Merge pull request #1951 from worldbeater/master

feature: Support ReactiveUI WhenActivated

build.cake

@@ -170,6 +170,7 @@ Task("Run-Unit-Tests-Impl")
     RunCoreTest("./tests/Avalonia.Styling.UnitTests", data.Parameters, false);
     RunCoreTest("./tests/Avalonia.Visuals.UnitTests", data.Parameters, false);
     RunCoreTest("./tests/Avalonia.Skia.UnitTests", data.Parameters, false);
+    RunCoreTest("./tests/Avalonia.ReactiveUI.UnitTests", data.Parameters, false);
     if (data.Parameters.IsRunningOnWindows)
     {
         RunCoreTest("./tests/Avalonia.Direct2D1.UnitTests", data.Parameters, false);

build/ReactiveUI.props

@@ -1,5 +1,5 @@
 <Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <ItemGroup>
-    <PackageReference Include="reactiveui" Version="8.7.1" />
+    <PackageReference Include="reactiveui" Version="9.0.1" />
   </ItemGroup>
 </Project>

samples/VirtualizationDemo/ViewModels/MainWindowViewModel.cs

@@ -7,6 +7,7 @@ using System.Linq;
 using Avalonia.Collections;
 using Avalonia.Controls;
 using Avalonia.Controls.Primitives;
+using ReactiveUI.Legacy;
 using ReactiveUI;
 
 namespace VirtualizationDemo.ViewModels

src/Avalonia.ReactiveUI/AppBuilderExtensions.cs

@@ -4,6 +4,7 @@
 using Avalonia.Controls;
 using Avalonia.Threading;
 using ReactiveUI;
+using Splat;
 
 namespace Avalonia
 {
@@ -15,6 +16,9 @@ namespace Avalonia
             return builder.AfterSetup(_ =>
             {
                 RxApp.MainThreadScheduler = AvaloniaScheduler.Instance;
+                Locator.CurrentMutable.Register(
+                    () => new AvaloniaActivationForViewFetcher(), 
+                    typeof(IActivationForViewFetcher));
             });
         }
     }

src/Avalonia.ReactiveUI/AvaloniaActivationForViewFetcher.cs

@@ -0,0 +1,38 @@
+// 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.Reflection;
+using System.Reactive.Linq;
+using Avalonia;
+using Avalonia.VisualTree;
+using ReactiveUI;
+
+namespace Avalonia
+{
+    public class AvaloniaActivationForViewFetcher : IActivationForViewFetcher
+    {
+        public int GetAffinityForView(Type view)
+        {
+            return typeof(IVisual).GetTypeInfo().IsAssignableFrom(view.GetTypeInfo()) ? 10 : 0;
+        }
+
+        public IObservable<bool> GetActivationForView(IActivatable view)
+        {
+            if (!(view is IVisual visual)) return Observable.Return(false);
+             var viewLoaded = Observable
+                .FromEventPattern<VisualTreeAttachmentEventArgs>(
+                    x => visual.AttachedToVisualTree += x,
+                    x => visual.DetachedFromVisualTree -= x)
+                .Select(args => true);
+             var viewUnloaded = Observable
+                .FromEventPattern<VisualTreeAttachmentEventArgs>(
+                    x => visual.DetachedFromVisualTree += x,
+                    x => visual.DetachedFromVisualTree -= x)
+                .Select(args => false);
+             return viewLoaded
+                .Merge(viewUnloaded)
+                .DistinctUntilChanged();
+        }
+    }
+}

tests/Avalonia.ReactiveUI.UnitTests/Avalonia.ReactiveUI.UnitTests.csproj

@@ -0,0 +1,14 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>netcoreapp2.0</TargetFramework>
+  </PropertyGroup>
+  <Import Project="..\..\build\UnitTests.NetCore.targets" />
+  <Import Project="..\..\build\Moq.props" />
+  <Import Project="..\..\build\XUnit.props" />
+  <Import Project="..\..\build\Rx.props" />
+  <Import Project="..\..\build\Microsoft.Reactive.Testing.props" />
+  <ItemGroup>
+    <ProjectReference Include="..\Avalonia.UnitTests\Avalonia.UnitTests.csproj" />
+    <ProjectReference Include="..\..\src\Avalonia.ReactiveUI\Avalonia.ReactiveUI.csproj"/>
+  </ItemGroup>
+</Project>

tests/Avalonia.ReactiveUI.UnitTests/AvaloniaActivationForViewFetcherTest.cs

@@ -0,0 +1,89 @@
+using System;
+using System.Reactive.Concurrency;
+using System.Reactive.Disposables;
+using Avalonia.Controls;
+using Avalonia.Rendering;
+using Avalonia.Platform;
+using Avalonia.UnitTests;
+using Avalonia;
+using ReactiveUI;
+using DynamicData;
+using Xunit;
+using Splat;
+
+namespace Avalonia 
+{
+    public class AvaloniaActivationForViewFetcherTest
+    {
+        public class TestUserControl : UserControl, IActivatable { }
+
+        public class TestUserControlWithWhenActivated : UserControl, IActivatable
+        {
+            public bool Active { get; private set; }
+
+            public TestUserControlWithWhenActivated()
+            {
+                this.WhenActivated(disposables => {
+                    Active = true;
+                    Disposable
+                        .Create(() => Active = false)
+                        .DisposeWith(disposables);
+                });
+            }
+        }
+
+        [Fact]
+        public void Visual_Element_Is_Activated_And_Deactivated()
+        {
+            var userControl = new TestUserControl();
+            var activationForViewFetcher = new AvaloniaActivationForViewFetcher();
+
+            activationForViewFetcher
+                .GetActivationForView(userControl)
+                .ToObservableChangeSet(scheduler: ImmediateScheduler.Instance)
+                .Bind(out var activated)
+                .Subscribe();
+
+            var fakeRenderedDecorator = new TestRoot();
+            fakeRenderedDecorator.Child = userControl;
+            Assert.True(activated[0]);
+            Assert.Equal(1, activated.Count);
+
+            fakeRenderedDecorator.Child = null;
+            Assert.True(activated[0]);
+            Assert.False(activated[1]);
+            Assert.Equal(2, activated.Count);
+        }
+
+        [Fact]
+        public void Get_Affinity_For_View_Should_Return_Non_Zero_For_Visual_Elements() 
+        {
+            var userControl = new TestUserControl();
+            var activationForViewFetcher = new AvaloniaActivationForViewFetcher();
+
+            var forUserControl = activationForViewFetcher.GetAffinityForView(userControl.GetType());
+            var forNonUserControl = activationForViewFetcher.GetAffinityForView(typeof(object));
+
+            Assert.NotEqual(0, forUserControl);
+            Assert.Equal(0, forNonUserControl);
+        }
+
+        [Fact]
+        public void Activation_For_View_Fetcher_Should_Support_When_Activated()
+        {
+            Locator.CurrentMutable.RegisterConstant(
+                new AvaloniaActivationForViewFetcher(), 
+                typeof(IActivationForViewFetcher));
+
+            var userControl = new TestUserControlWithWhenActivated();
+            Assert.False(userControl.Active);
+
+            var fakeRenderedDecorator = new TestRoot();
+            fakeRenderedDecorator.Child = userControl;
+            Assert.True(userControl.Active);
+
+            fakeRenderedDecorator.Child = null;
+            Assert.False(userControl.Active);
+        }
+    }
+}