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Visual.AddVisualChild Method

Defines the parent-child relationship between two visuals.

Namespace:  System.Windows.Media
Assembly:  PresentationCore (in PresentationCore.dll)
protected void AddVisualChild(
	Visual child
)

Parameters

child
Type: System.Windows.Media.Visual

The child visual object to add to parent visual.

The AddVisualChild method sets up the parent-child relationship between two visual objects. 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.

NoteNote

Although 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.

// 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;
    }

.NET Framework

Supported in: 4.5.1, 4.5, 4, 3.5, 3.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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