Added local 2.5 dsm to samples in case system doesn't have it.

samples/WinForm32/DsmLoader.cs

@@ -0,0 +1,37 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Reflection;
+using System.Runtime.InteropServices;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace WinFormSample
+{
+  /// <summary>
+  /// For demoing loading dsm from custom path in case
+  /// it's not installed on system and can't be placed 
+  /// besides the exe.
+  /// </summary>
+  static class DsmLoader
+  {
+    static IntPtr __dllPtr;
+
+    public static bool TryUseCustomDSM()
+    {
+      if (__dllPtr == IntPtr.Zero)
+      {
+        var dll = Path.Combine(
+          Path.GetDirectoryName(Environment.ProcessPath ?? Assembly.GetExecutingAssembly().Location)!,
+          "platforms\\TWAINDSM.dll");
+
+        __dllPtr = LoadLibraryW(dll);
+      }
+      return __dllPtr != IntPtr.Zero;
+    }
+
+    [DllImport("kernel32", SetLastError = true)]
+    static extern IntPtr LoadLibraryW([MarshalAs(UnmanagedType.LPWStr)] string lpFileName);
+  }
+}

samples/WinForm32/Form1.cs

@@ -17,7 +17,16 @@ namespace WinFormSample
       InitializeComponent();
       var libVer = FileVersionInfo.GetVersionInfo(typeof(TwainAppSession).Assembly.Location).FileVersion;
       Text += $"{(TwainPlatform.Is32bit ? " 32bit" : " 64bit")} on NTwain {libVer}";
-      
+
+      if (DsmLoader.TryUseCustomDSM())
+      {
+        Debug.WriteLine("Using our own dsm now :)");
+      }
+      else
+      {
+        Debug.WriteLine("Will attempt to use default dsm :(");
+      }
+
       TwainPlatform.PreferLegacyDSM = false;
 
       twain = new TwainAppSession(new WinformMarshaller(this), Assembly.GetExecutingAssembly().Location);

samples/WinForm32/WinForm32.csproj

@@ -17,6 +17,9 @@
 	  <None Update="platforms\qwindows.dll">
 	    <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
 	  </None>
+	  <None Update="platforms\TWAINDSM.dll">
+	    <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+	  </None>
 	</ItemGroup>
 
 </Project>

samples/WinForm64/WinForm64.csproj

@@ -26,5 +26,8 @@
     <None Update="platforms\qwindows.dll">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </None>
+    <None Update="platforms\TWAINDSM.dll">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
   </ItemGroup>
 </Project>