Added SelectedItemChanged event

XFBindableStackLayout/Controls/BindableStackLayout.cs

@@ -1,55 +1,134 @@
-using System.Collections;
+using System;
+using System.Collections;
+using System.Windows.Input;
 using Xamarin.Forms;
 
 namespace XFBindableStackLayout
 {
     public class BindableStackLayout : StackLayout
     {
         readonly Label header;
-
         public BindableStackLayout()
         {
             header = new Label();
             Children.Add(header);
+
+            ItemSelectedCommand = new Command<object>(item =>
+            {
+                SelectedItem = item;
+            });
         }
 
+        public event EventHandler<SelectedItemChangedEventArgs> SelectedItemChanged;
+
         public IEnumerable ItemsSource
         {
             get { return (IEnumerable)GetValue(ItemsSourceProperty); }
             set { SetValue(ItemsSourceProperty, value); }
         }
-        public static readonly BindableProperty ItemsSourceProperty =
-            BindableProperty.Create(nameof(ItemsSource), typeof(IEnumerable), typeof(BindableStackLayout),
-                                    propertyChanged: (bindable, oldValue, newValue) => ((BindableStackLayout)bindable).PopulateItems());
+        public static readonly BindableProperty ItemsSourceProperty = BindableProperty.Create(
+            nameof(ItemsSource),
+            typeof(IEnumerable),
+            typeof(BindableStackLayout),
+            propertyChanged: (bindable, oldValue, newValue) => ((BindableStackLayout)bindable).PopulateItems()
+        );
 
         public DataTemplate ItemDataTemplate
         {
             get { return (DataTemplate)GetValue(ItemDataTemplateProperty); }
             set { SetValue(ItemDataTemplateProperty, value); }
         }
-        public static readonly BindableProperty ItemDataTemplateProperty =
-            BindableProperty.Create(nameof(ItemDataTemplate), typeof(DataTemplate), typeof(BindableStackLayout));
+        public static readonly BindableProperty ItemDataTemplateProperty = BindableProperty.Create(
+            nameof(ItemDataTemplate), typeof(DataTemplate), typeof(BindableStackLayout)
+        );
 
         public string Title
         {
             get { return (string)GetValue(TitleProperty); }
             set { SetValue(TitleProperty, value); }
         }
-        public static readonly BindableProperty TitleProperty =
-            BindableProperty.Create(nameof(Title), typeof(string), typeof(BindableStackLayout),
-                                    propertyChanged: (bindable, oldValue, newValue) => ((BindableStackLayout)bindable).PopulateHeader());
+        public static readonly BindableProperty TitleProperty = BindableProperty.Create(
+            nameof(Title), typeof(string),
+            typeof(BindableStackLayout),
+            propertyChanged: (bindable, oldValue, newValue) => ((BindableStackLayout)bindable).PopulateHeader()
+        );
+
+        public object SelectedItem
+        {
+            get { return GetValue(SelectedItemProperty); }
+            set { SetValue(SelectedItemProperty, value); }
+        }
+
+        public static BindableProperty SelectedItemProperty = BindableProperty.Create(
+            propertyName: "SelectedItem",
+            returnType: typeof(object),
+            declaringType: typeof(BindableStackLayout),
+            defaultValue: null,
+            defaultBindingMode: BindingMode.OneWay,
+            propertyChanged: OnSelectedItemChanged
+        );
+
+        private static void OnSelectedItemChanged(BindableObject bindable, object oldValue, object newValue)
+        {
+            var itemsView = (BindableStackLayout)bindable;
+            if (newValue == oldValue)
+                return;
+
+            itemsView.SetSelectedItem(newValue);
+        }
+
+        protected virtual void SetSelectedItem(object selectedItem)
+        {
+            var handler = SelectedItemChanged;
+            if (handler != null)
+                handler(this, new SelectedItemChangedEventArgs(selectedItem));
+        }
 
         void PopulateItems()
         {
             if (ItemsSource == null) return;
             foreach (var item in ItemsSource)
             {
-                var itemTemplate = ItemDataTemplate.CreateContent() as View;
-                itemTemplate.BindingContext = item;
-                Children.Add(itemTemplate);
+                Children.Add(GetItemView(item));
             }
         }
 
         void PopulateHeader() => header.Text = Title;
+
+        protected virtual View GetItemView(object item)
+        {
+            var content = ItemDataTemplate.CreateContent();
+
+            var view = content as View;
+            if (view == null)
+                return null;
+
+            view.BindingContext = item;
+
+            var gesture = new TapGestureRecognizer
+            {
+                Command = ItemSelectedCommand,
+                CommandParameter = item
+            };
+
+            AddGesture(view, gesture);
+
+            return view;
+        }
+
+        protected readonly ICommand ItemSelectedCommand;
+
+        protected void AddGesture(View view, TapGestureRecognizer gesture)
+        {
+            view.GestureRecognizers.Add(gesture);
+
+            var layout = view as Layout<View>;
+
+            if (layout == null)
+                return;
+
+            foreach (var child in layout.Children)
+                AddGesture(child, gesture);
+        }
     }
-}
+}

XFBindableStackLayout/Views/MainPage.xaml

@@ -7,11 +7,12 @@
     <ContentPage.BindingContext>
         <local:MainViewModel />
     </ContentPage.BindingContext>
-    <local:BindableStackLayout
+    <local:BindableStackLayout 
         Title="Colors:"
         ItemsSource="{Binding MyColors}"
         VerticalOptions="Center"
-        HorizontalOptions="Center">
+        HorizontalOptions="Center"
+        SelectedItemChanged="OnSelectedItemChanged">
         <local:BindableStackLayout.ItemDataTemplate>
             <DataTemplate>
                 <StackLayout

XFBindableStackLayout/Views/MainPage.xaml.cs

@@ -13,5 +13,12 @@ public MainPage()
         {
             InitializeComponent();
         }
+
+        public void OnSelectedItemChanged(object sender, SelectedItemChangedEventArgs e)
+        {
+            var selectedItem = (MyColor)e.SelectedItem;
+            System.Diagnostics.Debug.WriteLine(selectedItem.Name);
+
+        }
     }
 }