Extracted used parts of nativemethods.

src/NTwain/NTwain.csproj

@@ -5,10 +5,11 @@
     <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'">
+    <UseWindowsForms>true</UseWindowsForms>
     <UseWPF>true</UseWPF>
   </PropertyGroup>
 
@@ -27,8 +28,4 @@
       <LastGenOutput>DSMGenerator.dummy</LastGenOutput>
     </None>
   </ItemGroup>
-
-  <ItemGroup>
-    <Service Include="{508349b6-6b84-4df5-91f0-309beebad82d}" />
-  </ItemGroup>
 </Project>

src/NTwain/Native/MemoryMgmt.cs

@@ -0,0 +1,41 @@
+using System;
+using System.Runtime.InteropServices;
+
+namespace NTwain.Native
+{
+  static class NativeMemoryMethods
+  {
+    [DllImport("kernel32", SetLastError = true, EntryPoint = "GlobalAlloc")]
+    public static extern IntPtr WinGlobalAlloc(AllocFlag uFlags, UIntPtr dwBytes);
+
+    [DllImport("kernel32", SetLastError = true, EntryPoint = "GlobalFree")]
+    public static extern IntPtr WinGlobalFree(IntPtr hMem);
+
+    [DllImport("kernel32", SetLastError = true, EntryPoint = "GlobalLock")]
+    public static extern IntPtr WinGlobalLock(IntPtr handle);
+
+    [DllImport("kernel32", SetLastError = true, EntryPoint = "GlobalUnlock")]
+    [return: MarshalAs(UnmanagedType.Bool)]
+    public static extern bool WinGlobalUnlock(IntPtr handle);
+
+    [Flags]
+    public enum AllocFlag : uint
+    {
+      /// <summary>
+      /// Allocates fixed memory. The return value is a pointer.
+      /// </summary>
+      GMEM_FIXED = 0,
+      /// <summary>
+      /// Allocates movable memory. Memory blocks are never moved in physical memory, but they can be moved within the default heap.
+      /// The return value is a handle to the memory object. To translate the handle into a pointer, use the GlobalLock function.
+      /// </summary>
+      GMEM_MOVEABLE = 2,
+      /// <summary>
+      /// Initializes memory contents to zero.
+      /// </summary>
+      GMEM_ZEROINIT = 0x40,
+      GPTR = GMEM_FIXED | GMEM_ZEROINIT,
+      GHND = GMEM_MOVEABLE | GMEM_ZEROINIT
+    }
+  }
+}

src/NTwain/TwainSession.Callbacks.cs

@@ -3,7 +3,6 @@ using NTwain.Triplets;
 using System;
 using System.Diagnostics;
 using System.Runtime.InteropServices;
-using TWAINWorkingGroup;
 
 namespace NTwain
 {
@@ -11,10 +10,26 @@ namespace NTwain
 
   partial class TwainSession
   {
+
+    delegate ushort LegacyIDCallbackDelegate(
+      ref TW_IDENTITY_LEGACY origin, ref TW_IDENTITY_LEGACY dest,
+        DG dg, DAT dat, MSG msg, IntPtr twnull
+    );
+    delegate ushort BotchedLinuxCallbackDelegate
+    (
+        ref TW_IDENTITY origin, ref TW_IDENTITY dest,
+        DG dg, DAT dat, MSG msg, IntPtr twnull
+    );
+    delegate ushort OSXCallbackDelegate
+    (
+        ref TW_IDENTITY_MACOSX origin, ref TW_IDENTITY_MACOSX dest,
+        DG dg, DAT dat, MSG msg, IntPtr twnull
+    );
+
     // these are kept around while a callback ptr is registered so they
     // don't get gc'd
-    readonly NativeMethods.WindowsDsmEntryCallbackDelegate _legacyCallbackDelegate;
-    readonly NativeMethods.MacosxDsmEntryCallbackDelegate _osxCallbackDelegate;
+    readonly LegacyIDCallbackDelegate _legacyCallbackDelegate;
+    readonly OSXCallbackDelegate _osxCallbackDelegate;
 
     /// <summary>
     /// Try to registers callbacks for after opening the source.
@@ -50,12 +65,8 @@ namespace NTwain
 
     private ushort LegacyCallbackHandler
     (
-        ref TW_IDENTITY_LEGACY origin,
-        ref TW_IDENTITY_LEGACY dest,
-        DG dg,
-        DAT dat,
-        MSG msg,
-        IntPtr twnull
+        ref TW_IDENTITY_LEGACY origin, ref TW_IDENTITY_LEGACY dest,
+        DG dg, DAT dat, MSG msg, IntPtr twnull
     )
     {
       Debug.WriteLine($"Legacy callback got {msg}");
@@ -65,12 +76,8 @@ namespace NTwain
 
     private ushort OSXCallbackHandler
     (
-        ref TW_IDENTITY_MACOSX origin,
-        ref TW_IDENTITY_MACOSX dest,
-        DG dg,
-        DAT dat,
-        MSG msg,
-        IntPtr twnull
+        ref TW_IDENTITY_MACOSX origin, ref TW_IDENTITY_MACOSX dest,
+        DG dg, DAT dat, MSG msg, IntPtr twnull
     )
     {
       Debug.WriteLine($"OSX callback got {msg}");

src/NTwain/TwainSession.Memory.cs

@@ -1,7 +1,7 @@
 using NTwain.Data;
+using NTwain.Native;
 using System;
 using System.Runtime.InteropServices;
-using TWAINWorkingGroup;
 
 namespace NTwain
 {
@@ -19,7 +19,7 @@ namespace NTwain
       }
       else if (TwainPlatform.IsWindows)
       {
-        return NativeMethods.GlobalAlloc(0x0042 /* GHND */, (UIntPtr)size);
+        return NativeMemoryMethods.WinGlobalAlloc(NativeMemoryMethods.AllocFlag.GHND, (UIntPtr)size);
       }
       else if (TwainPlatform.IsLinux)
       {
@@ -45,7 +45,7 @@ namespace NTwain
       }
       else if (TwainPlatform.IsWindows)
       {
-        NativeMethods.GlobalFree(handle);
+        NativeMemoryMethods.WinGlobalFree(handle);
       }
       else if (TwainPlatform.IsLinux)
       {
@@ -71,7 +71,7 @@ namespace NTwain
       }
       else if (TwainPlatform.IsWindows)
       {
-        return NativeMethods.GlobalLock(handle);
+        return NativeMemoryMethods.WinGlobalLock(handle);
       }
       else if (TwainPlatform.IsLinux)
       {
@@ -97,7 +97,7 @@ namespace NTwain
       }
       else if (TwainPlatform.IsWindows)
       {
-        NativeMethods.GlobalUnlock(handle);
+        NativeMemoryMethods.WinGlobalUnlock(handle);
       }
       else if (TwainPlatform.IsLinux)
       {

src/NTwain/TwainSession.cs

@@ -3,7 +3,6 @@ using NTwain.Triplets;
 using System;
 using System.Diagnostics;
 using System.Text;
-using TWAINWorkingGroup;
 
 namespace NTwain
 {