Added SelectingItemsControl.AutoSelect.

Perspex.Controls/Primitives/SelectingItemsControl.cs

@@ -22,8 +22,14 @@ namespace Perspex.Controls.Primitives
     /// <remarks>
     /// TODO: Support multiple selection.
     /// </remarks>
-    public abstract class SelectingItemsControl : ItemsControl
+    public class SelectingItemsControl : ItemsControl
     {
+        /// <summary>
+        /// Defines the <see cref="AutoSelect"/> property.
+        /// </summary>
+        public static readonly PerspexProperty<bool> AutoSelectProperty =
+            PerspexProperty.Register<SelectingItemsControl, bool>("AutoSelect");
+
         /// <summary>
         /// Defines the <see cref="SelectedIndex"/> property.
         /// </summary>
@@ -67,6 +73,16 @@ namespace Perspex.Controls.Primitives
             this.ItemContainerGenerator.ContainersInitialized.Subscribe(this.ContainersInitialized);
         }
 
+        /// <summary>
+        /// Gets or sets a value indicating whether the control should always try to keep an item
+        /// selected where possible.
+        /// </summary>
+        public bool AutoSelect
+        {
+            get { return this.GetValue(AutoSelectProperty); }
+            set { this.SetValue(AutoSelectProperty, value); }
+        }
+
         /// <summary>
         /// Gets or sets the index of the selected item.
         /// </summary>
@@ -106,7 +122,14 @@ namespace Perspex.Controls.Primitives
                     if (selectedIndex >= e.OldStartingIndex &&
                         selectedIndex < e.OldStartingIndex + e.OldItems.Count)
                     {
-                        this.SelectedIndex = -1;
+                        if (!this.AutoSelect)
+                        {
+                            this.SelectedIndex = -1;
+                        }
+                        else
+                        {
+                            this.LostSelection();
+                        }
                     }
 
                     break;
@@ -121,7 +144,7 @@ namespace Perspex.Controls.Primitives
         protected override void OnGotFocus(GotFocusEventArgs e)
         {
             base.OnGotFocus(e);
-            this.TrySetSelectionFromContainerEvent(e.Source);
+            this.TrySetSelectionFromContainerEvent(e.Source, true);
         }
 
         /// <summary>
@@ -229,6 +252,10 @@ namespace Perspex.Controls.Primitives
                 var container = containers.Items[selectedIndex - containers.StartingIndex];
                 MarkContainerSelected(container, true);
             }
+            else if (selectedIndex == -1 && this.AutoSelect)
+            {
+                this.SelectedIndex = 0;
+            }
         }
 
         /// <summary>
@@ -237,7 +264,12 @@ namespace Perspex.Controls.Primitives
         /// <param name="e">The event.</param>
         private void ContainerSelectionChanged(RoutedEventArgs e)
         {
-            this.TrySetSelectionFromContainerEvent(e.Source);
+            var selectable = (ISelectable)e.Source;
+
+            if (selectable != null)
+            {
+                this.TrySetSelectionFromContainerEvent(e.Source, selectable.IsSelected);
+            }
         }
 
         /// <summary>
@@ -278,22 +310,64 @@ namespace Perspex.Controls.Primitives
         }
 
         /// <summary>
-        /// Tries to set the selection to a container that raised an event.
+        /// Tries to get the container that was the source of an event.
         /// </summary>
         /// <param name="eventSource">The control that raised the event.</param>
-        private void TrySetSelectionFromContainerEvent(IInteractive eventSource)
+        /// <returns>The container or null if the event did not originate in a container.</returns>
+        private IControl GetContainerFromEvent(IInteractive eventSource)
         {
             var item = ((IVisual)eventSource).GetSelfAndVisualAncestors()
                 .OfType<ILogical>()
                 .FirstOrDefault(x => x.LogicalParent == this);
 
+            return item as IControl;
+        }
+
+        /// <summary>
+        /// Called when the currently selected item is lost and the selection must be changed
+        /// depending on the <see cref="AutoSelect"/> property.
+        /// </summary>
+        private void LostSelection()
+        {
+            var items = this.Items?.Cast<object>();
+
+            if (items != null && this.AutoSelect)
+            {
+                var index = Math.Min(this.SelectedIndex, items.Count() - 1);
+
+                if (index > -1)
+                {
+                    this.SelectedItem = items.ElementAt(index);
+                    return;
+                }
+            }
+
+            this.SelectedIndex = -1;
+        }
+
+        /// <summary>
+        /// Tries to set the selection to a container that raised an event.
+        /// </summary>
+        /// <param name="eventSource">The control that raised the event.</param>
+        /// <param name="select">Whether the container should be selected or unselected.</param>
+        private void TrySetSelectionFromContainerEvent(IInteractive eventSource, bool select)
+        {
+            var item = this.GetContainerFromEvent(eventSource);
+
             if (item != null)
             {
-                var index = this.ItemContainerGenerator.IndexFromContainer((IControl)item);
+                var index = this.ItemContainerGenerator.IndexFromContainer(item);
 
                 if (index != -1)
                 {
-                    this.SelectedIndex = index;
+                    if (select)
+                    {
+                        this.SelectedIndex = index;
+                    }
+                    else
+                    {
+                        this.LostSelection();
+                    }
                 }
             }
         }

Perspex.Controls/Primitives/TabStrip.cs

@@ -18,6 +18,7 @@ namespace Perspex.Controls.Primitives
 
         static TabStrip()
         {
+            AutoSelectProperty.OverrideDefaultValue<TabStrip>(true);
             FocusableProperty.OverrideDefaultValue(typeof(TabStrip), false);
         }
 

Perspex.Controls/TabControl.cs

@@ -30,7 +30,7 @@ namespace Perspex.Controls
 
         static TabControl()
         {
-            FocusableProperty.OverrideDefaultValue(typeof(TabControl), false);
+            FocusableProperty.OverrideDefaultValue<TabControl>(false);
         }
 
         public TabControl()

Tests/Perspex.Controls.UnitTests/Perspex.Controls.UnitTests.csproj

@@ -99,6 +99,7 @@
     <Compile Include="Presenters\ScrollContentPresenterTests.cs" />
     <Compile Include="Primitives\ScrollBarTests.cs" />
     <Compile Include="Primitives\RangeBaseTests.cs" />
+    <Compile Include="Primitives\SelectingItemsControlTests_AutoSelect.cs" />
     <Compile Include="ScrollViewerTests.cs" />
     <Compile Include="Primitives\SelectingItemsControlTests.cs" />
     <Compile Include="ListBoxTests.cs" />
@@ -107,7 +108,7 @@
     <Compile Include="DecoratorTests.cs" />
     <Compile Include="DeckTests.cs" />
     <Compile Include="TopLevelTests.cs" />
-    <Compile Include="TabStripTests.cs" />
+    <Compile Include="Primitives\TabStripTests.cs" />
     <Compile Include="TabControlTests.cs" />
     <Compile Include="PanelTests.cs" />
     <Compile Include="ControlTests.cs" />

Tests/Perspex.Controls.UnitTests/Primitives/SelectingItemsControlTests.cs

@@ -26,7 +26,7 @@ namespace Perspex.Controls.UnitTests.Primitives
                 new Item(),
             };
 
-            var target = new Target
+            var target = new SelectingItemsControl
             {
                 Items = items,
                 Template = this.Template(),
@@ -44,7 +44,7 @@ namespace Perspex.Controls.UnitTests.Primitives
                 new Item(),
             };
 
-            var target = new Target
+            var target = new SelectingItemsControl
             {
                 Items = items,
                 Template = this.Template(),
@@ -65,7 +65,7 @@ namespace Perspex.Controls.UnitTests.Primitives
                 new Item(),
             };
 
-            var target = new Target
+            var target = new SelectingItemsControl
             {
                 Items = items,
                 Template = this.Template(),
@@ -87,7 +87,7 @@ namespace Perspex.Controls.UnitTests.Primitives
                 new Item(),
             };
 
-            var target = new Target
+            var target = new SelectingItemsControl
             {
                 Items = items,
                 Template = this.Template(),
@@ -109,7 +109,7 @@ namespace Perspex.Controls.UnitTests.Primitives
                 new Item(),
             };
 
-            var target = new Target
+            var target = new SelectingItemsControl
             {
                 Items = items,
                 Template = this.Template(),
@@ -131,7 +131,7 @@ namespace Perspex.Controls.UnitTests.Primitives
                 new Item(),
             };
 
-            var target = new Target
+            var target = new SelectingItemsControl
             {
                 Items = items,
                 Template = this.Template(),
@@ -153,7 +153,7 @@ namespace Perspex.Controls.UnitTests.Primitives
                 new Item(),
             };
 
-            var target = new Target
+            var target = new SelectingItemsControl
             {
                 Items = items,
                 Template = this.Template(),
@@ -180,7 +180,7 @@ namespace Perspex.Controls.UnitTests.Primitives
                 new Item(),
             };
 
-            var target = new Target
+            var target = new SelectingItemsControl
             {
                 Items = items,
                 Template = this.Template(),
@@ -201,7 +201,7 @@ namespace Perspex.Controls.UnitTests.Primitives
                 new Item(),
             };
 
-            var target = new Target
+            var target = new SelectingItemsControl
             {
                 Items = items,
                 Template = this.Template(),
@@ -216,7 +216,7 @@ namespace Perspex.Controls.UnitTests.Primitives
         [Fact]
         public void Setting_SelectedItem_To_Non_Existent_Item_Should_Clear_Selection()
         {
-            var target = new Target
+            var target = new SelectingItemsControl
             {
                 Template = this.Template(),
             };
@@ -237,7 +237,7 @@ namespace Perspex.Controls.UnitTests.Primitives
                 new Item(),
             });
 
-            var target = new Target
+            var target = new SelectingItemsControl
             {
                 Items = items,
                 Template = this.Template(),
@@ -259,7 +259,7 @@ namespace Perspex.Controls.UnitTests.Primitives
                 new Item(),
             };
 
-            var target = new Target
+            var target = new SelectingItemsControl
             {
                 Items = items,
                 Template = this.Template(),
@@ -286,7 +286,7 @@ namespace Perspex.Controls.UnitTests.Primitives
                 new Item(),
             };
 
-            var target = new Target
+            var target = new SelectingItemsControl
             {
                 Items = items,
                 Template = this.Template(),
@@ -315,7 +315,7 @@ namespace Perspex.Controls.UnitTests.Primitives
                 new Item(),
             };
 
-            var target = new Target
+            var target = new SelectingItemsControl
             {
                 Items = items,
                 Template = this.Template(),
@@ -336,7 +336,7 @@ namespace Perspex.Controls.UnitTests.Primitives
         [Fact]
         public void Focusing_Item_Should_Select_It()
         {
-            var target = new Target
+            var target = new SelectingItemsControl
             {
                 Template = this.Template(),
                 Items = new[] { "foo", "bar" },
@@ -364,7 +364,7 @@ namespace Perspex.Controls.UnitTests.Primitives
                 new Item(),
             };
 
-            var target = new Target
+            var target = new SelectingItemsControl
             {
                 Items = items,
                 Template = this.Template(),
@@ -379,12 +379,40 @@ namespace Perspex.Controls.UnitTests.Primitives
             items[0].IsSelected = true;
             items[0].RaiseEvent(new RoutedEventArgs(SelectingItemsControl.IsSelectedChangedEvent));
 
-            Assert.Equal(target.SelectedIndex, 0);
-            Assert.Equal(target.SelectedItem, items[0]);
+            Assert.Equal(0, target.SelectedIndex);
+            Assert.Equal(items[0], target.SelectedItem);
             Assert.True(items[0].IsSelected);
             Assert.False(items[1].IsSelected);
         }
 
+        [Fact]
+        public void Clearing_IsSelected_And_Raising_IsSelectedChanged_On_Item_Should_Update_Selection()
+        {
+            var items = new[]
+            {
+                new Item(),
+                new Item(),
+            };
+
+            var target = new SelectingItemsControl
+            {
+                Items = items,
+                Template = this.Template(),
+            };
+
+            target.ApplyTemplate();
+            target.SelectedItem = items[1];
+
+            Assert.False(items[0].IsSelected);
+            Assert.True(items[1].IsSelected);
+
+            items[1].IsSelected = false;
+            items[1].RaiseEvent(new RoutedEventArgs(SelectingItemsControl.IsSelectedChangedEvent));
+
+            Assert.Equal(-1, target.SelectedIndex);
+            Assert.Null(target.SelectedItem);
+        }
+
         [Fact]
         public void Raising_IsSelectedChanged_On_Someone_Elses_Item_Should_Not_Update_Selection()
         {
@@ -394,7 +422,7 @@ namespace Perspex.Controls.UnitTests.Primitives
                 new Item(),
             };
 
-            var target = new Target
+            var target = new SelectingItemsControl
             {
                 Items = items,
                 Template = this.Template(),
@@ -420,7 +448,7 @@ namespace Perspex.Controls.UnitTests.Primitives
 
         private ControlTemplate Template()
         {
-            return new ControlTemplate<Target>(control =>
+            return new ControlTemplate<SelectingItemsControl>(control =>
                 new ItemsPresenter
                 {
                     Name = "itemsPresenter",
@@ -429,10 +457,6 @@ namespace Perspex.Controls.UnitTests.Primitives
                 });
         }
 
-        private class Target : SelectingItemsControl
-        {
-        }
-
         private class Item : Control, ISelectable
         {
             public bool IsSelected { get; set; }

Tests/Perspex.Controls.UnitTests/Primitives/SelectingItemsControlTests_AutoSelect.cs

@@ -0,0 +1,91 @@
+// -----------------------------------------------------------------------
+// <copyright file="SelectingItemsControlTests_AutoSelect.cs" company="Steven Kirk">
+// Copyright 2014 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex.Controls.UnitTests.Primitives
+{
+    using Perspex.Collections;
+    using Perspex.Controls.Presenters;
+    using Perspex.Controls.Primitives;
+    using Perspex.Controls.Templates;
+    using Perspex.Interactivity;
+    using Xunit;
+
+    public class SelectingItemsControlTests_AutoSelect
+    {
+        [Fact]
+        public void First_Item_Should_Be_Selected()
+        {
+            var target = new SelectingItemsControl
+            {
+                AutoSelect = true,
+                Items = new[] { "foo", "bar" },
+                Template = this.Template(),
+            };
+
+            target.ApplyTemplate();
+
+            Assert.Equal(0, target.SelectedIndex);
+            Assert.Equal("foo", target.SelectedItem);
+        }
+
+        [Fact]
+        public void Item_Should_Be_Selected_When_Selection_Removed()
+        {
+            var items = new PerspexList<string>(new[] { "foo", "bar", "baz", "qux" });
+
+            var target = new SelectingItemsControl
+            {
+                AutoSelect = true,
+                Items = items,
+                Template = this.Template(),
+            };
+
+            target.ApplyTemplate();
+            target.SelectedIndex = 2;
+            items.RemoveAt(2);
+
+            Assert.Equal(2, target.SelectedIndex);
+            Assert.Equal("qux", target.SelectedItem);
+        }
+
+        [Fact]
+        public void Selection_Should_Be_Cleared_When_No_Items_Left()
+        {
+            var items = new PerspexList<string>(new[] { "foo", "bar" });
+
+            var target = new SelectingItemsControl
+            {
+                AutoSelect = true,
+                Items = items,
+                Template = this.Template(),
+            };
+
+            target.ApplyTemplate();
+            target.SelectedIndex = 1;
+            items.RemoveAt(1);
+            items.RemoveAt(0);
+
+            Assert.Equal(-1, target.SelectedIndex);
+            Assert.Null(target.SelectedItem);
+        }
+
+        private ControlTemplate Template()
+        {
+            return new ControlTemplate<SelectingItemsControl>(control =>
+                new ItemsPresenter
+                {
+                    Name = "itemsPresenter",
+                    [~ItemsPresenter.ItemsProperty] = control[~ListBox.ItemsProperty],
+                    [~ItemsPresenter.ItemsPanelProperty] = control[~ListBox.ItemsPanelProperty],
+                });
+        }
+
+        private class Item : Control, ISelectable
+        {
+            public bool IsSelected { get; set; }
+        }
+    }
+}

Tests/Perspex.Controls.UnitTests/TabStripTests.cs → Tests/Perspex.Controls.UnitTests/Primitives/TabStripTests.cs

@@ -4,7 +4,7 @@
 // </copyright>
 // -----------------------------------------------------------------------
 
-namespace Perspex.Controls.UnitTests
+namespace Perspex.Controls.UnitTests.Primitives
 {
     using System.Linq;
     using Perspex.Controls.Presenters;