Added source open/close methods and callback placeholder.

samples/NetCoreConsole/NetCoreConsole.csproj

@@ -5,6 +5,11 @@
     <TargetFramework>netcoreapp2.1</TargetFramework>
   </PropertyGroup>
 
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|AnyCPU'">
+    <PlatformTarget>AnyCPU</PlatformTarget>
+    <Prefer32Bit>true</Prefer32Bit>
+  </PropertyGroup>
+
   <ItemGroup>
     <ProjectReference Include="..\..\src\NTwain\NTwain.csproj" />
   </ItemGroup>

samples/NetCoreConsole/Program.cs

@@ -22,12 +22,14 @@ namespace NetCoreConsole
                 {
                     session.PropertyChanged += Session_PropertyChanged;
 
-                    var handle = IntPtr.Zero;
+                    if (session.Open(IntPtr.Zero) == NTwain.Data.ReturnCode.Success)
-                    if (session.Open(ref handle) == NTwain.Data.ReturnCode.Success)
                     {
                         Console.WriteLine("Available data sources:");
+
+                        DataSource firstSrc = null;
                         foreach (var src in session.GetSources())
                         {
+                            if (firstSrc == null) firstSrc = src;
                             Console.WriteLine($"\t{src}");
                         }
                         Console.WriteLine();
@@ -39,6 +41,18 @@ namespace NetCoreConsole
                         var selectSrc = session.ShowSourceSelector();
                         Console.WriteLine($"Selected data source = {selectSrc}");
                         Console.WriteLine();
+
+                        var targetSrc = selectSrc ?? defaultSrc ?? firstSrc;
+
+                        if (targetSrc != null)
+                        {
+                            TestThisSource(targetSrc);
+                        }
+                        else
+                        {
+                            Console.WriteLine("No data source to test.");
+                            Console.WriteLine();
+                        }
                     }
 
                 }
@@ -52,6 +66,15 @@ namespace NetCoreConsole
             Console.ReadLine();
         }
 
+        private static void TestThisSource(DataSource targetSrc)
+        {
+            Console.WriteLine($"Testing data source {targetSrc}");
+            Console.WriteLine();
+
+            targetSrc.Open();
+            targetSrc.Close();
+        }
+
         private static void Session_PropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
         {
             var session = (TwainSession)sender;

src/NTwain/Data/TwainTypes.cs

@@ -89,19 +89,19 @@ namespace NTwain.Data
 
     
     [StructLayout(LayoutKind.Sequential, Pack = 2)]
-    partial struct TW_CALLBACK
+    partial class TW_CALLBACK
     {
         [MarshalAs(UnmanagedType.FunctionPtr)]
-        public CallbackDelegate _callBackProc;
+        CallbackDelegate _callBackProc;
         TW_UINT32 _refCon;
         TW_INT16 _message;
     }
 
     [StructLayout(LayoutKind.Sequential, Pack = 2)]
-    partial struct TW_CALLBACK2
+    partial class TW_CALLBACK2
     {
         [MarshalAs(UnmanagedType.FunctionPtr)]
-        public CallbackDelegate _callBackProc;
+        CallbackDelegate _callBackProc;
         TW_UINTPTR _refCon;
         TW_INT16 _message;
     }

src/NTwain/Data/TwainTypesExtended.cs

@@ -571,6 +571,69 @@ namespace NTwain.Data
     }
 
 
+    /// <summary>
+    /// Used in Callback mechanism for sending messages from the Source to the Application.
+    /// Applications version 2.2 or higher must use <see cref="TW_CALLBACK2"/>.
+    /// </summary>
+    partial class TW_CALLBACK
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="TWCallback"/> class.
+        /// </summary>
+        /// <param name="callback">The callback function’s entry point.</param>
+        public TW_CALLBACK(CallbackDelegate callback)
+        {
+            _callBackProc = callback;
+        }
+
+        ///// <summary>
+        ///// An application defined reference constant.
+        ///// </summary>
+        ///// <value>
+        ///// The reference constant.
+        ///// </value>
+        //public uint RefCon { get { return _refCon; } set { _refCon = value; } }
+
+        ///// <summary>
+        ///// Initialized to any valid DG_CONTROL / DAT_NULL message.
+        ///// </summary>
+        ///// <value>
+        ///// The message.
+        ///// </value>
+        //public short Message { get { return _message; } set { _message = value; } }
+    }
+    /// <summary>
+    /// Used in the Callback mechanism for sending messages from the Source to the Application.
+    /// </summary>
+    partial class TW_CALLBACK2
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="TW_CALLBACK2"/> class.
+        /// </summary>
+        /// <param name="callback">The callback function’s entry point.</param>
+        public TW_CALLBACK2(CallbackDelegate callback)
+        {
+            _callBackProc = callback;
+        }
+
+        ///// <summary>
+        ///// An application defined reference constant. It has a different size on different
+        ///// platforms.
+        ///// </summary>
+        ///// <value>
+        ///// The reference constant.
+        ///// </value>
+        //public UIntPtr RefCon { get { return _refCon; } set { _refCon = value; } }
+
+        ///// <summary>
+        ///// Initialized to any valid DG_CONTROL / DAT_NULL message.
+        ///// </summary>
+        ///// <value>
+        ///// The message.
+        ///// </value>
+        //public short Message { get { return _message; } set { _message = value; } }
+    }
+
 
     //    /// <summary>
     //    /// Used by an application either to get information about, or control the setting of a capability.

src/NTwain/DataSource.cs

@@ -19,6 +19,7 @@ namespace NTwain
         {
             this.Session = session;
             this.Identity = src;
+            ProtocolVersion = new Version(src.ProtocolMajor, src.ProtocolMinor);
         }
 
         /// <summary>
@@ -27,10 +28,51 @@ namespace NTwain
         public string Name => Identity.ProductName;
 
         /// <summary>
-        /// Gets the source version info.
+        /// Gets the source's manufacturer name.
+        /// </summary>
+        public string Manufacturer => Identity.Manufacturer;
+
+        /// <summary>
+        /// Gets the source's product family.
+        /// </summary>
+        public string ProductFamily => Identity.ProductFamily;
+
+        /// <summary>
+        /// Gets the source's version info.
         /// </summary>
         public TW_VERSION Version => Identity.Version;
 
+        /// <summary>
+        /// Gets the supported data group.
+        /// </summary>
+        public DataGroups DataGroup => Identity.DataGroup;
+
+        /// <summary>
+        /// Gets the supported TWAIN protocol version.
+        /// </summary>
+        public Version ProtocolVersion { get; }
+
+        /// <summary>
+        /// Gets a value indicating whether this data source is open.
+        /// </summary>
+        public bool IsOpen => Session.State > TwainState.DsmOpened && Session.CurrentSource == this;
+
+
+
+        /// <summary>
+        /// Opens the source for capability negotiation.
+        /// </summary>
+        /// <returns></returns>
+        public ReturnCode Open() => Session.DGControl.Identity.OpenDS(Identity);
+
+        /// <summary>
+        /// Closes the source.
+        /// </summary>
+        /// <returns></returns>
+        public ReturnCode Close() => Session.DGControl.Identity.CloseDS(Identity);
+
+
+
         /// <summary>
         /// Returns a <see cref="System.String"/> that represents this instance.
         /// </summary>

src/NTwain/NTwain.csproj

@@ -15,7 +15,7 @@
     <SignAssembly>true</SignAssembly>
     <AssemblyOriginatorKeyFile>Sign.snk</AssemblyOriginatorKeyFile>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
-    <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
+    <GeneratePackageOnBuild>false</GeneratePackageOnBuild>
     <AssemblyVersion>4.0.0.0</AssemblyVersion>
     <FileVersion>4.0.0.0</FileVersion>
     <Version>4.0.0</Version>

src/NTwain/Triplets/DGControl.Callback.cs

@@ -0,0 +1,16 @@
+using NTwain.Data;
+using NTwain.Internals;
+
+namespace NTwain.Triplets
+{
+	sealed class Callback : BaseTriplet
+	{
+		internal Callback(TwainSession session) : base(session) { }
+
+		public ReturnCode RegisterCallback(TW_CALLBACK callback)
+        {
+            return NativeMethods.DsmWin32(Session.Config.AppWin32, Session.CurrentSource.Identity,
+                DataGroups.Control, DataArgumentType.Callback2, Message.RegisterCallback, callback);
+        }
+	}
+}

src/NTwain/Triplets/DGControl.Callback2.cs

@@ -0,0 +1,16 @@
+using NTwain.Data;
+using NTwain.Internals;
+
+namespace NTwain.Triplets
+{
+    sealed class Callback2 : BaseTriplet
+    {
+        internal Callback2(TwainSession session) : base(session) { }
+
+        public ReturnCode RegisterCallback(TW_CALLBACK2 callback)
+        {
+            return NativeMethods.DsmWin32(Session.Config.AppWin32, Session.CurrentSource.Identity,
+                DataGroups.Control, DataArgumentType.Callback2, Message.RegisterCallback, callback);
+        }
+    }
+}

src/NTwain/Triplets/DGControl.Identity.cs

@@ -16,6 +16,7 @@ namespace NTwain.Triplets
             {
                 Session.State = TwainState.S3;
                 Session.CurrentSource = null;
+                Session.UpdateCallback();
             }
             return rc;
         }
@@ -50,6 +51,7 @@ namespace NTwain.Triplets
             {
                 Session.CurrentSource = Session.GetSourceSingleton(source);
                 Session.State = TwainState.S4;
+                Session.UpdateCallback();
             }
             return rc;
         }

src/NTwain/Triplets/DGControl.cs

@@ -21,5 +21,11 @@ namespace NTwain.Triplets
 
         Identity _identity;
         internal Identity Identity => _identity ?? (_identity = new Identity(Session));
+
+        Callback _callback;
+        internal Callback Callback => _callback ?? (_callback = new Callback(Session));
+
+        Callback2 _callback2;
+        internal Callback2 Callback2 => _callback2 ?? (_callback2 = new Callback2(Session));
     }
 }

src/NTwain/Triplets/NativeMethods.Win32.cs

@@ -70,7 +70,7 @@ namespace NTwain.Triplets
             DataGroups dg,
             DataArgumentType dat,
             Message msg,
-            ref TW_CALLBACK data);
+            [In, Out]TW_CALLBACK data);
 
         [DllImport(WinDsmDll, EntryPoint = EntryName)]
         public static extern ReturnCode DsmWin32(
@@ -79,7 +79,7 @@ namespace NTwain.Triplets
             DataGroups dg,
             DataArgumentType dat,
             Message msg,
-            ref TW_CALLBACK2 data);
+            [In, Out]TW_CALLBACK2 data);
 
         [DllImport(WinDsmDll, EntryPoint = EntryName)]
         public static extern ReturnCode DsmWin32(

src/NTwain/TwainSession.cs

@@ -15,6 +15,7 @@ namespace NTwain
     {
         internal readonly TwainConfig Config;
         private IntPtr _hWnd;
+        object _callbackObj; // kept around in this class so it doesn't get gc'ed
         // cache generated twain sources so if you get same source from same session it'll return the same object
         readonly Dictionary<string, DataSource> _ownedSources = new Dictionary<string, DataSource>();
 
@@ -32,7 +33,7 @@ namespace NTwain
         /// </summary>
         /// <param name="hWnd"></param>
         /// <returns></returns>
-        public ReturnCode Open(ref IntPtr hWnd)
+        public ReturnCode Open(IntPtr hWnd)
         {
             _hWnd = hWnd;
             return DGControl.Parent.OpenDSM(ref hWnd);
@@ -63,6 +64,44 @@ namespace NTwain
             return rc;
         }
 
+        internal void UpdateCallback()
+        {
+            if (State < TwainState.S4)
+            {
+                _callbackObj = null;
+            }
+            else
+            {
+                var rc = ReturnCode.Failure;
+                // per the spec (8-10) apps for 2.2 or higher uses callback2 so try this first
+                if (Config.AppWin32.ProtocolMajor > 2 ||
+                    (Config.AppWin32.ProtocolMajor >= 2 && Config.AppWin32.ProtocolMinor >= 2))
+                {
+                    var cb = new TW_CALLBACK2(HandleCallback);
+                    rc = DGControl.Callback2.RegisterCallback(cb);
+
+                    if (rc == ReturnCode.Success)
+                    {
+                        _callbackObj = cb;
+                    }
+                }
+
+                if (rc != ReturnCode.Success)
+                {
+                    // always try old callback
+                    var cb = new TW_CALLBACK(HandleCallback);
+
+                    rc = DGControl.Callback.RegisterCallback(cb);
+
+                    if (rc == ReturnCode.Success)
+                    {
+                        _callbackObj = cb;
+                    }
+                }
+            }
+        }
+
+
         /// <summary>
         /// Gets list of sources available on the machine.
         /// </summary>
@@ -142,5 +181,36 @@ namespace NTwain
             }
             return source;
         }
+
+        ReturnCode HandleCallback(TW_IDENTITY origin, TW_IDENTITY destination,
+            DataGroups dg, DataArgumentType dat, Message msg, IntPtr data)
+        {
+            //if (origin != null && CurrentSource != null && origin.Id == CurrentSource.Identity.Id && State >= S5)
+            //{
+            //    // spec says we must handle this on the thread that enabled the DS.
+            //    // by using the internal dispatcher this will be the case.
+
+            //    // In any event the trick to get this thing working is to return from the callback first
+            //    // before trying to process the msg or there will be unpredictable errors.
+
+            //    // changed to sync invoke instead of begininvoke for hp scanjet.
+            //    if (origin.ProductName.IndexOf("scanjet", StringComparison.OrdinalIgnoreCase) > -1)
+            //    {
+            //        _msgLoopHook?.Invoke(() =>
+            //        {
+            //            HandleSourceMsg(msg);
+            //        });
+            //    }
+            //    else
+            //    {
+            //        _msgLoopHook?.BeginInvoke(() =>
+            //        {
+            //            HandleSourceMsg(msg);
+            //        });
+            //    }
+            //    return ReturnCode.Success;
+            //}
+            return ReturnCode.Failure;
+        }
     }
 }