Re: ctypes and twain_32.dll

It turns out, that the code does work when run with Administrator rights.

Patrick

 

  _____  

Van: Patrick Vrijlandt [mailto:[email protected]] 
Verzonden: dinsdag 3 mei 2011 8:08
Aan: [email protected]
Onderwerp: [ctypes-users] ctypes and twain_32.dll

 

Hi,

I'm trying to access TWAIN from python 3.2 on Vista, using ctypes. I'm stuck
at line 2:

PythonWin 3.2 (r32:88445, Feb 20 2011, 21:29:02) [MSC v.1500 32 bit (Intel)]
on win32.
>>> from ctypes import *
>>> windll.twain_32
Traceback (most recent call last):
 File "<interactive input>", line 1, in <module>
 File "C:\Python32\lib\ctypes\__init__.py", line 410, in __getattr__
   dll = self._dlltype(name)
 File "C:\Python32\lib\ctypes\__init__.py", line 340, in __init__
   self._handle = _dlopen(self._name, mode)
WindowsError: [Error 1114] Een initialisatieroutine van de dynamic link
library (DLL-bestand) is mislukt

[Yes, I'm Dutch. It says: An initialisation procedure of the DLL has failed]

This is from a .NET / TWAIN example on  <http://www.codeproject.com/>
http://www.codeproject.com:

As the TWAIN API is exposed by the Windows DLL, twain_32.dll, we have to use
the .NET DllImport mechanism for interop with legacy code. This DLL has the
central DSM_Entry(), ordinal #1 function exported as the entry point to
TWAIN. This call has numerous parameters, and the last one is of variable
type! It was found to be best if we declare multiple variants of the call
like:

[DllImport("twain_32.dll", EntryPoint="#1")]
private static extern TwRC DSMparent(
   [In, Out] TwIdentity origin,
   IntPtr zeroptr,
   TwDG dg, TwDAT dat, TwMSG msg,
   ref IntPtr refptr );

I suspect that initialisation may fail because of missing arguments, but I
see no way of sending any arguments. Also, contrary to the .NET example,  I
cannot express that the DLL entrypoint has ordinal 1. Of course, I may be
totally wrong!

I'm hoping for your suggestions!

TIA,

 

Patrick

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