XAML-Map-Control/MapControl/Shared/MapPolyline.cs

// XAML Map Control - https://github.com/ClemensFischer/XAML-Map-Control
// © 2017 Clemens Fischer
// Licensed under the Microsoft Public License (Ms-PL)

using System.Collections.Generic;
using System.Collections.Specialized;
#if WINDOWS_UWP
using Windows.UI.Xaml;
using Windows.UI.Xaml.Media;
#else
using System.Windows;
using System.Windows.Media;
#endif

namespace MapControl
{
    /// <summary>
    /// A polyline or polygon created from a collection of Locations.
    /// </summary>
    public partial class MapPolyline : MapPath
    {
        public static readonly DependencyProperty LocationsProperty = DependencyProperty.Register(
            nameof(Locations), typeof(IEnumerable<Location>), typeof(MapPolyline),
            new PropertyMetadata(null, (o, e) => ((MapPolyline)o).LocationsPropertyChanged(e)));

        public static readonly DependencyProperty IsClosedProperty = DependencyProperty.Register(
            nameof(IsClosed), typeof(bool), typeof(MapPolyline),
            new PropertyMetadata(false, (o, e) => ((MapPolyline)o).UpdateData()));

        /// <summary>
        /// Gets or sets a value that indicates if the polyline is closed, i.e. is a polygon.
        /// </summary>
        public bool IsClosed
        {
            get { return (bool)GetValue(IsClosedProperty); }
            set { SetValue(IsClosedProperty, value); }
        }

        /// <summary>
        /// Gets or sets the FillRule of the PathGeometry that represents the polyline.
        /// </summary>
        public FillRule FillRule
        {
            get { return (FillRule)GetValue(FillRuleProperty); }
            set { SetValue(FillRuleProperty, value); }
        }

        private void LocationsPropertyChanged(DependencyPropertyChangedEventArgs e)
        {
            var oldCollection = e.OldValue as INotifyCollectionChanged;
            var newCollection = e.NewValue as INotifyCollectionChanged;

            if (oldCollection != null)
            {
                oldCollection.CollectionChanged -= LocationCollectionChanged;
            }

            if (newCollection != null)
            {
                newCollection.CollectionChanged += LocationCollectionChanged;
            }

            UpdateData();
        }

        private void LocationCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
        {
            UpdateData();
        }
    }
}