Added cap query support example.

NTwain/Data/TwainValues.cs

@@ -2037,18 +2037,20 @@ namespace NTwain.Data
     /// Bit mask for querying the operation that are supported by the data source on a capability.
     /// Corresponds to TWQC_*.
     /// </summary>
-    public static class QuerySupportMask
+    [Flags]
+    public enum QuerySupport
     {
-        public const int Get = 0x1;
-        public const int Set = 0x2;
-        public const int GetDefault = 0x4;
-        public const int GetCurrent = 0x8;
-        public const int Reset = 0x10;
-        public const int SetConstraint = 0x20;
-        public const int Constrainable = 0x40;
-        public const int GetHelp = 0x100;
-        public const int GetLabel = 0x200;
-        public const int GetLabelEnum = 0x400;
+        None = 0,
+        Get = 0x1,
+        Set = 0x2,
+        GetDefault = 0x4,
+        GetCurrent = 0x8,
+        Reset = 0x10,
+        SetConstraint = 0x20,
+        Constrainable = 0x40,
+        GetHelp = 0x100,
+        GetLabel = 0x200,
+        GetLabelEnum = 0x400
     }
 
     /// <summary>

NTwain/Internals/ITwainSessionInternal.cs

@@ -3,9 +3,6 @@ using System.Collections.Generic;
 
 namespace NTwain.Internals
 {
-    /// <summary>
-    /// Internal interface for state management.
-    /// </summary>
     interface ITwainSessionInternal : ITwainSession
     {
         /// <summary>

NTwain/Internals/UnsafeNativeMethods.cs

@@ -1,26 +1,26 @@
 using System;
 using System.Runtime.InteropServices;
+using System.Security;
 
 namespace NTwain.Internals
 {
-    static class NativeMethods
+    [SuppressUnmanagedCodeSecurity]
+    static class UnsafeNativeMethods
     {
-        // should be unsafe native methods?
-
         #region mem stuff for twain 1.x
 
         [DllImport("kernel32", SetLastError = true, EntryPoint = "GlobalAlloc")]
-        public static extern IntPtr WinGlobalAlloc(uint uFlags, UIntPtr dwBytes);
+        internal static extern IntPtr WinGlobalAlloc(uint uFlags, UIntPtr dwBytes);
 
         [DllImport("kernel32", SetLastError = true, EntryPoint = "GlobalFree")]
-        public static extern IntPtr WinGlobalFree(IntPtr hMem);
+        internal static extern IntPtr WinGlobalFree(IntPtr hMem);
 
         [DllImport("kernel32", SetLastError = true, EntryPoint = "GlobalLock")]
-        public static extern IntPtr WinGlobalLock(IntPtr handle);
+        internal static extern IntPtr WinGlobalLock(IntPtr handle);
 
         [DllImport("kernel32", SetLastError = true, EntryPoint = "GlobalUnlock")]
         [return: MarshalAs(UnmanagedType.Bool)]
-        public static extern bool WinGlobalUnlock(IntPtr handle);
+        internal static extern bool WinGlobalUnlock(IntPtr handle);
 
         #endregion
     }

NTwain/Internals/WinMemoryManager.cs

@@ -13,7 +13,7 @@ namespace NTwain
     {
         public IntPtr Allocate(uint size)
         {
-            IntPtr retVal = NativeMethods.WinGlobalAlloc(0x0040, new UIntPtr(size));
+            IntPtr retVal = UnsafeNativeMethods.WinGlobalAlloc(0x0040, new UIntPtr(size));
 
             if (retVal == IntPtr.Zero)
             {
@@ -24,17 +24,17 @@ namespace NTwain
 
         public void Free(IntPtr handle)
         {
-            NativeMethods.WinGlobalFree(handle);
+            UnsafeNativeMethods.WinGlobalFree(handle);
         }
 
         public IntPtr Lock(IntPtr handle)
         {
-            return NativeMethods.WinGlobalLock(handle);
+            return UnsafeNativeMethods.WinGlobalLock(handle);
         }
 
         public void Unlock(IntPtr handle)
         {
-            NativeMethods.WinGlobalUnlock(handle);
+            UnsafeNativeMethods.WinGlobalUnlock(handle);
         }
     }
 }

NTwain/NTwain.csproj

@@ -69,7 +69,7 @@
     <Compile Include="ITwainState.cs" />
     <Compile Include="Internals\WinMemoryManager.cs" />
     <Compile Include="Internals\MessageLoop.cs" />
-    <Compile Include="Internals\NativeMethods.cs" />
+    <Compile Include="Internals\UnsafeNativeMethods.cs" />
     <Compile Include="Platform.cs" />
     <Compile Include="Properties\Resources.Designer.cs">
       <AutoGen>True</AutoGen>

NTwain/Platform.cs

@@ -64,7 +64,7 @@ namespace NTwain
         }
 
 
-        static readonly WinMemoryManager _defaultMemManager;
+        static readonly IMemoryManager _defaultMemManager;
         static IMemoryManager _specifiedMemManager;
 
         /// <summary>

NTwain/TwainSessionExtensions.cs

@@ -6,8 +6,8 @@ using System.Linq;
 namespace NTwain
 {
     /// <summary>
-    /// Defines common methods on <see cref="TwainSession"/> using the raw
-    /// TWAIN triplet api.
+    /// Defines useful methods on <see cref="TwainSession"/> without having to dive into
+    /// the raw TWAIN triplet API.
     /// </summary>
     public static class TwainSessionExtensions
     {
@@ -68,6 +68,33 @@ namespace NTwain
 
         #region caps routines
 
+        /// <summary>
+        /// Gets the actual supported operations for a capability.
+        /// </summary>
+        /// <param name="session">The session.</param>
+        /// <param name="capId">The cap identifier.</param>
+        /// <returns></returns>
+        public static QuerySupport GetCapSupport(this ITwainOperation session, CapabilityId capId)
+        {
+            if (session == null) { throw new ArgumentNullException("session"); }
+
+            QuerySupport retVal = QuerySupport.None;
+            using (TWCapability cap = new TWCapability(capId))
+            {
+                var rc = session.DGControl.Capability.QuerySupport(cap);
+                if (rc == ReturnCode.Success)
+                {
+                    var read = CapReadOut.ReadValue(cap);
+
+                    if (read.ContainerType == ContainerType.OneValue)
+                    {
+                        retVal = read.OneValue.ConvertToEnum<QuerySupport>();
+                    }
+                }
+            }
+            return retVal;
+        }
+
         /// <summary>
         /// Gets the current value for a capability.
         /// </summary>