[PyQt] PyKDE dcopext string marshalling; no unicode chars in a QString?

[Mark Summerfield]

On Mon 30-Apr-07, Danny Pansters wrote:
> Hi,
>
> It seems I can't retrieve a QString object containing non-ASCII characters.

You can if you use unicode() instead of str(). 

> I have a TV application (on FreeBSD) and it exports most of its functions
> via dcop. I now added functionality to retrieve (raw YUV) framedata over
> dcop, the idea being to eventually write a minimal dcopclient in C++ and
> patch that into Kopete to be used for webcam purposes.
>
> The code that does the video capturing is written in C and used in the rest
> of the app as a python module (using SWIG to expose a dozen simple control
> functions). Currently, as a first starting point, I strncpy() the
> framebuffer data into a string and any calling code recieves it as such.
> From my DCOP export code: self.addMethod("QString frameData()",
> obj.frameData). The frameData method simply returns
> QString(my_swig_module.frame_data()).
>
> Using the dcop cmdline utility or kdcop it seems to work alright:
>
> %dcop kbtv Kbtv wantFrameData 1
> %dcop kbtv Kbtv frameData
> < lots of gibberish on the console >
> %dcop kbtv Kbtv wantFrameData 0
>
> But when trying to write a proof-of-concept in Python (most taken from
> dcopext example):
>
> %python dcoptest.py
> --------------------------
> The DCOPObjects for kbtv:
> Kbtv not running!
>
> Start a kbtv instance
> errcode: 0   error:    dcopService: kbtv  pid: 57545
> --------------------------
> Check if wantFrameData and frameData are valid functions
> valid True True
> --------------------------
> wantFrameData's arg types and names
> [[('int', 2)]] [[None]]
> --------------------------
> frameData's arg types and names
> [[]] [[]]
> --------------------------
> Set wantFrameData to yes
> call returns: (True, None)
> --------------------------
> Get frameData for a frame
> call returns: (True, '')
> --------------------------
> Sleep for 1/2 second
> --------------------------
> Get frameData for another frame
> call returns:
> Traceback (most recent call last):
>   File "dcoptest.py", line 150, in ?
>     print "call returns:", o1.frameData()
>   File "/usr/local/lib/python2.4/site-packages/dcopext.py", line 591, in
> __call__
>     return self.dcop_call(args)
>   File "/usr/local/lib/python2.4/site-packages/dcopext.py", line 611, in
> dcop_call
>     return ok, self.__unmarshall(replyData, replyType)
>   File "/usr/local/lib/python2.4/site-packages/dcopext.py", line 719, in
> __unmarshall
>     return str(dcop_next(s, type_))
> UnicodeEncodeError: 'ascii' codec can't encode character u'\x80' in
> position 2: ordinal not in range(128)
>
> Note that the first time there is no framedata yet. I realize that this is
> because of how the auto-[un]marshalling works. Any suggestions? I'd like to
> have a simple test consumer in python so I can work out the issues of 
> dcop, RGB conversion and getting something drawn on a pixmap etc, before
> moving over to C++ (which I don't even know ;-)
>
> Should I use another datatype instead? Note that the actual framebuffer
> data will come in the form of a char* so basically it can be treated as a
> ustring (or Array?) on the main app's python side. I don't want expensive
> conversions in the main app's code (the consumer is a different thing, it
> will have expensive operations anyway).
>
> Thanks,
>
> Dan
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-- 
Mark Summerfield, Qtrac Ltd., www.qtrac.eu