static IEnumerable <IVisual> HitTest(
IVisual visual,
Point p,
Func <IVisual, bool> filter)
{
Contract.Requires <ArgumentNullException>(visual != null);
if (filter?.Invoke(visual) != false)
{
bool containsPoint = BoundsTracker.GetTransformedBounds((Visual)visual)?.Contains(p) == true;
if ((containsPoint || !visual.ClipToBounds) && visual.VisualChildren.Count > 0)
{
foreach (var child in visual.VisualChildren.SortByZIndex())
{
foreach (var result in HitTest(child, p, filter))
{
yield return(result);
}
}
}
if (containsPoint)
{
yield return(visual);
}
}
}
/// <summary>
/// Returns the active input elements at a point on an <see cref="IInputElement"/>.
/// </summary>
/// <param name="element">The element to test.</param>
/// <param name="p">The point on <paramref name="element"/>.</param>
/// <returns>
/// The active input elements found at the point, ordered topmost first.
/// </returns>
public static IEnumerable <IInputElement> GetInputElementsAt(this IInputElement element, Point p)
{
Contract.Requires <ArgumentNullException>(element != null);
if (element.IsVisible &&
element.IsHitTestVisible &&
element.IsEnabledCore)
{
bool containsPoint = BoundsTracker.GetTransformedBounds((Visual)element).Contains(p);
if ((containsPoint || !element.ClipToBounds) && element.VisualChildren.Any())
{
foreach (var child in ZSort(element.VisualChildren.OfType <IInputElement>()))
{
foreach (var result in child.GetInputElementsAt(p))
{
yield return(result);
}
}
}
if (containsPoint)
{
yield return(element);
}
}
}
/// <summary>
/// Determines whether the specified element is currently visible to the user.
/// </summary>
/// <param name="element">The element.</param>
/// <returns><c>true</c> if if the specified element is currently visible to the user; otherwise, <c>false</c>.</returns>
private static bool IsUserVisible(Control element)
{
return(element.IsEffectivelyVisible && BoundsTracker.GetTransformedBounds(element).HasValue);
}