Merge pull request #558 from boukenka/dispose

Handle Dispose exceptions

Author: zHaytam

src/Blazor.Diagrams/Components/DiagramCanvas.razor.cs

@@ -29,15 +29,23 @@ public partial class DiagramCanvas : IAsyncDisposable
 
     public async ValueTask DisposeAsync()
     {
-        BlazorDiagram.Changed -= OnDiagramChanged;
+        try
+        {
+            BlazorDiagram.Changed -= OnDiagramChanged;
 
-        if (_reference == null)
-            return;
+            if (_reference == null)
+                return;
 
-        if (elementReference.Id != null)
-            await JSRuntime.UnobserveResizes(elementReference);
+            if (elementReference.Id != null && JSRuntime != null)
+                await JSRuntime.UnobserveResizes(elementReference);
 
-        _reference.Dispose();
+            _reference.Dispose();
+        }
+        catch (Exception ex) when (ex is JSDisconnectedException || ex is OperationCanceledException)
+        {
+            // This exception is expected when the user navigates away from the page
+            // and the component is disposed. It can be ignored.
+        }
     }
 
     private string GetLayerStyle(int order)
@@ -56,12 +64,20 @@ protected override void OnInitialized()
 
     protected override async Task OnAfterRenderAsync(bool firstRender)
     {
-        await base.OnAfterRenderAsync(firstRender);
+        try
+        {
+            await base.OnAfterRenderAsync(firstRender);
 
-        if (firstRender)
+            if (firstRender)
+            {
+                BlazorDiagram.SetContainer(await JSRuntime.GetBoundingClientRect(elementReference));
+                await JSRuntime.ObserveResizes(elementReference, _reference!);
+            }
+        }
+        catch (Exception ex) when (ex is JSDisconnectedException || ex is OperationCanceledException)
         {
-            BlazorDiagram.SetContainer(await JSRuntime.GetBoundingClientRect(elementReference));
-            await JSRuntime.ObserveResizes(elementReference, _reference!);
+            // This exception is expected when the user navigates away from the page
+            // and the component is disposed. It can be ignored
         }
     }
 

src/Blazor.Diagrams/Components/Renderers/GroupRenderer.cs

@@ -8,6 +8,7 @@
 using Microsoft.AspNetCore.Components;
 using Microsoft.AspNetCore.Components.Rendering;
 using Microsoft.AspNetCore.Components.Web;
+using Microsoft.JSInterop;
 
 namespace Blazor.Diagrams.Components.Renderers;
 
@@ -53,17 +54,25 @@ protected override bool ShouldRender()
 
     protected override void OnAfterRender(bool firstRender)
     {
-        if (Size.Zero.Equals(Group.Size))
-            return;
-
-        // Update the port positions (and links) when the size of the group changes
-        // This will save us some JS trips as well as useless rerenders
-
-        if (_lastSize == null || !_lastSize.Equals(Group.Size))
+        try
+        {
+            if (Size.Zero.Equals(Group.Size))
+                return;
+
+            // Update the port positions (and links) when the size of the group changes
+            // This will save us some JS trips as well as useless rerenders
+
+            if (_lastSize == null || !_lastSize.Equals(Group.Size))
+            {
+                Group.ReinitializePorts();
+                Group.RefreshLinks();
+                _lastSize = Group.Size;
+            }
+        }
+        catch (Exception ex) when (ex is JSDisconnectedException || ex is OperationCanceledException)
         {
-            Group.ReinitializePorts();
-            Group.RefreshLinks();
-            _lastSize = Group.Size;
+            // This exception is expected when the user navigates away from the page
+            // and the component is disposed. It can be ignored
         }
     }
 

src/Blazor.Diagrams/Components/Renderers/NodeRenderer.cs

@@ -28,15 +28,22 @@ public class NodeRenderer : ComponentBase, IDisposable
 
     public void Dispose()
     {
-        Node.Changed -= OnNodeChanged;
-        Node.VisibilityChanged -= OnVisibilityChanged;
+        try
+        {
+            Node.Changed -= OnNodeChanged;
+            Node.VisibilityChanged -= OnVisibilityChanged;
+
+            if (_element.Id != null && !Node.ControlledSize && JsRuntime != null)
+            {
+                _ = JsRuntime.UnobserveResizes(_element);
+            }
 
-        if (_element.Id != null && !Node.ControlledSize)
+            _reference?.Dispose();
+        }
+        catch (Exception ex) when (ex is JSDisconnectedException || ex is ObjectDisposedException)
         {
-            _ = JsRuntime.UnobserveResizes(_element);
+            // This exception can be ignored.
         }
-
-        _reference?.Dispose();
     }
 
     [JSInvokable]
@@ -127,18 +134,26 @@ protected override void BuildRenderTree(RenderTreeBuilder builder)
 
     protected override async Task OnAfterRenderAsync(bool firstRender)
     {
-        if (firstRender && !Node.Visible)
-            return;
-
-        if (firstRender || _becameVisible)
+        try
         {
-            _becameVisible = false;
+            if (firstRender && !Node.Visible)
+                return;
 
-            if (!Node.ControlledSize)
+            if (firstRender || _becameVisible)
             {
-                await JsRuntime.ObserveResizes(_element, _reference!);
+                _becameVisible = false;
+
+                if (!Node.ControlledSize)
+                {
+                    await JsRuntime.ObserveResizes(_element, _reference!);
+                }
             }
         }
+        catch (Exception ex) when (ex is JSDisconnectedException || ex is OperationCanceledException)
+        {
+            // This exception is expected when the user navigates away from the page
+            // and the component is disposed. It can be ignored
+        }
     }
 
     private void OnNodeChanged(Model _)

src/Blazor.Diagrams/Components/Renderers/PortRenderer.cs

@@ -80,9 +80,17 @@ protected override void BuildRenderTree(RenderTreeBuilder builder)
 
     protected override async Task OnAfterRenderAsync(bool firstRender)
     {
-        if (!Port.Initialized)
+        try
         {
-            await UpdateDimensions();
+            if (!Port.Initialized)
+            {
+                await UpdateDimensions();
+            }
+        }
+        catch (Exception ex) when (ex is JSDisconnectedException || ex is OperationCanceledException)
+        {
+            // This exception is expected when the user navigates away from the page
+            // and the component is disposed. It can be ignored
         }
     }