From 135753b6a3bcdfbfe05bbac160ee30437bf57084 Mon Sep 17 00:00:00 2001
From: Pavel Leonenko <pleonenko@halocollar.com>
Date: Thu, 27 Jun 2024 19:11:42 +0200
Subject: [PATCH] Added unsubscribing from CanExecute-related events when
 disposing SetCommandWithDisposing subscription

---
 .../DroidBindingFactory.cs                    | 39 +++++++++++++------
 .../AppleBindingFactory.cs                    | 39 +++++++++++++------
 Softeq.XToolkit.Bindings/BindingExtensions.cs | 16 +++++---
 .../BindingFactoryBase.cs                     |  2 +-
 Softeq.XToolkit.Bindings/IBindingFactory.cs   |  3 +-
 5 files changed, 67 insertions(+), 32 deletions(-)

diff --git a/Softeq.XToolkit.Bindings.Droid/DroidBindingFactory.cs b/Softeq.XToolkit.Bindings.Droid/DroidBindingFactory.cs
index 2459e3fa0..96c834724 100644
--- a/Softeq.XToolkit.Bindings.Droid/DroidBindingFactory.cs
+++ b/Softeq.XToolkit.Bindings.Droid/DroidBindingFactory.cs
@@ -8,6 +8,7 @@
 using System.Windows.Input;
 using Android.Views;
 using Android.Widget;
+using Softeq.XToolkit.Common.Disposables;
 using Softeq.XToolkit.Common.Threading;
 
 namespace Softeq.XToolkit.Bindings.Droid
@@ -147,18 +148,20 @@ public override Delegate GetCommandHandler<T>(
         }
 
         /// <inheritdoc />
-        public override void HandleCommandCanExecute<T>(
+        public override IDisposable HandleCommandCanExecute<T>(
             object element,
             ICommand command,
             Binding<T, T>? commandParameterBinding)
         {
             if (element is View view)
             {
-                HandleViewEnabled(view, command, commandParameterBinding);
+                return HandleViewEnabled(view, command, commandParameterBinding);
             }
+
+            return Disposable.Create(() => { });
         }
 
-        private static void HandleViewEnabled<T>(
+        private static IDisposable HandleViewEnabled<T>(
             View view,
             ICommand command,
             Binding<T, T>? commandParameterBinding)
@@ -171,20 +174,32 @@ private static void HandleViewEnabled<T>(
                 () => view.Enabled = command.CanExecute(commandParameter));
 
             // set by CanExecute
-            command.CanExecuteChanged += (s, args) =>
-            {
-                Execute.BeginOnUIThread(
-                    () => view.Enabled = command.CanExecute(commandParameter));
-            };
+            command.CanExecuteChanged += OnCommandCanExecuteChanged;
 
             // set by bindable command parameter
             if (commandParameterBinding != null)
             {
-                commandParameterBinding.ValueChanged += (s, args) =>
+                commandParameterBinding.ValueChanged += OnCommandParameterBindingValueChanged;
+            }
+
+            return Disposable.Create(() =>
+            {
+                if (commandParameterBinding != null)
                 {
-                    Execute.BeginOnUIThread(
-                        () => view.Enabled = command.CanExecute(commandParameterBinding.Value));
-                };
+                    commandParameterBinding.ValueChanged -= OnCommandParameterBindingValueChanged;
+                }
+
+                command.CanExecuteChanged -= OnCommandCanExecuteChanged;
+            });
+
+            void OnCommandCanExecuteChanged(object? s, EventArgs args)
+            {
+                Execute.BeginOnUIThread(() => view.Enabled = command.CanExecute(commandParameter));
+            }
+
+            void OnCommandParameterBindingValueChanged(object? s, EventArgs args)
+            {
+                Execute.BeginOnUIThread(() => view.Enabled = command.CanExecute(commandParameterBinding.Value));
             }
         }
     }
diff --git a/Softeq.XToolkit.Bindings.iOS/AppleBindingFactory.cs b/Softeq.XToolkit.Bindings.iOS/AppleBindingFactory.cs
index d0700aeea..38d8df550 100644
--- a/Softeq.XToolkit.Bindings.iOS/AppleBindingFactory.cs
+++ b/Softeq.XToolkit.Bindings.iOS/AppleBindingFactory.cs
@@ -5,6 +5,7 @@
 using System.Diagnostics.CodeAnalysis;
 using System.Linq.Expressions;
 using System.Windows.Input;
+using Softeq.XToolkit.Common.Disposables;
 using UIKit;
 
 namespace Softeq.XToolkit.Bindings.iOS
@@ -98,18 +99,20 @@ public override Binding<TSource, TTarget> CreateBinding<TSource, TTarget>(
         }
 
         /// <inheritdoc />
-        public override void HandleCommandCanExecute<T>(
+        public override IDisposable HandleCommandCanExecute<T>(
             object element,
             ICommand command,
             Binding<T, T>? commandParameterBinding)
         {
             if (element is UIControl control)
             {
-                HandleControlEnabled(control, command, commandParameterBinding);
+                return HandleControlEnabled(control, command, commandParameterBinding);
             }
+
+            return Disposable.Create(() => { });
         }
 
-        private static void HandleControlEnabled<T>(
+        private static IDisposable HandleControlEnabled<T>(
             UIControl control,
             ICommand command,
             Binding<T, T>? commandParameterBinding)
@@ -122,20 +125,32 @@ private static void HandleControlEnabled<T>(
                 () => control.Enabled = command.CanExecute(commandParameter));
 
             // set by CanExecute
-            command.CanExecuteChanged += (s, args) =>
-            {
-                control.BeginInvokeOnMainThread(
-                    () => control.Enabled = command.CanExecute(commandParameter));
-            };
+            command.CanExecuteChanged += OnCommandCanExecuteChanged;
 
             // set by bindable command parameter
             if (commandParameterBinding != null)
             {
-                commandParameterBinding.ValueChanged += (s, args) =>
+                commandParameterBinding.ValueChanged += OnCommandParameterBindingValueChanged;
+            }
+
+            return Disposable.Create(() =>
+            {
+                if (commandParameterBinding != null)
                 {
-                    control.BeginInvokeOnMainThread(
-                        () => control.Enabled = command.CanExecute(commandParameterBinding.Value));
-                };
+                    commandParameterBinding.ValueChanged -= OnCommandParameterBindingValueChanged;
+                }
+
+                command.CanExecuteChanged -= OnCommandCanExecuteChanged;
+            });
+
+            void OnCommandCanExecuteChanged(object? s, EventArgs args)
+            {
+                control.BeginInvokeOnMainThread(() => control.Enabled = command.CanExecute(commandParameter));
+            }
+
+            void OnCommandParameterBindingValueChanged(object? s, EventArgs args)
+            {
+                control.BeginInvokeOnMainThread(() => control.Enabled = command.CanExecute(commandParameterBinding.Value));
             }
         }
     }
diff --git a/Softeq.XToolkit.Bindings/BindingExtensions.cs b/Softeq.XToolkit.Bindings/BindingExtensions.cs
index 1ed231d5d..c2828336c 100644
--- a/Softeq.XToolkit.Bindings/BindingExtensions.cs
+++ b/Softeq.XToolkit.Bindings/BindingExtensions.cs
@@ -565,9 +565,13 @@ public static IDisposable SetCommandWithDisposing(
 
             e.AddEventHandler(element, handler);
 
-            HandleCommandCanExecute(element, command);
+            var canExecuteSubscriptions = HandleCommandCanExecute(element, command);
 
-            return Disposable.Create(() => e.RemoveEventHandler(element, handler));
+            return Disposable.Create(() =>
+            {
+                canExecuteSubscriptions.Dispose();
+                e.RemoveEventHandler(element, handler);
+            });
         }
 
         /// <inheritdoc cref="SetCommand(object,string,ICommand)" />
@@ -659,19 +663,19 @@ internal static EventInfo GetEventInfoForControl(this Type type, string? eventNa
             return info;
         }
 
-        private static void HandleCommandCanExecute(
+        private static IDisposable HandleCommandCanExecute(
             object element,
             ICommand command)
         {
-            HandleCommandCanExecute<object>(element, command);
+            return HandleCommandCanExecute<object>(element, command);
         }
 
-        private static void HandleCommandCanExecute<T>(
+        private static IDisposable HandleCommandCanExecute<T>(
             object element,
             ICommand command,
             Binding<T, T>? commandParameterBinding = null)
         {
-            BindingFactory.HandleCommandCanExecute(element, command, commandParameterBinding);
+            return BindingFactory.HandleCommandCanExecute(element, command, commandParameterBinding);
         }
     }
 }
diff --git a/Softeq.XToolkit.Bindings/BindingFactoryBase.cs b/Softeq.XToolkit.Bindings/BindingFactoryBase.cs
index d686f50eb..5ab10a8bd 100644
--- a/Softeq.XToolkit.Bindings/BindingFactoryBase.cs
+++ b/Softeq.XToolkit.Bindings/BindingFactoryBase.cs
@@ -49,7 +49,7 @@ public abstract Binding<TSource, TTarget> CreateBinding<TSource, TTarget>(
         public abstract string? GetDefaultEventNameForControl(Type type);
 
         /// <inheritdoc />
-        public abstract void HandleCommandCanExecute<T>(
+        public abstract IDisposable HandleCommandCanExecute<T>(
             object element,
             ICommand command,
             Binding<T, T>? commandParameterBinding);
diff --git a/Softeq.XToolkit.Bindings/IBindingFactory.cs b/Softeq.XToolkit.Bindings/IBindingFactory.cs
index 1f23d10ac..b909b7736 100644
--- a/Softeq.XToolkit.Bindings/IBindingFactory.cs
+++ b/Softeq.XToolkit.Bindings/IBindingFactory.cs
@@ -248,6 +248,7 @@ Delegate GetCommandHandler<T, TEventArgs>(
         ///     that will passed to the <see cref="T:System.Windows.Input.ICommand"/>. Used to determine new value of CanExecute.
         /// </param>
         /// <typeparam name="T">Type of command parameter.</typeparam>
-        void HandleCommandCanExecute<T>(object element, ICommand command, Binding<T, T>? commandParameterBinding);
+        /// <returns>Disposable subscriptions to CanExecute related events.</returns>
+        IDisposable HandleCommandCanExecute<T>(object element, ICommand command, Binding<T, T>? commandParameterBinding);
     }
 }