Some refactor ideas

NTwain/Data/TypesExtended.cs

@@ -1,7 +1,9 @@
 using NTwain.Properties;
 using NTwain.Values;
 using System;
+using System.Diagnostics;
 using System.Globalization;
+using System.Reflection;
 using System.Runtime.InteropServices;
 using System.Security.Permissions;
 using System.Text;
@@ -663,7 +665,7 @@ namespace NTwain.Data
             var value = new TWOneValue();
             if (_hContainer != IntPtr.Zero)
             {
-                IntPtr baseAddr = MemoryManager.Global.MemLock(_hContainer);
+                IntPtr baseAddr = MemoryManager.Instance.MemLock(_hContainer);
                 try
                 {
                     int offset = 0;
@@ -672,7 +674,7 @@ namespace NTwain.Data
                     value.Item = (uint)ReadValue(baseAddr, ref offset, ItemType.UInt32);
                 }
                 catch { }
-                MemoryManager.Global.MemUnlock(_hContainer);
+                MemoryManager.Instance.MemUnlock(_hContainer);
             }
             return value;
         }
@@ -686,7 +688,7 @@ namespace NTwain.Data
             // since one value can only house UInt32 we will not allow type size > 4
             if (GetItemTypeSize(value.ItemType) > 4) { throw new ArgumentException("Invalid one value type"); }
 
-            _hContainer = MemoryManager.Global.MemAllocate((uint)Marshal.SizeOf(value));
+            _hContainer = MemoryManager.Instance.MemAllocate((uint)Marshal.SizeOf(value));
             if (_hContainer != IntPtr.Zero)
             {
                 Marshal.StructureToPtr(value, _hContainer, false);
@@ -705,7 +707,7 @@ namespace NTwain.Data
             var value = new TWArray();
             if (_hContainer != IntPtr.Zero)
             {
-                IntPtr baseAddr = MemoryManager.Global.MemLock(_hContainer);
+                IntPtr baseAddr = MemoryManager.Instance.MemLock(_hContainer);
                 int offset = 0;
                 value.ItemType = (ItemType)(ushort)Marshal.ReadInt16(baseAddr, offset);
                 offset += 2;
@@ -719,7 +721,7 @@ namespace NTwain.Data
                         value.ItemList[i] = ReadValue(baseAddr, ref offset, value.ItemType);
                     }
                 }
-                MemoryManager.Global.MemUnlock(_hContainer);
+                MemoryManager.Instance.MemUnlock(_hContainer);
             }
             return value;
         }
@@ -736,7 +738,7 @@ namespace NTwain.Data
             var value = new TWEnumeration();
             if (_hContainer != IntPtr.Zero)
             {
-                IntPtr baseAddr = MemoryManager.Global.MemLock(_hContainer);
+                IntPtr baseAddr = MemoryManager.Instance.MemLock(_hContainer);
                 int offset = 0;
                 value.ItemType = (ItemType)(ushort)Marshal.ReadInt16(baseAddr, offset);
                 offset += 2;
@@ -754,7 +756,7 @@ namespace NTwain.Data
                         value.ItemList[i] = ReadValue(baseAddr, ref offset, value.ItemType);
                     }
                 }
-                MemoryManager.Global.MemUnlock(_hContainer);
+                MemoryManager.Instance.MemUnlock(_hContainer);
             }
             return value;
         }
@@ -768,8 +770,8 @@ namespace NTwain.Data
             Int32 valueSize = value.ItemOffset + value.ItemList.Length * GetItemTypeSize(value.ItemType);
 
             int offset = 0;
-            _hContainer = MemoryManager.Global.MemAllocate((uint)valueSize);
+            _hContainer = MemoryManager.Instance.MemAllocate((uint)valueSize);
-            IntPtr baseAddr = MemoryManager.Global.MemLock(_hContainer);
+            IntPtr baseAddr = MemoryManager.Instance.MemLock(_hContainer);
 
             // can't safely use StructureToPtr here so write it our own
             WriteValue(baseAddr, ref offset, ItemType.UInt16, value.ItemType);
@@ -780,7 +782,7 @@ namespace NTwain.Data
             {
                 WriteValue(baseAddr, ref offset, value.ItemType, item);
             }
-            MemoryManager.Global.MemUnlock(_hContainer);
+            MemoryManager.Instance.MemUnlock(_hContainer);
         }
 
         /// <summary>
@@ -795,7 +797,7 @@ namespace NTwain.Data
             var value = new TWRange();
             if (_hContainer != IntPtr.Zero)
             {
-                IntPtr baseAddr = MemoryManager.Global.MemLock(_hContainer);
+                IntPtr baseAddr = MemoryManager.Instance.MemLock(_hContainer);
 
                 int offset = 0;
                 value.ItemType = (ItemType)(ushort)Marshal.ReadInt16(baseAddr, offset);
@@ -810,7 +812,7 @@ namespace NTwain.Data
                 offset += 4;
                 value.CurrentValue = (uint)Marshal.ReadInt32(baseAddr, offset);
 
-                MemoryManager.Global.MemUnlock(_hContainer);
+                MemoryManager.Instance.MemUnlock(_hContainer);
             }
             return value;
         }
@@ -823,7 +825,7 @@ namespace NTwain.Data
             // since range value can only house UInt32 we will not allow type size > 4
             if (GetItemTypeSize(value.ItemType) > 4) { throw new ArgumentException("Invalid range value type"); }
 
-            _hContainer = MemoryManager.Global.MemAllocate((uint)Marshal.SizeOf(value));
+            _hContainer = MemoryManager.Instance.MemAllocate((uint)Marshal.SizeOf(value));
             if (_hContainer != IntPtr.Zero)
             {
                 Marshal.StructureToPtr(value, _hContainer, false);
@@ -1123,7 +1125,7 @@ namespace NTwain.Data
         {
             if (_hContainer != IntPtr.Zero)
             {
-                MemoryManager.Global.MemFree(_hContainer);
+                MemoryManager.Instance.MemFree(_hContainer);
                 _hContainer = IntPtr.Zero;
             }
             GC.SuppressFinalize(this);
@@ -1136,7 +1138,7 @@ namespace NTwain.Data
         {
             if (_hContainer != IntPtr.Zero)
             {
-                MemoryManager.Global.MemFree(_hContainer);
+                MemoryManager.Instance.MemFree(_hContainer);
                 _hContainer = IntPtr.Zero;
             }
         }
@@ -1857,12 +1859,24 @@ namespace NTwain.Data
         /// </summary>
         public string ProductName { get { return _productName; } set { value.VerifyLengthUnder(TwainConst.String32 - 1); _productName = value; } }
 
-        //public static TWIdentity CreateFromAssembly(DataGroups supportedGroups)
-        //{
-        //	return Create(supportedGroups);
-        //}
         /// <summary>
-        /// Creates a <see cref="TWIdentity"/> specified values.
+        /// Creates a <see cref="TWIdentity"/> from assembly values.
+        /// </summary>
+        /// <param name="supportedGroups">The supported groups.</param>
+        /// <param name="assembly">The assembly.</param>
+        /// <returns></returns>
+        /// <exception cref="ArgumentNullException">assembly</exception>
+        public static TWIdentity CreateFromAssembly(DataGroups supportedGroups, Assembly assembly)
+        {
+            if (assembly == null) { throw new ArgumentNullException("assembly"); }
+
+            var info = FileVersionInfo.GetVersionInfo(assembly.Location);
+
+            return Create(supportedGroups, assembly.GetName().Version, info.CompanyName, info.ProductName, info.ProductName, info.FileDescription);
+        }
+
+        /// <summary>
+        /// Creates a <see cref="TWIdentity"/> from specified values.
         /// </summary>
         /// <param name="supportedGroups">The supported groups.</param>
         /// <param name="version">The version.</param>

NTwain/ITwainState.cs

@@ -1,4 +1,5 @@
 using NTwain.Data;
+using NTwain.Triplets;
 using System;
 using System.ComponentModel;
 namespace NTwain
@@ -6,7 +7,7 @@ namespace NTwain
     /// <summary>
     /// Interface for keeping track of current TWAIN state with current app and source ids.
     /// </summary>
-    public interface ITwainSession : INotifyPropertyChanged
+    public interface ITwainState : INotifyPropertyChanged
     {
         /// <summary>
         /// Gets the app id used for the session.
@@ -27,10 +28,11 @@ namespace NTwain
         int State { get; }
     }
 
+
     /// <summary>
     /// Internal interface for state management.
     /// </summary>
-    interface ITwainSessionInternal : ITwainSession
+    interface ITwainStateInternal : ITwainState
     {
         /// <summary>
         /// Gets or sets a value indicating whether calls to triplets will verify the current twain session state.
@@ -54,6 +56,8 @@ namespace NTwain
         /// <param name="newState">The new state.</param>
         /// <returns></returns>
         ICommitable GetPendingStateChanger(int newState);
+
+        void ChangeSourceId(TWIdentity sourceId);
     }
 
     interface ICommitable : IDisposable

NTwain/MemoryManager.cs

@@ -9,15 +9,14 @@ namespace NTwain
 {
     /// <summary>
     /// Provides methods for managing memory on data exchanged with twain sources.
-    /// This should only be used after the DSM has been opened in <see cref="TwainSession"/>
+    /// This should only be used after the DSM has been opened.
-    /// via <see cref="TwainSession.OpenManager"/>.
     /// </summary>
-    public class MemoryManager
+    public class MemoryManager : IMemoryManager
     {
         /// <summary>
-        /// Gets the global <see cref="MemoryManager"/> instance.
+        /// Gets the singleton <see cref="MemoryManager"/> instance.
         /// </summary>
-        public static readonly MemoryManager Global = new MemoryManager();
+        public static readonly MemoryManager Instance = new MemoryManager();
 
         private MemoryManager() { }
 
@@ -46,7 +45,7 @@ namespace NTwain
             else
             {
                 // 0x0040 is GPTR
-                return GlobalAlloc(0x0040, new UIntPtr(size));
+                return WinGlobalAlloc(0x0040, new UIntPtr(size));
             }
         }
 
@@ -62,7 +61,7 @@ namespace NTwain
             }
             else
             {
-                GlobalFree(handle);
+                WinGlobalFree(handle);
             }
         }
 
@@ -79,7 +78,7 @@ namespace NTwain
             }
             else
             {
-                return GlobalLock(handle);
+                return WinGlobalLock(handle);
             }
         }
 
@@ -95,24 +94,25 @@ namespace NTwain
             }
             else
             {
-                GlobalUnlock(handle);
+                WinGlobalUnlock(handle);
             }
         }
 
         #region old mem stuff for twain 1.x
 
-        [DllImport("kernel32", SetLastError = true, ExactSpelling = true)]
-        static extern IntPtr GlobalAlloc(uint uFlags, UIntPtr dwBytes);
 
-        [DllImport("kernel32", SetLastError = true, ExactSpelling = true)]
+        [DllImport("kernel32", SetLastError = true, EntryPoint = "GlobalAlloc")]
-        static extern IntPtr GlobalFree(IntPtr hMem);
+        static extern IntPtr WinGlobalAlloc(uint uFlags, UIntPtr dwBytes);
 
-        [DllImport("kernel32", SetLastError = true, ExactSpelling = true)]
+        [DllImport("kernel32", SetLastError = true, EntryPoint = "GlobalFree")]
-        static extern IntPtr GlobalLock(IntPtr handle);
+        static extern IntPtr WinGlobalFree(IntPtr hMem);
 
-        [DllImport("kernel32", SetLastError = true, ExactSpelling = true)]
+        [DllImport("kernel32", SetLastError = true, EntryPoint = "GlobalLock")]
+        static extern IntPtr WinGlobalLock(IntPtr handle);
+
+        [DllImport("kernel32", SetLastError = true, EntryPoint = "GlobalUnlock")]
         [return: MarshalAs(UnmanagedType.Bool)]
-        static extern bool GlobalUnlock(IntPtr handle);
+        static extern bool WinGlobalUnlock(IntPtr handle);
 
         #endregion
     }

NTwain/NTwain.csproj

@@ -48,9 +48,6 @@
   <ItemGroup>
     <Reference Include="PresentationCore" />
     <Reference Include="System" />
-    <Reference Include="System.Core" />
-    <Reference Include="System.Data.DataSetExtensions" />
-    <Reference Include="System.Data" />
     <Reference Include="System.Drawing" />
     <Reference Include="System.Windows.Forms" />
     <Reference Include="WindowsBase" />
@@ -60,7 +57,9 @@
     <Compile Include="DeviceEventArgs.cs" />
     <Compile Include="Extensions.cs" />
     <Compile Include="DataTransferredEventArgs.cs" />
-    <Compile Include="ITwainSession.cs" />
+    <Compile Include="IMemoryManager.cs" />
+    <Compile Include="ITwainOperation.cs" />
+    <Compile Include="ITwainState.cs" />
     <Compile Include="MemoryManager.cs" />
     <Compile Include="Properties\Resources.Designer.cs">
       <AutoGen>True</AutoGen>
@@ -68,6 +67,7 @@
       <DependentUpon>Resources.resx</DependentUpon>
     </Compile>
     <Compile Include="Properties\VersionInfo.cs" />
+    <Compile Include="TentativeStateCommitable.cs" />
     <Compile Include="TransferReadyEventArgs.cs" />
     <Compile Include="Triplets\DGControl\DGControl.Callback2.cs" />
     <Compile Include="Triplets\DGImage\DGImage.Filter.cs" />
@@ -75,6 +75,7 @@
     <Compile Include="Triplets\PInvokes.32bit.cs" />
     <Compile Include="Triplets\PInvokes.64bit.cs" />
     <Compile Include="TwainSessionExtensions.cs" />
+    <Compile Include="TwainSessionBase.cs" />
     <Compile Include="TwainStateException.cs" />
     <Compile Include="Data\Types.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />

NTwain/TentativeStateCommitable.cs

@@ -0,0 +1,47 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace NTwain
+{
+    class TentativeStateCommitable : ICommitable
+    {
+        bool _commit;
+        ITwainStateInternal _session;
+        int _origState;
+        int _newState;
+        public TentativeStateCommitable(ITwainStateInternal session, int newState)
+        {
+            _session = session;
+            _origState = session.State;
+            _newState = newState;
+            _session.ChangeState(newState, false);
+        }
+
+        #region ICommitable Members
+
+        public void Commit()
+        {
+            if (_session.State == _newState)
+            {
+                _session.ChangeState(_newState, true);
+            }
+            _commit = true;
+        }
+
+        #endregion
+
+        #region IDisposable Members
+
+        public void Dispose()
+        {
+            if (!_commit && _session.State == _newState)
+            {
+                _session.ChangeState(_origState, false);
+            }
+        }
+
+        #endregion
+    }
+}

NTwain/Triplets/DGAudio/DGAudio.AudioFileXfer.cs

@@ -8,7 +8,7 @@ namespace NTwain.Triplets
     /// </summary>
 	sealed class AudioFileXfer : OpBase
 	{
-        internal AudioFileXfer(ITwainSessionInternal session) : base(session) { }
+        internal AudioFileXfer(ITwainStateInternal session) : base(session) { }
 		/// <summary>
 		/// This operation is used to initiate the transfer of audio from the Source to the application via the
 		/// disk-file transfer mechanism. It causes the transfer to begin.

NTwain/Triplets/DGAudio/DGAudio.AudioInfo.cs

@@ -8,7 +8,7 @@ namespace NTwain.Triplets
     /// </summary>
 	public sealed class AudioInfo : OpBase
 	{
-		internal AudioInfo(ITwainSessionInternal session) : base(session) { }
+		internal AudioInfo(ITwainStateInternal session) : base(session) { }
 		/// <summary>
 		/// Used to get the information of the current audio data ready to transfer.
 		/// </summary>

NTwain/Triplets/DGAudio/DGAudio.AudioNativeXfer.cs

@@ -8,7 +8,7 @@ namespace NTwain.Triplets
     /// </summary>
 	sealed class AudioNativeXfer : OpBase
 	{
-		internal AudioNativeXfer(ITwainSessionInternal session) : base(session) { }
+		internal AudioNativeXfer(ITwainStateInternal session) : base(session) { }
 		/// <summary>
 		/// Causes the transfer of an audio data from the Source to the application, via the Native
 		/// transfer mechanism, to begin. The resulting data is stored in main memory in a single block.

NTwain/Triplets/DGAudio/DGAudio.cs

@@ -7,8 +7,8 @@ namespace NTwain.Triplets
 	/// </summary>
 	public sealed class DGAudio
 	{
-        ITwainSessionInternal _session;
+        ITwainStateInternal _session;
-        internal DGAudio(ITwainSessionInternal session)
+        internal DGAudio(ITwainStateInternal session)
 		{
 			if (session == null) { throw new ArgumentNullException("session"); }
 			_session = session;

NTwain/Triplets/DGControl/DGControl.Callback.cs

@@ -6,7 +6,7 @@ namespace NTwain.Triplets
 {
 	sealed class Callback : OpBase
 	{
-		internal Callback(ITwainSessionInternal session) : base(session) { }
+		internal Callback(ITwainStateInternal session) : base(session) { }
 		/// <summary>
 		/// This triplet is sent to the DSM by the Application to register the application’s entry point with
 		/// the DSM, so that the DSM can use callbacks to inform the application of events generated by the

NTwain/Triplets/DGControl/DGControl.Callback2.cs

@@ -6,7 +6,7 @@ namespace NTwain.Triplets
 {
 	sealed class Callback2 : OpBase
 	{
-		internal Callback2(ITwainSessionInternal session) : base(session) { }
+		internal Callback2(ITwainStateInternal session) : base(session) { }
 		/// <summary>
 		/// This triplet is sent to the DSM by the Application to register the application’s entry point with
 		/// the DSM, so that the DSM can use callbacks to inform the application of events generated by the

NTwain/Triplets/DGControl/DGControl.Capability.cs

@@ -9,7 +9,7 @@ namespace NTwain.Triplets
     /// </summary>
 	public sealed class Capability : OpBase
 	{
-		internal Capability(ITwainSessionInternal session) : base(session) { }
+		internal Capability(ITwainStateInternal session) : base(session) { }
 		/// <summary>
 		/// Returns the Source’s Current, Default and Available Values for a specified capability.
 		/// </summary>

NTwain/Triplets/DGControl/DGControl.CustomDSData.cs

@@ -9,7 +9,7 @@ namespace NTwain.Triplets
     /// </summary>
 	public sealed class CustomDSData : OpBase
 	{
-		internal CustomDSData(ITwainSessionInternal session) : base(session) { }
+		internal CustomDSData(ITwainStateInternal session) : base(session) { }
 		/// <summary>
 		/// This operation is used by the application to query the data source for its current settings, e.g.
         /// DPI, paper size, color format. The actual format of the data is data source dependent and not

NTwain/Triplets/DGControl/DGControl.DeviceEvent.cs

@@ -9,7 +9,7 @@ namespace NTwain.Triplets
     /// </summary>
 	public sealed class DeviceEvent : OpBase
 	{
-		internal DeviceEvent(ITwainSessionInternal session) : base(session) { }
+		internal DeviceEvent(ITwainStateInternal session) : base(session) { }
 		public ReturnCode Get(out TWDeviceEvent sourceDeviceEvent)
 		{
 			Session.VerifyState(4, 7, DataGroups.Control, DataArgumentType.DeviceEvent, Message.Get);

NTwain/Triplets/DGControl/DGControl.EntryPoint.cs

@@ -9,7 +9,7 @@ namespace NTwain.Triplets
     /// </summary>
 	sealed class EntryPoint : OpBase
 	{
-		internal EntryPoint(ITwainSessionInternal session) : base(session) { }
+		internal EntryPoint(ITwainStateInternal session) : base(session) { }
 		/// <summary>
 		/// Gets the function entry points for twain 2.0 or higher.
 		/// </summary>

NTwain/Triplets/DGControl/DGControl.Event.cs

@@ -6,7 +6,7 @@ namespace NTwain.Triplets
 {
 	sealed class Event : OpBase
 	{
-		internal Event(ITwainSessionInternal session) : base(session) { }
+		internal Event(ITwainStateInternal session) : base(session) { }
 
 		/// <summary>
 		/// This operation supports the distribution of events from the application to Sources so that the

NTwain/Triplets/DGControl/DGControl.FileSystem.cs

@@ -9,7 +9,7 @@ namespace NTwain.Triplets
     /// </summary>
 	public sealed class FileSystem : OpBase
 	{
-		internal FileSystem(ITwainSessionInternal session) : base(session) { }
+		internal FileSystem(ITwainStateInternal session) : base(session) { }
 		/// <summary>
 		/// This operation selects the destination directory within the Source (camera, storage, etc), where
 		/// images captured using CapAutomaticCapture will be stored. This command only selects

NTwain/Triplets/DGControl/DGControl.Identity.cs

@@ -9,7 +9,7 @@ namespace NTwain.Triplets
     /// </summary>
 	public sealed class Identity : OpBase
 	{
-		internal Identity(ITwainSessionInternal session) : base(session) { }
+		internal Identity(ITwainStateInternal session) : base(session) { }
 		/// <summary>
 		/// When an application is finished with a Source, it must formally close the session between them
 		/// using this operation. This is necessary in case the Source only supports connection with a single
@@ -23,6 +23,7 @@ namespace NTwain.Triplets
 			var rc = PInvoke.DsmEntry(Session.AppId, Message.CloseDS, Session.SourceId);
 			if (rc == ReturnCode.Success)
             {
+                Session.ChangeSourceId(null);
                 Session.ChangeState(3, true);
 			}
 			return rc;
@@ -78,6 +79,7 @@ namespace NTwain.Triplets
 			var rc = PInvoke.DsmEntry(Session.AppId, Message.OpenDS, source);
 			if (rc == ReturnCode.Success)
             {
+                Session.ChangeSourceId(source);
                 Session.ChangeState(4, true);
 			}
 			return rc;

NTwain/Triplets/DGControl/DGControl.Parent.cs

@@ -10,7 +10,7 @@ namespace NTwain.Triplets
     /// </summary>
     sealed class Parent : OpBase
     {
-        internal Parent(ITwainSessionInternal session) : base(session) { }
+        internal Parent(ITwainStateInternal session) : base(session) { }
 
         /// <summary>
         /// When the application has closed all the Sources it had previously opened, and is finished with

NTwain/Triplets/DGControl/DGControl.PassThru.cs

@@ -9,7 +9,7 @@ namespace NTwain.Triplets
     /// </summary>
 	public sealed class PassThru : OpBase
 	{
-		internal PassThru(ITwainSessionInternal session) : base(session) { }
+		internal PassThru(ITwainStateInternal session) : base(session) { }
 		/// <summary>
 		/// PASSTHRU is intended for the use of Source writers writing diagnostic applications. It allows
 		/// raw communication with the currently selected device in the Source.

NTwain/Triplets/DGControl/DGControl.PendingXfers.cs

@@ -9,7 +9,7 @@ namespace NTwain.Triplets
     /// </summary>
 	sealed class PendingXfers : OpBase
 	{
-		internal PendingXfers(ITwainSessionInternal session) : base(session) { }
+		internal PendingXfers(ITwainStateInternal session) : base(session) { }
 		/// <summary>
 		/// This triplet is used to cancel or terminate a transfer. Issued in state 6, this triplet cancels the next
 		/// pending transfer, discards the transfer data, and decrements the pending transfers count. In

NTwain/Triplets/DGControl/DGControl.SetupFileXfer.cs

@@ -9,7 +9,7 @@ namespace NTwain.Triplets
     /// </summary>
 	public sealed class SetupFileXfer : OpBase
 	{
-		internal SetupFileXfer(ITwainSessionInternal session) : base(session) { }
+		internal SetupFileXfer(ITwainStateInternal session) : base(session) { }
 		/// <summary>
 		/// Returns information about the file into which the Source has or will put the acquired image
 		/// or audio data.

NTwain/Triplets/DGControl/DGControl.SetupMemXfer.cs

@@ -9,7 +9,7 @@ namespace NTwain.Triplets
     /// </summary>
 	public sealed class SetupMemXfer : OpBase
 	{
-		internal SetupMemXfer(ITwainSessionInternal session) : base(session) { }
+		internal SetupMemXfer(ITwainStateInternal session) : base(session) { }
 		/// <summary>
 		/// Returns the Source’s preferred, minimum, and maximum allocation sizes for transfer memory
 		/// buffers.

NTwain/Triplets/DGControl/DGControl.Status.cs

@@ -9,7 +9,7 @@ namespace NTwain.Triplets
     /// </summary>
 	public sealed class Status : OpBase
 	{
-		internal Status(ITwainSessionInternal session) : base(session) { }
+		internal Status(ITwainStateInternal session) : base(session) { }
 		/// <summary>
 		/// Returns the current Condition Code for the Source Manager.
 		/// </summary>

NTwain/Triplets/DGControl/DGControl.StatusUtf8.cs

@@ -9,7 +9,7 @@ namespace NTwain.Triplets
     /// </summary>
 	public sealed class StatusUtf8 : OpBase
 	{
-		internal StatusUtf8(ITwainSessionInternal session) : base(session) { }
+		internal StatusUtf8(ITwainStateInternal session) : base(session) { }
 		/// <summary>
 		/// Translate the contents of a TW_STATUS structure received from a Source into a localized UTF-8
 		/// encoded string.

NTwain/Triplets/DGControl/DGControl.UserInterface.cs

@@ -9,7 +9,7 @@ namespace NTwain.Triplets
     /// </summary>
     sealed class UserInterface : OpBase
     {
-        internal UserInterface(ITwainSessionInternal session) : base(session) { }
+        internal UserInterface(ITwainStateInternal session) : base(session) { }
         /// <summary>
         /// This operation causes the Source’s user interface, if displayed during the
         /// EnableDS operation, to be lowered. The Source is returned to

NTwain/Triplets/DGControl/DGControl.XferGroup.cs

@@ -9,7 +9,7 @@ namespace NTwain.Triplets
     /// </summary>
 	public sealed class XferGroup : OpBase
 	{
-		internal XferGroup(ITwainSessionInternal session) : base(session) { }
+		internal XferGroup(ITwainStateInternal session) : base(session) { }
 
 		/// <summary>
 		/// Returns the Data Group (the type of data) for the upcoming transfer. The Source is required to

NTwain/Triplets/DGControl/DGControl.cs

@@ -7,8 +7,8 @@ namespace NTwain.Triplets
 	/// </summary>
 	public sealed class DGControl
 	{
-        ITwainSessionInternal _session;
+        ITwainStateInternal _session;
-        internal DGControl(ITwainSessionInternal session)
+        internal DGControl(ITwainStateInternal session)
 		{
 			if (session == null) { throw new ArgumentNullException("session"); }
 			_session = session;

NTwain/Triplets/DGImage/DGImage.CieColor.cs

@@ -9,7 +9,7 @@ namespace NTwain.Triplets
     /// </summary>
 	public sealed class CieColor : OpBase
 	{
-		internal CieColor(ITwainSessionInternal session) : base(session) { }
+		internal CieColor(ITwainStateInternal session) : base(session) { }
 
 		/// <summary>
 		/// This operation causes the Source to report the currently active parameters to be used in

NTwain/Triplets/DGImage/DGImage.ExtImageInfo.cs

@@ -9,7 +9,7 @@ namespace NTwain.Triplets
     /// </summary>
 	public sealed class ExtImageInfo : OpBase
 	{
-		internal ExtImageInfo(ITwainSessionInternal session) : base(session) { }
+		internal ExtImageInfo(ITwainStateInternal session) : base(session) { }
 
 		public ReturnCode Get(TWExtImageInfo info)
 		{

NTwain/Triplets/DGImage/DGImage.Filter.cs

@@ -9,7 +9,7 @@ namespace NTwain.Triplets
     /// </summary>
 	public sealed class Filter : OpBase
 	{
-        internal Filter(ITwainSessionInternal session) : base(session) { }
+        internal Filter(ITwainStateInternal session) : base(session) { }
 
 
         /// <summary>

NTwain/Triplets/DGImage/DGImage.GrayResponse.cs

@@ -9,7 +9,7 @@ namespace NTwain.Triplets
     /// </summary>
 	public sealed class GrayResponse : OpBase
 	{
-		internal GrayResponse(ITwainSessionInternal session) : base(session) { }
+		internal GrayResponse(ITwainStateInternal session) : base(session) { }
 
 		/// <summary>
 		/// The Reset operation causes the Source to use its "identity response curve." The identity

NTwain/Triplets/DGImage/DGImage.IccProfile.cs

@@ -9,7 +9,7 @@ namespace NTwain.Triplets
     /// </summary>
 	public sealed class IccProfile : OpBase
 	{
-		internal IccProfile(ITwainSessionInternal session) : base(session) { }
+		internal IccProfile(ITwainStateInternal session) : base(session) { }
 
 		/// <summary>
 		/// This operation provides the application with the ICC profile associated with the image which is

NTwain/Triplets/DGImage/DGImage.ImageFileXfer.cs

@@ -9,7 +9,7 @@ namespace NTwain.Triplets
     /// </summary>
 	sealed class ImageFileXfer : OpBase
 	{
-		internal ImageFileXfer(ITwainSessionInternal session) : base(session) { }
+		internal ImageFileXfer(ITwainStateInternal session) : base(session) { }
 
 		/// <summary>
 		/// This operation is used to initiate the transfer of an image from the Source to the application via

NTwain/Triplets/DGImage/DGImage.ImageInfo.cs

@@ -9,7 +9,7 @@ namespace NTwain.Triplets
     /// </summary>
 	public sealed class ImageInfo : OpBase
 	{
-		internal ImageInfo(ITwainSessionInternal session) : base(session) { }
+		internal ImageInfo(ITwainStateInternal session) : base(session) { }
 
 		public ReturnCode Get(out TWImageInfo info)
 		{

NTwain/Triplets/DGImage/DGImage.ImageLayout.cs

@@ -9,7 +9,7 @@ namespace NTwain.Triplets
     /// </summary>
 	public sealed class ImageLayout : OpBase
 	{
-		internal ImageLayout(ITwainSessionInternal session) : base(session) { }
+		internal ImageLayout(ITwainStateInternal session) : base(session) { }
 
 		public ReturnCode Get(out TWImageLayout layout)
 		{

NTwain/Triplets/DGImage/DGImage.ImageMemFileXfer.cs

@@ -6,7 +6,7 @@ namespace NTwain.Triplets
 {
 	sealed class ImageMemFileXfer : OpBase
 	{
-		internal ImageMemFileXfer(ITwainSessionInternal session) : base(session) { }
+		internal ImageMemFileXfer(ITwainStateInternal session) : base(session) { }
 
 		/// <summary>
 		/// This operation is used to initiate the transfer of an image from the Source to the application via

NTwain/Triplets/DGImage/DGImage.ImageMemXfer.cs

@@ -6,7 +6,7 @@ namespace NTwain.Triplets
 {
 	sealed class ImageMemXfer : OpBase
 	{
-		internal ImageMemXfer(ITwainSessionInternal session) : base(session) { }
+		internal ImageMemXfer(ITwainStateInternal session) : base(session) { }
 
 		/// <summary>
 		/// This operation is used to initiate the transfer of an image from the Source to the application via

NTwain/Triplets/DGImage/DGImage.ImageNativeXfer.cs

@@ -6,7 +6,7 @@ namespace NTwain.Triplets
 {
 	sealed class ImageNativeXfer : OpBase
 	{
-		internal ImageNativeXfer(ITwainSessionInternal session) : base(session) { }
+		internal ImageNativeXfer(ITwainStateInternal session) : base(session) { }
 
 		/// <summary>
 		/// Causes the transfer of an image’s data from the Source to the application, via the Native transfer

NTwain/Triplets/DGImage/DGImage.JpegCompression.cs

@@ -9,7 +9,7 @@ namespace NTwain.Triplets
     /// </summary>
 	public sealed class JpegCompression : OpBase
 	{
-		internal JpegCompression(ITwainSessionInternal session) : base(session) { }
+		internal JpegCompression(ITwainStateInternal session) : base(session) { }
 
 		/// <summary>
 		/// Causes the Source to return the parameters that will be used during the compression of data

NTwain/Triplets/DGImage/DGImage.Palette8.cs

@@ -9,7 +9,7 @@ namespace NTwain.Triplets
     /// </summary>
 	public sealed class Palette8 : OpBase
 	{
-		internal Palette8(ITwainSessionInternal session) : base(session) { }
+		internal Palette8(ITwainStateInternal session) : base(session) { }
 
 		/// <summary>
 		/// This operation causes the Source to report its current palette information.

NTwain/Triplets/DGImage/DGImage.RgbResponse.cs

@@ -9,7 +9,7 @@ namespace NTwain.Triplets
     /// </summary>
 	public sealed class RgbResponse : OpBase
 	{
-		internal RgbResponse(ITwainSessionInternal session) : base(session) { }
+		internal RgbResponse(ITwainStateInternal session) : base(session) { }
 
 		/// <summary>
 		/// Causes the Source to use its "identity" response curves for future RGB transfers. The identity

NTwain/Triplets/DGImage/DGImage.cs

@@ -7,8 +7,8 @@ namespace NTwain.Triplets
 	/// </summary>
 	public sealed class DGImage
 	{
-        ITwainSessionInternal _session;
+        ITwainStateInternal _session;
-        internal DGImage(ITwainSessionInternal session)
+        internal DGImage(ITwainStateInternal session)
 		{
 			if (session == null) { throw new ArgumentNullException("session"); }
 			_session = session;

NTwain/Triplets/OpBase.cs

@@ -16,7 +16,7 @@ namespace NTwain.Triplets
 		/// </summary>
 		/// <param name="session">The session.</param>
 		/// <exception cref="System.ArgumentNullException"></exception>
-        internal OpBase(ITwainSessionInternal session)
+        internal OpBase(ITwainStateInternal session)
 		{
 			if (session == null) { throw new ArgumentNullException("session"); }
 			Session = session;
@@ -28,6 +28,6 @@ namespace NTwain.Triplets
 		/// <value>
 		/// The session.
 		/// </value>
-        internal ITwainSessionInternal Session { get; private set; }
+        internal ITwainStateInternal Session { get; private set; }
 	}
 }

NTwain/TwainSession.cs

@@ -19,7 +19,7 @@ namespace NTwain
     /// <summary>
     /// Provides a session for working with TWAIN api in an application.
     /// </summary>
-    public class TwainSession : ITwainSessionInternal, IMessageFilter, INotifyPropertyChanged
+    public class TwainSession : ITwainStateInternal, IMessageFilter, INotifyPropertyChanged
     {
         /// <summary>
         /// Initializes a new instance of the <see cref="TwainSession" /> class.
@@ -29,7 +29,7 @@ namespace NTwain
         public TwainSession(TWIdentity appId)
         {
             if (appId == null) { throw new ArgumentNullException("appId"); }
-            _appId = appId;
+            AppId = appId;
             State = 1;
             EnforceState = true;
         }
@@ -40,27 +40,17 @@ namespace NTwain
         SynchronizationContext _syncer;
 
 
-        TWIdentity _appId;
         /// <summary>
         /// Gets the app id used for the session.
         /// </summary>
         /// <value>The app id.</value>
-        public TWIdentity AppId { get { return _appId; } }
+        public TWIdentity AppId { get; private set; }
 
-        TWIdentity _sourceId;
         /// <summary>
         /// Gets the source id used for the session.
         /// </summary>
         /// <value>The source id.</value>
-        public TWIdentity SourceId
+        public TWIdentity SourceId { get; private set; }
-        {
-            get { return _sourceId; }
-            private set
-            {
-                _sourceId = value;
-                RaisePropertyChanged("SourceId");
-            }
-        }
 
         /// <summary>
         /// Gets the current state number as defined by the TWAIN spec.
@@ -157,15 +147,20 @@ namespace NTwain
 
         #region state transition calls
 
-        void ITwainSessionInternal.ChangeState(int newState, bool notifyChange)
+        void ITwainStateInternal.ChangeState(int newState, bool notifyChange)
         {
             Debug.WriteLine("TWAIN State = " + newState);
             State = newState;
             if (notifyChange) { RaisePropertyChanged("State"); }
         }
-        ICommitable ITwainSessionInternal.GetPendingStateChanger(int newState)
+        ICommitable ITwainStateInternal.GetPendingStateChanger(int newState)
         {
-            return new TentativeStateChanger(this, newState);
+            return new TentativeStateCommitable(this, newState);
+        }
+        void ITwainStateInternal.ChangeSourceId(TWIdentity sourceId)
+        {
+            SourceId = sourceId;
+            RaisePropertyChanged("SourceId");
         }
 
 
@@ -193,7 +188,7 @@ namespace NTwain
                     rc = DGControl.EntryPoint.Get(out entry);
                     if (rc == ReturnCode.Success)
                     {
-                        MemoryManager.Global.UpdateEntryPoint(entry);
+                        MemoryManager.Instance.UpdateEntryPoint(entry);
                         Debug.WriteLine("Using TWAIN2 memory functions.");
                     }
                     else
@@ -218,7 +213,7 @@ namespace NTwain
             if (rc == ReturnCode.Success)
             {
                 _parentHandle = default(HandleRef);
-                MemoryManager.Global.UpdateEntryPoint(null);
+                MemoryManager.Instance.UpdateEntryPoint(null);
             }
             return rc;
         }
@@ -258,7 +253,7 @@ namespace NTwain
                 if (!DisableCallback)
                 {
                     // app v2.2 or higher uses callback2
-                    if (_appId.ProtocolMajor >= 2 && _appId.ProtocolMinor >= 2)
+                    if (AppId.ProtocolMajor >= 2 && AppId.ProtocolMinor >= 2)
                     {
                         var cb = new TWCallback2(new CallbackDelegate(CallbackHandler));
                         var rc2 = DGControl.Callback2.RegisterCallback(cb);
@@ -289,7 +284,7 @@ namespace NTwain
         ReturnCode CallbackHandler(TWIdentity origin, TWIdentity dest,
             DataGroups dg, DataArgumentType dat, Values.Message msg, IntPtr data)
         {
-            if (origin != null && _sourceId != null && origin.Id == _sourceId.Id)
+            if (origin != null && SourceId != null && origin.Id == SourceId.Id)
             {
                 Debug.WriteLine(string.Format("Thread {0}: GOT TWAIN callback for msg {1}.", Thread.CurrentThread.ManagedThreadId, msg));
                 // spec says should handle this on the thread that enabled the DS, 
@@ -509,7 +504,7 @@ namespace NTwain
                                 {
                                     if (dataPtr != IntPtr.Zero)
                                     {
-                                        lockedPtr = MemoryManager.Global.MemLock(dataPtr);
+                                        lockedPtr = MemoryManager.Instance.MemLock(dataPtr);
                                     }
                                     dtHand(this, new DataTransferredEventArgs(lockedPtr, file));
                                 }
@@ -528,7 +523,7 @@ namespace NTwain
                         //			var dtHand = DataTransferred;
                         //			if (dtHand != null)
                         //			{
-                        //				lockedPtr = MemoryManager.Global.MemLock(dataPtr);
+                        //				lockedPtr = MemoryManager.Instance.MemLock(dataPtr);
                         //				dtHand(this, new DataTransferredEventArgs(lockedPtr));
                         //			}
                         //		}
@@ -542,12 +537,12 @@ namespace NTwain
                         // data here is allocated by source so needs to use shared mem calls
                         if (lockedPtr != IntPtr.Zero)
                         {
-                            MemoryManager.Global.MemUnlock(lockedPtr);
+                            MemoryManager.Instance.MemUnlock(lockedPtr);
                             lockedPtr = IntPtr.Zero;
                         }
                         if (dataPtr != IntPtr.Zero)
                         {
-                            MemoryManager.Global.MemFree(dataPtr);
+                            MemoryManager.Instance.MemFree(dataPtr);
                             dataPtr = IntPtr.Zero;
                         }
                     }
@@ -723,14 +718,14 @@ namespace NTwain
                 try
                 {
                     // no need to lock for marshal alloc
-                    msgPtr = MemoryManager.Global.MemAllocate((uint)Marshal.SizeOf(winmsg));
+                    msgPtr = MemoryManager.Instance.MemAllocate((uint)Marshal.SizeOf(winmsg));
                     Marshal.StructureToPtr(winmsg, msgPtr, false);
                     return HandleLoopMsgEvent(ref msgPtr);
                 }
                 finally
                 {
                     if (msgPtr != IntPtr.Zero)
-                        MemoryManager.Global.MemFree(msgPtr);
+                        MemoryManager.Instance.MemFree(msgPtr);
                 }
             }
             return false;
@@ -762,14 +757,14 @@ namespace NTwain
                 try
                 {
                     // no need to lock for marshal alloc
-                    msgPtr = MemoryManager.Global.MemAllocate((uint)Marshal.SizeOf(winmsg));
+                    msgPtr = MemoryManager.Instance.MemAllocate((uint)Marshal.SizeOf(winmsg));
                     Marshal.StructureToPtr(winmsg, msgPtr, false);
                     handled = HandleLoopMsgEvent(ref msgPtr);
                 }
                 finally
                 {
                     if (msgPtr != IntPtr.Zero)
-                        MemoryManager.Global.MemFree(msgPtr);
+                        MemoryManager.Instance.MemFree(msgPtr);
                 }
             }
             return IntPtr.Zero;
@@ -791,44 +786,5 @@ namespace NTwain
 
         #endregion
 
-        #region nested stuff
-
-        class TentativeStateChanger : ICommitable
-        {
-            bool _commit;
-            ITwainSessionInternal _session;
-            int _origState;
-            int _newState;
-            public TentativeStateChanger(ITwainSessionInternal session, int newState)
-            {
-                _session = session;
-                _origState = session.State;
-                _newState = newState;
-                _session.ChangeState(newState, false);
-            }
-
-            public void Commit()
-            {
-                if (_session.State == _newState)
-                {
-                    _session.ChangeState(_newState, true);
-                }
-                _commit = true;
-            }
-
-            #region IDisposable Members
-
-            public void Dispose()
-            {
-                if (!_commit && _session.State == _newState)
-                {
-                    _session.ChangeState(_origState, false);
-                }
-            }
-
-            #endregion
-        }
-
-        #endregion
     }
 }

NTwain/TwainSessionExtensions.cs

@@ -73,7 +73,7 @@ namespace NTwain
         /// <param name="dataArgumentType">The triplet data argument type.</param>
         /// <param name="message">The triplet message.</param>
         /// <exception cref="TwainStateException"></exception>
-        internal static void VerifyState(this ITwainSessionInternal session, int allowedMinimum, int allowedMaximum, DataGroups group, DataArgumentType dataArgumentType, NTwain.Values.Message message)
+        internal static void VerifyState(this ITwainStateInternal session, int allowedMinimum, int allowedMaximum, DataGroups group, DataArgumentType dataArgumentType, NTwain.Values.Message message)
         {
             if (session.EnforceState && (session.State < allowedMinimum || session.State > allowedMaximum))
             {

NTwain/Values/DataValues.cs

@@ -346,7 +346,7 @@ namespace NTwain.Values
     /// CapClearBuffers values.
     /// Corresponds to TWCB_* values.
     /// </summary>
-    public enum ClearBuffers : ushort
+    public enum ClearBuffer : ushort
     {
         Auto = 0,
         Clear = 1,

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()
         {
-            ITwainSessionInternal session = new TwainSession(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()
         {
-            ITwainSessionInternal session = new TwainSession(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.Winform/Tester.Winform.csproj

@@ -16,7 +16,7 @@
     <SolutionDir Condition="$(SolutionDir) == '' Or $(SolutionDir) == '*Undefined*'">..\..\</SolutionDir>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|x86' ">
-    <PlatformTarget>x86</PlatformTarget>
+    <PlatformTarget>x64</PlatformTarget>
     <DebugSymbols>true</DebugSymbols>
     <DebugType>full</DebugType>
     <Optimize>false</Optimize>
@@ -40,10 +40,6 @@
       <HintPath>..\..\packages\CommonWin32.2.0.4\lib\net35-Client\CommonWin32.dll</HintPath>
     </Reference>
     <Reference Include="System" />
-    <Reference Include="System.Core" />
-    <Reference Include="System.Data.DataSetExtensions" />
-    <Reference Include="System.Data" />
-    <Reference Include="System.Deployment" />
     <Reference Include="System.Drawing" />
     <Reference Include="System.Windows.Forms" />
     <Reference Include="System.Xml" />