Re: COM Interop with ActiveX nightmare...

I dont think the ActiveX would be exporting the method directly via ordinal,
they typically provide an interface though which you call the methods.

You could try declaring the interface yourself and then getting an instance
to that interface by using CoCreateInstance via p/Invoke (or
CoGetClassObject and then creating the instace).

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"Wizfrog" <googleaccount@xxxxxxxxxxx> wrote in message
news:42f17886-03cb-4ef5-b2ef-93b5d5b508c4@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Hello and thanks for reading...

I am using a C++ unmanaged ActiveX (ocx) that allows me to read a
specific file format, and get data out of those.

I use C# .Net.
To use the ActiveX, I simply added it to my toolbox, and create an
instance in a form. Until there, all is good. I can read files, get
the data etc... even if I need to 'copy' the data from the unmanaged
side to the managed side.

Now where I hit a rodblock is when I try to copy the data back to the
ActiveX:
I need to pass a float[] to the COM object to then 'save' the data in
the original (proprietary) file format.
The ActiveX function in C++ is defined as

PutValue(int dataID, float* parray, uint size)

however in C#, the converted function by the ActiveX importer becomes

PutValue(int dataID, ref float parray, int size)

All the research I've done to figure out a solution leads me to
conclude that I need to Marshal the float* parameter into "IntPtr"

That's where I am stuck:
The imported library is already in managed C#, and shows as non-
editable 'MetaData', and it doesn't seem like I can override an
Interface declaration. So I don't see a way to Marshal the parameter.

So I tried to use COM interop directly, by calling the ActiveX.ocx
using [DllImport]

[DllImport(@"MyACTIVEX.ocx", EntryPoint = "#3")]
[return] int ID public static extern int Load(string
filename);

[DllImport(@"MyACTIVEX.ocx", EntryPoint = "#60")]
public static extern int PutValueEx(int ID, IntPtr pt, int
size);

I first had to figure out the entry point # in order to access the
functions, but got so far.
Now, calling the ocx directly, I get "Attempted to read or write
protected memory" error when trying to load the file.

Obviously there is something else that's being done when importing an
ActiveX through the toolbox.


I also tried to import the library directly, using AXIMP.EXE
It created 2 DLLs. One seems to be the managed interop library I can
get the code from if I use the "/source" tag, the other is the actual
COM DLL.

Problem, if I reference the 1st DLL, or import the source in my
project, I see that it calls the second DLL that includes the actual
functions.
So I tried to use [DllImport] directly on that second DLL, but there
it is not able to find an entry point.

Using LibDump, I could see the type library information from the ocx
file, but I can't see anything one either of the 2 DLLs generated,
which leads me to think they are missing the interface definition.

So, I'm trying to figure out a way out of this mess:
Either by finding a way to override the interface in the imported
ActiveX control from the toolbox, and marshal the paramter properly
Or
By finding the way to generate the DLL properly so I can import it
directly with [DllImport]
Or
figure out what is wrong when calling the .ocx file directly with
[DllImport]

Any suggestion would be greatly appreciated.


Note:
1) I do not need any of the 'control' form features, only to load the
file, read the data, put data back in and save it.
2) I did ask the vendor for the file format, so I could read/write it
directly in C#, but I didn't get anywhere. Would have been my
preference but this is not an option.


.

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