Initial internal loop idea that compiles.

NTwain/AsyncPump.cs

@@ -1,50 +0,0 @@
-//using System;
-//using System.Collections.Generic;
-//using System.Linq;
-//using System.Text;
-//using System.Threading;
-//using System.Windows.Threading;
-
-//namespace NTwain
-//{
-//    // from http://blogs.msdn.com/b/pfxteam/archive/2012/01/20/10259049.aspx
-
-//    /// <summary>
-//    /// Provides a pump that supports running asynchronous methods on the current thread.
-//    /// </summary>
-//    public static class AsyncPump
-//    {
-//        /// <summary>
-//        /// Runs the specified asynchronous function.
-//        /// </summary>
-//        /// <param name="func">The asynchronous function to execute.</param>
-//        /// <exception cref="System.ArgumentNullException">func</exception>
-//        /// <exception cref="System.InvalidOperationException">No task provided.</exception>
-//        public static void Run(Func<Task> func)
-//        {
-//            if (func == null) throw new ArgumentNullException("func");
-
-//            var prevCtx = SynchronizationContext.Current;
-//            try
-//            {
-//                var syncCtx = new DispatcherSynchronizationContext();
-//                SynchronizationContext.SetSynchronizationContext(syncCtx);
-
-//                var t = func();
-//                if (t == null) throw new InvalidOperationException();
-
-//                var frame = new DispatcherFrame();
-//                t.ContinueWith(_ => { frame.Continue = false; },
-//                    TaskScheduler.Default);
-//                Dispatcher.PushFrame(frame);
-
-//                t.GetAwaiter().GetResult();
-//            }
-//            finally
-//            {
-//                SynchronizationContext.SetSynchronizationContext(prevCtx);
-//            }
-
-//        }
-//    }
-//}

NTwain/NTwain.csproj

@@ -53,7 +53,6 @@
     <Reference Include="WindowsBase" />
   </ItemGroup>
   <ItemGroup>
-    <Compile Include="AsyncPump.cs" />
     <Compile Include="Data\CapReadOut.cs" />
     <Compile Include="Data\TypeReader.cs" />
     <Compile Include="Data\TypesExtended.cs" />
@@ -64,6 +63,7 @@
     <Compile Include="ITwainOperation.cs" />
     <Compile Include="ITwainState.cs" />
     <Compile Include="MemoryManager.cs" />
+    <Compile Include="MessageLoop.cs" />
     <Compile Include="NativeMethods.cs" />
     <Compile Include="Properties\Resources.Designer.cs">
       <AutoGen>True</AutoGen>
@@ -82,8 +82,6 @@
     <Compile Include="Triplets\Dsm.WinNew.cs" />
     <Compile Include="TwainSessionExtensions.cs" />
     <Compile Include="TwainSession.cs" />
-    <Compile Include="TwainSessionWPF.cs" />
-    <Compile Include="TwainSessionWinform.cs" />
     <Compile Include="TwainStateException.cs" />
     <Compile Include="Data\Types.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
@@ -125,7 +123,6 @@
     <Compile Include="Triplets\DGImage\DGImage.RgbResponse.cs" />
     <Compile Include="Triplets\Dsm.cs" />
     <Compile Include="TwainException.cs" />
-    <Compile Include="TwainSessionOld.cs" />
     <Compile Include="Values\DataValues.cs" />
     <Compile Include="Values\SourceEnableMode.cs" />
     <Compile Include="Values\TwainConst.cs" />

NTwain/Properties/VersionInfo.cs

@@ -14,6 +14,6 @@ namespace NTwain
         // keep this same in majors releases
         public const string Release = "0.10.0.0";
         // change this for each nuget release
-        public const string Build = "0.10.1";
+        public const string Build = "0.10.2";
     }
 }

NTwain/Triplets/Dsm.cs

@@ -21,7 +21,7 @@ namespace NTwain.Triplets
         // in essence it only exists in 64 bit systems and thus
         // the 2 sets of identical pinvokes for windows :(
 
-        public static readonly bool CanUseNewDSM = CheckIfCanUseNewDSM();
+        internal static readonly bool UseNewDSM = CheckIfCanUseNewDSM();
 
         private static bool CheckIfCanUseNewDSM()
         {
@@ -35,7 +35,7 @@ namespace NTwain.Triplets
 #endif
         }
 
-        static readonly bool IsWin = Environment.OSVersion.Platform == PlatformID.Win32NT;
+        internal static readonly bool IsWin = Environment.OSVersion.Platform == PlatformID.Win32NT;
         static readonly bool IsLinux = Environment.OSVersion.Platform == PlatformID.Unix;
 
         // define sig for each different data type since "object" doesn't work
@@ -52,7 +52,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, dg, dat, msg, ref data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, dg, dat, msg, ref data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, dg, dat, msg, ref data); }
             }
             else if (IsLinux)
@@ -72,7 +72,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, dg, dat, msg, ref data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, dg, dat, msg, ref data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, dg, dat, msg, ref data); }
             }
             else if (IsLinux)
@@ -90,7 +90,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Audio, DataArgumentType.AudioInfo, msg, data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Audio, DataArgumentType.AudioInfo, msg, data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, DataGroups.Audio, DataArgumentType.AudioInfo, msg, data); }
             }
             else if (IsLinux)
@@ -109,7 +109,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.Capability, msg, data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.Capability, msg, data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, DataGroups.Control, DataArgumentType.Capability, msg, data); }
             }
             else if (IsLinux)
@@ -128,7 +128,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.CustomDSData, msg, data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.CustomDSData, msg, data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, DataGroups.Control, DataArgumentType.CustomDSData, msg, data); }
             }
             else if (IsLinux)
@@ -147,7 +147,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.DeviceEvent, msg, data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.DeviceEvent, msg, data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, DataGroups.Control, DataArgumentType.DeviceEvent, msg, data); }
             }
             else if (IsLinux)
@@ -166,7 +166,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.Callback, msg, data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.Callback, msg, data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, DataGroups.Control, DataArgumentType.Callback, msg, data); }
             }
             else if (IsLinux)
@@ -185,7 +185,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.Callback, msg, data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.Callback, msg, data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, DataGroups.Control, DataArgumentType.Callback, msg, data); }
             }
             else if (IsLinux)
@@ -204,7 +204,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.EntryPoint, msg, data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.EntryPoint, msg, data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, DataGroups.Control, DataArgumentType.EntryPoint, msg, data); }
             }
             else if (IsLinux)
@@ -223,7 +223,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.Event, msg, data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.Event, msg, data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, DataGroups.Control, DataArgumentType.Event, msg, data); }
             }
             else if (IsLinux)
@@ -242,7 +242,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.FileSystem, msg, data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.FileSystem, msg, data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, DataGroups.Control, DataArgumentType.FileSystem, msg, data); }
             }
             else if (IsLinux)
@@ -259,7 +259,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, IntPtr.Zero, DataGroups.Control, DataArgumentType.Identity, msg, data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, IntPtr.Zero, DataGroups.Control, DataArgumentType.Identity, msg, data); }
                 else { return NativeMethods.DsmWinOld(origin, IntPtr.Zero, DataGroups.Control, DataArgumentType.Identity, msg, data); }
             }
             else if (IsLinux)
@@ -278,7 +278,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.PassThru, msg, data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.PassThru, msg, data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, DataGroups.Control, DataArgumentType.PassThru, msg, data); }
             }
             else if (IsLinux)
@@ -297,7 +297,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.PendingXfers, msg, data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.PendingXfers, msg, data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, DataGroups.Control, DataArgumentType.PendingXfers, msg, data); }
             }
             else if (IsLinux)
@@ -316,7 +316,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.SetupFileXfer, msg, data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.SetupFileXfer, msg, data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, DataGroups.Control, DataArgumentType.SetupFileXfer, msg, data); }
             }
             else if (IsLinux)
@@ -335,7 +335,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.SetupMemXfer, msg, data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.SetupMemXfer, msg, data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, DataGroups.Control, DataArgumentType.SetupMemXfer, msg, data); }
             }
             else if (IsLinux)
@@ -354,7 +354,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.StatusUtf8, msg, data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.StatusUtf8, msg, data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, DataGroups.Control, DataArgumentType.StatusUtf8, msg, data); }
             }
             else if (IsLinux)
@@ -373,7 +373,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.UserInterface, msg, data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.UserInterface, msg, data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, DataGroups.Control, DataArgumentType.UserInterface, msg, data); }
             }
             else if (IsLinux)
@@ -392,7 +392,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Image, DataArgumentType.CieColor, msg, data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Image, DataArgumentType.CieColor, msg, data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, DataGroups.Image, DataArgumentType.CieColor, msg, data); }
             }
             else if (IsLinux)
@@ -411,7 +411,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Image, DataArgumentType.ExtImageInfo, msg, data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Image, DataArgumentType.ExtImageInfo, msg, data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, DataGroups.Image, DataArgumentType.ExtImageInfo, msg, data); }
             }
             else if (IsLinux)
@@ -429,7 +429,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Image, DataArgumentType.Filter, msg, data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Image, DataArgumentType.Filter, msg, data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, DataGroups.Image, DataArgumentType.Filter, msg, data); }
             }
             else if (IsLinux)
@@ -447,7 +447,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Image, DataArgumentType.GrayResponse, msg, data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Image, DataArgumentType.GrayResponse, msg, data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, DataGroups.Image, DataArgumentType.GrayResponse, msg, data); }
             }
             else if (IsLinux)
@@ -466,7 +466,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Image, DataArgumentType.ImageInfo, msg, data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Image, DataArgumentType.ImageInfo, msg, data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, DataGroups.Image, DataArgumentType.ImageInfo, msg, data); }
             }
             else if (IsLinux)
@@ -485,7 +485,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Image, DataArgumentType.ImageLayout, msg, data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Image, DataArgumentType.ImageLayout, msg, data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, DataGroups.Image, DataArgumentType.ImageLayout, msg, data); }
             }
             else if (IsLinux)
@@ -504,7 +504,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Image, DataArgumentType.ImageMemXfer, msg, data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Image, DataArgumentType.ImageMemXfer, msg, data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, DataGroups.Image, DataArgumentType.ImageMemXfer, msg, data); }
             }
             else if (IsLinux)
@@ -523,7 +523,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Image, DataArgumentType.JpegCompression, msg, data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Image, DataArgumentType.JpegCompression, msg, data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, DataGroups.Image, DataArgumentType.JpegCompression, msg, data); }
             }
             else if (IsLinux)
@@ -542,7 +542,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Image, DataArgumentType.Palette8, msg, data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Image, DataArgumentType.Palette8, msg, data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, DataGroups.Image, DataArgumentType.Palette8, msg, data); }
             }
             else if (IsLinux)
@@ -561,7 +561,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Image, DataArgumentType.RgbResponse, msg, data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Image, DataArgumentType.RgbResponse, msg, data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, DataGroups.Image, DataArgumentType.RgbResponse, msg, data); }
             }
             else if (IsLinux)
@@ -580,7 +580,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.Status, msg, data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, DataArgumentType.Status, msg, data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, DataGroups.Control, DataArgumentType.Status, msg, data); }
             }
             else if (IsLinux)
@@ -600,7 +600,7 @@ namespace NTwain.Triplets
         {
             if (IsWin)
             {
-                if (CanUseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, dat, msg, ref data); }
+                if (UseNewDSM) { return NativeMethods.DsmWinNew(origin, destination, DataGroups.Control, dat, msg, ref data); }
                 else { return NativeMethods.DsmWinOld(origin, destination, DataGroups.Control, dat, msg, ref data); }
             }
             else if (IsLinux)

NTwain/TwainSession.cs

@@ -8,8 +8,10 @@ using System.Diagnostics;
 using System.IO;
 using System.Linq;
 using System.Runtime.InteropServices;
+using System.Security.Permissions;
 using System.Text;
 using System.Threading;
+using System.Windows.Threading;
 
 namespace NTwain
 {
@@ -29,11 +31,13 @@ namespace NTwain
             _appId = appId;
             ((ITwainStateInternal)this).ChangeState(1, false);
             EnforceState = true;
+
+            Debug.WriteLine("current thread id =" + Thread.CurrentThread.ManagedThreadId);
+
+            MessageLoop.Instance.EnsureStarted();
         }
 
         TWIdentity _appId;
-        IntPtr _appHandle;
-        SynchronizationContext _syncer;
         object _callbackObj; // kept around so it doesn't get gc'ed
         TWUserInterface _twui;
 
@@ -205,17 +209,14 @@ namespace NTwain
         /// Opens the data source manager. This must be the first method used
         /// before using other TWAIN functions. Calls to this must be followed by <see cref="CloseManager"/> when done with a TWAIN session.
         /// </summary>
-        /// <param name="appHandle">On Windows = points to the window handle (hWnd) that will act as the Source’s
-        /// "parent". On Macintosh = should be a NULL value.</param>
         /// <returns></returns>
-        public ReturnCode OpenManager(IntPtr appHandle)
+        public ReturnCode OpenManager()
         {
             Debug.WriteLine(string.Format("Thread {0}: OpenManager.", Thread.CurrentThread.ManagedThreadId));
 
-            var rc = DGControl.Parent.OpenDsm(appHandle);
+            var rc = DGControl.Parent.OpenDsm(MessageLoop.Instance.LoopHandle);
             if (rc == ReturnCode.Success)
             {
-                _appHandle = appHandle;
                 // if twain2 then get memory management functions
                 if ((_appId.DataFunctionalities & DataFunctionalities.Dsm2) == DataFunctionalities.Dsm2)
                 {
@@ -243,11 +244,7 @@ namespace NTwain
         {
             Debug.WriteLine(string.Format("Thread {0}: CloseManager.", Thread.CurrentThread.ManagedThreadId));
 
-            var rc = DGControl.Parent.CloseDsm(_appHandle);
+            var rc = DGControl.Parent.CloseDsm(MessageLoop.Instance.LoopHandle);
-            if (rc == ReturnCode.Success)
-            {
-                _appHandle = IntPtr.Zero;
-            }
             return rc;
         }
 
@@ -289,6 +286,7 @@ namespace NTwain
             var rc = DGControl.Identity.CloseDS();
             if (rc == ReturnCode.Success)
             {
+                MessageLoop.Instance.RemoveHook(HandleWndProcMessage);
                 _callbackObj = null;
                 SupportedCaps = null;
             }
@@ -301,23 +299,16 @@ namespace NTwain
         /// <param name="mode">The mode.</param>
         /// <param name="modal">if set to <c>true</c> any driver UI will display as modal.</param>
         /// <param name="windowHandle">The window handle if modal.</param>
-        /// <param name="context">
-        /// The
-        /// <see cref="SynchronizationContext" /> is required if TWAIN is using callback mode 
-        /// instead of the typical WndProc message loop.
-        /// It is recommended you call this method in an UI thread and pass in
-        /// <see cref="SynchronizationContext.Current" />
-        /// if you do not have a custom one setup.</param>
         /// <returns></returns>
         /// <exception cref="ArgumentNullException">context</exception>
-        public ReturnCode EnableSource(SourceEnableMode mode, bool modal, IntPtr windowHandle, SynchronizationContext context)
+        public ReturnCode EnableSource(SourceEnableMode mode, bool modal, IntPtr windowHandle)
         {
-            if (context == null && _callbackObj != null) { throw new ArgumentNullException("SynchronizationContext is required when not using message loop.", "context"); }
-
             Debug.WriteLine(string.Format("Thread {0}: EnableSource.", Thread.CurrentThread.ManagedThreadId));
 
-            _syncer = context;
+            ReturnCode rc = ReturnCode.Success;
 
+            MessageLoop.Instance.Invoke(() =>
+            {
                 // app v2.2 or higher uses callback2
                 if (_appId.ProtocolMajor >= 2 && _appId.ProtocolMinor >= 2)
                 {
@@ -343,6 +334,12 @@ namespace NTwain
                     }
                 }
 
+                if (_callbackObj == null)
+                {
+                    // must use msg loop if callback is not available
+                    MessageLoop.Instance.AddHook(HandleWndProcMessage);
+                }
+
                 _twui = new TWUserInterface();
                 _twui.ShowUI = mode == SourceEnableMode.ShowUI;
                 _twui.ModalUI = modal;
@@ -350,13 +347,14 @@ namespace NTwain
 
                 if (mode == SourceEnableMode.ShowUIOnly)
                 {
-                return DGControl.UserInterface.EnableDSUIOnly(_twui);
+                    rc = DGControl.UserInterface.EnableDSUIOnly(_twui);
                 }
                 else
                 {
-                return DGControl.UserInterface.EnableDS(_twui);
+                    rc = DGControl.UserInterface.EnableDS(_twui);
                 }
-
+            });
+            return rc;
         }
 
         /// <summary>
@@ -367,25 +365,29 @@ namespace NTwain
         {
             Debug.WriteLine(string.Format("Thread {0}: DisableSource.", Thread.CurrentThread.ManagedThreadId));
 
-            var rc = DGControl.UserInterface.DisableDS(_twui);
+            ReturnCode rc = ReturnCode.Success;
+
+            MessageLoop.Instance.Invoke(() =>
+            {
+                rc = DGControl.UserInterface.DisableDS(_twui);
                 if (rc == ReturnCode.Success)
                 {
                     OnSourceDisabled();
                 }
+            });
             return rc;
         }
 
         /// <summary>
         /// Forces the stepping down of an opened source when things gets out of control.
         /// Used when session state and source state become out of sync.
-        /// This should be called on the Thread that originally called the <see cref="EnableSource"/>
-        /// method, if applicable.
         /// </summary>
         /// <param name="targetState">State of the target.</param>
         public void ForceStepDown(int targetState)
         {
             Debug.WriteLine(string.Format("Thread {0}: ForceStepDown.", Thread.CurrentThread.ManagedThreadId));
-
+            MessageLoop.Instance.Invoke(() =>
+            {
                 bool origFlag = EnforceState;
                 EnforceState = false;
 
@@ -425,6 +427,7 @@ namespace NTwain
                     CloseManager();
                 }
                 EnforceState = origFlag;
+            });
         }
 
         #endregion
@@ -583,14 +586,13 @@ namespace NTwain
 
         #region TWAIN logic during xfer work
 
-        /// <summary>
+        //[EnvironmentPermissionAttribute(SecurityAction.LinkDemand)]
-        /// Handles the message from a typical WndProc message loop and check if it's from the TWAIN source.
+        IntPtr HandleWndProcMessage(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
-        /// </summary>
-        /// <param name="message">The message.</param>
-        /// <returns>True if handled by TWAIN.</returns>
-        protected bool HandleWndProcMessage(ref MESSAGE message)
         {
-            var handled = false;
+            // this handles the message from a typical WndProc message loop and check if it's from the TWAIN source.
+
+            var winmsg = new MESSAGE(hwnd, msg, wParam, lParam);
+
             if (State >= 4) // technically we should only handle on state >= 5 but there might be missed msgs if we wait until state changes after enabling ds
             {
                 // transform it into a pointer for twain
@@ -598,15 +600,19 @@ namespace NTwain
                 try
                 {
                     // no need to do another lock call when using marshal alloc
-                    msgPtr = Marshal.AllocHGlobal(Marshal.SizeOf(message));
+                    msgPtr = Marshal.AllocHGlobal(Marshal.SizeOf(winmsg));
-                    Marshal.StructureToPtr(message, msgPtr, false);
+                    Marshal.StructureToPtr(winmsg, msgPtr, false);
 
                     TWEvent evt = new TWEvent();
                     evt.pEvent = msgPtr;
-                    if (handled = DGControl.Event.ProcessEvent(evt) == ReturnCode.DSEvent)
+                    if (handled = (DGControl.Event.ProcessEvent(evt) == ReturnCode.DSEvent))
                     {
                         Debug.WriteLine(string.Format("Thread {0}: HandleWndProcMessage at state {1} with MSG={2}.", Thread.CurrentThread.ManagedThreadId, State, evt.TWMessage));
+
+                        MessageLoop.Instance.BeginInvoke(() =>
+                        {
                             HandleSourceMsg(evt.TWMessage);
+                        });
                     }
                 }
                 finally
@@ -614,7 +620,8 @@ namespace NTwain
                     if (msgPtr != IntPtr.Zero) { Marshal.FreeHGlobal(msgPtr); }
                 }
             }
-            return handled;
+
+            return IntPtr.Zero;
         }
 
         ReturnCode HandleCallback(TWIdentity origin, TWIdentity destination, DataGroups dg, DataArgumentType dat, Message msg, IntPtr data)
@@ -622,28 +629,13 @@ namespace NTwain
             if (origin != null && SourceId != null && origin.Id == SourceId.Id)
             {
                 Debug.WriteLine(string.Format("Thread {0}: CallbackHandler at state {1} with MSG={2}.", Thread.CurrentThread.ManagedThreadId, State, msg));
-                // spec says we must handle this on the thread that enabled the DS, 
+                // spec says we must handle this on the thread that enabled the DS.
-                // but it's usually already the same thread and doesn't work (failure + seqError) w/o jumping to another thread and back.
+                // by using the internal dispatcher this will be the case.
-                // My guess is the DS needs to see the Success return code first before letting transfer happen
-                // so this is an hack to make it happen.
 
-                // TODO: find a better method without needing a SynchronizationContext.
+                MessageLoop.Instance.BeginInvoke(() =>
-                ThreadPool.QueueUserWorkItem(o =>
-                {
-                    var ctx = o as SynchronizationContext;
-                    if (ctx != null)
-                    {
-                        _syncer.Post(blah =>
                 {
                     HandleSourceMsg(msg);
-                        }, null);
+                });
-                    }
-                    else
-                    {
-                        // no context? better hope for the best!
-                        HandleSourceMsg(msg);
-                    }
-                }, _syncer);
                 return ReturnCode.Success;
             }
             return ReturnCode.Failure;

NTwain/TwainSessionOld.cs

@@ -1,229 +0,0 @@
-using System;
-using NTwain.Triplets;
-using NTwain.Data;
-using NTwain.Values;
-using System.Windows.Forms;
-using System.Security.Permissions;
-
-namespace NTwain
-{
-    /// <summary>
-    /// Provides a session for working with TWAIN api in an application.
-    /// This is the old implementation for reference purposes only.
-    /// </summary>
-    [Obsolete("For reference purposes only.")]
-    public class TwainSessionOld : TwainSession, IMessageFilter
-    {
-        /// <summary>
-        /// Initializes a new instance of the <see cref="TwainSessionOld" /> class.
-        /// </summary>
-        /// <param name="appId">The app id.</param>
-        /// <exception cref="System.ArgumentNullException"></exception>
-        public TwainSessionOld(TWIdentity appId) : base(appId) { }
-
-        protected override void DoTransferRoutine()
-        {
-            TWPendingXfers pending = new TWPendingXfers();
-            var rc = ReturnCode.Success;
-
-            do
-            {
-                //IList<FileFormat> formats = Enumerable.Empty<FileFormat>().ToList();
-                //IList<Compression> compressions = Enumerable.Empty<Compression>().ToList();
-                //bool canDoFileXfer = this.CapGetImageXferMech().Contains(XferMech.File);
-                //var curFormat = this.GetCurrentCap<FileFormat>(CapabilityId.ICapImageFileFormat);
-                //var curComp = this.GetCurrentCap<Compression>(CapabilityId.ICapCompression);
-                TWImageInfo imgInfo;
-                bool skip = false;
-                if (DGImage.ImageInfo.Get(out imgInfo) != ReturnCode.Success)
-                {
-                    // bad!
-                    skip = true;
-                }
-
-                //try
-                //{
-                //    formats = this.CapGetImageFileFormat();
-                //}
-                //catch { }
-                //try
-                //{
-                //    compressions = this.CapGetCompression();
-                //}
-                //catch { }
-
-                // ask consumer for cancel in case of non-ui multi-page transfers
-                //TransferReadyEventArgs args = new TransferReadyEventArgs(pending, formats, curFormat, compressions,
-                //    curComp, canDoFileXfer, imgInfo);
-                var args = new TransferReadyEventArgs
-                {
-                    PendingImageInfo = imgInfo,
-                    PendingTransferCount = pending.Count,
-                    EndOfJob = pending.EndOfJob == 0
-                };
-                args.CancelCurrent = skip;
-
-                OnTransferReady(args);
-
-
-                if (!args.CancelAll && !args.CancelCurrent)
-                {
-                    Values.XferMech mech = this.GetCurrentCap(CapabilityId.ICapXferMech).ConvertToEnum<XferMech>();
-
-                    //if (args.CanDoFileXfer && !string.IsNullOrEmpty(args.OutputFile))
-                    //{
-                    //    var setXferRC = DGControl.SetupFileXfer.Set(new TWSetupFileXfer
-                    //    {
-                    //        FileName = args.OutputFile,
-                    //        Format = args.ImageFormat
-                    //    });
-                    //    if (setXferRC == ReturnCode.Success)
-                    //    {
-                    //        mech = XferMech.File;
-                    //    }
-                    //}
-
-                    // I don't know how this is supposed to work so it probably doesn't
-                    //this.CapSetImageFormat(args.ImageFormat);
-                    //this.CapSetImageCompression(args.ImageCompression);
-
-                    #region do xfer
-
-                    IntPtr dataPtr = IntPtr.Zero;
-                    IntPtr lockedPtr = IntPtr.Zero;
-                    string file = null;
-                    try
-                    {
-                        ReturnCode xrc = ReturnCode.Cancel;
-                        switch (mech)
-                        {
-                            case Values.XferMech.Native:
-                                xrc = DGImage.ImageNativeXfer.Get(ref dataPtr);
-                                break;
-                            case Values.XferMech.File:
-                                //xrc = DGImage.ImageFileXfer.Get();
-                                //if (File.Exists(args.OutputFile))
-                                //{
-                                //    file = args.OutputFile;
-                                //}
-                                break;
-                            case Values.XferMech.MemFile:
-                                // not supported yet
-                                //TWImageMemXfer memxfer = new TWImageMemXfer();
-                                //xrc = DGImage.ImageMemXfer.Get(memxfer);
-                                break;
-                        }
-                        if (xrc == ReturnCode.XferDone)
-                        {
-                            State = 7;
-                            if (dataPtr != IntPtr.Zero)
-                            {
-                                lockedPtr = MemoryManager.Instance.Lock(dataPtr);
-                            }
-                            OnDataTransferred(new DataTransferredEventArgs { NativeData = lockedPtr, FileDataPath = file });
-                        }
-                        //}
-                        //else if (group == DataGroups.Audio)
-                        //{
-                        //	var xrc = DGAudio.AudioNativeXfer.Get(ref dataPtr);
-                        //	if (xrc == ReturnCode.XferDone)
-                        //	{
-                        //		State = 7;
-                        //		try
-                        //		{
-                        //			var dtHand = DataTransferred;
-                        //			if (dtHand != null)
-                        //			{
-                        //				lockedPtr = MemoryManager.Instance.MemLock(dataPtr);
-                        //				dtHand(this, new DataTransferredEventArgs(lockedPtr));
-                        //			}
-                        //		}
-                        //		catch { }
-                        //	}
-                        //}
-                    }
-                    finally
-                    {
-                        State = 6;
-                        // data here is allocated by source so needs to use shared mem calls
-                        if (lockedPtr != IntPtr.Zero)
-                        {
-                            MemoryManager.Instance.Unlock(lockedPtr);
-                            lockedPtr = IntPtr.Zero;
-                        }
-                        if (dataPtr != IntPtr.Zero)
-                        {
-                            MemoryManager.Instance.Free(dataPtr);
-                            dataPtr = IntPtr.Zero;
-                        }
-                    }
-                    #endregion
-                }
-
-                if (args.CancelAll)
-                {
-                    rc = DGControl.PendingXfers.Reset(pending);
-                    if (rc == ReturnCode.Success)
-                    {
-                        // if audio exit here
-                        //if (group == DataGroups.Audio)
-                        //{
-                        //	//???
-                        //	return;
-                        //}
-
-                    }
-                }
-                else
-                {
-                    rc = DGControl.PendingXfers.EndXfer(pending);
-                }
-            } while (rc == ReturnCode.Success && pending.Count != 0);
-
-            State = 5;
-            DisableSource();
-
-        }
-
-        #region messaging use
-
-        /// <summary>
-        /// Message loop processor for winform. 
-        /// Use this by adding the <see cref="TwainSessionOld"/> as an <see cref="IMessageFilter "/>.
-        /// </summary>
-        /// <param name="m">The message to be dispatched. You cannot modify this message.</param>
-        /// <returns>
-        /// true to filter the message and stop it from being dispatched; false to allow the message to continue to the next filter or control.
-        /// </returns>
-        //[EnvironmentPermissionAttribute(SecurityAction.LinkDemand)]
-        [SecurityPermission(SecurityAction.LinkDemand, Flags = SecurityPermissionFlag.UnmanagedCode)]
-        bool IMessageFilter.PreFilterMessage(ref System.Windows.Forms.Message m)
-        {
-            var winmsg = new MESSAGE(m.HWnd, m.Msg, m.WParam, m.LParam);
-
-            return HandleWndProcMessage(ref winmsg);
-        }
-
-        /// <summary>
-        /// Message loop processor for WPF.
-        /// </summary>
-        /// <param name="hwnd">The window handle.</param>
-        /// <param name="msg">The message ID.</param>
-        /// <param name="wParam">The message's wParam value.</param>
-        /// <param name="lParam">The message's lParam value.</param>
-        /// <param name="handled">A value that indicates whether the message was handled. Set the value to true if the message was handled; otherwise, false.</param>
-        /// <returns></returns>
-        [EnvironmentPermissionAttribute(SecurityAction.LinkDemand)]
-        public IntPtr PreFilterMessage(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
-        {
-            var winmsg = new MESSAGE(hwnd, msg, wParam, lParam);
-
-            handled = base.HandleWndProcMessage(ref winmsg);
-
-            return IntPtr.Zero;
-        }
-
-        #endregion
-
-    }
-}

NTwain/TwainSessionWPF.cs

@@ -1,39 +0,0 @@
-using NTwain.Data;
-using System;
-using System.Security.Permissions;
-
-namespace NTwain
-{
-    /// <summary>
-    /// A customized TWAIN session for use in WPF environment.
-    /// Use this by using <see cref="PreFilterMessage"/> method as the target of <see cref="System.Windows.Interop.HwndSource.AddHook"/> delegate.
-    /// </summary>
-    public class TwainSessionWPF : TwainSession
-    {
-        /// <summary>
-        /// Initializes a new instance of the <see cref="TwainSessionWPF" /> class.
-        /// </summary>
-        /// <param name="appId">The app id.</param>
-        /// <exception cref="System.ArgumentNullException"></exception>
-        public TwainSessionWPF(TWIdentity appId) : base(appId) { }
-
-        /// <summary>
-        /// Message loop processor for WPF.
-        /// </summary>
-        /// <param name="hwnd">The window handle.</param>
-        /// <param name="msg">The message ID.</param>
-        /// <param name="wParam">The message's wParam value.</param>
-        /// <param name="lParam">The message's lParam value.</param>
-        /// <param name="handled">A value that indicates whether the message was handled. Set the value to true if the message was handled; otherwise, false.</param>
-        /// <returns></returns>
-        [EnvironmentPermissionAttribute(SecurityAction.LinkDemand)]
-        public IntPtr PreFilterMessage(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
-        {
-            var winmsg = new MESSAGE(hwnd, msg, wParam, lParam);
-            
-            handled = base.HandleWndProcMessage(ref winmsg);
-
-            return IntPtr.Zero;
-        }
-    }
-}

NTwain/TwainSessionWinform.cs

@@ -1,32 +0,0 @@
-using NTwain.Data;
-using System.Security.Permissions;
-using System.Windows.Forms;
-
-namespace NTwain
-{
-    /// <summary>
-    /// A customized TWAIN session for use in winform environment.
-    /// Use this by adding this as an <see cref="IMessageFilter "/> via <see cref="Application.AddMessageFilter"/>.
-    /// </summary>
-    public class TwainSessionWinform : TwainSession, IMessageFilter
-    {
-        /// <summary>
-        /// Initializes a new instance of the <see cref="TwainSessionWinform" /> class.
-        /// </summary>
-        /// <param name="appId">The app id.</param>
-        /// <exception cref="System.ArgumentNullException"></exception>
-        public TwainSessionWinform(TWIdentity appId) : base(appId) { }
-
-        #region IMessageFilter Members
-
-        [SecurityPermission(SecurityAction.LinkDemand, Flags = SecurityPermissionFlag.UnmanagedCode)]
-        public bool PreFilterMessage(ref Message m)
-        {
-            var winmsg = new MESSAGE(m.HWnd, m.Msg, m.WParam, m.LParam);
-
-            return HandleWndProcMessage(ref winmsg);
-        }
-
-        #endregion
-    }
-}

Tests/NTwain.Tests/TwainSessionTests.cs

@@ -12,7 +12,7 @@ namespace NTwain.Tests
         [ExpectedException(typeof(TwainStateException), "State check failed to throw.")]
         public void VerifyState_Throws_When_State_Is_Enforced()
         {
-            ITwainStateInternal session = new TwainSessionOld(TWIdentity.Create(DataGroups.Image, new Version(1, 0), "test", "test", "test", "test"));
+            ITwainStateInternal session = new TwainSession(TWIdentity.Create(DataGroups.Image, new Version(1, 0), "test", "test", "test", "test"));
             session.EnforceState = true;
             session.ChangeState(4, false);
 
@@ -22,7 +22,7 @@ namespace NTwain.Tests
         [TestMethod]
         public void VerifyState_No_Throws_When_State_Is_Not_Enforced()
         {
-            ITwainStateInternal session = new TwainSessionOld(TWIdentity.Create(DataGroups.Image, new Version(1, 0), "test", "test", "test", "test"));
+            ITwainStateInternal session = new TwainSession(TWIdentity.Create(DataGroups.Image, new Version(1, 0), "test", "test", "test", "test"));
             session.EnforceState = false;
             session.ChangeState(4, false);
 

Tests/Tester.Console/Program.cs

@@ -17,14 +17,9 @@ namespace Tester
     {
         static void Main(string[] args)
         {
-            // just an amusing example to do twain in console without UI, but may not work in real life
+            // just an amusing example to do twain in console without UI
-
+            DoTwainWork();
-            Console.WriteLine("Running Main on thread {0}", Thread.CurrentThread.ManagedThreadId);
+            Console.WriteLine("Test completed, press Enter to exit.");
-            new Thread(new ParameterizedThreadStart(DoTwainWork)).Start(Dispatcher.CurrentDispatcher);
-
-            // basically just needs a msg loop to act as the UI thread
-            Dispatcher.Run();
-            Console.WriteLine("Test completed.");
             Console.ReadLine();
         }
 
@@ -41,19 +36,12 @@ namespace Tester
         }
 
 
-        static void DoTwainWork(object obj)
+        static void DoTwainWork()
         {
             Console.WriteLine("Getting ready to do twain stuff on thread {0}", Thread.CurrentThread.ManagedThreadId);
             Thread.Sleep(1000);
 
-            var mySyncer = SynchronizationContext.Current;
+            var rc = twain.OpenManager();
-
-            if (mySyncer == null)
-            {
-                mySyncer = new DispatcherSynchronizationContext(obj as Dispatcher);
-            }
-
-            var rc = twain.OpenManager(IntPtr.Zero);
 
             if (rc == ReturnCode.Success)
             {
@@ -61,20 +49,13 @@ namespace Tester
 
                 if (rc == ReturnCode.Success)
                 {
-                    // enablesource must be on the thread the sync context works on
+                    rc = twain.EnableSource(SourceEnableMode.NoUI, false, IntPtr.Zero);
-                    mySyncer.Post(blah =>
-                    {
-                        rc = twain.EnableSource(SourceEnableMode.NoUI, false, IntPtr.Zero, blah as SynchronizationContext);
-                    }, mySyncer);
-                    return;
                 }
                 else
                 {
                     twain.CloseManager();
                 }
             }
-
-            Dispatcher.ExitAllFrames();
         }
 
         static void twain_SourceDisabled(object sender, EventArgs e)
@@ -82,8 +63,6 @@ namespace Tester
             Console.WriteLine("Source disabled on thread {0}", Thread.CurrentThread.ManagedThreadId);
             var rc = twain.CloseSource();
             rc = twain.CloseManager();
-
-            Dispatcher.ExitAllFrames();
         }
 
         static void twain_TransferReady(object sender, TransferReadyEventArgs e)

Tests/Tester.WPF/MainWindow.xaml.cs

@@ -68,12 +68,7 @@ namespace Tester.WPF
         {
             base.OnSourceInitialized(e);
 
-            var hwnd = new WindowInteropHelper(this).Handle;
+            var rc = _twainVM.OpenManager();
-
-            // this line is unnecessary if using twain 2 dsm but doesn't hurt to use it
-            HwndSource.FromHwnd(hwnd).AddHook(_twainVM.PreFilterMessage);
-
-            var rc = _twainVM.OpenManager(hwnd);
             if (rc == ReturnCode.Success)
             {
                 SrcList.ItemsSource = _twainVM.GetSources().Select(s => new DSVM { DS = s });

Tests/Tester.WPF/TwainVM.cs

@@ -17,7 +17,7 @@ namespace Tester.WPF
     /// <summary>
     /// Wraps the twain session as a view model for databinding.
     /// </summary>
-    class TwainVM : TwainSessionWPF
+    class TwainVM : TwainSession
     {
         public TwainVM()
             : base(TWIdentity.CreateFromAssembly(DataGroups.Image | DataGroups.Audio, Assembly.GetEntryAssembly()))
@@ -86,6 +86,8 @@ namespace Tester.WPF
         }
 
         protected override void OnDataTransferred(DataTransferredEventArgs e)
+        {
+            App.Current.Dispatcher.Invoke(new Action(() =>
             {
                 if (e.NativeData != IntPtr.Zero)
                 {
@@ -96,6 +98,7 @@ namespace Tester.WPF
                     var img = new BitmapImage(new Uri(e.FileDataPath));
                     Image = img;
                 }
+            }));
             base.OnDataTransferred(e);
         }
 
@@ -113,7 +116,7 @@ namespace Tester.WPF
                     this.CapSetImageXferMech(XferMech.File);
                 }
 
-                var rc = EnableSource(SourceEnableMode.NoUI, false, hwnd, SynchronizationContext.Current);
+                var rc = EnableSource(SourceEnableMode.NoUI, false, hwnd);
             }
         }
     }

Tests/Tester.Winform/TestForm.cs

@@ -20,7 +20,7 @@ namespace Tester.Winform
     sealed partial class TestForm : Form
     {
         ImageCodecInfo _tiffCodecInfo;
-        TwainSessionWinform _twain;
+        TwainSession _twain;
         bool _stopScan;
         bool _loadingCaps;
 
@@ -61,8 +61,10 @@ namespace Tester.Winform
         private void SetupTwain()
         {
             var appId = TWIdentity.CreateFromAssembly(DataGroups.Image, Assembly.GetEntryAssembly());
-            _twain = new TwainSessionWinform(appId);
+            _twain = new TwainSession(appId);
             _twain.DataTransferred += (s, e) =>
+            {
+                this.Invoke(new Action(() =>
                 {
                     if (pictureBox1.Image != null)
                     {
@@ -81,24 +83,26 @@ namespace Tester.Winform
                         var img = new Bitmap(e.FileDataPath);
                         pictureBox1.Image = img;
                     }
+                }));
             };
             _twain.SourceDisabled += (s, e) =>
+            {
+                this.Invoke(new Action(() =>
                 {
                     btnStopScan.Enabled = false;
                     btnStartCapture.Enabled = true;
                     panelOptions.Enabled = true;
                     LoadSourceCaps();
+                }));
             };
             _twain.TransferReady += (s, e) =>
             {
                 e.CancelAll = _stopScan;
             };
-            Application.AddMessageFilter(_twain);
         }
 
         private void CleanupTwain()
         {
-            Application.RemoveMessageFilter(_twain);
             if (_twain.State == 4)
             {
                 _twain.CloseSource();
@@ -164,7 +168,7 @@ namespace Tester.Winform
                 if (_twain.SupportedCaps.Contains(CapabilityId.CapUIControllable))
                 {
                     // hide scanner ui if possible
-                    if (_twain.EnableSource(SourceEnableMode.NoUI, false, this.Handle, SynchronizationContext.Current) == ReturnCode.Success)
+                    if (_twain.EnableSource(SourceEnableMode.NoUI, false, this.Handle) == ReturnCode.Success)
                     {
                         btnStopScan.Enabled = true;
                         btnStartCapture.Enabled = false;
@@ -173,7 +177,7 @@ namespace Tester.Winform
                 }
                 else
                 {
-                    if (_twain.EnableSource(SourceEnableMode.ShowUI, true, this.Handle, SynchronizationContext.Current) == ReturnCode.Success)
+                    if (_twain.EnableSource(SourceEnableMode.ShowUI, true, this.Handle) == ReturnCode.Success)
                     {
                         btnStopScan.Enabled = true;
                         btnStartCapture.Enabled = false;
@@ -229,7 +233,7 @@ namespace Tester.Winform
         {
             if (_twain.State < 3)
             {
-                _twain.OpenManager(this.Handle);
+                _twain.OpenManager();
             }
 
             if (_twain.State >= 3)
@@ -356,7 +360,7 @@ namespace Tester.Winform
 
         private void btnAllSettings_Click(object sender, EventArgs e)
         {
-            _twain.EnableSource(SourceEnableMode.ShowUIOnly, true, this.Handle, SynchronizationContext.Current);
+            _twain.EnableSource(SourceEnableMode.ShowUIOnly, true, this.Handle);
         }
 
         #endregion