Added CapabilitiesExt.cs to handle custom capabilities if present in CapSupportedCaps

src/NTwain/Capabilities.cs

@@ -21,6 +21,7 @@ namespace NTwain
         {
             if (source == null) { throw new ArgumentNullException("source"); }
             _source = source;
+
         }
 
 
@@ -37,7 +38,9 @@ namespace NTwain
             using (TWCapability cap = new TWCapability(capabilityId))
             {
                 cap.ContainerType = ContainerType.OneValue;
+
                 var rc = _source.DGControl.Capability.QuerySupport(cap);
+                
                 if (rc == ReturnCode.Success)
                 {
                     var read = CapabilityReader.ReadValue(cap);
@@ -46,6 +49,8 @@ namespace NTwain
                     {
                         retVal = read.OneValue.ConvertToEnum<QuerySupports>();
                     }
+
+                    //ICapWrapper<Int64> cw = new CapWrapper<Int64>(_source, capabilityId, ValueExtensions.ConvertToEnum<Int64>, false);
                 }
             }
             return retVal;

src/NTwain/CapabilitiesExt.cs

@@ -0,0 +1,137 @@
+using NTwain.Data;
+using System;
+using System.Collections.Generic;
+
+namespace NTwain
+{
+    public class CapabilitiesExt : Capabilities
+    {
+        private IDataSource _source;
+        public CapabilitiesExt(IDataSource dataSource) : base(dataSource) { _source = dataSource; }
+
+        private List<CapabilityId> _custom;
+
+        public List<CapabilityId> CustomCapabilities
+        {
+            get
+            {
+                return _custom ?? LoadCustomCapabilities();
+            }
+        }
+
+        private List<CapabilityId> LoadCustomCapabilities()
+        {
+            List<CapabilityId> custom = new List<CapabilityId>();
+            foreach (CapabilityId capId in CapSupportedCaps.GetValues())
+            {
+                var capName = capId.ToString();
+                var wrapper = GetType().GetProperty(capName);
+
+                // not defined in Capabilites
+                if (wrapper == null)
+                {
+                    custom.Add(capId);
+                }
+            }
+            return custom;
+        }
+
+
+        private Func<BoolType, TWOneValue> boolFunc = value => new TWOneValue
+        {
+            Item = (uint)value,
+            ItemType = ItemType.Bool
+        };
+
+        private Func<int, TWOneValue> intFunc = value => new TWOneValue
+        {
+            Item = (uint)value,
+            ItemType = ItemType.UInt16
+        };
+
+        private Func<byte, TWOneValue> byteFunc = value => new TWOneValue
+        {
+            Item = value,
+            ItemType = ItemType.UInt8
+        };
+
+        private Func<uint, TWOneValue> uintFunc = value => new TWOneValue
+        {
+            Item = value,
+            ItemType = ItemType.UInt32
+        };
+
+
+    public object GetCap<TValue> (CapabilityId Capability)
+        {
+            QuerySupports? s = QuerySupport(Capability);
+            bool readOnly = true;
+            byte b = 0;
+            if (s != null)
+            {
+                b = (byte)s;
+                if ((b & (1 << 2)) != 0)
+                {
+                    readOnly = false;
+                }
+            }
+
+            if (typeof(TValue) == typeof(string))
+            {
+                return new CapWrapper<string>(_source, Capability, ValueExtensions.ConvertToString, readOnly);
+            }
+            else if (typeof(TValue) == typeof(int))
+            {
+                if (readOnly)
+                {
+                    return new CapWrapper<int>(_source, Capability, ValueExtensions.ConvertToEnum<int>, true);
+                }
+                return new CapWrapper<int>(_source, Capability, ValueExtensions.ConvertToEnum<int>, intFunc);
+            }
+            else if (typeof(TValue) == typeof(byte))
+            {
+                if (readOnly)
+                {
+                    return new CapWrapper<byte>(_source, Capability, ValueExtensions.ConvertToEnum<byte>, true);
+                }
+                return new CapWrapper<byte>(_source, Capability, ValueExtensions.ConvertToEnum<byte>, byteFunc);
+            }
+            else if (typeof(TValue) == typeof(uint))
+            {
+                if (readOnly)
+                {
+                    return new CapWrapper<uint>(_source, Capability, ValueExtensions.ConvertToEnum<uint>, true);
+                }
+                return new CapWrapper<uint>(_source, Capability, ValueExtensions.ConvertToEnum<uint>, uintFunc);
+            }
+            else if (typeof(TValue) == typeof(TWFrame))
+            {
+                return new CapWrapper<TWFrame>(_source, Capability, ValueExtensions.ConvertToFrame, readOnly);
+            }
+            else if (typeof(TValue) == typeof(BoolType))
+            {
+                if (readOnly)
+                {
+                    return new CapWrapper<BoolType>(_source, Capability, ValueExtensions.ConvertToEnum<BoolType>, true);
+                }
+
+                return new CapWrapper<BoolType>(_source, Capability, ValueExtensions.ConvertToEnum<BoolType>, boolFunc);
+            }
+            else if (typeof(TValue) == typeof(TWFix32))
+            {
+
+                if (readOnly)
+                {
+                    return new CapWrapper<TWFix32>(_source, Capability, ValueExtensions.ConvertToFix32, true);
+                }
+                return new CapWrapper<TWFix32>(_source, Capability, ValueExtensions.ConvertToFix32, value => value.ToOneValue());
+
+                
+            }
+            else
+            {
+                throw new Exception($"Unknown defintion for type of {typeof(TValue)} in GetCap");
+            }
+        }
+    }
+}

src/NTwain/DataSource.cs

@@ -255,7 +255,7 @@ namespace NTwain
         //    }
         //}
 
-        private Capabilities _caps;
+        private CapabilitiesExt _caps;
 
         /// <summary>
         /// Gets the capabilities for this data source.
@@ -265,7 +265,7 @@ namespace NTwain
         /// </value>
         public ICapabilities Capabilities
         {
-            get { return _caps ?? (_caps = new Capabilities(this)); }
+            get { return _caps ?? (_caps = new CapabilitiesExt(this)); }
         }