[Python.NET] Problem with System.ArgumentException in call to method from dll

[Daniel Krause]

That is right, I want to get the value of the output parameter.

The following variant looks much more logical to me, but than I get another
error:
bitmapsrc = cam.GetImage(timeout)
TypeError: No method matches given arguments

So it seems that I have to pass the "out"-parameter to the method as well,
but that was not working either.



2013/1/22 brad at fie.us <brad at fie.us>

> You are setting the bitmapsrc variable to be equal to the class
> BitmapSource.  I assume you mean to get the value of an output parameter,
> rather than pass a class object into the method.
>
> Though I do not speak german.  But I think that's it.
>
> On Jan 22, 2013, at 2:58 PM, Daniel Krause <m.daniel.krause at googlemail.com>
> wrote:
>
> > I want to use a method from an API to control a camera
> (xiApi.NETX64.dll).
> >
> > The method is described in two ways:
> > //
> > void GetImage( out WriteableBitmap image, int timeout)
> > Description : This function acquires image and returns fills
> WritableBitmap object. Supports UNSAFE buffer policy mode.
> > Parameters :
> > out WriteableBitmap image : WPF BitmapSource to be filled.
> > int timeout : Time interval required to wait for the image (in
> milliseconds).
> > //
> > void GetImage(WriteableBitmap image, int timeout)
> > Description : This function acquires image and returns fills
> WritableBitmap object. Supports SAFE buffer policy mode.
> > Parameters :
> > WriteableBitmap image : WPF BitmapSource to be filled.
> > int timeout : Time interval required to wait for the image (in
> milliseconds).
> > //
> >
> > The code in a c#-sample looks like this (I skipped the initialisation of
> myCam, but if it helps I can provide the complete code):
> > //
> > using System.Windows.Media.Imaging;
> > int timeout = 10000;
> > BitmapSource myBitmapSrc;
> > myCam.GetImage(out myBitmapSrc, timeout);
> > //
> > This code I can compile, and it is working.
> >
> > I tried to keep the python code as close as possible, but I get errors I
> do not understand:
> > ##
> > import clr
> > import sys
> >
> sys.path.append("C:\\Windows\\Microsoft.NET\\Framework64\\v4.0.30319\\WPF")
> > clr.AddReference("PresentationCore")
> > clr.AddReference("xiAPI.NETX64")
> > from xiApi.NET import *
> > from System.Windows.Media.Imaging import BitmapSource
> > bitmapsrc = BitmapSource
> > print bitmapsrc
> > cam = xiCam()
> > cam.OpenDevice(0)
> > cam.SetParam(PRM.BUFFER_POLICY, BUFF_POLICY.SAFE)
> > cam.SetParam(PRM.IMAGE_DATA_FORMAT,  IMG_FORMAT.MONO8)
> > cam.StartAcquisition()
> > timeout = 1000
> > bitmapsrc = cam.GetImage(bitmapsrc, timeout)
> > cam.StopAcquisition()
> > ##
> >
> > Console output:
> > <class 'System.Windows.Media.Imaging.BitmapSource'>
> > Traceback (most recent call last):
> >   File "C:\Users\mdk\workspace\camera\testbitmap.py",
> > line 17, in <module>
> >     bitmapsrc = cam.GetImage(bitmapsrc, timeout)
> > System.ArgumentException: Das Objekt mit dem Typ "System.RuntimeType"
> kann nicht
> >  in den Typ "System.Drawing.Bitmap&" konvertiert werden.
> >    bei System.RuntimeType.TryChangeType(Object value, Binder binder,
> CultureInfo
> >  culture, Boolean needsSpecialCast)
> >
> >    bei System.Reflection.MethodBase.CheckArguments(Object[] parameters,
> Binder b
> > inder, BindingFlags invokeAttr, CultureInfo culture, Signature sig)
> >
> >    bei System.Reflection.RuntimeMethodInfo.InvokeArgumentsCheck(Object
> obj, Bind
> > ingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo
> culture)
> >
> >    bei System.Reflection.RuntimeMethodInfo.Invoke(Object obj,
> BindingFlags invok
> > eAttr, Binder binder, Object[] parameters, CultureInfo culture)
> >
> >    bei Python.Runtime.MethodBinder.Invoke(IntPtr inst, IntPtr args,
> IntPtr kw, M
> > ethodBase info, MethodInfo[] methodinfo)
> > _________________________________________________
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> > http://mail.python.org/mailman/listinfo/pythondotnet
>
>
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