Re: Stuck inside button click callback

[Tristan Van Berkom <tristan van berkom gmail com>]

Fabio Margarido wrote:
> Hey there folks,
>
> I'm new to this list, and tried to search for similar questions, but
> couldn't find anything (actually I was not quite sure how to search
> for this :)), so sorry if this has been answered here before.
> As a matter of fact, I'm a GTK newbie, and this is my first try. I'm
> trying to create a GUI with some buttons, text entry fields and a
> progress bar. When the user clicks the Run button, I want to make
> everything in the window uneditable and unclickable while processing
> is taking place, while I update the progress bar. The problem is that
> when I click the run button, the callback attached is called, and it
> seems the window only gets refreshed when the callback function
> finishes running, i. e., the button remains clicked through all the
> processing, and when it comes back, the progress bar is already at
> 100%. I would like to know how to make the window immediately reflect
> the changes I make to the other widgets while inside the button click
> callback.

   The problem is that you are hijacking the main loop, there are a few
ways you can get around this:

    - Split up your "Run" code whatever it is into small itterations and
      run one itteration at a time in an idle or timeout handler
      (see glib API reference "Mainloop and events bla bla section")
      This is what I'd recommend.

    - Inside your run code while loop, insert the lines
        while (gtk_events_pending())
           gtk_main_itteration (FALSE);
      at the end of every itteration.

    - If you are calling a third party library function that takes
      a long time to finish and cannot split up into itterations,
      you'll have to use threads, WAIT, this does *not* mean that
      you need to use the gdk_threads_mutex described in the API/tutorial,
      you only need to report your progress via a g_idle_add and
      *dont make any gtk+ calls from your thread*.

The moral of the story is; no `while (1)'s in your code, and when you would
usually do something like `sched_yield()', just `return' instead ;-)

Cheers,
                                        -Tristan