Simplified the marshaling code by just calling generated methods to do the marshaling instead of doing full marshaling in each instance.

src/Generator/Generators/CSharp/CSharpMarshal.cs

@@ -391,67 +391,7 @@ namespace CppSharp.Generators.CSharp
 
         private void MarshalValueClass(Class @class)
         {
-            var marshalVar = Helpers.GeneratedIdentifier("marshal")
-                + Context.ParameterIndex++;
-
-            Context.SupportBefore.WriteLine("var {0} = new {1}.Internal();", marshalVar,
-                @class.Name);
-
-            MarshalValueClassFields(@class, marshalVar);
-
-            Context.Return.Write(marshalVar);
-        }
-
-        private void MarshalValueClassFields(Class @class, string marshalVar)
-        {
-            foreach (var @base in @class.Bases)
-            {
-                if (!@base.IsClass || @base.Class.Ignore)
-                    continue;
-
-                var baseClass = @base.Class;
-                MarshalValueClassFields(baseClass, marshalVar);
-            }
-
-            foreach (var field in @class.Fields)
-            {
-                if (field.Ignore)
-                    continue;
-
-                MarshalValueClassField(field, marshalVar);
-            }
-        }
-
-        private void MarshalValueClassField(Field field, string marshalVar)
-        {
-            var fieldRef = string.Format("{0}.{1}", Context.Parameter.Name,
-                                         field.Name);
-
-            var marshalCtx = new CSharpMarshalContext(Context.Driver)
-            {
-                ArgName = fieldRef,
-                ParameterIndex = Context.ParameterIndex++
-            };
-
-            var marshal = new CSharpMarshalManagedToNativePrinter(marshalCtx);
-            field.Visit(marshal);
-
-            Context.ParameterIndex = marshalCtx.ParameterIndex;
-
-            if (!string.IsNullOrWhiteSpace(marshal.Context.SupportBefore))
-                Context.SupportBefore.Write(marshal.Context.SupportBefore);
-
-            if (field.Type.IsPointer())
-            {
-                Context.SupportBefore.WriteLine("if ({0} != nullptr)", fieldRef);
-                Context.SupportBefore.PushIndent();
-            }
-
-            Context.SupportBefore.WriteLine("{0}.{1} = {2};", marshalVar,
-                field.OriginalName, marshal.Context.Return);
-
-            if (field.Type.IsPointer())
-                Context.SupportBefore.PopIndent();
+            Context.Return.Write("{0}.ToInternal()", Helpers.SafeIdentifier(Context.Parameter.Name));
         }
 
         public override bool VisitFieldDecl(Field field)

src/Generator/Generators/CSharp/CSharpTextTemplate.cs

@@ -376,6 +376,61 @@ namespace CppSharp.Generators.CSharp
             }
         }
 
+        private void GenerateStructInternalMarshaling(Class @class)
+        {
+            var marshalVar = Helpers.GeneratedIdentifier("native");
+
+            WriteLine("var {0} = new {1}.Internal();", marshalVar, @class.Name);
+            GenerateStructInternalMarshalingFields(@class, marshalVar);
+
+            WriteLine("return {0};", marshalVar);
+        }
+
+        private void GenerateStructInternalMarshalingFields(Class @class, string marshalVar)
+        {
+            foreach (var @base in @class.Bases)
+            {
+                if (!@base.IsClass || @base.Class.Ignore)
+                    continue;
+
+                var baseClass = @base.Class;
+                GenerateStructInternalMarshalingFields(baseClass, marshalVar);
+            }
+
+            foreach (var field in @class.Fields)
+            {
+                if (field.Ignore)
+                    continue;
+
+                GenerateStructInternalMarshalingField(field, marshalVar);
+            }
+        }
+
+        private void GenerateStructInternalMarshalingField(Field field, string marshalVar)
+        {
+            var marshalCtx = new CSharpMarshalContext(Driver)
+            {
+                ArgName = field.Name,
+            };
+
+            var marshal = new CSharpMarshalManagedToNativePrinter(marshalCtx);
+            field.Visit(marshal);
+
+            if (!string.IsNullOrWhiteSpace(marshal.Context.SupportBefore))
+               WriteLine(marshal.Context.SupportBefore);
+
+            if (field.Type.IsPointer())
+            {
+                WriteLine("if ({0} != null)", field.Name);
+                PushIndent();
+            }
+
+           WriteLine("{0}.{1} = {2};", marshalVar, field.OriginalName, marshal.Context.Return);
+
+            if (field.Type.IsPointer())
+                PopIndent();
+        }
+
         public bool ShouldGenerateClassNativeField(Class @class)
         {
             if (!@class.IsRefType)
@@ -806,6 +861,24 @@ namespace CppSharp.Generators.CSharp
             }
 
             WriteCloseBraceIndent();
+            NeedNewLine();
+
+            if (@class.IsValueType)
+            {
+                NewLineIfNeeded();
+                WriteLine("internal Internal ToInternal()");
+                WriteStartBraceIndent();
+                GenerateStructInternalMarshaling(@class);
+                WriteCloseBraceIndent();
+                NewLine();
+
+                WriteLine("internal void FromInternal(Internal* native)");
+                WriteStartBraceIndent();
+                WriteLine("var {0} = {1};", Helpers.GeneratedIdentifier("ptr"), "native");
+                GenerateStructMarshalingFields(@class);
+                WriteCloseBraceIndent();
+                NeedNewLine();
+            }
         }
 
         private bool GenerateClassConstructorBase(Class @class, Method method)