Add UpdateDetectedAsync

See #571

UPGRADING.md

@@ -94,6 +94,7 @@
 * `AppCast? SparkleUpdater.AppCastCache` holds the most recently deserialized app cast information.
 * `AppCastItem` has a new `Channel` property. Use it along with `ChannelAppCastFilter` if you want to use channels that way instead of via your `<Version>` property. In the app cast generator, use the `--channel` option to set this (note that using this will set ALL items added to the app cast to that specific channel; to add only new items to your app cast instead of rewriting the whole thing, use the `--reparse-existing` option).
 * App cast generator has a new `--use-ed25519-signature-attribute` to use `edSignature` in its XML output instead of `signature` (json output unaffected) to match the original Sparkle library
+* Added `UpdateDetectedAsync` -- prioritized over `UpdateDetected` if both `UpdateDetectedAsync` and `UpdateDetected` are implemented.
 
 ## Updating from 0.X or 1.X to 2.X
 

src/NetSparkle/NetSparkleDelegates.cs

@@ -22,12 +22,21 @@ namespace NetSparkleUpdater
     public delegate void LoopFinishedOperation(object sender, bool updateRequired);
 
     /// <summary>
-    /// An update was detected for the user's currently running software  
+    /// An update was detected for the user's currently running software.
+    /// If both this and UpdateDetectedAsync are implemented, UpdateDetectedAsync is prioritized.
     /// </summary>
     /// <param name="sender">the object that initiated the call</param>
     /// <param name="e">Information about the update that was detected</param>
     public delegate void UpdateDetected(object sender, UpdateDetectedEventArgs e);
 
+    /// <summary>
+    /// An update was detected for the user's currently running software.
+    /// If both this and UpdateDetected are implemented, UpdateDetectedAsync is prioritized.
+    /// </summary>
+    /// <param name="sender">the object that initiated the call</param>
+    /// <param name="e">Information about the update that was detected</param>
+    public delegate Task UpdateDetectedAsync(object sender, UpdateDetectedEventArgs e);
+
     /// <summary>
     /// <see cref="SparkleUpdater"/> has started checking for updates
     /// </summary>

src/NetSparkle/SparkleUpdater.cs

@@ -1801,9 +1801,16 @@ private async Task<UpdateInfo> CheckForUpdates(bool isUserManuallyCheckingForUpd
                 // UpdateDetected allows for catching and overriding the update handling,
                 // so if the user has implemented it, tell them there is an update and stop
                 // handling everything.
-                if (UpdateDetected != null)
+                if (UpdateDetected != null || UpdateDetectedAsync != null)
                 {
-                    UpdateDetected(this, ev); // event's next action can change, here
+                    if (UpdateDetectedAsync != null)
+                    {
+                        await UpdateDetectedAsync(this, ev); // event's next action can change, here
+                    }
+                    else if (UpdateDetected != null)
+                    {
+                        UpdateDetected(this, ev); // event's next action can change, here
+                    }
                     switch (ev.NextAction)
                     {
                         case NextUpdateAction.PerformUpdateUnattended:
@@ -1977,12 +1984,19 @@ private async void OnWorkerDoWork()
                                     updates[0],
                                     updates
                                 );
-                                if (UpdateDetected != null)
+                                if (UpdateDetected != null || UpdateDetectedAsync != null)
                                 {
                                     var re = new AutoResetEvent(false);
-                                    _syncContextForWorkerLoop.Post((state) =>
+                                    _syncContextForWorkerLoop.Post(async (state) =>
                                     {
-                                        UpdateDetected?.Invoke(this, ev);
+                                        if (UpdateDetectedAsync != null)
+                                        {
+                                            await UpdateDetectedAsync(this, ev);
+                                        }
+                                        else if (UpdateDetected != null)
+                                        {
+                                            UpdateDetected.Invoke(this, ev);
+                                        }
                                         re.Set();
                                     }, null);
                                     re.WaitOne(); // wait for UpdateDetected to finish even though we called back to UI thread

src/NetSparkle/SparkleUpdaterEvents.cs

@@ -1,6 +1,7 @@
 using System;
 using System.ComponentModel;
 using System.Diagnostics;
+using NetSparkleUpdater.Events;
 
 namespace NetSparkleUpdater
 {
@@ -21,10 +22,23 @@ public partial class SparkleUpdater : IDisposable
         public event UpdateCheckStarted? UpdateCheckStarted;
         /// <summary>
         /// This event can be used to override the standard user interface
-        /// process when an update is detected
+        /// process when an update is detected. To modify the next action,
+        /// change the value of the <seealso cref="UpdateDetectedEventArgs.NextAction"/>
+        /// property.
+        /// If both this and UpdateDetectedAsync are implemented, UpdateDetectedAsync is
+        /// used, and UpdateDetected is not called.
         /// </summary>
         public event UpdateDetected? UpdateDetected;
         /// <summary>
+        /// This event can be used to override the standard user interface
+        /// process when an update is detected. To modify the next action,
+        /// change the value of the <seealso cref="UpdateDetectedEventArgs.NextAction"/>
+        /// property.
+        /// If both this and UpdateDetected are implemented, UpdateDetectedAsync is
+        /// used, and UpdateDetected is not called.
+        /// </summary>
+        public event UpdateDetectedAsync? UpdateDetectedAsync;
+        /// <summary>
         /// Called when update check is all done. <see cref="UpdateDetected"/> may have been 
         /// called between the start and end of the update check.
         /// </summary>