I just love reorganizing.

samples/Console32/Program.cs

@@ -1,8 +1,8 @@
 using NTwain;
+using NTwain.Data;
 using System;
 using System.Diagnostics;
 using System.Reflection;
-using TWAINWorkingGroup;
 
 namespace SampleConsole
 {

samples/WinForm32/Form1.cs

@@ -1,10 +1,10 @@
 using NTwain;
+using NTwain.Data;
 using System;
 using System.ComponentModel;
 using System.Diagnostics;
 using System.Reflection;
 using System.Windows.Forms;
-using TWAINWorkingGroup;
 
 namespace WinForm32
 {

src/NTwain/DSM/OSXLegacyDSM.cs

@@ -1,92 +1,123 @@
-using System;
+using NTwain.Data;
+using System;
 using System.Runtime.InteropServices;
-using TWAINWorkingGroup;
 
 namespace NTwain.DSM
 {
-  static class OSXLegacyDSM
+  /// <summary>
+  /// Low-level pinvoke methods for /System/Library/Frameworks/framework/TWAIN.
+  /// </summary>
+  public static class OSXLegacyDSM
   {
     const string DsmName = "/System/Library/Frameworks/framework/TWAIN";
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_MACOSX origin, IntPtr dest,
         DG dg, DAT dat, MSG msg, ref IntPtr hwnd
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_MACOSX origin, IntPtr dest,
         DG dg, DAT dat, MSG msg, ref TW_IDENTITY_MACOSX twidentity
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_MACOSX origin, ref TW_IDENTITY_MACOSX dest,
         DG dg, DAT dat, MSG msg, ref TW_STATUS twstatus
     );
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_MACOSX origin, IntPtr dest,
         DG dg, DAT dat, MSG msg, ref TW_STATUS twstatus
     );
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_MACOSX origin, IntPtr dest,
         DG dg, DAT dat, MSG msg, ref TW_STATUSUTF8 twstatusutf8
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_MACOSX origin, IntPtr dest,
         DG dg, DAT dat, MSG msg, ref TW_ENTRYPOINT twentrypoint
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_MACOSX origin, ref TW_IDENTITY_MACOSX dest,
         DG dg, DAT dat, MSG msg, ref TW_DEVICEEVENT twdeviceevent
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_MACOSX origin, ref TW_IDENTITY_MACOSX dest,
         DG dg, DAT dat, MSG msg, ref TW_CUSTOMDSDATA twcustomedsdata
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_MACOSX origin, ref TW_IDENTITY_MACOSX dest,
         DG dg, DAT dat, MSG msg, ref TW_CALLBACK twcallback
     );
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_MACOSX origin, ref TW_IDENTITY_MACOSX dest,
         DG dg, DAT dat, MSG msg, ref TW_CALLBACK2 twcallback
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_MACOSX origin, ref TW_IDENTITY_MACOSX dest,
         DG dg, DAT dat, MSG msg, ref DG xfergroup
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_MACOSX origin, ref TW_IDENTITY_MACOSX dest,
         DG dg, DAT dat, MSG msg, ref TW_USERINTERFACE userinterface
     );
+
+    [DllImport(DsmName, CharSet = CharSet.Ansi)]
+    public static extern ushort DSM_Entry
+    (
+        ref TW_IDENTITY_MACOSX origin, ref TW_IDENTITY_MACOSX dest,
+        DG dg, DAT dat, MSG msg, ref TW_EVENT evt
+    );
+
+    [DllImport(DsmName, CharSet = CharSet.Ansi)]
+    public static extern ushort DSM_Entry
+    (
+        ref TW_IDENTITY_MACOSX origin, ref TW_IDENTITY_MACOSX dest,
+        DG dg, DAT dat, MSG msg, ref TW_PENDINGXFERS pendingxfers
+    );
+
+    [DllImport(DsmName, CharSet = CharSet.Ansi)]
+    public static extern ushort DSM_Entry
+    (
+        ref TW_IDENTITY_MACOSX origin, ref TW_IDENTITY_MACOSX dest,
+        DG dg, DAT dat, MSG msg, ref TW_SETUPMEMXFER memxfer
+    );
+
+    [DllImport(DsmName, CharSet = CharSet.Ansi)]
+    public static extern ushort DSM_Entry
+    (
+        ref TW_IDENTITY_MACOSX origin, ref TW_IDENTITY_MACOSX dest,
+        DG dg, DAT dat, MSG msg, ref TW_SETUPFILEXFER filexfer
+    );
   }
 }

src/NTwain/DSM/OSXNewDSM.cs

@@ -1,92 +1,123 @@
-using System;
+using NTwain.Data;
+using System;
 using System.Runtime.InteropServices;
-using TWAINWorkingGroup;
 
 namespace NTwain.DSM
 {
-  static class OSXNewDSM
+  /// <summary>
+  /// Low-level pinvoke methods for /Library/Frameworks/TWAINDSM.framework/TWAINDSM.
+  /// </summary>
+  public static class OSXNewDSM
   {
     const string DsmName = "/Library/Frameworks/TWAINDSM.framework/TWAINDSM";
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_MACOSX origin, IntPtr dest,
         DG dg, DAT dat, MSG msg, ref IntPtr hwnd
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_MACOSX origin, IntPtr dest,
         DG dg, DAT dat, MSG msg, ref TW_IDENTITY_MACOSX twidentity
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_MACOSX origin, ref TW_IDENTITY_MACOSX dest,
         DG dg, DAT dat, MSG msg, ref TW_STATUS twstatus
     );
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_MACOSX origin, IntPtr dest,
         DG dg, DAT dat, MSG msg, ref TW_STATUS twstatus
     );
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_MACOSX origin, IntPtr dest,
         DG dg, DAT dat, MSG msg, ref TW_STATUSUTF8 twstatusutf8
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_MACOSX origin, IntPtr dest,
         DG dg, DAT dat, MSG msg, ref TW_ENTRYPOINT twentrypoint
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_MACOSX origin, ref TW_IDENTITY_MACOSX dest,
         DG dg, DAT dat, MSG msg, ref TW_DEVICEEVENT twdeviceevent
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_MACOSX origin, ref TW_IDENTITY_MACOSX dest,
         DG dg, DAT dat, MSG msg, ref TW_CUSTOMDSDATA twcustomedsdata
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_MACOSX origin, ref TW_IDENTITY_MACOSX dest,
         DG dg, DAT dat, MSG msg, ref TW_CALLBACK twcallback
     );
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_MACOSX origin, ref TW_IDENTITY_MACOSX dest,
         DG dg, DAT dat, MSG msg, ref TW_CALLBACK2 twcallback
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_MACOSX origin, ref TW_IDENTITY_MACOSX dest,
         DG dg, DAT dat, MSG msg, ref DG xfergroup
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_MACOSX origin, ref TW_IDENTITY_MACOSX dest,
         DG dg, DAT dat, MSG msg, ref TW_USERINTERFACE userinterface
     );
+
+    [DllImport(DsmName, CharSet = CharSet.Ansi)]
+    public static extern ushort DSM_Entry
+    (
+        ref TW_IDENTITY_MACOSX origin, ref TW_IDENTITY_MACOSX dest,
+        DG dg, DAT dat, MSG msg, ref TW_EVENT evt
+    );
+
+    [DllImport(DsmName, CharSet = CharSet.Ansi)]
+    public static extern ushort DSM_Entry
+    (
+        ref TW_IDENTITY_MACOSX origin, ref TW_IDENTITY_MACOSX dest,
+        DG dg, DAT dat, MSG msg, ref TW_PENDINGXFERS pendingxfers
+    );
+
+    [DllImport(DsmName, CharSet = CharSet.Ansi)]
+    public static extern ushort DSM_Entry
+    (
+        ref TW_IDENTITY_MACOSX origin, ref TW_IDENTITY_MACOSX dest,
+        DG dg, DAT dat, MSG msg, ref TW_SETUPMEMXFER memxfer
+    );
+
+    [DllImport(DsmName, CharSet = CharSet.Ansi)]
+    public static extern ushort DSM_Entry
+    (
+        ref TW_IDENTITY_MACOSX origin, ref TW_IDENTITY_MACOSX dest,
+        DG dg, DAT dat, MSG msg, ref TW_SETUPFILEXFER filexfer
+    );
   }
 }

src/NTwain/DSM/Readme.md

@@ -0,0 +1,7 @@
+This contains the pinvoke methods for the DSM entry.
+This is the lowest API level of the lib and should not
+be used directly unless you know what you're doing. 
+
+A higher level abstraction such as the ones in the
+Triplets namespace or the TwainSession object
+would be easier to use.

src/NTwain/DSM/WinLegacyDSM.cs

@@ -1,92 +1,123 @@
-using System;
+using NTwain.Data;
+using System;
 using System.Runtime.InteropServices;
-using TWAINWorkingGroup;
 
 namespace NTwain.DSM
 {
-  static class WinLegacyDSM
+  /// <summary>
+  /// Low-level pinvoke methods for twain_32.dll.
+  /// </summary>
+  public static class WinLegacyDSM
   {
     const string DsmName = "twain_32.dll";
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_LEGACY origin, IntPtr dest,
         DG dg, DAT dat, MSG msg, ref IntPtr hwnd
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_LEGACY origin, IntPtr dest,
         DG dg, DAT dat, MSG msg, ref TW_IDENTITY_LEGACY twidentity
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_LEGACY origin, ref TW_IDENTITY_LEGACY dest,
         DG dg, DAT dat, MSG msg, ref TW_STATUS twstatus
     );
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_LEGACY origin, IntPtr dest,
         DG dg, DAT dat, MSG msg, ref TW_STATUS twstatus
     );
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_LEGACY origin, IntPtr dest,
         DG dg, DAT dat, MSG msg, ref TW_STATUSUTF8 twstatusutf8
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_LEGACY origin, IntPtr dest,
         DG dg, DAT dat, MSG msg, ref TW_ENTRYPOINT twentrypoint
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_LEGACY origin, ref TW_IDENTITY_LEGACY dest,
         DG dg, DAT dat, MSG msg, ref TW_DEVICEEVENT twdeviceevent
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_LEGACY origin, ref TW_IDENTITY_LEGACY dest,
         DG dg, DAT dat, MSG msg, ref TW_CUSTOMDSDATA twcustomedsdata
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_LEGACY origin, ref TW_IDENTITY_LEGACY dest,
         DG dg, DAT dat, MSG msg, ref TW_CALLBACK twcallback
     );
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_LEGACY origin, ref TW_IDENTITY_LEGACY dest,
         DG dg, DAT dat, MSG msg, ref TW_CALLBACK2 twcallback
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_LEGACY origin, ref TW_IDENTITY_LEGACY dest,
         DG dg, DAT dat, MSG msg, ref DG xfergroup
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_LEGACY origin, ref TW_IDENTITY_LEGACY dest,
         DG dg, DAT dat, MSG msg, ref TW_USERINTERFACE userinterface
     );
+
+    [DllImport(DsmName, CharSet = CharSet.Ansi)]
+    public static extern ushort DSM_Entry
+    (
+        ref TW_IDENTITY_LEGACY origin, ref TW_IDENTITY_LEGACY dest,
+        DG dg, DAT dat, MSG msg, ref TW_EVENT evt
+    );
+
+    [DllImport(DsmName, CharSet = CharSet.Ansi)]
+    public static extern ushort DSM_Entry
+    (
+        ref TW_IDENTITY_LEGACY origin, ref TW_IDENTITY_LEGACY dest,
+        DG dg, DAT dat, MSG msg, ref TW_PENDINGXFERS pendingxfers
+    );
+
+    [DllImport(DsmName, CharSet = CharSet.Ansi)]
+    public static extern ushort DSM_Entry
+    (
+        ref TW_IDENTITY_LEGACY origin, ref TW_IDENTITY_LEGACY dest,
+        DG dg, DAT dat, MSG msg, ref TW_SETUPMEMXFER memxfer
+    );
+
+    [DllImport(DsmName, CharSet = CharSet.Ansi)]
+    public static extern ushort DSM_Entry
+    (
+        ref TW_IDENTITY_LEGACY origin, ref TW_IDENTITY_LEGACY dest,
+        DG dg, DAT dat, MSG msg, ref TW_SETUPFILEXFER filexfer
+    );
   }
 }

src/NTwain/DSM/WinNewDSM.cs

@@ -1,92 +1,123 @@
-using System;
+using NTwain.Data;
+using System;
 using System.Runtime.InteropServices;
-using TWAINWorkingGroup;
 
 namespace NTwain.DSM
 {
-  static class WinNewDSM
+  /// <summary>
+  /// Low-level pinvoke methods for twaindsm.dll.
+  /// </summary>
+  public static class WinNewDSM
   {
     const string DsmName = "twaindsm.dll";
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_LEGACY origin, IntPtr dest,
         DG dg, DAT dat, MSG msg, ref IntPtr hwnd
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_LEGACY origin, IntPtr dest,
         DG dg, DAT dat, MSG msg, ref TW_IDENTITY_LEGACY twidentity
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_LEGACY origin, ref TW_IDENTITY_LEGACY dest,
         DG dg, DAT dat, MSG msg, ref TW_STATUS twstatus
     );
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_LEGACY origin, IntPtr dest,
         DG dg, DAT dat, MSG msg, ref TW_STATUS twstatus
     );
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_LEGACY origin, IntPtr dest,
         DG dg, DAT dat, MSG msg, ref TW_STATUSUTF8 twstatusutf8
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_LEGACY origin, IntPtr dest,
         DG dg, DAT dat, MSG msg, ref TW_ENTRYPOINT twentrypoint
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_LEGACY origin, ref TW_IDENTITY_LEGACY dest,
         DG dg, DAT dat, MSG msg, ref TW_DEVICEEVENT twdeviceevent
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_LEGACY origin, ref TW_IDENTITY_LEGACY dest,
         DG dg, DAT dat, MSG msg, ref TW_CUSTOMDSDATA twcustomedsdata
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_LEGACY origin, ref TW_IDENTITY_LEGACY dest,
         DG dg, DAT dat, MSG msg, ref TW_CALLBACK twcallback
     );
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_LEGACY origin, ref TW_IDENTITY_LEGACY dest,
         DG dg, DAT dat, MSG msg, ref TW_CALLBACK2 twcallback
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_LEGACY origin, ref TW_IDENTITY_LEGACY dest,
         DG dg, DAT dat, MSG msg, ref DG xfergroup
     );
 
     [DllImport(DsmName, CharSet = CharSet.Ansi)]
-    internal static extern ushort DSM_Entry
+    public static extern ushort DSM_Entry
     (
         ref TW_IDENTITY_LEGACY origin, ref TW_IDENTITY_LEGACY dest,
         DG dg, DAT dat, MSG msg, ref TW_USERINTERFACE userinterface
     );
+
+    [DllImport(DsmName, CharSet = CharSet.Ansi)]
+    public static extern ushort DSM_Entry
+    (
+        ref TW_IDENTITY_LEGACY origin, ref TW_IDENTITY_LEGACY dest,
+        DG dg, DAT dat, MSG msg, ref TW_EVENT evt
+    );
+
+    [DllImport(DsmName, CharSet = CharSet.Ansi)]
+    public static extern ushort DSM_Entry
+    (
+        ref TW_IDENTITY_LEGACY origin, ref TW_IDENTITY_LEGACY dest,
+        DG dg, DAT dat, MSG msg, ref TW_PENDINGXFERS pendingxfers
+    );
+
+    [DllImport(DsmName, CharSet = CharSet.Ansi)]
+    public static extern ushort DSM_Entry
+    (
+        ref TW_IDENTITY_LEGACY origin, ref TW_IDENTITY_LEGACY dest,
+        DG dg, DAT dat, MSG msg, ref TW_SETUPMEMXFER memxfer
+    );
+
+    [DllImport(DsmName, CharSet = CharSet.Ansi)]
+    public static extern ushort DSM_Entry
+    (
+        ref TW_IDENTITY_LEGACY origin, ref TW_IDENTITY_LEGACY dest,
+        DG dg, DAT dat, MSG msg, ref TW_SETUPFILEXFER filexfer
+    );
   }
 }

src/NTwain/Data/README.md

@@ -0,0 +1,11 @@
+This namespace contains types and utilities that were modified 
+from the [twaincs project](https://github.com/twain/twain-cs).
+
+Version initially used is 2.5.0.0.
+
+I just couldn't trust myself with making correct struct definitions
+so used those instead.
+
+The TWAINH.cs file are minimally modified so they could be updated
+easily should I need to. Most modifications are added in
+TWAINH_EXTRAS.cs.

src/NTwain/Data/TWAINH.cs

@@ -46,7 +46,7 @@ using System.Diagnostics.CodeAnalysis;
 using System.Runtime.InteropServices;
 using System.Text;
 
-namespace TWAINWorkingGroup
+namespace NTwain.Data
 {
   ///// <summary>
   ///// This file contains content gleaned from version 2.4 of the C/C++ H

src/NTwain/Data/TWAINH_EXTRAS.cs

@@ -4,9 +4,9 @@ using System.Globalization;
 using System.Runtime.InteropServices;
 using System.Text;
 
-namespace TWAINWorkingGroup
+namespace NTwain.Data
 {
-  // this contains my additions under the TWAINWorkingGroup namespace
+  // this contains my additions 
   // that makes some twain types easier to work with.
 
   /// <summary>

src/NTwain/NTwain.csproj

@@ -1,15 +1,18 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
-	<PropertyGroup>
-		<PackageId>NTwain</PackageId>
-		<Description>Library containing the TWAIN API for dotnet.</Description>
-		<TargetFrameworks>net6.0;net462;</TargetFrameworks>
+  <PropertyGroup>
+    <PackageId>NTwain</PackageId>
+    <Description>Library containing the TWAIN API for dotnet.</Description>
+    <TargetFrameworks>net6.0;net6.0-windows;net462;</TargetFrameworks>
     <Nullable>enable</Nullable>
-		<AllowUnsafeBlocks>true</AllowUnsafeBlocks>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
 
+  <PropertyGroup Condition=" '$(TargetFramework)' == 'net462' OR '$(TargetFramework)' == 'net6.0-windows'">
+    <UseWPF>true</UseWPF>
+  </PropertyGroup>
 
-	<ItemGroup>
+  <ItemGroup>
     <PackageReference Include="System.Text.Encoding.CodePages" Version="7.0.0" />
-	</ItemGroup>
+  </ItemGroup>
 </Project>

src/NTwain/TWAINWorkingGroup/NativeMethods.cs

@@ -41,6 +41,7 @@
 //  DEALINGS IN THE SOFTWARE.
 ///////////////////////////////////////////////////////////////////////////////////////
 
+using NTwain.Data;
 using System;
 using System.Diagnostics.CodeAnalysis;
 using System.Runtime.InteropServices;

src/NTwain/TWAINWorkingGroup/README.md

@@ -1,4 +0,0 @@
-This namespace contains types and utilities that were modified 
-from the [twaincs project](https://github.com/twain/twain-cs).
-
-Version initially used is 2.5.0.0.

src/NTwain/Triplets/ControlDATs/Callback.cs

@@ -1,5 +1,5 @@
-using NTwain.DSM;
-using TWAINWorkingGroup;
+using NTwain.Data;
+using NTwain.DSM;
 
 namespace NTwain.Triplets.ControlDATs
 {
@@ -8,11 +8,6 @@ namespace NTwain.Triplets.ControlDATs
   /// </summary>
   public class Callback
   {
-    /// <summary>
-    /// Registers the callback function.
-    /// </summary>
-    /// <param name="data"></param>
-    /// <returns></returns>
     public STS RegisterCallback(ref TW_IDENTITY_LEGACY app, ref TW_IDENTITY_LEGACY ds, ref TW_CALLBACK data)
     {
       var rc = STS.FAILURE;

src/NTwain/Triplets/ControlDATs/Callback2.cs

@@ -1,5 +1,5 @@
-using NTwain.DSM;
-using TWAINWorkingGroup;
+using NTwain.Data;
+using NTwain.DSM;
 
 namespace NTwain.Triplets.ControlDATs
 {
@@ -8,11 +8,6 @@ namespace NTwain.Triplets.ControlDATs
   /// </summary>
   public class Callback2
   {
-    /// <summary>
-    /// Registers the callback function.
-    /// </summary>
-    /// <param name="data"></param>
-    /// <returns></returns>
     public STS RegisterCallback(ref TW_IDENTITY_LEGACY app, ref TW_IDENTITY_LEGACY ds, ref TW_CALLBACK2 data)
     {
       var rc = STS.FAILURE;

src/NTwain/Triplets/ControlDATs/CustomDsData.cs

@@ -1,5 +1,5 @@
-using NTwain.DSM;
-using TWAINWorkingGroup;
+using NTwain.Data;
+using NTwain.DSM;
 
 namespace NTwain.Triplets.ControlDATs
 {
@@ -8,22 +8,12 @@ namespace NTwain.Triplets.ControlDATs
   /// </summary>
   public class CustomDsData
   {
-    /// <summary>
-    /// Loads the custom DS data.
-    /// </summary>
-    /// <param name="data"></param>
-    /// <returns></returns>
     public STS Get(ref TW_IDENTITY_LEGACY app, ref TW_IDENTITY_LEGACY ds, out TW_CUSTOMDSDATA data)
     {
       data = default;
       return DoIt(ref app, ref ds, MSG.GET, ref data);
     }
 
-    /// <summary>
-    /// Sets the custom DS data.
-    /// </summary>
-    /// <param name="data"></param>
-    /// <returns></returns>
     public STS Set(ref TW_IDENTITY_LEGACY app, ref TW_IDENTITY_LEGACY ds, ref TW_CUSTOMDSDATA data)
       => DoIt(ref app, ref ds, MSG.SET, ref data);
 

src/NTwain/Triplets/ControlDATs/DeviceEvent.cs

@@ -1,5 +1,5 @@
-using NTwain.DSM;
-using TWAINWorkingGroup;
+using NTwain.Data;
+using NTwain.DSM;
 
 namespace NTwain.Triplets.ControlDATs
 {
@@ -16,21 +16,16 @@ namespace NTwain.Triplets.ControlDATs
     public STS Get(ref TW_IDENTITY_LEGACY app, ref TW_IDENTITY_LEGACY ds, out TW_DEVICEEVENT data)
     {
       data = default;
-      return DoIt(ref app, ref ds, MSG.GET, ref data);
-    }
-
-    static STS DoIt(ref TW_IDENTITY_LEGACY app, ref TW_IDENTITY_LEGACY ds, MSG msg, ref TW_DEVICEEVENT data)
-    {
       var rc = STS.FAILURE;
       if (TwainPlatform.IsWindows)
       {
         if (TwainPlatform.Is32bit && TwainPlatform.PreferLegacyDSM)
         {
-          rc = (STS)WinLegacyDSM.DSM_Entry(ref app, ref ds, DG.CONTROL, DAT.DEVICEEVENT, msg, ref data);
+          rc = (STS)WinLegacyDSM.DSM_Entry(ref app, ref ds, DG.CONTROL, DAT.DEVICEEVENT, MSG.GET, ref data);
         }
         else
         {
-          rc = (STS)WinNewDSM.DSM_Entry(ref app, ref ds, DG.CONTROL, DAT.DEVICEEVENT, msg, ref data);
+          rc = (STS)WinNewDSM.DSM_Entry(ref app, ref ds, DG.CONTROL, DAT.DEVICEEVENT, MSG.GET, ref data);
         }
       }
       else if (TwainPlatform.IsMacOSX)
@@ -39,11 +34,11 @@ namespace NTwain.Triplets.ControlDATs
         TW_IDENTITY_MACOSX ds2 = ds;
         if (TwainPlatform.PreferLegacyDSM)
         {
-          rc = (STS)OSXLegacyDSM.DSM_Entry(ref app2, ref ds2, DG.CONTROL, DAT.DEVICEEVENT, msg, ref data);
+          rc = (STS)OSXLegacyDSM.DSM_Entry(ref app2, ref ds2, DG.CONTROL, DAT.DEVICEEVENT, MSG.GET, ref data);
         }
         else
         {
-          rc = (STS)OSXNewDSM.DSM_Entry(ref app2, ref ds2, DG.CONTROL, DAT.DEVICEEVENT, msg, ref data);
+          rc = (STS)OSXNewDSM.DSM_Entry(ref app2, ref ds2, DG.CONTROL, DAT.DEVICEEVENT, MSG.GET, ref data);
         }
       }
       return rc;

src/NTwain/Triplets/ControlDATs/EntryPoint.cs

@@ -1,7 +1,7 @@
-using NTwain.DSM;
+using NTwain.Data;
+using NTwain.DSM;
 using System;
 using System.Runtime.InteropServices;
-using TWAINWorkingGroup;
 
 namespace NTwain.Triplets.ControlDATs
 {
@@ -10,11 +10,6 @@ namespace NTwain.Triplets.ControlDATs
   /// </summary>
   public class EntryPoint
   {
-    /// <summary>
-    /// Loads and opens the DSM.
-    /// </summary>
-    /// <param name="entry"></param>
-    /// <returns></returns>
     public STS Get(ref TW_IDENTITY_LEGACY app, out TW_ENTRYPOINT_DELEGATES entry)
     {
       entry = default;

src/NTwain/Triplets/ControlDATs/Event.cs

@@ -0,0 +1,41 @@
+using NTwain.Data;
+using NTwain.DSM;
+
+namespace NTwain.Triplets.ControlDATs
+{
+  /// <summary>
+  /// Contains calls used with <see cref="DG.CONTROL"/> and <see cref="DAT.EVENT"/>.
+  /// </summary>
+  public class Event
+  {
+    public STS ProcessEvent(ref TW_IDENTITY_LEGACY app, ref TW_IDENTITY_LEGACY ds, ref TW_EVENT data)
+    {
+      var rc = STS.FAILURE;
+      if (TwainPlatform.IsWindows)
+      {
+        if (TwainPlatform.Is32bit && TwainPlatform.PreferLegacyDSM)
+        {
+          rc = (STS)WinLegacyDSM.DSM_Entry(ref app, ref ds, DG.CONTROL, DAT.DEVICEEVENT, MSG.PROCESSEVENT, ref data);
+        }
+        else
+        {
+          rc = (STS)WinNewDSM.DSM_Entry(ref app, ref ds, DG.CONTROL, DAT.DEVICEEVENT, MSG.PROCESSEVENT, ref data);
+        }
+      }
+      else if (TwainPlatform.IsMacOSX)
+      {
+        TW_IDENTITY_MACOSX app2 = app;
+        TW_IDENTITY_MACOSX ds2 = ds;
+        if (TwainPlatform.PreferLegacyDSM)
+        {
+          rc = (STS)OSXLegacyDSM.DSM_Entry(ref app2, ref ds2, DG.CONTROL, DAT.DEVICEEVENT, MSG.PROCESSEVENT, ref data);
+        }
+        else
+        {
+          rc = (STS)OSXNewDSM.DSM_Entry(ref app2, ref ds2, DG.CONTROL, DAT.DEVICEEVENT, MSG.PROCESSEVENT, ref data);
+        }
+      }
+      return rc;
+    }
+  }
+}

src/NTwain/Triplets/ControlDATs/Identity.cs

@@ -1,6 +1,6 @@
-using NTwain.DSM;
+using NTwain.Data;
+using NTwain.DSM;
 using System;
-using TWAINWorkingGroup;
 
 namespace NTwain.Triplets.ControlDATs
 {
@@ -9,18 +9,9 @@ namespace NTwain.Triplets.ControlDATs
   /// </summary>
   public class Identity
   {
-    /// <summary>
-    /// Loads and opens the specified data source.
-    /// </summary>
-    /// <param name="ds"></param>
-    /// <returns></returns>
     public STS OpenDS(ref TW_IDENTITY_LEGACY app, ref TW_IDENTITY_LEGACY ds)
       => DoIt(ref app, MSG.OPENDS, ref ds);
 
-    /// <summary>
-    /// Closes the currently open data source.
-    /// </summary>
-    /// <returns></returns>
     public STS CloseDS(ref TW_IDENTITY_LEGACY app, ref TW_IDENTITY_LEGACY ds)
       => DoIt(ref app, MSG.CLOSEDS, ref ds);
 
@@ -35,11 +26,6 @@ namespace NTwain.Triplets.ControlDATs
       return DoIt(ref app, MSG.USERSELECT, ref ds);
     }
 
-    /// <summary>
-    /// Gets the default data source.
-    /// </summary>
-    /// <param name="ds"></param>
-    /// <returns></returns>
     public STS GetDefault(ref TW_IDENTITY_LEGACY app, out TW_IDENTITY_LEGACY ds)
     {
       ds = default;

src/NTwain/Triplets/ControlDATs/Parent.cs

@@ -1,6 +1,6 @@
-using NTwain.DSM;
+using NTwain.Data;
+using NTwain.DSM;
 using System;
-using TWAINWorkingGroup;
 
 namespace NTwain.Triplets.ControlDATs
 {

src/NTwain/Triplets/ControlDATs/PendingXfers.cs

@@ -0,0 +1,51 @@
+using NTwain.Data;
+using NTwain.DSM;
+
+namespace NTwain.Triplets.ControlDATs
+{
+  /// <summary>
+  /// Contains calls used with <see cref="DG.CONTROL"/> and <see cref="DAT.PENDINGXFERS"/>.
+  /// </summary>
+  public class PendingXfers
+  {
+    public STS EndXfer(ref TW_IDENTITY_LEGACY app, ref TW_IDENTITY_LEGACY ds, ref TW_PENDINGXFERS data)
+      => DoIt(ref app, ref ds, MSG.ENDXFER, ref data);
+    public STS Get(ref TW_IDENTITY_LEGACY app, ref TW_IDENTITY_LEGACY ds, ref TW_PENDINGXFERS data)
+      => DoIt(ref app, ref ds, MSG.GET, ref data);
+    public STS Reset(ref TW_IDENTITY_LEGACY app, ref TW_IDENTITY_LEGACY ds, ref TW_PENDINGXFERS data)
+      => DoIt(ref app, ref ds, MSG.RESET, ref data);
+    public STS StopFeeder(ref TW_IDENTITY_LEGACY app, ref TW_IDENTITY_LEGACY ds, ref TW_PENDINGXFERS data)
+      => DoIt(ref app, ref ds, MSG.STOPFEEDER, ref data);
+
+
+    static STS DoIt(ref TW_IDENTITY_LEGACY app, ref TW_IDENTITY_LEGACY ds, MSG msg, ref TW_PENDINGXFERS data)
+    {
+      var rc = STS.FAILURE;
+      if (TwainPlatform.IsWindows)
+      {
+        if (TwainPlatform.Is32bit && TwainPlatform.PreferLegacyDSM)
+        {
+          rc = (STS)WinLegacyDSM.DSM_Entry(ref app, ref ds, DG.CONTROL, DAT.DEVICEEVENT, msg, ref data);
+        }
+        else
+        {
+          rc = (STS)WinNewDSM.DSM_Entry(ref app, ref ds, DG.CONTROL, DAT.DEVICEEVENT, msg, ref data);
+        }
+      }
+      else if (TwainPlatform.IsMacOSX)
+      {
+        TW_IDENTITY_MACOSX app2 = app;
+        TW_IDENTITY_MACOSX ds2 = ds;
+        if (TwainPlatform.PreferLegacyDSM)
+        {
+          rc = (STS)OSXLegacyDSM.DSM_Entry(ref app2, ref ds2, DG.CONTROL, DAT.DEVICEEVENT, msg, ref data);
+        }
+        else
+        {
+          rc = (STS)OSXNewDSM.DSM_Entry(ref app2, ref ds2, DG.CONTROL, DAT.DEVICEEVENT, msg, ref data);
+        }
+      }
+      return rc;
+    }
+  }
+}

src/NTwain/Triplets/ControlDATs/SetupFileXfer.cs

@@ -0,0 +1,51 @@
+using NTwain.Data;
+using NTwain.DSM;
+
+namespace NTwain.Triplets.ControlDATs
+{
+  /// <summary>
+  /// Contains calls used with <see cref="DG.SetupMemXfer"/> and <see cref="DAT.SETUPFILEXFER"/>.
+  /// </summary>
+  public class SetupFileXfer
+  {
+    public STS Get(ref TW_IDENTITY_LEGACY app, ref TW_IDENTITY_LEGACY ds, ref TW_SETUPFILEXFER data)
+      => DoIt(ref app, ref ds, MSG.GET, ref data);
+    public STS Set(ref TW_IDENTITY_LEGACY app, ref TW_IDENTITY_LEGACY ds, ref TW_SETUPFILEXFER data)
+      => DoIt(ref app, ref ds, MSG.SET, ref data);
+    public STS GetDefault(ref TW_IDENTITY_LEGACY app, ref TW_IDENTITY_LEGACY ds, ref TW_SETUPFILEXFER data)
+      => DoIt(ref app, ref ds, MSG.GETDEFAULT, ref data);
+    public STS Reset(ref TW_IDENTITY_LEGACY app, ref TW_IDENTITY_LEGACY ds, ref TW_SETUPFILEXFER data)
+      => DoIt(ref app, ref ds, MSG.RESET, ref data);
+
+
+    static STS DoIt(ref TW_IDENTITY_LEGACY app, ref TW_IDENTITY_LEGACY ds, MSG msg, ref TW_SETUPFILEXFER data)
+    {
+      var rc = STS.FAILURE;
+      if (TwainPlatform.IsWindows)
+      {
+        if (TwainPlatform.Is32bit && TwainPlatform.PreferLegacyDSM)
+        {
+          rc = (STS)WinLegacyDSM.DSM_Entry(ref app, ref ds, DG.CONTROL, DAT.DEVICEEVENT, msg, ref data);
+        }
+        else
+        {
+          rc = (STS)WinNewDSM.DSM_Entry(ref app, ref ds, DG.CONTROL, DAT.DEVICEEVENT, msg, ref data);
+        }
+      }
+      else if (TwainPlatform.IsMacOSX)
+      {
+        TW_IDENTITY_MACOSX app2 = app;
+        TW_IDENTITY_MACOSX ds2 = ds;
+        if (TwainPlatform.PreferLegacyDSM)
+        {
+          rc = (STS)OSXLegacyDSM.DSM_Entry(ref app2, ref ds2, DG.CONTROL, DAT.DEVICEEVENT, msg, ref data);
+        }
+        else
+        {
+          rc = (STS)OSXNewDSM.DSM_Entry(ref app2, ref ds2, DG.CONTROL, DAT.DEVICEEVENT, msg, ref data);
+        }
+      }
+      return rc;
+    }
+  }
+}

src/NTwain/Triplets/ControlDATs/SetupMemXfer.cs

@@ -0,0 +1,41 @@
+using NTwain.Data;
+using NTwain.DSM;
+
+namespace NTwain.Triplets.ControlDATs
+{
+  /// <summary>
+  /// Contains calls used with <see cref="DG.SetupMemXfer"/> and <see cref="DAT.SETUPMEMXFER"/>.
+  /// </summary>
+  public class SetupMemXfer
+  {
+    public STS Get(ref TW_IDENTITY_LEGACY app, ref TW_IDENTITY_LEGACY ds, ref TW_SETUPMEMXFER data)
+    {
+      var rc = STS.FAILURE;
+      if (TwainPlatform.IsWindows)
+      {
+        if (TwainPlatform.Is32bit && TwainPlatform.PreferLegacyDSM)
+        {
+          rc = (STS)WinLegacyDSM.DSM_Entry(ref app, ref ds, DG.CONTROL, DAT.DEVICEEVENT, MSG.GET, ref data);
+        }
+        else
+        {
+          rc = (STS)WinNewDSM.DSM_Entry(ref app, ref ds, DG.CONTROL, DAT.DEVICEEVENT, MSG.GET, ref data);
+        }
+      }
+      else if (TwainPlatform.IsMacOSX)
+      {
+        TW_IDENTITY_MACOSX app2 = app;
+        TW_IDENTITY_MACOSX ds2 = ds;
+        if (TwainPlatform.PreferLegacyDSM)
+        {
+          rc = (STS)OSXLegacyDSM.DSM_Entry(ref app2, ref ds2, DG.CONTROL, DAT.DEVICEEVENT, MSG.GET, ref data);
+        }
+        else
+        {
+          rc = (STS)OSXNewDSM.DSM_Entry(ref app2, ref ds2, DG.CONTROL, DAT.DEVICEEVENT, MSG.GET, ref data);
+        }
+      }
+      return rc;
+    }
+  }
+}

src/NTwain/Triplets/ControlDATs/Status.cs

@@ -1,6 +1,6 @@
-using NTwain.DSM;
+using NTwain.Data;
+using NTwain.DSM;
 using System;
-using TWAINWorkingGroup;
 
 namespace NTwain.Triplets.ControlDATs
 {

src/NTwain/Triplets/ControlDATs/StatusUtf8.cs

@@ -1,6 +1,6 @@
-using NTwain.DSM;
+using NTwain.Data;
+using NTwain.DSM;
 using System;
-using TWAINWorkingGroup;
 
 namespace NTwain.Triplets.ControlDATs
 {

src/NTwain/Triplets/ControlDATs/UserInterface.cs

@@ -1,5 +1,5 @@
-using NTwain.DSM;
-using TWAINWorkingGroup;
+using NTwain.Data;
+using NTwain.DSM;
 
 namespace NTwain.Triplets.ControlDATs
 {
@@ -8,27 +8,12 @@ namespace NTwain.Triplets.ControlDATs
   /// </summary>
   public class UserInterface
   {
-    /// <summary>
-    /// Disables source to bring state down to <see cref="STATE.S4"/>.
-    /// </summary>
-    /// <param name="data"></param>
-    /// <returns></returns>
     public STS DisableDS(ref TW_IDENTITY_LEGACY app, ref TW_IDENTITY_LEGACY ds, ref TW_USERINTERFACE data)
       => DoIt(ref app, ref ds, MSG.DISABLEDS, ref data);
 
-    /// <summary>
-    /// Enables source to bring state up to <see cref="STATE.S5"/>.
-    /// </summary>
-    /// <param name="data"></param>
-    /// <returns></returns>
     public STS EnableDS(ref TW_IDENTITY_LEGACY app, ref TW_IDENTITY_LEGACY ds, ref TW_USERINTERFACE data)
       => DoIt(ref app, ref ds, MSG.ENABLEDS, ref data);
 
-    /// <summary>
-    /// Enables source to bring state up to <see cref="STATE.S5"/>.
-    /// </summary>
-    /// <param name="data"></param>
-    /// <returns></returns>
     public STS EnableDSUIOnly(ref TW_IDENTITY_LEGACY app, ref TW_IDENTITY_LEGACY ds, ref TW_USERINTERFACE data)
       => DoIt(ref app, ref ds, MSG.ENABLEDSUIONLY, ref data);
 

src/NTwain/Triplets/ControlDATs/XferGroup.cs

@@ -1,5 +1,5 @@
-using NTwain.DSM;
-using TWAINWorkingGroup;
+using NTwain.Data;
+using NTwain.DSM;
 
 namespace NTwain.Triplets.ControlDATs
 {

src/NTwain/Triplets/DGAudio.cs

@@ -3,9 +3,9 @@
 namespace NTwain.Triplets
 {
   /// <summary>
-  /// Contains calls used with <see cref="DG.AUDIO"/>.
+  /// Contains triplet calls starting with <see cref="DG.AUDIO"/>.
   /// </summary>
-  public class DGAudio
+  public static class DGAudio
   {
   }
 }

src/NTwain/Triplets/DGControl.cs

@@ -3,42 +3,35 @@
 namespace NTwain.Triplets
 {
   /// <summary>
-  /// Contains calls used with <see cref="DG.CONTROL"/>.
+  /// Contains triplet calls starting with <see cref="DG.CONTROL"/>.
   /// </summary>
-  public class DGControl
+  public static class DGControl
   {
-    private Parent? _parent;
-    public Parent Parent => _parent ??= new Parent();
+    public static readonly Parent Parent = new();
 
-    private EntryPoint? _entryPoint;
-    public EntryPoint EntryPoint => _entryPoint ??= new EntryPoint();
+    public static readonly EntryPoint EntryPoint = new();
 
-    private Identity? _identity;
-    public Identity Identity => _identity ??= new Identity();
+    public static readonly Identity Identity = new();
 
-    private Status? _status;
-    public Status Status => _status ??= new Status();
+    public static readonly Status Status = new();
 
-    private StatusUtf8? _statusUtf8;
-    public StatusUtf8 StatusUtf8 => _statusUtf8 ??= new StatusUtf8();
+    public static readonly StatusUtf8 StatusUtf8 = new();
 
-    private CustomDsData? _customDsData;
-    public CustomDsData CustomDsData => _customDsData ??= new CustomDsData();
+    public static readonly CustomDsData CustomDsData = new();
 
-    private DeviceEvent? _deviceEvent;
-    public DeviceEvent DeviceEvent => _deviceEvent ??= new DeviceEvent();
+    public static readonly DeviceEvent DeviceEvent = new();
 
-    private Callback? _callback;
-    public Callback Callback => _callback ??= new Callback();
+    public static readonly Callback Callback = new();
 
-    private Callback2? _callback2;
-    public Callback2 Callback2 => _callback2 ??= new Callback2();
+    public static readonly Callback2 Callback2 = new();
 
-    private XferGroup? _xferGroup;
-    public XferGroup XferGroup => _xferGroup ??= new XferGroup();
+    public static readonly XferGroup XferGroup = new();
 
-    private UserInterface? _userInterface;
-    public UserInterface UserInterface => _userInterface ??= new UserInterface();
+    public static readonly UserInterface UserInterface = new();
+
+    public static readonly Event Event = new();
+
+    public static readonly PendingXfers PendingXfers = new();
 
   }
 }

src/NTwain/Triplets/DGImage.cs

@@ -3,9 +3,9 @@
 namespace NTwain.Triplets
 {
   /// <summary>
-  /// Contains calls used with <see cref="DG.IMAGE"/>.
+  /// Contains triplet calls starting with <see cref="DG.IMAGE"/>.
   /// </summary>
-  public class DGImage
+  public static class DGImage
   {
   }
 }

src/NTwain/Triplets/Readme.md

@@ -1,9 +1,8 @@
 All TWAIN operations are done through the a combination of 
 Data Group (DG), Data Argument Type (DAT), and Message (MSG) 
-triplets. Rather than letting consumers of this lib deal 
-with all the combinations themselves and risk passing the 
-wrong thing, all valid triplet combinations are simply 
-made available under this namespace.
+triplets. Rather than dealing with all the combinations 
+directly and risk passing the wrong thing, all valid triplet 
+combinations are simply made available under this namespace.
 
 Example:
 To get the status of the DS, just use the 
@@ -18,5 +17,5 @@ DGControl.Status.Get(...)
 Only triplets usable by the
 application-side are defined here.
 
-Due to the number of things involved, the properties are 
-lazy-loaded until used.
+These are still low-level calls and TwainSession is the higher
+level abstraction with some state keeping and other checks for ease of use.

src/NTwain/TwainSession.Callbacks.cs

@@ -1,4 +1,6 @@
-using System;
+using NTwain.Data;
+using NTwain.Triplets;
+using System;
 using System.Diagnostics;
 using System.Runtime.InteropServices;
 using TWAINWorkingGroup;

src/NTwain/TwainSession.Memory.cs

@@ -1,4 +1,5 @@
-using System;
+using NTwain.Data;
+using System;
 using System.Runtime.InteropServices;
 using TWAINWorkingGroup;
 

src/NTwain/TwainSession.PropEvents.cs

@@ -1,7 +1,7 @@
-using NTwain.Triplets;
+using NTwain.Data;
+using NTwain.Triplets;
 using System;
 using System.Runtime.InteropServices;
-using TWAINWorkingGroup;
 
 namespace NTwain
 {
@@ -116,22 +116,6 @@ namespace NTwain
     }
 
 
-    /// <summary>
-    /// TWAIN triplet API calls with <see cref="DG.CONTROL"/>.
-    /// </summary>
-    public DGControl DGControl { get; }
-    /// <summary>
-    /// TWAIN triplet API calls with <see cref="DG.IMAGE"/>.
-    /// </summary>
-    public DGImage DGImage { get; }
-    /// <summary>
-    /// TWAIN triplet API calls with <see cref="DG.AUDIO"/>.
-    /// </summary>
-    public DGAudio DGAudio { get; }
-
-
-
-
     /// <summary>
     /// Fires when <see cref="State"/> changes.
     /// </summary>

src/NTwain/TwainSession.Sources.cs

@@ -1,6 +1,6 @@
-using NTwain.Triplets;
+using NTwain.Data;
+using NTwain.Triplets;
 using System.Collections.Generic;
-using TWAINWorkingGroup;
 
 namespace NTwain
 {
@@ -34,6 +34,10 @@ namespace NTwain
       }
     }
 
+    /// <summary>
+    /// Loads and opens the specified data source.
+    /// </summary>
+    /// <param name="source"></param>
     public void OpenSource(TW_IDENTITY_LEGACY source)
     {
       if (DGControl.Identity.OpenDS(ref _appIdentity, ref source) == STS.SUCCESS)
@@ -44,6 +48,9 @@ namespace NTwain
       }
     }
 
+    /// <summary>
+    /// Closes the currently open data source.
+    /// </summary>
     public void CloseSource()
     {
       if (DGControl.Identity.CloseDS(ref _appIdentity, ref _currentDS) == STS.SUCCESS)
@@ -53,8 +60,15 @@ namespace NTwain
       }
     }
 
+    /// <summary>
+    /// Sets the default data source.
+    /// </summary>
+    /// <param name="source"></param>
+    /// <returns></returns>
     public STS SetDefaultSource(TW_IDENTITY_LEGACY source)
     {
+      // TODO: this doesn't work???
+
       var rc = DGControl.Identity.Set(ref _appIdentity, ref source);
       if (rc == STS.SUCCESS)
       {

src/NTwain/TwainSession.cs

@@ -1,4 +1,5 @@
-using NTwain.Triplets;
+using NTwain.Data;
+using NTwain.Triplets;
 using System;
 using System.Diagnostics;
 using System.Text;
@@ -77,10 +78,6 @@ namespace NTwain
         }
       };
 
-      DGControl = new DGControl();
-      DGImage = new DGImage();
-      DGAudio = new DGAudio();
-
       _legacyCallbackDelegate = LegacyCallbackHandler;
       _osxCallbackDelegate = OSXCallbackHandler;
     }