Telerik RadSyntaxEditor does not load or highlight text

Question

I am Trying to use the new RadSyntaxEditor from Telerik by following this guide.

This is the code I created:

    private RadSyntaxEditor _syntaxEditor;

    public RadSyntaxEditor SyntaxEditor
    {
        get => _syntaxEditor;
        set
        {
            if (Equals(value, _syntaxEditor)) return;
            _syntaxEditor = value;
            OnPropertyChanged();
        }
    }

    public CodeEditorViewModel()
    {
        SyntaxEditor = new RadSyntaxEditor();

    }

    public void Test()
    {
        using (StreamReader reader = new StreamReader("../../ViewModels/ShellViewModel.cs", Encoding.UTF8))
        {
            SyntaxEditor.Document = new TextDocument(reader);
        }
        var cSharpTagger = new CSharpTagger(SyntaxEditor);
        SyntaxEditor.TaggersRegistry.RegisterTagger(cSharpTagger);
    }

my xaml file:

<UserControl x:Class="CodeEditorControl.Views.CodeEditorView"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation"
             mc:Ignorable="d" >
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="auto"/>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
        <Button x:Name="Test" Grid.Row="0">Test</Button>
        <telerik:RadSyntaxEditor  x:Name="SyntaxEditor"  Grid.Row="1"/>
    </Grid>
</UserControl>

The control is showing without a problem and is responding to input etc. But neihter does the document load, nor is there any syntax highlighting. The Reader loads correct and ReadToEnd() outputs the correct text (ShellViewModel is just a standard cs file with 36 lines).

I am using caliburn.micro and the MVVM design.

Edit: I set up a project with the same template but using code behind instead of binding. This works as intended. So the problem lies within the binding from caliburn.micro and telerik.

Any help is appreciated.

Answer 1

I've noticed that the property in CodeEditorViewModel is of type RadSyntaxEditor and the corresponding UI element is also RadSytanxEditor. Note that this produces a binding error in the Output pane of Visual Studio. I think that the Caliburn.Micro binding engine cannot create this type of relation and currently there are two separate instances of RadSyntaxEditor. The one defined in XAML and the other one defined in the view model. The document is loaded to the one defined in code, but because it is never used in the UI, there is nothing in the application.

To resolve this you can research the Caliburn.Micro framework and more specifically, how to use the naming conventions to data bind the model property to a corresponding property of the UI element. I think the current binding (via the convention) defaults to the Visibility property of RadSyntaxEditor.

Or you can simply use an explicit data binding like this:

<Button x:Name="Test" Grid.Row="0">Test</Button>
<ContentControl  Content="{Binding SyntaxEditor}" Grid.Row="1"/>

Note that I've replaced the RadSyntaxEditor control with a ContentControl.