Some more type reading update.

NTwain/Data/CapReadOut.cs

@@ -166,7 +166,7 @@ namespace NTwain.Data
             int offset = 0;
             ItemType = (ItemType)(ushort)Marshal.ReadInt16(baseAddr, offset);
             offset += 2;
-            OneValue = ReadValue(baseAddr, ref offset, ItemType);
+            OneValue = TypeReader.ReadValue(baseAddr, ref offset, ItemType);
             return this;
         }
 
@@ -182,7 +182,7 @@ namespace NTwain.Data
                 CollectionValues = new object[count];
                 for (int i = 0; i < count; i++)
                 {
-                    CollectionValues[i] = ReadValue(baseAddr, ref offset, ItemType);
+                    CollectionValues[i] = TypeReader.ReadValue(baseAddr, ref offset, ItemType);
                 }
             }
             return this;
@@ -204,7 +204,7 @@ namespace NTwain.Data
                 CollectionValues = new object[count];
                 for (int i = 0; i < count; i++)
                 {
-                    CollectionValues[i] = ReadValue(baseAddr, ref offset, ItemType);
+                    CollectionValues[i] = TypeReader.ReadValue(baseAddr, ref offset, ItemType);
                 }
             }
             return this;
@@ -228,125 +228,6 @@ namespace NTwain.Data
             return this;
         }
 
-        static object ReadValue(IntPtr baseAddr, ref int offset, ItemType type)
-        {
-            object val = null;
-            switch (type)
-            {
-                case ItemType.Int8:
-                    val = (sbyte)Marshal.ReadByte(baseAddr, offset);
-                    break;
-                case ItemType.UInt8:
-                    val = Marshal.ReadByte(baseAddr, offset);
-                    break;
-                case ItemType.Bool:
-                case ItemType.UInt16:
-                    val = (ushort)Marshal.ReadInt16(baseAddr, offset);
-                    break;
-                case ItemType.Int16:
-                    val = Marshal.ReadInt16(baseAddr, offset);
-                    break;
-                case ItemType.UInt32:
-                    val = (uint)Marshal.ReadInt32(baseAddr, offset);
-                    break;
-                case ItemType.Int32:
-                    val = Marshal.ReadInt32(baseAddr, offset);
-                    break;
-                case ItemType.Fix32:
-                    TWFix32 f32 = new TWFix32();
-                    f32.Whole = Marshal.ReadInt16(baseAddr, offset);
-                    f32.Fraction = (ushort)Marshal.ReadInt16(baseAddr, offset + 2);
-                    val = f32;
-                    break;
-                case ItemType.Frame:
-                    TWFrame frame = new TWFrame();
-                    frame.Left = (TWFix32)ReadValue(baseAddr, ref offset, ItemType.Fix32);
-                    frame.Top = (TWFix32)ReadValue(baseAddr, ref offset, ItemType.Fix32);
-                    frame.Right = (TWFix32)ReadValue(baseAddr, ref offset, ItemType.Fix32);
-                    frame.Bottom = (TWFix32)ReadValue(baseAddr, ref offset, ItemType.Fix32);
-                    return frame; // no need to update offset again after reading fix32
-                case ItemType.String128:
-                    val = ReadString(baseAddr, offset, TwainConst.String128 - 2);
-                    break;
-                case ItemType.String255:
-                    val = ReadString(baseAddr, offset, TwainConst.String255 - 1);
-                    break;
-                case ItemType.String32:
-                    val = ReadString(baseAddr, offset, TwainConst.String32 - 2);
-                    break;
-                case ItemType.String64:
-                    val = ReadString(baseAddr, offset, TwainConst.String64 - 2);
-                    break;
-                case ItemType.Handle:
-                    val = new IntPtr(baseAddr.ToInt64() + offset);
-                    break;
-            }
-            offset += GetItemTypeSize(type);
-            return val;
-        }
-
-        /// <summary>
-        /// Read string value.
-        /// </summary>
-        /// <param name="baseAddr"></param>
-        /// <param name="offset"></param>
-        /// <param name="maxLength"></param>
-        /// <returns></returns>
-        static string ReadString(IntPtr baseAddr, int offset, int maxLength)
-        {
-            // does this work cross-platform?
-            var val = Marshal.PtrToStringAnsi(new IntPtr(baseAddr.ToInt64() + offset));
-            if (val.Length > maxLength)
-            {
-                // bad source, whatever
-            }
-            return val;
-            //var sb = new StringBuilder(maxLength);
-            //byte bt;
-            //while (sb.Length < maxLength &&
-            //    (bt = Marshal.ReadByte(baseAddr, offset++)) != 0)
-            //{
-            //    sb.Append((char)bt);
-            //}
-            //return sb.ToString();
-        }
-
-
-        /// <summary>
-        /// Gets the byte size of the item type.
-        /// </summary>
-        /// <param name="type"></param>
-        /// <returns></returns>
-        internal static int GetItemTypeSize(ItemType type)
-        {
-            switch (type)
-            {
-                case ItemType.Int8:
-                case ItemType.UInt8:
-                    return 1;
-                case ItemType.UInt16:
-                case ItemType.Int16:
-                case ItemType.Bool:
-                    return 2;
-                case ItemType.Int32:
-                case ItemType.UInt32:
-                case ItemType.Fix32:
-                    return 4;
-                case ItemType.Frame:
-                    return 16;
-                case ItemType.String32:
-                    return TwainConst.String32;
-                case ItemType.String64:
-                    return TwainConst.String64;
-                case ItemType.String128:
-                    return TwainConst.String128;
-                case ItemType.String255:
-                    return TwainConst.String255;
-                case ItemType.Handle:
-                    return IntPtr.Size;
-            }
-            return 0;
-        }
         #endregion
     }
 }

NTwain/Data/TypesExtended.cs

@@ -691,7 +691,7 @@ namespace NTwain.Data
             if (ContainerType != Values.ContainerType.OneValue) { throw new ArgumentException(Resources.BadContainerType, "value"); }
 
             // since one value can only house UInt32 we will not allow type size > 4
-            if (CapReadOut.GetItemTypeSize(value.ItemType) > 4) { throw new ArgumentException("Invalid one value type"); }
+            if (TypeReader.GetItemTypeSize(value.ItemType) > 4) { throw new ArgumentException("Invalid one value type"); }
 
             _hContainer = MemoryManager.Instance.Allocate((uint)Marshal.SizeOf(value));
             if (_hContainer != IntPtr.Zero)
@@ -707,7 +707,7 @@ namespace NTwain.Data
             if (ContainerType != Values.ContainerType.Enum) { throw new ArgumentException(Resources.BadContainerType, "value"); }
 
 
-            Int32 valueSize = value.ItemOffset + value.ItemList.Length * CapReadOut.GetItemTypeSize(value.ItemType);
+            Int32 valueSize = value.ItemOffset + value.ItemList.Length * TypeReader.GetItemTypeSize(value.ItemType);
 
             int offset = 0;
             _hContainer = MemoryManager.Instance.Allocate((uint)valueSize);
@@ -733,7 +733,7 @@ namespace NTwain.Data
             if (ContainerType != Values.ContainerType.Range) { throw new ArgumentException(Resources.BadContainerType, "value"); }
 
             // since range value can only house UInt32 we will not allow type size > 4
-            if (CapReadOut.GetItemTypeSize(value.ItemType) > 4) { throw new ArgumentException("Invalid range value type"); }
+            if (TypeReader.GetItemTypeSize(value.ItemType) > 4) { throw new ArgumentException("Invalid range value type"); }
 
             _hContainer = MemoryManager.Instance.Allocate((uint)Marshal.SizeOf(value));
             if (_hContainer != IntPtr.Zero)
@@ -808,7 +808,7 @@ namespace NTwain.Data
                 //    WriteUString(baseAddr, offset, value as string, 512);
                 //    break;
             }
-            offset += CapReadOut.GetItemTypeSize(type);
+            offset += TypeReader.GetItemTypeSize(type);
         }
         /// <summary>
         /// Writes string value.
@@ -1325,7 +1325,7 @@ namespace NTwain.Data
         /// If the Item field contains a handle to data, then the Application is
         /// responsible for freeing that memory.
         /// </summary>
-        public UIntPtr Item { get { return _item; } }
+        public UIntPtr Item { get { return _item; } internal set { _item = value; } }
     }
 
     /// <summary>
@@ -1352,6 +1352,9 @@ namespace NTwain.Data
 
         #region IDisposable Members
 
+        /// <summary>
+        /// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
+        /// </summary>
         public void Dispose()
         {
             Dispose(true);
@@ -1364,22 +1367,27 @@ namespace NTwain.Data
             // this is iffy & may have to flatten info array as individual fields in this class to work
             if (_info != null)
             {
-                foreach (var i in _info)
+                for (int i = 0; i < _info.Length; i++)
                 {
-                    if (i.Item != UIntPtr.Zero)
+                    var it = _info[i];
+                    if (it.Item != UIntPtr.Zero)
                     {
-                        var sz = i.NumItems * CapReadOut.GetItemTypeSize(i.ItemType);
+                        var sz = it.NumItems * TypeReader.GetItemTypeSize(it.ItemType);
-                        if (sz > UIntPtr.Size || i.ItemType == ItemType.Handle)
+                        if (sz > UIntPtr.Size || it.ItemType == ItemType.Handle)
                         {
                             // uintptr to intptr could be bad
-                            var ptr = new IntPtr(BitConverter.ToInt64(BitConverter.GetBytes(i.Item.ToUInt64()), 0));
+                            var ptr = new IntPtr(BitConverter.ToInt64(BitConverter.GetBytes(it.Item.ToUInt64()), 0));
                             MemoryManager.Instance.Free(ptr);
                         }
                     }
+                    it.Item = UIntPtr.Zero;
                 }
             }
         }
 
+        /// <summary>
+        /// Finalizes an instance of the <see cref="TWExtImageInfo"/> class.
+        /// </summary>
         ~TWExtImageInfo()
         {
             Dispose(false);
@@ -2239,6 +2247,9 @@ namespace NTwain.Data
 
         #region IDisposable Members
 
+        /// <summary>
+        /// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
+        /// </summary>
         public void Dispose()
         {
             Dispose(true);
@@ -2258,6 +2269,9 @@ namespace NTwain.Data
             }
         }
 
+        /// <summary>
+        /// Finalizes an instance of the <see cref="TWStatusUtf8"/> class.
+        /// </summary>
         ~TWStatusUtf8()
         {
             Dispose(false);

NTwain/NTwain.csproj

@@ -55,6 +55,7 @@
   <ItemGroup>
     <Compile Include="AsyncPump.cs" />
     <Compile Include="Data\CapReadOut.cs" />
+    <Compile Include="Data\TypeReader.cs" />
     <Compile Include="Data\TypesExtended.cs" />
     <Compile Include="DeviceEventArgs.cs" />
     <Compile Include="Extensions.cs" />