VisualTreeHelper.GetChild(DependencyObject, Int32) Method

Definition

Namespace:

Windows.UI.Xaml.Media

Using the provided index, obtains a specific child object of the provided object by examining the visual tree.

public:
 static DependencyObject ^ GetChild(DependencyObject ^ reference, int childIndex);

 static DependencyObject GetChild(DependencyObject const& reference, int const& childIndex);

public static DependencyObject GetChild(DependencyObject reference, int childIndex);

function getChild(reference, childIndex)

Public Shared Function GetChild (reference As DependencyObject, childIndex As Integer) As DependencyObject

Parameters

reference

DependencyObject

The object that holds the child collection.

childIndex

Int32

int

The index of the requested child object in the reference child collection.

Returns

DependencyObject

The child object as referenced by childIndex.

Examples

Here's an example of a utility function that can copy a list of child elements of a particular type from within a visual tree. It uses the basic traversal methods GetChildrenCount and GetChild. It uses recursion so that elements can be found no matter what level of nesting within intermediate containers exists. It also uses an IsSubclassOf extension method from System.Reflection that extends the type comparison to consider subtypes as a match for a Type.

internal static void FindChildren<T>(List<T> results, DependencyObject startNode)
  where T : DependencyObject
{
    int count = VisualTreeHelper.GetChildrenCount(startNode);
    for (int i = 0; i < count; i++)
    {
        DependencyObject current = VisualTreeHelper.GetChild(startNode, i);
        if ((current.GetType()).Equals(typeof(T)) || (current.GetType().GetTypeInfo().IsSubclassOf(typeof(T))))
        {
            T asType = (T)current;
            results.Add(asType);
        }
        FindChildren<T>(results, current);
    }
}