From 0a7ff8b140d0f36fafc020d1574373b19f82842a Mon Sep 17 00:00:00 2001
From: Eugene Wang <8755753+soukoku@users.noreply.github.com>
Date: Fri, 7 Apr 2023 21:20:57 -0400
Subject: [PATCH] Tweak double buffer use in sample.

---
 samples/WinForm32/ControlExtensions.cs |  6 ++----
 samples/WinForm32/Form1.cs             | 22 ++++++++++++++++++----
 2 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/samples/WinForm32/ControlExtensions.cs b/samples/WinForm32/ControlExtensions.cs
index 8993568..ee36178 100644
--- a/samples/WinForm32/ControlExtensions.cs
+++ b/samples/WinForm32/ControlExtensions.cs
@@ -10,12 +10,10 @@ namespace WinFormSample
 {
   static class ControlExtensions
   {
-    public static void SetDoubleBuffered(this Control control, bool value)
+    public static void SetDoubleBufferedAsNeeded(this Control control)
     {
-      if (SystemInformation.TerminalServerSession) return;
-
       var dbprop = control.GetType().GetProperty("DoubleBuffered", BindingFlags.NonPublic | BindingFlags.Instance);
-      dbprop!.SetValue(control, value);
+      dbprop!.SetValue(control, !SystemInformation.TerminalServerSession);
     }
 
   }
diff --git a/samples/WinForm32/Form1.cs b/samples/WinForm32/Form1.cs
index bca04eb..45230d2 100644
--- a/samples/WinForm32/Form1.cs
+++ b/samples/WinForm32/Form1.cs
@@ -1,3 +1,4 @@
+using Microsoft.Win32;
 using NTwain;
 using NTwain.Data;
 using System;
@@ -34,7 +35,8 @@ namespace WinFormSample
       twain.TransferError += Twain_TransferError;
       twain.DeviceEvent += Twain_DeviceEvent;
 
-      capListView.SetDoubleBuffered(true);
+      capListView.SetDoubleBufferedAsNeeded();
+      SystemEvents.SessionSwitch += SystemEvents_SessionSwitch;
 
       saveFolder = Path.Combine(Path.GetTempPath(), "ntwain-sample");
       Directory.CreateDirectory(saveFolder);
@@ -42,6 +44,18 @@ namespace WinFormSample
       this.Disposed += Form1_Disposed;
     }
 
+    private void SystemEvents_SessionSwitch(object sender, SessionSwitchEventArgs e)
+    {
+      switch (e.Reason)
+      {
+        case SessionSwitchReason.RemoteConnect:
+        case SessionSwitchReason.SessionUnlock:
+        case SessionSwitchReason.SessionLogon:
+          capListView.SetDoubleBufferedAsNeeded();
+          break;
+      }
+    }
+
     protected override void OnHandleCreated(EventArgs e)
     {
       base.OnHandleCreated(e);
@@ -88,7 +102,7 @@ namespace WinFormSample
 
     private void Twain_DataTransferred(TwainAppSession sender, DataTransferredEventArgs e)
     {
-      Debug.WriteLine($"[thread {Environment.CurrentManagedThreadId}] data transferred with info {e.ImageInfo}");
+      Debug.WriteLine($"[thread {Environment.CurrentManagedThreadId}] data transferred with info {e.GetImageInfo()}");
       if (e.Data == null) return;
       using (var stream = new MemoryStream(e.Data))
       using (var img = Image.FromStream(stream))
@@ -116,7 +130,7 @@ namespace WinFormSample
 
     private void Twain_CurrentSourceChanged(TwainAppSession sender, TW_IDENTITY_LEGACY ds)
     {
-      lblCurrent.Text = ds.ProductName;
+      lblCurrent.Text = ds.ToString();
       if (twain.State == STATE.S4)
       {
         LoadCapInfoList();
@@ -291,7 +305,7 @@ namespace WinFormSample
 
     private void btnStart_Click(object sender, EventArgs e)
     {
-      twain.EnableSource(true, false);
+      twain.EnableSource(false, false);
     }
   }
 }
\ No newline at end of file