From 62c091fd127c1f865e702df53a6875a1b459a24e Mon Sep 17 00:00:00 2001
From: Eugene Wang <8755753+soukoku@users.noreply.github.com>
Date: Sun, 9 Apr 2023 13:15:45 -0400
Subject: [PATCH] Added transfercanceled event like PR #35.

---
 src/NTwain/TransferCanceledEventArgs.cs  | 10 ++++++++++
 src/NTwain/TwainAppSession.PropEvents.cs |  5 +++++
 src/NTwain/TwainAppSession.Xfers.cs      |  8 ++++++++
 3 files changed, 23 insertions(+)
 create mode 100644 src/NTwain/TransferCanceledEventArgs.cs

diff --git a/src/NTwain/TransferCanceledEventArgs.cs b/src/NTwain/TransferCanceledEventArgs.cs
new file mode 100644
index 0000000..462148d
--- /dev/null
+++ b/src/NTwain/TransferCanceledEventArgs.cs
@@ -0,0 +1,10 @@
+using NTwain.Data;
+using System;
+
+namespace NTwain
+{
+  public class TransferCanceledEventArgs : EventArgs
+  {
+
+  }
+}
\ No newline at end of file
diff --git a/src/NTwain/TwainAppSession.PropEvents.cs b/src/NTwain/TwainAppSession.PropEvents.cs
index ab776ae..c6770e3 100644
--- a/src/NTwain/TwainAppSession.PropEvents.cs
+++ b/src/NTwain/TwainAppSession.PropEvents.cs
@@ -156,6 +156,11 @@ namespace NTwain
     /// </summary>
     public event TwainEventDelegate<TransferReadyEventArgs>? TransferReady;
 
+    /// <summary>
+    /// Fires when there's a transfer cancellation, e.g. if the user pressed the "Cancel" button.
+    /// </summary>
+    public event TwainEventDelegate<TransferCanceledEventArgs>? TransferCanceled;
+
     /// <summary>
     /// Fires when transferred data is available for app to use.
     /// </summary>
diff --git a/src/NTwain/TwainAppSession.Xfers.cs b/src/NTwain/TwainAppSession.Xfers.cs
index 0667439..e8c2c0f 100644
--- a/src/NTwain/TwainAppSession.Xfers.cs
+++ b/src/NTwain/TwainAppSession.Xfers.cs
@@ -176,6 +176,14 @@ namespace NTwain
           // ok to keep going
           break;
         case TWRC.CANCEL:
+          // might eventually have option to cancel this or all like transfer ready
+          if (TransferCanceled != null)
+          {
+            _uiThreadMarshaller.Invoke(() =>
+            {
+              TransferCanceled.Invoke(this, new TransferCanceledEventArgs());
+            });
+          };
           TW_PENDINGXFERS pending = default;
           DGControl.PendingXfers.EndXfer(ref _appIdentity, ref _currentDS, ref pending);
           // todo: also reset?