gtk callback

gtk callback

Post by pab.. » Fri, 30 Mar 2001 23:16:01

Hi all,
I'm writing a gtk app to acquire from a videocamera and display the
acquired frames.
When I start the acquisition pressing a button, the callback, connected
to the button, doesn't return the control to the applcation and I can't
stop the acquire!
How can I make a not blocking callback?



gtk callback

Post by Kevin Lacquemen » Sat, 31 Mar 2001 02:14:56


    p> How can I make a not blocking callback?

You could try starting a new thread in the callback.  If you go this
route, you may want some code to prevent too many of these threads
from being created (eg disable the button while the code is running).


He that breaks a thing to find out what it is has left the path of
wisdom                                         -- Gandalf the Grey


1. Help! GTK Segfault using PPDEV driver in a GTK callback


I'm using the user-mode parport driver (ppdev on a 2.4.3 kernel) in a
little GTK test application and I've got a really bizarre problem!

I've set up a GTK item menu callback that should send commands and read
result from a device that is connected on my parallel port, in ECP mode.

The communication is working, and I make sure to release the port at the
end of the callback.

If I'm doing IO (using write and read from ppdev) *IN* a function which is
called from the callback, the communication will be ok, but GTK (i'm
pretty sure it is GTK) will segfault after the callback return.

I can initialize the port and close it in a function without problem. But
if I'm doing write and read in a function, it will segfault.

If I'm doing exactly the same things, but without putting the ppdev code
in some functions (so this code is right in the callback) everything will
be ok!

I hope someone can help me understand what kind of problem I have! I can
post a little example code if someone want to see that.

thank you,


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