How do I clear the visuals from a class derived from canvas?

See more:

WPF

controls

Canvas

Following an example from 'Pro WPF in C# 2008' by Matthew Macdonald, I have implemented a custom version of a Canvas (relevant code shown below).

The AddVisual() and RemoveVisual() methods have no effect on the values I print out from the base Canvas class, and so I am wondering what collections are modified by Canvas.AddVisualChild(), Canvas.AddLogicalChild(), Canvas.RemoveVisualChild() and Canvas.RemoveLogicalChild().

The main point of why I am asking is that I want to be able to 'reset' my custom canvas - i.e. I want to remove all Visual instances from it and start from scratch. I can call _visuals.Clear() to clear my custom list but what do I need to do in the base class?

Any help would be appreciated.

public class MyCanvas : Canvas
{
	public void AddVisual( Visual visual )
	{
		_visuals.Add( visual );
		base.AddVisualChild( visual );
		base.AddLogicalChild( visual );
		Console.WriteLine( $"_visuals.Count={_visuals.Count}" );
		Console.WriteLine( $"base.Children.Count={base.Children.Count}" );
		Console.WriteLine( $"base.VisualChildrenCount={base.VisualChildrenCount}" );
	}

	public void RemoveVisual( Visual visual )
	{
		_visuals.Remove( visual );
		base.RemoveVisualChild( visual );
		base.RemoveLogicalChild( visual );
		Console.WriteLine( $"_visuals.Count={_visuals.Count}" );
		Console.WriteLine( $"base.Children.Count={base.Children.Count}" );
		Console.WriteLine( $"base.VisualChildrenCount={base.VisualChildrenCount}" );
	}

	public void ClearAll()
	{
		_visuals.Clear();
		// WHAT GOES HERE?
	}
		
	protected override int VisualChildrenCount { get { return _visuals.Count; } }

	protected override Visual GetVisualChild( int index ) { return _visuals[ index ]; }

	private List<Visual> _visuals = new List<Visual>();
}

What I have tried:

I have tried searching articles on AddLogicalChild() and AddVisualChild(), but nowhere can I get an explanation of what collections these functions manipulate and how to 'reset' them.