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Visual.AddVisualChild Method

Sets up the parent-child relationship between two visuals.

Namespace: System.Windows.Media
Assembly: PresentationCore (in presentationcore.dll)

protected void AddVisualChild (
	Visual child
)
protected void AddVisualChild (
	Visual child
)
protected function AddVisualChild (
	child : Visual
)
You cannot use methods in XAML.

Parameters

child

The child visual object to add to parent visual.

The AddVisualChild method sets up the parent-child relationship between two visuals. This method must be used when you need greater low-level control over the underlying storage implementation of visual child objects. VisualCollection can be used as a default implementation for storing child objects.

The following example shows how to define custom storage requirements for a visual child. The example uses the AddVisualChild and RemoveVisualChild methods to sets up the parent-child relationship between the parent visual and child. In order for the visual tree to be enumerated correctly, the example provides overridden implementations of the GetVisualChild method and VisualChildrenCount property.

// Create a host visual derived from the FrameworkElement class.
// This class provides layout, event handling, and container support for
// the child visual object.
public class MyVisualHost : FrameworkElement
{
    private DrawingVisual _child;

    public MyVisualHost(DrawingVisual drawingVisual)
    {
        _child = drawingVisual;
        this.AddVisualChild(_child);
    }

    public DrawingVisual Child
    {
        get
        {
            return _child;
        }

        set
        {
            if (_child != value)
            {
                this.RemoveVisualChild(_child);
                _child = value;
                this.AddVisualChild(_child);
            }
        }
    }

    // Provide a required override for the VisualChildrenCount property.
    protected override int VisualChildrenCount
    {
        get { return _child == null ? 0 : 1; }
    }

    // Provide a required override for the GetVisualChild method.
    protected override Visual GetVisualChild(int index)
    {
        if (_child == null)
        {
            throw new ArgumentOutOfRangeException();
        }

        return _child;
    }

NoteNote:

While it is possible to use VisualCollection to create parent-child relationships between visual objects, it is more efficient to provide your own custom storage implementation when only one child is linked to a parent.

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0
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