Add cancellation support to AsyncPlugin methods

src/DesktopMagic/BuiltInPlugins/WeatherPlugin.cs

@@ -7,6 +7,7 @@ using System.Drawing;
 using System.Globalization;
 using System.Net.Http;
 using System.Text.Json;
+using System.Threading;
 using System.Threading.Tasks;
 
 namespace DesktopMagic.BuiltInPlugins;
@@ -46,7 +47,7 @@ public class WeatherPlugin : AsyncPlugin
     private string lastUpdated = "";
     private bool isLoading = false;
 
-    public override async void Start()
+    public override async Task StartAsync(CancellationToken cancellationToken)
     {
         httpClient.DefaultRequestHeaders.UserAgent.ParseAdd("Mozilla/5.0 (DesktopMagic)");
 
@@ -74,7 +75,7 @@ public class WeatherPlugin : AsyncPlugin
         };
     }
 
-    public override async Task<Bitmap?> MainAsync()
+    public override async Task<Bitmap?> MainAsync(CancellationToken cancellationToken)
     {
         // Periodic background update
         if (!isLoading && cachedLat != null && cachedLon != null)

src/DesktopMagic/Plugins/PluginWindow.xaml.cs

@@ -37,6 +37,8 @@ public partial class PluginWindow : Window, IPluginWindow
     private Plugin? pluginClassInstance;
     private readonly AssemblyLoadContext assemblyLoadContext;
 
+    private CancellationTokenSource? pluginCancellationTokenSource;
+
     public bool IsRunning { get; private set; } = true;
     public PluginMetadata PluginMetadata { get; private set; }
     public string PluginFolderPath { get; private set; }
@@ -315,6 +317,12 @@ public partial class PluginWindow : Window, IPluginWindow
         updateTimer.Elapsed += UpdateTimer_Elapsed;
 
         pluginClassInstance.Start();
+        if (pluginClassInstance is AsyncPlugin asyncPluginStart)
+        {
+            pluginCancellationTokenSource?.Dispose();
+            pluginCancellationTokenSource = new CancellationTokenSource();
+            await asyncPluginStart.StartAsync(pluginCancellationTokenSource.Token);
+        }
         UpdatePluginWindow();
         await Dispatcher.InvokeAsync(ThemeChanged);
 
@@ -602,7 +610,8 @@ public partial class PluginWindow : Window, IPluginWindow
 
                 if (pluginClassInstance is AsyncPlugin asyncPlugin)
                 {
-                    result = await asyncPlugin.MainAsync();
+                    CancellationToken token = pluginCancellationTokenSource?.Token ?? CancellationToken.None;
+                    result = await asyncPlugin.MainAsync(token);
                 }
                 else
                 {
@@ -678,6 +687,20 @@ public partial class PluginWindow : Window, IPluginWindow
 
         try
         {
+            pluginCancellationTokenSource?.Cancel();
+
+            if (pluginClassInstance is AsyncPlugin asyncPluginStop)
+            {
+                try
+                {
+                    _ = asyncPluginStop.StopAsync(pluginCancellationTokenSource?.Token ?? CancellationToken.None);
+                }
+                catch (Exception ex)
+                {
+                    App.Logger.LogError($"\"{PluginMetadata.Name}\" - {ex}", source: "Plugin");
+                }
+            }
+
             if (pluginClassInstance is not null)
             {
                 SaveState(pluginClassInstance);
@@ -690,6 +713,9 @@ public partial class PluginWindow : Window, IPluginWindow
         }
 
         assemblyLoadContext.Unload();
+
+        pluginCancellationTokenSource?.Dispose();
+        pluginCancellationTokenSource = null;
     }
 
     #region Window Events

src/DesktopMagicPluginAPI/AsyncPlugin.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Drawing;
+using System.Threading;
 using System.Threading.Tasks;
 
 namespace DesktopMagic.Api;
@@ -15,11 +16,23 @@ namespace DesktopMagic.Api;
 /// intervals, and configuration changes as needed.</remarks>
 public abstract class AsyncPlugin : Plugin
 {
+    /// <summary>
+    /// Occurs once when the plugin gets activated. Override for async initialization.
+    /// </summary>
+    /// <param name="cancellationToken">Token signaled when the host requests cancellation.</param>
+    public virtual Task StartAsync(CancellationToken cancellationToken) => Task.CompletedTask;
+
+    /// <summary>
+    /// Occurs once when the plugin gets deactivated. Override for async cleanup.
+    /// </summary>
+    /// <param name="cancellationToken">Token signaled when the host requests cancellation.</param>
+    public virtual Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;
+
     /// <summary>
     /// Occurs when the <see cref="Plugin.UpdateInterval"/> elapses.
     /// </summary>
     /// <returns></returns>
-    public abstract Task<Bitmap?> MainAsync();
+    public abstract Task<Bitmap?> MainAsync(CancellationToken cancellationToken);
 
     /// <summary>
     /// This method should not be called directly! Override and use <see cref="MainAsync"/> for asynchronous plugin operations.