Is there a way to view COM entries by traversing a TLB file in .NET? - typelib

Question

I'm converting an application to use registration free COM. There are a few 3rd party COM dll's that would normally have regsvr32 called on them. I tested that I can create objects from these 3rd party dlls by making a side-by-side manifest.
I used the OLE/COM viewer built into Windows to get this information. However I would like to make a program that could do this for me manually, as these 3rd party libraries have lots of classes I need to put in the manifest.
Does anyone know of a way to programatically traverse a type library?

Answer 1

I took Hans' advice and used LoadTypeLib.
For anyone looking for example code, this should be a great starting point.
I wrote it this morning and was able to get xml that I needed.
Forgive me for not releasing the objects! I don't have time to fully flesh out the rest of this answer right now. Edits are welcome.
[DllImport("oleaut32.dll", PreserveSig = false)]
public static extern ITypeLib LoadTypeLib([In, MarshalAs(UnmanagedType.LPWStr)] string typelib);
public static void ParseTypeLib(string filePath)
{
string fileNameOnly = Path.GetFileNameWithoutExtension(filePath);
ITypeLib typeLib = LoadTypeLib(filePath);
int count = typeLib.GetTypeInfoCount();
IntPtr ipLibAtt = IntPtr.Zero;
typeLib.GetLibAttr(out ipLibAtt);
var typeLibAttr = (System.Runtime.InteropServices.ComTypes.TYPELIBATTR)
Marshal.PtrToStructure(ipLibAtt, typeof(System.Runtime.InteropServices.ComTypes.TYPELIBATTR));
Guid tlbId = typeLibAttr.guid;
for(int i=0; i< count; i++)
{
ITypeInfo typeInfo = null;
typeLib.GetTypeInfo(i, out typeInfo);
//figure out what guids, typekind, and names of the thing we're dealing with
IntPtr ipTypeAttr = IntPtr.Zero;
typeInfo.GetTypeAttr(out ipTypeAttr);
//unmarshal the pointer into a structure into something we can read
var typeattr = (System.Runtime.InteropServices.ComTypes.TYPEATTR)
Marshal.PtrToStructure(ipTypeAttr, typeof(System.Runtime.InteropServices.ComTypes.TYPEATTR));
System.Runtime.InteropServices.ComTypes.TYPEKIND typeKind = typeattr.typekind;
Guid typeId = typeattr.guid;
//get the name of the type
string strName, strDocString, strHelpFile;
int dwHelpContext;
typeLib.GetDocumentation(i, out strName, out strDocString, out dwHelpContext, out strHelpFile);
if (typeKind == System.Runtime.InteropServices.ComTypes.TYPEKIND.TKIND_COCLASS)
{
string xmlComClassFormat = "<comClass clsid=\"{0}\" tlbid=\"{1}\" description=\"{2}\" progid=\"{3}.{4}\"></comClass>";
string comClassXml = String.Format(xmlComClassFormat,
typeId.ToString("B").ToUpper(),
tlbId.ToString("B").ToUpper(),
strDocString,
fileNameOnly, strName
);
//Debug.WriteLine(comClassXml);
}
else if(typeKind == System.Runtime.InteropServices.ComTypes.TYPEKIND.TKIND_INTERFACE)
{
string xmlProxyStubFormat = "<comInterfaceExternalProxyStub name=\"{0}\" iid=\"{1}\" tlbid=\"{2}\" proxyStubClsid32=\"{3}\"></comInterfaceExternalProxyStub>";
string proxyStubXml = String.Format(xmlProxyStubFormat,
strName,
typeId.ToString("B").ToUpper(),
tlbId.ToString("B").ToUpper(),
"{00020424-0000-0000-C000-000000000046}"
);
//Debug.WriteLine(proxyStubXml);
}
}
return;
}
}