Fix memory leak by disposing entire tree if top node is being disposed. (helix-toolkit#1928)

* Fix WINUI package crash after diposing Viewport3DX.

* Dispose entire tree if top node is being disposed.

* Dispose all children while disposing viewport.

* Dispose all items in ModelContainer3DX.

Author: holance

Source/HelixToolkit.SharpDX.Shared/Model/Scene/Abstract/GroupNodeBase.cs

@@ -294,6 +294,10 @@ protected override bool OnHitTest(HitTestContext context, Matrix totalModelMatri
             protected override void OnDispose(bool disposeManagedResources)
             {
                 Cleared = null;
+                foreach (var c in this.ItemsInternal)
+                {
+                    c?.Dispose();
+                }
                 base.OnDispose(disposeManagedResources);
             }
         }

Source/HelixToolkit.SharpDX.Shared/Viewport/ViewportCore.cs

@@ -246,6 +246,10 @@ private void ViewCubeClicked(Vector3 lookDirection, Vector3 upDirection)
         protected override void OnDispose(bool disposeManagedResources)
         {
             Detach();
+            if (disposeManagedResources)
+            {
+                Items.Dispose();
+            }
             base.OnDispose(disposeManagedResources);
         }
     }

Source/HelixToolkit.SharpDX.SharedModel/Controls/ModelContainer3DX.cs

@@ -13,7 +13,7 @@
 #endif
 
 #if NETFX_CORE
-using  Windows.UI.Xaml;
+using Windows.UI.Xaml;
 using HelixToolkit.UWP.Utilities;
 namespace HelixToolkit.UWP
 #elif WINUI 
@@ -672,7 +672,7 @@ public void Detach(IRenderHost host)
                 if (Interlocked.Decrement(ref d3dCounter) == 0)
                 {
                     foreach (var renderable in Renderables)
-                    {                        
+                    {
                         renderable.Detach();
                         renderable.Invalidated -= RenderableInvalidated;
                     }
@@ -756,6 +756,13 @@ protected virtual void Dispose(bool disposing)
                 {
                     attachedRenderHosts.Clear();
                     Detach();
+                    foreach (var item in Items)
+                    {
+                        if (item is IDisposable d)
+                        {
+                            d.Dispose();
+                        }
+                    }
                     // TODO: dispose managed state (managed objects).
                     viewports.Clear();
                     currentRenderHost = null;

Source/HelixToolkit.UWP.Shared/Controls/Viewport3DX.cs

@@ -931,7 +931,13 @@ protected virtual void Dispose(bool disposing)
                 if (disposing)
                 {
                     EffectsManager = null;
-                    Camera = null;
+                    Camera = null; 
+                    foreach (var item in Items)
+                    {
+                        item.Dispose();
+                    }
+                    viewCube?.Dispose();
+                    coordinateSystem?.Dispose();
                     Items.Clear();
                     if (hostPresenter.Content is IDisposable host)
                     {

Source/HelixToolkit.UWP.Shared/Model/Element3D/Abstract/GroupElement3D.cs

@@ -37,7 +37,8 @@ public abstract class GroupElement3D : Element3D
         public static readonly DependencyProperty ItemsSourceProperty =
             DependencyProperty.Register("ItemsSource", typeof(IList<Element3D>), typeof(GroupElement3D),
                 new PropertyMetadata(null,
-                    (d, e) => {
+                    (d, e) =>
+                    {
                         (d as GroupElement3D).OnItemsSourceChanged(e.NewValue as IList<Element3D>);
                     }));
 
@@ -147,7 +148,7 @@ protected override void OnApplyTemplate()
                     Items.Add(item);
                 }
             }
-            if(OctreeManager is Element3D elem)
+            if (OctreeManager is Element3D elem)
             {
                 Items.Add(elem);
             }
@@ -233,7 +234,7 @@ private void OnItemsSourceChanged(IList<Element3D> itemsSource)
                     Children.Remove(child);
                 }
             }
-            if(itemsSourceInternal == null && itemsSource != null && Children.Count > 0)
+            if (itemsSourceInternal == null && itemsSource != null && Children.Count > 0)
             {
                 throw new InvalidOperationException("Children must be empty before using ItemsSource");
             }
@@ -287,5 +288,28 @@ private void S_CollectionChanged(object sender, NotifyCollectionChangedEventArgs
                     break;
             }
         }
+
+        protected override void Dispose(bool disposing)
+        {
+            if (disposing)
+            {
+                if (itemsSourceInternal is INotifyCollectionChanged s)
+                {
+                    s.CollectionChanged -= S_CollectionChanged;
+                }
+                if (itemsSourceInternal != null)
+                {
+                    foreach (var item in itemsSourceInternal)
+                    {
+                        item.Dispose();
+                    }
+                }
+                foreach (var child in Children)
+                {
+                    child.Dispose();
+                }
+            }
+            base.Dispose(disposing);
+        }
     }
 }

Source/HelixToolkit.UWP.Shared/Model/Element3D/ItemsModel3D.cs

@@ -392,7 +392,18 @@ public virtual void Clear()
 
         protected override void Dispose(bool disposing)
         {
-            Clear();
+            if (disposing)
+            {
+                if (itemsSource is INotifyCollectionChanged n)
+                {
+                    n.CollectionChanged -= ItemsModel3D_CollectionChanged;
+                }
+                foreach (var item in elementDict)
+                {
+                    item.Value?.Dispose();
+                }
+                Clear();
+            }
             base.Dispose(disposing);
         }
     }

Source/HelixToolkit.Wpf.SharpDX.Shared/Controls/Viewport3DX.cs

@@ -1926,6 +1926,12 @@ protected virtual void Dispose(bool disposing)
                         }
                         Camera = null;
                         EffectsManager = null;
+                        foreach (var item in Items)
+                        {
+                            item.Dispose();
+                        }
+                        viewCube?.Dispose();
+                        coordinateView?.Dispose();
                         Items.Clear();
                     }
                     // TODO: dispose managed state (managed objects).

Source/HelixToolkit.Wpf.SharpDX.Shared/Model/Elements3D/AbstractElements3D/GroupElement3D.cs

@@ -291,5 +291,28 @@ private void S_CollectionChanged(object sender, NotifyCollectionChangedEventArgs
                     break;
             }
         }
+
+        protected override void Dispose(bool disposing)
+        {
+            if (disposing)
+            {
+                if (itemsSourceInternal is INotifyCollectionChanged s)
+                {
+                    s.CollectionChanged -= S_CollectionChanged;
+                }
+                if (itemsSourceInternal != null)
+                {
+                    foreach (var item in itemsSourceInternal)
+                    {
+                        item.Dispose();
+                    }
+                }
+                foreach (var child in Children)
+                {
+                    child.Dispose();
+                }
+            }
+            base.Dispose(disposing);
+        }
     }
 }

Source/HelixToolkit.Wpf.SharpDX.Shared/Model/Elements3D/ItemsModel3D.cs

@@ -300,11 +300,28 @@ protected void ItemsModel3D_CollectionChanged(object sender, NotifyCollectionCha
                     break;
             }
         }
-
+        public virtual void Clear()
+        {
+            elementDict.Clear();
+            var node = SceneNode as GroupNode;
+            node.Clear();
+            Children.Clear();
+        }
 
         protected override void Dispose(bool disposing)
         {
-            elementDict.Clear();
+            if (disposing)
+            {
+                if (ItemsSource is INotifyCollectionChanged n)
+                {
+                    n.CollectionChanged -= ItemsModel3D_CollectionChanged;
+                }
+                foreach (var item in elementDict)
+                {
+                    item.Value?.Dispose();
+                }
+                Clear();
+            }
             base.Dispose(disposing);
         }
     }