Added a hard-coded for the time being option indicating whether the wrapped lib is 32-bit and used that option to generate the v-table offsets.

Signed-off-by: Dimitar Dobrev <dpldobrev@yahoo.com>

src/Generator/AST/VTables.cs

@@ -83,7 +83,8 @@ namespace CppSharp.AST
             throw new NotSupportedException();
         }
 
-        public static string GetVirtualCallDelegate(INamedDecl method, Class @class, out string delegateId)
+        public static string GetVirtualCallDelegate(INamedDecl method, Class @class,
+            bool is32Bit, out string delegateId)
         {
             var virtualCallBuilder = new StringBuilder();
             virtualCallBuilder.AppendFormat(
@@ -106,7 +107,7 @@ namespace CppSharp.AST
             }
 
             virtualCallBuilder.AppendFormat(
-                "void* slot = *((void**) vtable + {0} * IntPtr.Size);", i);
+                "void* slot = *((void**) vtable + {0} * {1});", i, is32Bit ? 4 : 8);
             virtualCallBuilder.AppendLine();
 
             string @delegate = method.Name + "Delegate";

src/Generator/Driver.cs

@@ -280,6 +280,8 @@ namespace CppSharp
         {
             get { return GeneratorKind == LanguageGeneratorKind.CLI; }
         }
+
+        public bool Is32Bit { get { return true; } }
     }
 
     public class InvalidOptionException : Exception

src/Generator/Generators/CSharp/CSharpTextTemplate.cs

@@ -1574,7 +1574,7 @@ namespace CppSharp.Generators.CSharp
         private void GenerateVirtualTableFunctionCall(Function method, Class @class)
         {
             string delegateId;
-            Write(VTables.GetVirtualCallDelegate(method, @class, out delegateId));
+            Write(VTables.GetVirtualCallDelegate(method, @class, Driver.Options.Is32Bit, out delegateId));
             GenerateFunctionCall(delegateId, method.Parameters, method);
         }