PyQt4 - widget signal trouble
Joacim Thomassen
joacim at net.homelinux.org
Sun Apr 26 06:38:39 EDT 2009
Den Sat, 25 Apr 2009 23:47:57 +0200, skrev Marco Bizzarri:
> Ciao, Joacim.
>
> Too much since I 'played' with low level calls, so I may be wrong. But
> it seems to me you're opening the image and monitoring for changes the
> directory. Hence the problem. If you read/write a file, I think the
> directory does not result as modified (but you should experiment by
> yourself).
>
> Regards
> Marco
Hello Marco,
python's fcntl() call the regular C fcntl() function and as stated in the
manual pages for C fcntl:
----------- Snippet from fcntl man pages ----------------
File and directory change notification (dnotify)
F_NOTIFY (long)
(Linux 2.4 onwards) Provide notification when the
directory referred to by fd or any of the files that it
contains is changed. The events to be notified are
specified in arg, which is a bit mask specified by ORing
together zero or more of the following bits:
DN_MODIFY A file was modified (write, pwrite, writev,
truncate, ftruncate).
------------- End snippet of fcntl man pages -------------------
The fact that my program actually trigger a signal as the monitored
directoy's image.jpg file change confirm that this part of the code do
work. I do get "Change happened!" as i manually do a "cp another.jpg
image.jpg", but this action is first seen after I close my application
window. (I do not get "Change happened!" if I don't do my manual cp
command. :-) )
Personaly I believe this has something to do with the GUI/Qt4 part that I
have not understood. Something about how a widget repaint itself or
something in that direction.
Best regards,
Joacim
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