Issue displaying a ReadOnlyObservableCollection on a canvas

[tomhornyak]

First off, I am a newbie to Avalonia - so be gentle :)
I am using Avalonia 11.3.12

I have a custom control which is composed of several Avalonia controls called "LabeledRtb". I am trying to display a collection of the controls on a grid. Here is a portion of my view model.

`public partial class MainWindowViewModel : ViewModelBase
{
private readonly SourceList _cards = new SourceList();
public readonly ReadOnlyObservableCollection _cardsList;

   public ReadOnlyObservableCollection<LabeledRtb> CardsList => _cardsList;

   public MainWindowViewModel()
   {
		...
_cards
           .Connect()
           .Sort(SortExpressionComparer<LabeledRtb>.Ascending(p => p.TopY))
           .Sort(SortExpressionComparer<LabeledRtb>.Ascending(p => p.LeftX))
           .Bind(out _cardsList)
           .Subscribe();
	}
	
    public void AddCard(LabeledRtb c)
    {
        _cards.Add(c);
    }

`
After calling AddCard, _cards, _cardsList, and CardsList all contain the card. But it is not displayed on the canvas.

Here is the axaml section where I try to display the items.
(For whatever reason , it wouldn't display properly without the blank lines.)

`

<ItemsControl.ItemsPanel>

	<ItemsPanelTemplate>
	
		<Canvas Background="LightGray">
		
		<CardsCanvas>
		
</ItemsPanelTemplate>

</ItemsControl.ItemsPanel>

<ItemsControl.ItemTemplate>

	<DataTemplate x:DataType="local:LabeledRtb">
	
		<local:LabeledRtb/>
		
	</DataTemplate>
	
</ItemsControl.ItemTemplate>

<ItemsControl.Styles>

	<Style Selector="ContentPresenter"x:DataType="local:LabeledRtb">
	
		<Setter Property="Canvas.Left" Value="{Binding LeftX}"/>
		
		<Setter Property="Canvas.Top" Value="{Binding TopY}"/>
		
	</Style>
	
</ItemsControl.Styles>

`

Thanks for reading this.
Any help would be appreciated.

[LaurentInSeattle]

I would first try to use the DevTools to verify the bounds of the UI elements, check positioning of elements and clipping.

See: https://docs.avaloniaui.net/tools/developer-tools/installation

Maybe... the Canvas is just of size zero...