XAML-Map-Control/MapControl/WinUI/MapPanel.WinUI.cs

#if UWP
using Windows.UI.Xaml;
using Windows.UI.Xaml.Media;
#else
using Microsoft.UI.Xaml;
using Microsoft.UI.Xaml.Media;
#endif

namespace MapControl;

public partial class MapPanel
{
    public static readonly DependencyProperty AutoCollapseProperty =
        DependencyPropertyHelper.RegisterAttached<bool>("AutoCollapse", typeof(MapPanel));

    public static readonly DependencyProperty LocationProperty =
        DependencyPropertyHelper.RegisterAttached<Location>("Location", typeof(MapPanel), null,
            (element, oldValue, newValue) => (element.Parent as MapPanel)?.InvalidateArrange());

    public static readonly DependencyProperty BoundingBoxProperty =
        DependencyPropertyHelper.RegisterAttached<BoundingBox>("BoundingBox", typeof(MapPanel), null,
            (element, oldValue, newValue) => (element.Parent as MapPanel)?.InvalidateArrange());

    public static readonly DependencyProperty MapRectProperty =
        DependencyPropertyHelper.RegisterAttached<Rect?>("MapRect", typeof(MapPanel), null,
            (element, oldValue, newValue) => (element.Parent as MapPanel)?.InvalidateArrange());

    public static void InitMapElement(FrameworkElement element)
    {
        // Workaround for missing property value inheritance.
        // Loaded and Unloaded handlers set and clear the ParentMap property value.
        //
        element.Loaded += (_, _) => GetParentMap(element);
        element.Unloaded += (_, _) => element.ClearValue(ParentMapProperty);
    }

    public static MapBase GetParentMap(FrameworkElement element)
    {
        var parentMap = (MapBase)element.GetValue(ParentMapProperty);

        // Traverse visual tree because of missing property value inheritance.
        //
        if (parentMap == null &&
            VisualTreeHelper.GetParent(element) is FrameworkElement parentElement)
        {
            parentMap = (parentElement as MapBase) ?? GetParentMap(parentElement);

            if (parentMap != null)
            {
                element.SetValue(ParentMapProperty, parentMap);
            }
        }

        return parentMap;
    }
}