Re: [comtypes-users] Problem calling method [SEC=PERSONAL]
Hi Andrew! On Wed, 17 Feb 2010, Andrew MacIntyre wrote: piezo1.GetMaxTravel(APTPiezoLib.CHAN1_ID, pointer(tr)) I'm curious as to any reasons to prefer the above instead of piezo1.GetMaxTravel(APTPiezoLib.CHAN1_ID, byref(tr)) You can chalk it up to my mind working more in C Mode that Visual Basic Mode, I guess. :-) Both seem to work and the first one is the one that popped up initially in my mind. Bye Good Luck! Pablo B. -- Download Intel#174; Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev ___ comtypes-users mailing list comtypes-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/comtypes-users
Re: [comtypes-users] Problem calling method
Hi Thomas! On Mon, 15 Feb 2010, Thomas Heller wrote: Here is a patch for comtypes that will pass byref(...) or pointer(...) arguments as VT_BYREF variants. It should workfor Pablos and Michaels use cases - also it demonstrates how to access the original object of a byref(..) call: Yup, it works! Now it is as easy (and intuitive, I'd say) as this: === tr = c_float() piezo1.GetMaxTravel(APTPiezoLib.CHAN1_ID, pointer(tr)) === Great! Thanks again! Bye Good Luck! Pablo B. -- SOLARIS 10 is the OS for Data Centers - provides features such as DTrace, Predictive Self Healing and Award Winning ZFS. Get Solaris 10 NOW http://p.sf.net/sfu/solaris-dev2dev ___ comtypes-users mailing list comtypes-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/comtypes-users
Re: [comtypes-users] Problem calling method [SEC=PERSONAL]
From: Pablo Bianucci Now it is as easy (and intuitive, I'd say) as this: === tr = c_float() piezo1.GetMaxTravel(APTPiezoLib.CHAN1_ID, pointer(tr)) === I'm curious as to any reasons to prefer the above instead of === tr = c_float() piezo1.GetMaxTravel(APTPiezoLib.CHAN1_ID, byref(tr)) === - These thoughts are mine alone! - Andrew MacIntyre Operations Branch tel: +61 2 6219 5356 Communications Infrastructure Division fax: +61 2 6253 3277 Australian Communications Media Authority email: andrew.macint...@acma.gov.auhttp://www.acma.gov.au/ If you have received this email in error, please notify the sender immediately and erase all copies of the email and any attachments to it. The information contained in this email and any attachments may be private, confidential and legally privileged or the subject of copyright. If you are not the addressee it may be illegal to review, disclose, use, forward, or distribute this email and/or its contents. Unless otherwise specified, the information in the email and any attachments is intended as a guide only and should not be relied upon as legal or technical advice or regarded as a substitute for legal or technical advice in individual cases. Opinions contained in this email or any of its attachments do not necessarily reflect the opinions of ACMA. -- SOLARIS 10 is the OS for Data Centers - provides features such as DTrace, Predictive Self Healing and Award Winning ZFS. Get Solaris 10 NOW http://p.sf.net/sfu/solaris-dev2dev ___ comtypes-users mailing list comtypes-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/comtypes-users
Re: [comtypes-users] Problem calling method
Here is a patch for comtypes that will pass byref(...) or pointer(...) arguments as VT_BYREF variants. It should workfor Pablos and Michaels use cases - also it demonstrates how to access the original object of a byref(..) call: Index: comtypes/automation.py === --- comtypes/automation.py (revision 564) +++ comtypes/automation.py (working copy) @@ -1,5 +1,6 @@ # comtypes.automation module from ctypes import * +from ctypes import _Pointer from _ctypes import CopyComPointer from comtypes import IUnknown, GUID, IID, STDMETHOD, BSTR, COMMETHOD, COMError from comtypes.hresult import * @@ -48,6 +49,7 @@ # helpers IID_NULL = GUID() riid_null = byref(IID_NULL) +_byref_type = type(byref(c_int())) # 30. December 1899, midnight. For VT_DATE. _com_null_date = datetime.datetime(1899, 12, 30, 0, 0, 0) @@ -296,6 +298,16 @@ elif isinstance(value, c_float): self.vt = VT_R4 self._.VT_R4 = value +elif isinstance(value, _byref_type): +ref = value._obj +self._.c_void_p = addressof(ref) +self.__keepref = value +self.vt = _ctype_to_vartype[type(ref)] | VT_BYREF +elif isinstance(value, _Pointer): +ref = value.contents +self._.c_void_p = addressof(ref) +self.__keepref = value +self.vt = _ctype_to_vartype[type(ref)] | VT_BYREF else: raise TypeError(Cannot put %r in VARIANT % value) # buffer - SAFEARRAY of VT_UI1 ? -- Thanks, Thomas -- SOLARIS 10 is the OS for Data Centers - provides features such as DTrace, Predictive Self Healing and Award Winning ZFS. Get Solaris 10 NOW http://p.sf.net/sfu/solaris-dev2dev ___ comtypes-users mailing list comtypes-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/comtypes-users
Re: [comtypes-users] Problem calling method
Am 11.02.2010 02:32, schrieb Pablo Bianucci: [...] From the documentation of this control, I get this prototype (I don't know if that's the right name): --- Function GetControlMode(lChanID As Long, plMode As Long) As Long Parameters lChanID - the channel identifier plMode - returns the control loop feedback status --- I found this other funcion, that seems similar and has a code example: --- Function GetMaxTravel(lChanID As Long, plMaxTravel As Long) As Long Parameters lChanID - the channel identifier plMaxTravel - returns the maximum travel (in microns) Example: Private Sub cmdGetTravel_Click() Dim sngMaxTravel As Single MG17Piezo1.GetMaxTravel CHAN1_ID, sngMaxTravel ' inform user of piezo max travel MsgBox Maximum travel of piezo = sngMaxTravel --- Does this help? Well, what you could try out are these code snippets in Python: snip chanid = 42 # or whatever this needs to be... print ptr.GetControlMode(chanid) # try to leave out the plMode parameter print ptr.GetControlMode(chanid, 0) # pass a number for plMode... print ptr.GetMaxTravle(chanid) print ptr.GetMaxTravel(chanid, 0) /snip If nonthing of the above works, I guess you would have to pass the second parameter by reference. The basic code would have to look something like this; it is basically what I assume that VB does: snip # create a variable containing the 'control loop feedback status', # initialized to some value mode = c_int(0) # Call the function, passing the VALUE of chanid, # and a REFERENCE to the 'mode' variable. print ptr.GetControlMode(chanid, pass_by_reference(mode)) # The result of the function call should now have been printed, # and the 'mode' variable should contain an updated value: print mode.value /snip Ok, but what is this pass_by_reference() function? It should take the argument (a ctypes c_int instance, for example), and convert to something that will eventually, in the Invoke call, used as BYREF VARIANT argument. I'll try to come up with some ideas for that if the first code snippet above really fails. However, it could be that comtypes is not able to call this method... I hope not! (crossing fingers... :-)) We'll see. -- Thanks, Thomas -- SOLARIS 10 is the OS for Data Centers - provides features such as DTrace, Predictive Self Healing and Award Winning ZFS. Get Solaris 10 NOW http://p.sf.net/sfu/solaris-dev2dev ___ comtypes-users mailing list comtypes-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/comtypes-users
Re: [comtypes-users] Problem calling method
Am 12.02.2010 20:24, schrieb Pablo Bianucci: Hi Thomas! On Fri, 12 Feb 2010, Pablo Bianucci wrote: Exception: Cannot put cparam 'P' (012D7468) in VARIANT The problem seems to be that the initialization of VARIANT does not know what to do with a pointer type. I think that VARIANT could be extended to handle those: Get the value of the pointer (no the contents but the actual address), store that as the content of the VARIANT instance and then set the VT_BYREF flag. Do you think that would work? Exactly. I cannot provide a patch, but here's a code snippet that creates such a beast: from comtypes.automation import * mode = c_int(42) # our variable v = VARIANT() v._.c_void_p = cast(pointer(mode), c_void_p) v.vt = VT_BYREF | VT_I4 print v # prints 'VARIANT(vt=0x4003, byref(42))' You could use this stuff and pass it to Invoke. I assume that is will be changed after the call. Pretty straightforward to retrieve the result; VARIANT contains code for that. Since the VARIANT is a kind of pointer, I have chosen the indexing to acces the contained value: print v # prints 'VARIANT(vt=0x4003, byref(42))' print v[0] # prints '42' What I don't see how to do is how to get the address pointed to as a plain number. cast does that for you, without worring about the actual address. -- Thanks, Thomas -- SOLARIS 10 is the OS for Data Centers - provides features such as DTrace, Predictive Self Healing and Award Winning ZFS. Get Solaris 10 NOW http://p.sf.net/sfu/solaris-dev2dev ___ comtypes-users mailing list comtypes-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/comtypes-users
Re: [comtypes-users] Problem calling method
Hi Thomas! On Fri, 12 Feb 2010, Thomas Heller wrote: Exactly. I cannot provide a patch, but here's a code snippet that creates such a beast: Yes! It works!! This is the final working snippet: snip travel = c_float(0) v = VARIANT() v._.c_void_p = cast(pointer(travel), c_void_p) v.vt = VT_BYREF | VT_R4 mode = c_int(0) vm = VARIANT() vm._.c_void_p = cast(pointer(mode), c_void_p) vm.vt = VT_BYREF | VT_I4 try: piezo1.GetMaxTravel(APTPiezoLib.CHAN1_ID, v) piezo1.GetControlMode(APTPiezoLib.CHAN1_ID, vm) except Exception, e: print Exception:, e print travel.value, mode.value /snip If you are not careful when setting the types you get a Type Mismatch error (even though the protoypes in the help were the same, I had to use different types for the two funcions there). I wonder why you can't integrate this into the package. I'm fine as this, as this will let me write the program I need, but it would be more user friendly to be able use pointers as arguments for the method invocation. But I don't understand COM internals, so it could be that implementing that could lead to other problems. Thank you very much for your help! Bye Good Luck! Pablo. P.S.: If you visit Canada and stay at a city I happen to be living in, consider yourself invited to a drink. ;-) -- SOLARIS 10 is the OS for Data Centers - provides features such as DTrace, Predictive Self Healing and Award Winning ZFS. Get Solaris 10 NOW http://p.sf.net/sfu/solaris-dev2dev ___ comtypes-users mailing list comtypes-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/comtypes-users
Re: [comtypes-users] Problem calling method
Hi, Recently we noticed the same problem with our project. We access the MS Word object model via IDispatch, but there is a GetPoint method which takes left, top, hight and width as byref arguments. As comtypes doesn't support vt_byref out of the box, our first idea was to rewrite the code for VARIANT._set_value(), and provide comtypes with a patch. However, looking at VARIANT._set_value(): There are lots of returns all the way through the function, so its clear it would have to be rewritten almost from the ground up. And since I'm not too skilled with all of the VARIANT types, I don't want to break any existing logic. So, what we currently do, is when our project imports comtypes at initialization time, we do the following: #Monkey patch comtypes to support byref in variants from comtypes.automation import VARIANT, VT_BYREF from ctypes import cast, c_void_p from _ctypes import _Pointer oldVARIANT_value_fset=VARIANT.value.fset def newVARIANT_value_fset(self,value): realValue=value if isinstance(value,_Pointer): try: value=value.contents except (NameError,AttributeError): pass oldVARIANT_value_fset(self,value) if realValue is not value: self.vt|=VT_BYREF self._.c_void_p=cast(realValue,c_void_p) VARIANT.value=property(VARIANT.value.fget,newVARIANT_value_fset,VARIANT.value.fdel) So, from then on, when ever passing an instance of a POINTER of a ctypes type, comtypes will automatically treet the value as byref. Some example code for GetPoint: from ctypes import c_long, pointer rangeLeft=c_long() rangeTop=c_long() rangeWidth=c_long() rangeHeight=c_long() self.obj.WinwordWindowObject.getPoint(pointer(rangeLeft),pointer(rangeTop),pointer(rangeWidth),pointer(rangeHeight),self._rangeObj) I would probably prefer that we use ctypes.byref, rather than ctypes.POINTER, as the name relates better to what its doing. But, ctypes.byref(x) yields an object who's type is something like type(cArgObject), which I can't find anywhere in ctypes or _ctypes. So, it would be a little hard for VARIANT._set_value to properly identify that value was a byref. Interestingly enough though, if comtypes compiles the actual COM interfaces for the MS Word object model, POINTER is used anyway, so I guess POINTER is ok. Mick On 13/02/2010 10:48 AM, Pablo Bianucci wrote: Hi Thomas! On Fri, 12 Feb 2010, Thomas Heller wrote: Exactly. I cannot provide a patch, but here's a code snippet that creates such a beast: Yes! It works!! This is the final working snippet: snip travel = c_float(0) v = VARIANT() v._.c_void_p = cast(pointer(travel), c_void_p) v.vt = VT_BYREF | VT_R4 mode = c_int(0) vm = VARIANT() vm._.c_void_p = cast(pointer(mode), c_void_p) vm.vt = VT_BYREF | VT_I4 try: piezo1.GetMaxTravel(APTPiezoLib.CHAN1_ID, v) piezo1.GetControlMode(APTPiezoLib.CHAN1_ID, vm) except Exception, e: print Exception:, e print travel.value, mode.value /snip If you are not careful when setting the types you get a Type Mismatch error (even though the protoypes in the help were the same, I had to use different types for the two funcions there). I wonder why you can't integrate this into the package. I'm fine as this, as this will let me write the program I need, but it would be more user friendly to be able use pointers as arguments for the method invocation. But I don't understand COM internals, so it could be that implementing that could lead to other problems. Thank you very much for your help! Bye Good Luck! Pablo. P.S.: If you visit Canada and stay at a city I happen to be living in, consider yourself invited to a drink. ;-) -- SOLARIS 10 is the OS for Data Centers - provides features such as DTrace, Predictive Self Healing and Award Winning ZFS. Get Solaris 10 NOW http://p.sf.net/sfu/solaris-dev2dev ___ comtypes-users mailing list comtypes-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/comtypes-users -- Michael Curran President, NV Access Inc Email: m...@nvaccess.org Website: www.nvaccess.org ABN 61773362390. -- SOLARIS 10 is the OS for Data Centers - provides features such as DTrace, Predictive Self Healing and Award Winning ZFS. Get Solaris 10 NOW http://p.sf.net/sfu/solaris-dev2dev ___ comtypes-users mailing list comtypes-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/comtypes-users
Re: [comtypes-users] Problem calling method
Am 30.01.2010 06:23, schrieb Pablo Bianucci: Hi! I am trying to use an ActiveX control (.OCX, from a piezo electric stage controller)) from a Python program. I have managed to get the control to work, but I am having problems calling a method. This is the method in question (from the autogenerated typelib): === DISPMETHOD([dispid(20)], c_int, 'GetControlMode', ( [], c_int, 'lChanID' ), ( [], POINTER(c_int), 'plMode' )), === This is what I am doing trying to use the method (it should give me an integer): === mode = 0 mode_ptr = cast(mode, POINTER(c_int)) What you are doing here is that you create a NULL pointer - which is probably not what you want. But see below. try: piezo1.GetControlMode(APTPiezoLib.CHAN1_ID, mode_ptr) except Exception, e: print Exception:, e === And I get: === Exception: Cannot put comtypes._safearray.LP_c_long object at 0x012D9440 in VARIANT ===i I have no previous experience with comtypes or ctypes (or Win32 programming, for that matter ;-)), so I might be doing something stupidly wrong. I've tried all the permutations I could think of already, so I need expert help. Ok, the interface that you have is a pure dispinterface, which means that all methods of the COM object are eventually called as IDispatch.Invoke() calls. The Invoke() method packs all parameters into a DISPPARAM structure which basically is an array of VARIANT instances. This explains the error that you get - comtypes is trying to pack the POINTER parameter that you have created into a VARIANT. This only works for 'automation-compatible' data types and your pointer is not one of those. I would guess that the 'mode_ptr' argument is an argument that must be passed by reference (this is visual basic speak). Do you have sample VB code that shows how this method is used? However, it could be that comtypes is not able to call this method... Thomas -- SOLARIS 10 is the OS for Data Centers - provides features such as DTrace, Predictive Self Healing and Award Winning ZFS. Get Solaris 10 NOW http://p.sf.net/sfu/solaris-dev2dev ___ comtypes-users mailing list comtypes-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/comtypes-users
