void addErrorLine(String errorMessage)
{
addText(errorMessage, Brushes.Red, true);
}
public void addNewTextLine()
{
String message = Guid.NewGuid().ToString();
var rand = new Random();
byte[] brushes = new byte[4];
rand.NextBytes(brushes);
ProcessTrackerInlines.Add(new LineBreak());
ProcessTrackerInlines.Add(addText(message, new SolidColorBrush(Color.FromArgb(brushes[0], brushes[1], brushes[2], brushes[3])), true));
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs("ProcessTrackerInlines"));
}
}
private void loadProcessTracker()
{
ProcessTrackerInlines = new ObservableCollection<Inline>();
var rand = new Random();
byte[] brushes = new byte[4];
for(int i=0; i<5; i++)
{
rand.NextBytes(brushes);
ProcessTrackerInlines.Add(addText($"{Guid.NewGuid().ToString()}\r\n", new SolidColorBrush(Color.FromArgb(brushes[0], brushes[1], brushes[2], brushes[3])), true));
}
}
private Run addText(String textToAdd, Brush foreground = null, Boolean? addTime = null)
{
if (addTime ?? false)
{
textToAdd = addCurrentTime(textToAdd);
}
if (foreground != null)
{
return new Run(textToAdd) { Foreground = foreground };
}
else
{
return new Run(textToAdd);
}
}
private String addCurrentTime(String prefixText)
{
return $"[{DateTime.Now.ToString("h:mm ss tt")}] {prefixText}";
}
}
public class buttonAddNewTextCommand : ICommand
{
private MainWindowModel owner;
public buttonAddNewTextCommand(MainWindowModel _object)
{
owner = _object;
}
public Boolean CanExecute(object parameter)
{
return true;
}
public void Execute(object parameter)
{
owner.addNewTextLine();
}
public event EventHandler CanExecuteChanged;
}
My TextBlockExtensions class:
public class TextBlockExtensions
{
public static IEnumerable<Inline> GetBindableInlines(DependencyObject obj)
{
return (IEnumerable<Inline>)obj.GetValue(BindableInlinesProperty);
}
public static void SetBindableInlines(DependencyObject obj, IEnumerable<Inline> value)
{
obj.SetValue(BindableInlinesProperty, value);
}
public static readonly DependencyProperty BindableInlinesProperty =
DependencyProperty.RegisterAttached("BindableInlines", typeof(IEnumerable<Inline>), typeof(TextBlockExtensions), new PropertyMetadata(null, OnBindableInlinesChanged));
private static void OnBindableInlinesChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
var Target = d as TextBlock;
if (Target != null)
{
Target.Inlines.Clear();
Target.Inlines.AddRange((System.Collections.IEnumerable)e.NewValue);
}
}
}
And my XAML:
<Window x:Class="MVVMTextBlock.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:MVVMTextBlock"
xmlns:viewModels="clr-namespace:MVVMTextBlock.ViewModels"
xmlns:extensions="clr-namespace:MVVMTextBlock"
mc:Ignorable="d"
Title="MainWindow" Height="450" Width="800">
<Window.DataContext>
<viewModels:MainWindowModel/>
</Window.DataContext>
<Grid>
<TextBlock extensions:TextBlockExtensions.BindableInlines="{Binding ProcessTrackerInlines, Mode=OneWay}" HorizontalAlignment="Left" TextWrapping="Wrap" VerticalAlignment="Top" Width="578" Margin="25,0,0,0" Height="398"/>
<Button Content="Add New Text" HorizontalAlignment="Left" VerticalAlignment="Top" Width="123" Margin="638,10,0,0" Command="{Binding btnAddNewTextCommand, Mode=OneWay}"/>
</Grid>
</Window>
When the button is clicked the MainWindowModel.addNewTextLine() method is getting hit but the TextBlockExtensions.OnBindableInlinesChanged() is not. So the TextBlock is not getting updated.
I have already changed the BindableInlinesProperty to be an ObservableCollection but it didn't work.
What I am doing wrong?