Gtk::ProgressBar doesn't work synchronously

[Garth's KidStuff]

Hi All,

I'm converting a large Windows/Mac project to run on Ubuntu, and I'm a
little stuck when trying to use a ProgressBar.  We have a cross-platform
class that assumes I can create a "Progress Monitor" dialog during
time-intensive tasks, and then periodically update the progress as the task
completes.

The problem that I'm having with using Gtk::ProgressBar seems to be a
fundemental one about when dialogs can actually appear in the main window.
For example, what I'd like to do is something along the lines of:

[in my main thread]
...
Start a complex task
Create a Progress Monitor dialog and show it
Update the dialog as the task progresses
Destroy the dialog
....

When I try this, nothing shows up *grin*.  As far as I can tell, I need to
let the run loop process so that the dialog can be shown. (i.e. if I omit
the "destroy" step in the above, I see the dialog as soon as I drop out of
"my" code in the main thread, but that's too late -- the task is already
completed)

One way to solve this is, of course, to rewrite all the places that use the
Progress Monitor so that the work is done in a thread and the main thread
can just be showing the progress bar.  I'd hesitate to try that with this
code base because of the number of places in cross-platform code that would
have to be rewritten.

Do any of you have any thoughts?

Thanks in advance!

--
Garth Upshaw
Garth's KidStuff
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[Gabriele Greco]

> Start a complex task
> Create a Progress Monitor dialog and show it
> Update the dialog as the task progresses
> Destroy the dialog
>
>
Every time you update the dialog (or also more often if you can) you should
do something like:

while (gtk_events_pending())
   gtk_main_iteration();

To let GTK update the interface.

GTK runs only when you give the control to gtk_main() or if you give him
some "space" with gtk_main_iteration() :)

--
Bye,
 Gabry
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[Till Harbaum / Lists]

Hi,

try calling gtk's main processing routine while your task is doing
its work. Something like

     while(gtk_events_pending ())
        gtk_main_iteration ();

right after your update of the state of the progress bar should do the trick.

Till

Am Mittwoch 09 April 2008 schrieb Garth's KidStuff:

> Hi All,
>
> I'm converting a large Windows/Mac project to run on Ubuntu, and I'm a
> little stuck when trying to use a ProgressBar.  We have a cross-platform
> class that assumes I can create a "Progress Monitor" dialog during
> time-intensive tasks, and then periodically update the progress as the task
> completes.
>
> The problem that I'm having with using Gtk::ProgressBar seems to be a
> fundemental one about when dialogs can actually appear in the main window.
> For example, what I'd like to do is something along the lines of:
>
> [in my main thread]
> ...
> Start a complex task
> Create a Progress Monitor dialog and show it
> Update the dialog as the task progresses
> Destroy the dialog
> ....
>
> When I try this, nothing shows up *grin*.  As far as I can tell, I need to
> let the run loop process so that the dialog can be shown. (i.e. if I omit
> the "destroy" step in the above, I see the dialog as soon as I drop out of
> "my" code in the main thread, but that's too late -- the task is already
> completed)
>
> One way to solve this is, of course, to rewrite all the places that use the
> Progress Monitor so that the work is done in a thread and the main thread
> can just be showing the progress bar.  I'd hesitate to try that with this
> code base because of the number of places in cross-platform code that would
> have to be rewritten.
>
> Do any of you have any thoughts?
>
> Thanks in advance!
>

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