marshalling structure

[VS 2005 , Vista]

Hi

I am having a bit of difficulty marshalling a structure which is the parameter in a unmanaged function call.

The structure is

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public struct FilterParams
{
public Int32 param1;
public Int32 param2;
public Int32 focus;
public bool show;
public bool contrast_stretch;
public bool sharpen;
}

and the com object function being called is:

[Guid("03556EB9-9BE8-4503-B788-ADC730A901B9"), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
public interface IECFilterInterface
{
int get_DShowFilter([In,Out] ref FilterParams rnValue);
}

The function is getting called ( I have checked this in the com object) , and should modify the values of the members of the structure passed, however when it is passed back the values of the structure are not modified.

Any ideas what i might be doing wrong

any help/comments would be appreciated

simon

Change from struct to class, mark with Serializable, and derive from MarshalByRefObject.

Hi Cilu

I tried that as follows:

[Serializable]
public class FilterParams : MarshalByRefObject
{
public Int32 param1 = 0;
public Int32 param2 = 0;
public Int32 focus = 100;
public bool show = true;
public bool contrast_stretch = false;
public bool sharpen = false;
}

It built ok, but it throws an ExecutionEngineException when I call get_DShowFilter

any ideas ?