[Xcb] Problem with xpyb and setCrtcConfig()

Peter Harris peter.harris at hummingbird.com
Mon Nov 3 09:51:02 PST 2008

Alberto Milone wrote:
> Now it says that "SetCrtcConfig" takes exactly 10 arguments (9 given).
> But I guess it should take 9 arguments:
> cookie = self.conn.randr.SetCrtcConfig(crtc.id, crtc.timestamp, 
> resources.config_timestamp, x, y, mode.id, rotation, map(lambda n: 
> n.id, outputs))

The C binding needs a length or count for the last parameter, since C
does not know how long a list is. I'm guessing (guessing, mind you,
since I don't actually know anything about the python binding) that the
python binding author decided to follow the XCB C binding implementation
as closely as possible, and you need to put in a redundant length or
count somewhere.

See also PolyPoint (and etc), as I mentioned previously.

> Also what's the function of padding bytes?

To allow the C binding (or Xlib before it) to cast a data buffer
directly to a structure.


Peter Harris
     Hummingbird Connectivity - A Division of Open Text
Peter Harris                    http://connectivity.hummingbird.com
Research and Development        Phone: +1 905 762 6001
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