Hi,
I'm working with a well-documented, but proprietary DLL I would like to
call from Python, meaning I have no ability to edit the DLL.
The method documentation itself follows something similar to the following:
GetDataFromScan(long nScanNumber,
LPVARIANT pvarScanData,
LPLONG pnArraySize)
Where pvarScanData is filled with ScanData structs of the similar format:
struct ScanData
{
double dMassWidth;
double dMass;
long nCharge;
long nScan;
};
So far, to try to extract data from the DLL, I have tried using various
parameters with comtypes.automation.VARIANT, with no success.
import comtypes
import ctypes
CLSID = '{........-....-....-....-............}'
handle = comtypes.client.CreateObject(CLSID)
scandata = comtypes.automation.VARIANT()
size = ctypes.c_long()
# response is 0 for success, > 0 for error
response = handle.GetDataFromScan(scandata, size)
Now, this works when no data is returned, however, for size > 1, an
error is returned and no data fills the variant. So I therefore looked
to initialize the variant. I also tried throwing various parameters,
such as `comtypes.automation.VARIANT(comtypes.automation.VT_ARRAY)`,
however, the few I tried (VT_ARRAY, VT_UNKNOWN) all caused the method to
fail (produce a response > 0) even when no data was returned.
I'm wondering if there's any method to initialize the Variant with a
method like VariantInit, and then copy the data to a numpy array using
the comtypes safearray. Any insight would be wonderful.
Thank you,
Alex
--
Alex Huszagh
Lan Huang Laboratory
Department of Physiology and Biophysics
University of California, Irvine
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