Range selection in MapItemsControl

MapControl/Avalonia/MapItem.Avalonia.cs

@@ -9,14 +9,12 @@
             DependencyPropertyHelper.AddOwner<MapItem, Location>(MapPanel.LocationProperty, null,
                 (item, oldValue, newValue) => item.UpdateMapTransform(newValue));
 
-        /// <summary>
-        /// Prevent range selection by Shift+PointerPressed.
-        /// </summary>
         protected override void OnPointerPressed(PointerPressedEventArgs e)
         {
             if (e.KeyModifiers.HasFlag(KeyModifiers.Shift))
             {
                 e.Handled = true;
+                MapItemsControl.SetSelectedItemsRange(this);
             }
             else
             {

MapControl/Shared/MapItemsControl.cs

@@ -78,5 +78,42 @@ namespace MapControl
         {
             SelectItemsByPosition(rect.Contains);
         }
+
+        internal static void SetSelectedItemsRange(MapItem mapItem)
+        {
+            if (ItemsControlFromItemContainer(mapItem) is MapItemsControl mapItemsControl &&
+                mapItemsControl.SelectionMode != SelectionMode.Single)
+            {
+                var pos = MapPanel.GetViewPosition(mapItem);
+
+                if (pos.HasValue)
+                {
+                    var xMin = pos.Value.X;
+                    var xMax = pos.Value.X;
+                    var yMin = pos.Value.Y;
+                    var yMax = pos.Value.Y;
+
+                    if (mapItemsControl.SelectedItem != null)
+                    {
+                        var selectedMapItem = mapItemsControl.ContainerFromItem(mapItemsControl.SelectedItem);
+
+                        if (selectedMapItem != mapItem)
+                        {
+                            pos = MapPanel.GetViewPosition(selectedMapItem);
+
+                            if (pos.HasValue)
+                            {
+                                xMin = Math.Min(xMin, pos.Value.X);
+                                xMax = Math.Max(xMax, pos.Value.X);
+                                yMin = Math.Min(yMin, pos.Value.Y);
+                                yMax = Math.Max(yMax, pos.Value.Y);
+                            }
+                        }
+                    }
+
+                    mapItemsControl.SelectItemsInRect(new Rect(xMin, yMin, xMax - xMin, yMax - yMin));
+                }
+            }
+        }
     }
 }

MapControl/WPF/MapItem.WPF.cs

@@ -1,4 +1,5 @@
 using System.Windows;
+using System.Windows.Controls;
 using System.Windows.Input;
 
 namespace MapControl
@@ -17,14 +18,12 @@ namespace MapControl
             DefaultStyleKeyProperty.OverrideMetadata(typeof(MapItem), new FrameworkPropertyMetadata(typeof(MapItem)));
         }
 
-        /// <summary>
-        /// Prevent range selection by Shift+MouseLeftButtonDown.
-        /// </summary>
         protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e)
         {
             if (Keyboard.Modifiers.HasFlag(ModifierKeys.Shift))
             {
                 e.Handled = true;
+                MapItemsControl.SetSelectedItemsRange(this);
             }
             else
             {

MapControl/WinUI/MapItem.WinUI.cs

@@ -31,14 +31,12 @@ namespace MapControl
             MapPanel.InitMapElement(this);
         }
 
-        /// <summary>
-        /// Prevent range selection by Shift+PointerPressed.
-        /// </summary>
         protected override void OnPointerPressed(PointerRoutedEventArgs e)
         {
             if (e.KeyModifiers.HasFlag(VirtualKeyModifiers.Shift))
             {
                 e.Handled = true;
+                MapItemsControl.SetSelectedItemsRange(this);
             }
             else
             {