CheckComboBox: Add setter for SelectedItems

Elwig/Controls/CheckComboBox.cs

@@ -1,10 +1,19 @@
-using System.Linq;
+using System.Collections;
+using System.Collections.ObjectModel;
+using System.Collections.Specialized;
+using System.Linq;
 using System.Windows;
 using System.Windows.Controls;
 
 namespace Elwig.Controls {
     public class CheckComboBox : ListBox {
 
+        public new static readonly DependencyProperty SelectedItemsProperty = DependencyProperty.Register(nameof(SelectedItems), typeof(IList), typeof(CheckComboBox), new FrameworkPropertyMetadata(new ObservableCollection<object>(), FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, OnSelectedItemsChangedCallback));
+        public new IList SelectedItems {
+            get => (IList)GetValue(SelectedItemsProperty);
+            set => SetValue(SelectedItemsProperty, value);
+        }
+
         public static readonly DependencyProperty DelimiterProperty = DependencyProperty.Register(nameof(Delimiter), typeof(string), typeof(CheckComboBox), new FrameworkPropertyMetadata(", "));
         public string Delimiter {
             get => (string)GetValue(DelimiterProperty);
@@ -47,27 +56,50 @@ namespace Elwig.Controls {
             set => SetValue(MaxDropDownHeightProperty, value);
         }
 
+        public new static readonly RoutedEvent SelectionChangedEvent = EventManager.RegisterRoutedEvent(nameof(SelectionChanged), RoutingStrategy.Bubble, typeof(SelectionChangedEventHandler), typeof(CheckComboBox));
+        public new event SelectionChangedEventHandler SelectionChanged {
+            add => AddHandler(SelectionChangedEvent, value);
+            remove => RemoveHandler(SelectionChangedEvent, value);
+        }
+
         static CheckComboBox() {
             DefaultStyleKeyProperty.OverrideMetadata(typeof(CheckComboBox), new FrameworkPropertyMetadata(typeof(CheckComboBox)));
         }
 
-        private TextBlock TextBox;
+        private bool _viewHandled;
+        private bool _modelHandled;
+        private TextBlock _textBox;
 
         public CheckComboBox() {
             SelectionMode = SelectionMode.Multiple;
         }
 
         public override void OnApplyTemplate() {
-            TextBox = (GetTemplateChild("TextBox") as TextBlock)!;
+            _textBox = (GetTemplateChild("TextBox") as TextBlock)!;
             var button = GetTemplateChild("Button") as Button;
             button!.Click += Button_MouseDown;
             var item = GetTemplateChild("SelectAllItem") as ListBoxItem;
             item!.PreviewMouseDown += SelectAllItem_MouseDown;
-            SelectionChanged += OnSelectionChanged;
+            if (SelectedItems is INotifyCollectionChanged collection) {
+                collection.CollectionChanged += (s, e) => { SelectItems(); };
+            }
             IsEnabledChanged += OnIsEnabledChanged;
+            base.SelectionChanged += OnSelectionChanged;
             base.OnApplyTemplate();
         }
 
+        private static void OnSelectedItemsChangedCallback(DependencyObject sender, DependencyPropertyChangedEventArgs e) {
+            if (sender is CheckComboBox ccb)
+                ccb.OnSelectedItemsChanged();
+        }
+
+        private void OnSelectedItemsChanged() {
+            if (SelectedItems is INotifyCollectionChanged collection) {
+                collection.CollectionChanged += (s, e) => { SelectItems(); };
+            }
+            SelectItems();
+        }
+
         private void Button_MouseDown(object sender, RoutedEventArgs evt) {
             IsDropDownOpen = !IsDropDownOpen;
         }
@@ -82,25 +114,47 @@ namespace Elwig.Controls {
         }
 
         private void OnSelectionChanged(object sender, SelectionChangedEventArgs evt) {
+            SelectItemsReverse();
             var dmp = DisplayMemberPath != null && DisplayMemberPath != "" ? DisplayMemberPath : null;
             if (SelectedItems.Count == ItemsSource.Cast<object>().Count() && AllItemsSelectedContent != null) {
-                TextBox.Text = AllItemsSelectedContent;
+                _textBox.Text = AllItemsSelectedContent;
                 AllItemsSelected = true;
             } else if (SelectedItems.Count == 0) {
-                TextBox.Text = "";
+                _textBox.Text = "";
                 AllItemsSelected = false;
             } else {
-                TextBox.Text = string.Join(Delimiter,
+                _textBox.Text = string.Join(Delimiter,
                     dmp == null ? SelectedItems.Cast<object>() :
                     SelectedItems.Cast<object>()
                         .Select(i => i.GetType().GetProperty(dmp)?.GetValue(i))
                 );
                 AllItemsSelected = null;
             }
+            RaiseEvent(new SelectionChangedEventArgs(SelectionChangedEvent, evt.RemovedItems, evt.AddedItems));
         }
 
         private void OnIsEnabledChanged(object sender, DependencyPropertyChangedEventArgs evt) {
             if (!IsEnabled) IsDropDownOpen = false;
         }
+
+        private void SelectItems() {
+            if (_viewHandled || _modelHandled)
+                return;
+            _viewHandled = true;
+            base.SelectedItems.Clear();
+            foreach (var item in SelectedItems)
+                base.SelectedItems.Add(item);
+            _viewHandled = false;
+        }
+
+        private void SelectItemsReverse() {
+            if (_modelHandled || _viewHandled)
+                return;
+            _modelHandled = true;
+            SelectedItems.Clear();
+            foreach (var item in base.SelectedItems)
+                SelectedItems.Add(item);
+            _modelHandled = false;
+        }
     }
 }