Merge pull request #712 from AvaloniaUI/fixes/706-dropdown-memory-leak

Memory leak fixes

src/Avalonia.Controls/Primitives/Popup.cs

@@ -68,6 +68,7 @@ namespace Avalonia.Controls.Primitives
         private PopupRoot _popupRoot;
         private TopLevel _topLevel;
         private IDisposable _nonClientListener;
+        bool _ignoreIsOpenChanged = false;
 
         /// <summary>
         /// Initializes static members of the <see cref="Popup"/> class.
@@ -220,7 +221,11 @@ namespace Avalonia.Controls.Primitives
             PopupRootCreated?.Invoke(this, EventArgs.Empty);
 
             _popupRoot.Show();
+
+            _ignoreIsOpenChanged = true;
             IsOpen = true;
+            _ignoreIsOpenChanged = false;
+
             Opened?.Invoke(this, EventArgs.Empty);
         }
 
@@ -268,8 +273,13 @@ namespace Avalonia.Controls.Primitives
         {
             base.OnDetachedFromLogicalTree(e);
             _topLevel = null;
-            _popupRoot?.Dispose();
-            _popupRoot = null;
+            
+            if (_popupRoot != null)
+            {
+                ((ISetLogicalParent)_popupRoot).SetParent(null);
+                _popupRoot.Dispose();
+                _popupRoot = null;
+            }
         }
 
         /// <summary>
@@ -278,13 +288,16 @@ namespace Avalonia.Controls.Primitives
         /// <param name="e">The event args.</param>
         private void IsOpenChanged(AvaloniaPropertyChangedEventArgs e)
         {
-            if ((bool)e.NewValue)
-            {
-                Open();
-            }
-            else
+            if (!_ignoreIsOpenChanged)
             {
-                Close();
+                if ((bool)e.NewValue)
+                {
+                    Open();
+                }
+                else
+                {
+                    Close();
+                }
             }
         }
 

src/Avalonia.Themes.Default/DropDown.xaml

@@ -10,10 +10,10 @@
                 BorderBrush="{TemplateBinding BorderBrush}"
                 BorderThickness="{TemplateBinding BorderThickness}">
           <Grid ColumnDefinitions="*,Auto">
-            <ContentPresenter Content="{TemplateBinding SelectionBoxItem}"
-                              Margin="{TemplateBinding Padding}"
-                              HorizontalAlignment="Left"
-                              VerticalAlignment="Center"/>
+            <ContentControl Content="{TemplateBinding SelectionBoxItem}"
+                            Margin="{TemplateBinding Padding}"
+                            HorizontalAlignment="Left"
+                            VerticalAlignment="Center"/>
             <ToggleButton Name="toggle"
                           BorderThickness="0"
                           Background="Transparent"

tests/Avalonia.Controls.UnitTests/DropDownTests.cs

@@ -1,20 +1,65 @@
 // Copyright (c) The Avalonia Project. All rights reserved.
 // Licensed under the MIT license. See licence.md file in the project root for full license information.
 
-using System;
 using System.Linq;
 using Avalonia.Controls.Presenters;
 using Avalonia.Controls.Primitives;
+using Avalonia.Controls.Shapes;
 using Avalonia.Controls.Templates;
-using Avalonia.Platform;
-using Ploeh.AutoFixture;
-using Ploeh.AutoFixture.AutoMoq;
+using Avalonia.LogicalTree;
+using Avalonia.Media;
+using Avalonia.UnitTests;
+using Avalonia.VisualTree;
 using Xunit;
 
 namespace Avalonia.Controls.UnitTests
 {
     public class DropDownTests
     {
+        [Fact]
+        public void SelectionBoxItem_Is_Rectangle_With_VisualBrush_When_Selection_Is_Control()
+        {
+            var items = new[] { new Canvas() };
+            var target = new DropDown
+            {
+                Items = items,
+                SelectedIndex = 0,
+            };
+
+            var rectangle = target.GetValue(DropDown.SelectionBoxItemProperty) as Rectangle;
+            Assert.NotNull(rectangle);
+
+            var brush = rectangle.Fill as VisualBrush;
+            Assert.NotNull(brush);
+            Assert.Same(items[0], brush.Visual);
+        }
+
+        [Fact]
+        public void SelectionBoxItem_Rectangle_Is_Removed_From_Logical_Tree()
+        {
+            var target = new DropDown
+            {
+                Items = new[] { new Canvas() },
+                SelectedIndex = 0,
+                Template = GetTemplate(),
+            };
+
+            var root = new TestRoot { Child = target };
+            target.ApplyTemplate();
+            target.Presenter.ApplyTemplate();
+
+            var rectangle = target.GetValue(DropDown.SelectionBoxItemProperty) as Rectangle;
+            Assert.True(((ILogical)target).IsAttachedToLogicalTree);
+            Assert.True(((ILogical)rectangle).IsAttachedToLogicalTree);
+
+            rectangle.DetachedFromLogicalTree += (s, e) => { };
+
+            root.Child = null;
+
+            Assert.False(((ILogical)target).IsAttachedToLogicalTree);
+            Assert.False(((ILogical)rectangle).IsAttachedToLogicalTree);
+        }
+
         private FuncControlTemplate GetTemplate()
         {
             return new FuncControlTemplate<DropDown>(parent =>
@@ -26,8 +71,7 @@ namespace Avalonia.Controls.UnitTests
                     {
                         new ContentControl
                         {
-                            Name = "contentControl",
-                            [~ContentPresenter.ContentProperty] = parent[~DropDown.SelectionBoxItemProperty],
+                            [!ContentControl.ContentProperty] = parent[!DropDown.SelectionBoxItemProperty],
                         },
                         new ToggleButton
                         {
@@ -35,7 +79,12 @@ namespace Avalonia.Controls.UnitTests
                         },
                         new Popup
                         {
-                            Name = "popup",
+                            Name = "PART_Popup",
+                            Child = new ItemsPresenter
+                            {
+                                Name = "PART_ItemsPresenter",
+                                [!ItemsPresenter.ItemsProperty] = parent[!DropDown.ItemsProperty],
+                            }
                         }
                     }
                 };

tests/Avalonia.Controls.UnitTests/Primitives/PopupTests.cs

@@ -166,6 +166,24 @@ namespace Avalonia.Controls.UnitTests.Primitives
             }
         }
 
+        [Fact]
+        public void PopupRoot_Should_Be_Detached_From_Logical_Tree_When_Popup_Is_Detached()
+        {
+            using (CreateServices())
+            {
+                var target = new Popup();
+                var root = new TestRoot { Child = target };
+
+                target.Open();
+
+                var popupRoot = (ILogical)target.PopupRoot;
+
+                Assert.True(popupRoot.IsAttachedToLogicalTree);
+                root.Child = null;
+                Assert.False(((ILogical)target).IsAttachedToLogicalTree);
+            }
+        }
+
         [Fact]
         public void PopupRoot_Should_Have_Template_Applied()
         {