Added events ViewModelAttached, ViewModelPropertyChanged and ViewMode…

…lDetached on MvvmWindow and MvvmUserControl
RolandKoenig · Jan 21, 2024 · 5dbc56f · 5dbc56f
1 parent 7544845
commit 5dbc56f
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Showing 7 changed files with 124 additions and 9 deletions.
diff --git a/src/Directory.Build.props b/src/Directory.Build.props
@@ -41,7 +41,7 @@
     <!-- Commn configuration-->
     <PropertyGroup>
         <Nullable>enable</Nullable>
-        <LangVersion>11.0</LangVersion>
+        <LangVersion>12</LangVersion>
         <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
         <WarningsAsErrors />
         <NoWarn>1591,1712</NoWarn>

diff --git a/src/RolandK.AvaloniaExtensions/Mvvm/CloseWindowRequestEventArgs.cs b/src/RolandK.AvaloniaExtensions/Mvvm/CloseWindowRequestEventArgs.cs
@@ -4,12 +4,7 @@
 
 namespace RolandK.AvaloniaExtensions.Mvvm;
 
-public class CloseWindowRequestEventArgs
+public class CloseWindowRequestEventArgs(object? dialogResult) : EventArgs
 {
-    public object? DialogResult { get; }
-
-    public CloseWindowRequestEventArgs(object? dialogResult)
-    {
-        this.DialogResult = dialogResult;
-    }
+    public object? DialogResult { get; } = dialogResult;
 }
diff --git a/src/RolandK.AvaloniaExtensions/Mvvm/Controls/MvvmUserControl.cs b/src/RolandK.AvaloniaExtensions/Mvvm/Controls/MvvmUserControl.cs
@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.ComponentModel;
 using Avalonia.Controls;
 using Avalonia.LogicalTree;
 using RolandK.AvaloniaExtensions.ViewServices;
@@ -14,6 +15,12 @@ public class MvvmUserControl : UserControl, IViewServiceHost
     private ViewServiceContainer _viewServiceContainer;
     private Type? _viewFor;
 
+    public event EventHandler<ViewModelAttachedEventArgs>? ViewModelAttached;
+
+    public event EventHandler<ViewModelPropertyChangedEventArgs>? ViewModelPropertyChanged;
+
+    public event EventHandler<ViewModelDetachedEventArgs>? ViewModelDetached; 
+
     public Type? ViewFor
     {
         get => _viewFor;
@@ -76,6 +83,21 @@ protected override void OnDataContextChanged(EventArgs e)
 
         this.TryAttachToDataContext();
     }
+
+    protected virtual void OnViewModelPropertyChanged(ViewModelPropertyChangedEventArgs args)
+    {
+        this.ViewModelPropertyChanged?.Invoke(this, args);
+    }
+
+    protected virtual void OnViewModelAttached(ViewModelAttachedEventArgs args)
+    {
+        this.ViewModelAttached?.Invoke(this, args);
+    }
+
+    protected virtual void OnViewModelDetached(ViewModelDetachedEventArgs args)
+    {
+        this.ViewModelDetached?.Invoke(this, args);
+    }
 
     private void OnViewForChanged()
     {
@@ -101,8 +123,14 @@ private void TryAttachToDataContext()
                     $"is already attached to a view of type {dataContextAttachable.AssociatedView.GetType().FullName}");
             }
 
+            var dataContextPropertyChanged = dataContextAttachable as INotifyPropertyChanged;
+
             dataContextAttachable.ViewServiceRequest += this.OnDataContextAttachable_ViewServiceRequest;
             dataContextAttachable.CloseWindowRequest += this.OnDataContextAttachable_CloseWindowRequest;
+            if (dataContextPropertyChanged != null)
+            {
+                dataContextPropertyChanged.PropertyChanged += this.OnDataContextAttachable_PropertyChanged;
+            }
             try
             {
                 dataContextAttachable.AssociatedView = this;
@@ -111,19 +139,32 @@ private void TryAttachToDataContext()
             {
                 dataContextAttachable.ViewServiceRequest -= this.OnDataContextAttachable_ViewServiceRequest;
                 dataContextAttachable.CloseWindowRequest -= this.OnDataContextAttachable_CloseWindowRequest;
+                if (dataContextPropertyChanged != null)
+                {
+                    dataContextPropertyChanged.PropertyChanged -= this.OnDataContextAttachable_PropertyChanged;
+                }
                 throw;
             }
+
             _currentlyAttachedViewModel = dataContextAttachable;
+            this.OnViewModelAttached(new ViewModelAttachedEventArgs(dataContextAttachable));
         }
     }
 
     private void DetachFromDataContext()
     {
         if (_currentlyAttachedViewModel != null)
         {
+            _currentlyAttachedViewModel.AssociatedView = null;
             _currentlyAttachedViewModel.ViewServiceRequest -= this.OnDataContextAttachable_ViewServiceRequest;
             _currentlyAttachedViewModel.CloseWindowRequest -= this.OnDataContextAttachable_CloseWindowRequest;
-            _currentlyAttachedViewModel.AssociatedView = null;
+
+            if (_currentlyAttachedViewModel is INotifyPropertyChanged dataContextPropertyChanged)
+            {
+                dataContextPropertyChanged.PropertyChanged -= this.OnDataContextAttachable_PropertyChanged;
+            }
+
+            this.OnViewModelDetached(new ViewModelDetachedEventArgs(_currentlyAttachedViewModel));
         }
         _currentlyAttachedViewModel = null;
     }
@@ -134,6 +175,15 @@ private void DetachFromDataContext()
         return DefaultViewServices.TryGetDefaultViewService(this, viewServiceType);
     }
 
+    private void OnDataContextAttachable_PropertyChanged(object sender, PropertyChangedEventArgs e)
+    {
+        if (_currentlyAttachedViewModel == null) { return; }
+
+        this.OnViewModelPropertyChanged(new ViewModelPropertyChangedEventArgs(
+            _currentlyAttachedViewModel,
+            e.PropertyName));
+    }
+
     private void OnDataContextAttachable_ViewServiceRequest(object? sender, ViewServiceRequestEventArgs e)
     {
         var viewService = this.TryFindViewService(e.ViewServiceType);

diff --git a/src/RolandK.AvaloniaExtensions/Mvvm/Controls/MvvmWindow.cs b/src/RolandK.AvaloniaExtensions/Mvvm/Controls/MvvmWindow.cs
@@ -1,3 +1,4 @@
+using System.ComponentModel;
 using Avalonia.Controls;
 using Avalonia.Platform;
 using RolandK.AvaloniaExtensions.ViewServices;
@@ -12,6 +13,12 @@ public class MvvmWindow : Window, IViewServiceHost
     private ViewServiceContainer _viewServiceContainer;
     private Type? _viewFor;
 
+    public event EventHandler<ViewModelAttachedEventArgs>? ViewModelAttached;
+
+    public event EventHandler<ViewModelPropertyChangedEventArgs>? ViewModelPropertyChanged;
+
+    public event EventHandler<ViewModelDetachedEventArgs>? ViewModelDetached; 
+
     public Type? ViewFor
     {
         get => _viewFor;
@@ -76,6 +83,21 @@ protected override void OnDataContextChanged(EventArgs e)
         }
     }
 
+    protected virtual void OnViewModelPropertyChanged(ViewModelPropertyChangedEventArgs args)
+    {
+        this.ViewModelPropertyChanged?.Invoke(this, args);
+    }
+
+    protected virtual void OnViewModelAttached(ViewModelAttachedEventArgs args)
+    {
+        this.ViewModelAttached?.Invoke(this, args);
+    }
+
+    protected virtual void OnViewModelDetached(ViewModelDetachedEventArgs args)
+    {
+        this.ViewModelDetached?.Invoke(this, args);
+    }
+
     private void OnViewForChanged()
     {
         if (!_isOpened) { return; }
@@ -100,8 +122,15 @@ private void TryAttachToDataContext()
                     $"is already attached to a view of type {dataContextAttachable.AssociatedView.GetType().FullName}");
             }
 
+            var dataContextPropertyChanged = dataContextAttachable as INotifyPropertyChanged;
+
             dataContextAttachable.ViewServiceRequest += this.OnDataContextAttachable_ViewServiceRequest;
             dataContextAttachable.CloseWindowRequest += this.OnDataContextAttachable_CloseWindowRequest;
+            if (dataContextPropertyChanged != null)
+            {
+                dataContextPropertyChanged.PropertyChanged += this.OnDataContextAttachable_PropertyChanged;
+            }
+
             try
             {
                 dataContextAttachable.AssociatedView = this;
@@ -110,9 +139,14 @@ private void TryAttachToDataContext()
             {
                 dataContextAttachable.ViewServiceRequest -= this.OnDataContextAttachable_ViewServiceRequest;
                 dataContextAttachable.CloseWindowRequest -= this.OnDataContextAttachable_CloseWindowRequest;
+                if (dataContextPropertyChanged != null)
+                {
+                    dataContextPropertyChanged.PropertyChanged -= this.OnDataContextAttachable_PropertyChanged;
+                }
                 throw;
             }
             _currentlyAttachedViewModel = dataContextAttachable;
+            this.OnViewModelAttached(new ViewModelAttachedEventArgs(dataContextAttachable));
         }
     }
 
@@ -123,6 +157,13 @@ private void DetachFromDataContext()
             _currentlyAttachedViewModel.AssociatedView = null;
             _currentlyAttachedViewModel.CloseWindowRequest -= this.OnDataContextAttachable_CloseWindowRequest;
             _currentlyAttachedViewModel.ViewServiceRequest -= this.OnDataContextAttachable_ViewServiceRequest;
+
+            if (_currentlyAttachedViewModel is INotifyPropertyChanged dataContextPropertyChanged)
+            {
+                dataContextPropertyChanged.PropertyChanged -= this.OnDataContextAttachable_PropertyChanged;
+            }
+
+            this.OnViewModelDetached(new ViewModelDetachedEventArgs(_currentlyAttachedViewModel));
         }
         _currentlyAttachedViewModel = null;
     }
@@ -133,6 +174,15 @@ private void DetachFromDataContext()
         return DefaultViewServices.TryGetDefaultViewService(this, viewServiceType);
     }
 
+    private void OnDataContextAttachable_PropertyChanged(object sender, PropertyChangedEventArgs e)
+    {
+        if (_currentlyAttachedViewModel == null) { return; }
+
+        this.OnViewModelPropertyChanged(new ViewModelPropertyChangedEventArgs(
+            _currentlyAttachedViewModel,
+            e.PropertyName));
+    }
+
     private void OnDataContextAttachable_ViewServiceRequest(object? sender, ViewServiceRequestEventArgs e)
     {
         var viewService = this.TryFindViewService(e.ViewServiceType);

diff --git a/src/RolandK.AvaloniaExtensions/Mvvm/ViewModelAttachedEventArgs.cs b/src/RolandK.AvaloniaExtensions/Mvvm/ViewModelAttachedEventArgs.cs
@@ -0,0 +1,6 @@
+namespace RolandK.AvaloniaExtensions.Mvvm;
+
+public class ViewModelAttachedEventArgs(IAttachableViewModel viewModel) : EventArgs
+{
+    public IAttachableViewModel ViewModel { get; } = viewModel;
+}
diff --git a/src/RolandK.AvaloniaExtensions/Mvvm/ViewModelDetachedEventArgs.cs b/src/RolandK.AvaloniaExtensions/Mvvm/ViewModelDetachedEventArgs.cs
@@ -0,0 +1,6 @@
+namespace RolandK.AvaloniaExtensions.Mvvm;
+
+public class ViewModelDetachedEventArgs(IAttachableViewModel viewModel) : EventArgs
+{
+    public IAttachableViewModel ViewModel { get; } = viewModel;
+}
diff --git a/src/RolandK.AvaloniaExtensions/Mvvm/ViewModelPropertyChangedEventArgs.cs b/src/RolandK.AvaloniaExtensions/Mvvm/ViewModelPropertyChangedEventArgs.cs
@@ -0,0 +1,8 @@
+namespace RolandK.AvaloniaExtensions.Mvvm;
+
+public class ViewModelPropertyChangedEventArgs(IAttachableViewModel viewModel, string propertyName) : EventArgs
+{
+    public IAttachableViewModel ViewModel { get; } = viewModel;
+
+    public string PropertyName { get; } = propertyName;
+}