My personal solution would be to wrap the camera code in a very thin assembly that manages this stuff and provides a clean interface for python.net to hook into. I'm lazy that way though...
From: PythonDotNet [mailto:pythondotnet-bounces+btribble=ea....@python.org] On Behalf Of Daniel Krause Sent: Tuesday, January 22, 2013 10:08 PM To: pythondotnet@python.org Subject: Re: [Python.NET] Problem with System.ArgumentException in call to method from dll @Brett When I try bitmapsrc = BitmapSource() I get the following error: Traceback (most recent call last): File "C:\Users\mdk\workspace\\camera\testbitmap.py", line 8, in <module> bitmapsrc = BitmapSource() TypeError: cannot instantiate abstract class I will have a look at System.Reflection, thanks for the hint. @Brad The documentation does not say anything about "safe" or "unsafe". I do not have the source for the dll, only for the examples shipped with the dll. If you would like to have a look at them, I could send them to you. Daniel 2013/1/23 b...@fie.us<mailto:b...@fie.us> <b...@fie.us<mailto:b...@fie.us>> Just to clarify: neither version of the methods you are calling are marked "unsafe" in the proper c# .net manner are they? I would not be surprised to find PythonNet not providing access to "unsafe" methods. I would need to take a trip through the source to verify. On Jan 22, 2013, at 4:10 PM, Daniel Krause <m.daniel.kra...@googlemail.com<mailto:m.daniel.kra...@googlemail.com>> wrote: 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 b...@fie.us<mailto:b...@fie.us> <b...@fie.us<mailto:b...@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.kra...@googlemail.com<mailto:m.daniel.kra...@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<http://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) > _________________________________________________ > Python.NET<http://Python.NET> mailing list - > PythonDotNet@python.org<mailto:PythonDotNet@python.org> > http://mail.python.org/mailman/listinfo/pythondotnet _________________________________________________ Python.NET<http://Python.NET> mailing list - PythonDotNet@python.org<mailto:PythonDotNet@python.org> http://mail.python.org/mailman/listinfo/pythondotnet
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