Re: Question on C

[Drew Hess <dhess ilm com>]

On a related note, I'd like to make the GTK+ event loop select/poll on a
blocking file descriptor.  When it's ready to read, I want the event loop
to make a callback.  Should I use g_source_new(), g_source_add_poll(), and
g_source_set_callback () for this?  Is there a higher-level GTK+ API that 
I should be using?

thanks
-dwh-



On Wed, 28 Jan 2004, Gus Koppel wrote:

> "Thomas Keaney" wrote:
> 
> > This hasnt anything to do with GTK+ but I was wondering would any one
> > know how to program in a delay( say a delay of  2 seconds after
> > clicking on a button before another event happens). Cheers
> 
> If you're just thinking of freezing / stopping your application for a
> specific amount of time: this is can be done with the sleep () function
> (in unistd.h) or the more capable nanosleep () function (in time.h).
> Both of them are not part of ANSI-C; they were defined in some later
> standard. They're independent from GTK+ indeed. They're pretty simple
> and there are lots of descriptions available for them in the internet.
> 
> However, these functions MUST NOT be used in any GUI application, like
> GTK+ programs! They are of use for console applications only! Don't code
> GUI applications if you prefer to use them, i.e. due to their simplicty!
> 
> Because of its event loop based execution and programming model GTK+
> (and virtually all other GUI toolkits / environments) provide different
> means and require different approaches for delays. See functions like
> 
> http://developer.gnome.org/doc/API/2.0/glib/glib-The-Main-Event-Loop.html#g-timeout-add
> 
> This is because a (proper) GUI application must not really freeze ever.
> Windows may be moved, resized and uncovered at any time by the user,
> requiring the application to be ready to refresh (redraw) windows
> contents any time. This isn't the case if an application is frozen
> (by use of one of the delay functions).
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