FrameworkElement.VisualChildrenCount Property
Definition
Important
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Gets the number of visual child elements within this element.
protected:
virtual property int VisualChildrenCount { int get(); };protected override int VisualChildrenCount { get; }member this.VisualChildrenCount : intProtected Overrides ReadOnly Property VisualChildrenCount As IntegerProperty Value
The number of visual child elements for this element.
Examples
The following example shows how a custom adorner uses the values declared by a VisualCollection that it maintains for its multiple visual children and reports these values through overrides of VisualChildrenCount and GetVisualChild.
// To store and manage the adorner's visual children.
VisualCollection visualChildren;
' To store and manage the adorner's visual children.
Private visualChildren As VisualCollection
// Override the VisualChildrenCount and GetVisualChild properties to interface with
// the adorner's visual collection.
protected override int VisualChildrenCount { get { return visualChildren.Count; } }
protected override Visual GetVisualChild(int index) { return visualChildren[index]; }
' Override the VisualChildrenCount and GetVisualChild properties to interface with
' the adorner's visual collection.
Protected Overrides ReadOnly Property VisualChildrenCount() As Integer
Get
Return visualChildren.Count
End Get
End Property
Protected Overrides Function GetVisualChild(ByVal index As Integer) As Visual
Return visualChildren(index)
End Function
Remarks
The FrameworkElement implementation of VisualChildrenCount always returns either zero or one. Classes that maintain a visual child collection that might exceed one must override both this property and GetVisualChild.
This property is generally used to determine the upper bounds of the current child collection for purposes of implementing the layout overrides (MeasureOverride, ArrangeOverride).
Notes to Inheritors
If your class supports more than one visual child in a child element collection, override this property to return the count of elements in that collection. You must do this even if the collection object itself returns a count. Element layout logic at the WPF framework level presumes that all elements will return a valid count through their VisualChildrenCount property.
