/// <summary>
/// Finds the child visuals of the given type based on the supplied filter functon.
/// </summary>
/// <typeparam name="T">The data type of the child visuals to locate.</typeparam>
/// <param name="visual">The visual whose children of a specific type is desired.</param>
/// <param name="filter">A filter to be applied to determine if a child of the requested type shall be accepted. If <c>null</c>, all children of the requested type match.</param>
/// <returns>The child visuals that satisfy the given <paramref name="filter"/>.</returns>
public static IEnumerable <T> FindChildren <T>(this NativeVisual visual, Predicate <T> filter) where T : NativeVisual
{
var children = new List <T>();
var numChildren = visual.GetChildVisualCount();
for (int i = 0; i < numChildren; ++i)
{
var child = visual.GetChildAtIndex <NativeVisual>(i);
var typedChild = child as T;
if ((typedChild != null) && ((filter == null) || filter(typedChild)))
{
children.Add(typedChild);
}
if (child != null)
{
children.AddRange(child.FindChildren <T>(filter));
}
}
return(children);
}
/// <summary>
/// Finds a child visual of the given type, applying a filter.
/// </summary>
/// <typeparam name="T">The data type of the child visual to locate.</typeparam>
/// <param name="visual">The visual whose child of a specific type is desired.</param>
/// <param name="filter">A filter to be applied to determine if a child of the requested type shall be accepted. If <c>null</c>, the first child of the requested type matches.</param>
/// <returns>The first child in the visual tree of the requested type that also satisfies the condition of the filter.</returns>
public static T FindChild <T>(this NativeVisual visual, Predicate <T> filter) where T : NativeVisual
{
var child = default(T);
var numChildren = visual.GetChildVisualCount();
for (int i = 0; (i < numChildren) && (child == null); ++i)
{
var typedChild = visual.GetChildAtIndex <T>(i);
if ((typedChild != null) && ((filter == null) || filter(typedChild)))
{
child = typedChild;
}
}
if (child == null)
{
for (int i = 0; (i < numChildren) && (child == null); ++i)
{
child = FindChild <T>(visual.GetChildAtIndex <NativeVisual>(i), filter);
}
}
return(child);
}