Question

I have a C++ library (Win32) that fills some fields in a web page that I would like to use from .NET (an IE toolbar) but I can’t figure out how to expose the method through COM. I already know I should add it to the interface in the .idl file like this:

interface IPlugin : IDispatch{
    #include <mshtml.h> 
    HRESULT FillFields(IHTMLDocument2* pDocument, BSTR value1, BSTR  value2);
};

but the #include of mshtml.h gives me the following errors:

error MIDL2003: redefinition : _LARGE_INTEGER
error MIDL2003: redefinition : _ULARGE_INTEGER
error MIDL2003: redefinition : INT
error MIDL2003: redefinition : Int64ShllMod32

Is there any way I can pass the IHTMLDocument object from C# to C++ and modify it’s content in C++ or is COM supposed to be used only with types meant for Automation, like BSTR?

Thanks

Answer 1

You would use #import to get the IDL definition of IHTMLDocument2 into scope in MIDL.

The MIDL compiler will generate the #include for you. Explicit #include in MIDL files is useful only in a very narrow set of corner cases.