java-gnome-hackers

[java-gnome-hackers] Widget delete_event and destroy_event

[Mark H. <mh...@ca...>]

One final thing to panic about before the api freeze..

I've always been confused about this so it could just be a case of me
not understanding.

If the user closes a window, how does the application pop up a window
saying "unsaved changed : save/discard/cancel" ?

AFAICT, we can't do this in java-gnome.

In the past, I thought we needed to send a boolean return value to
either delete_event or destroy_event - indeed, they are boolean
functions. In Widget.java, we just return true and false (why?) - I
suspect this is wrong

I can't find any documentation about these signals at the moment though.
grep -r delete_event gtk/* finds two functions which I don't really
understand
grep for destroy_event returns nothing!

-- 
  .''`. Mark Howard
 : :' :
 `. `'  http://www.tildemh.com 
   `-   mh...@de... | mh...@ti... | mh...@ca... 

Re: [java-gnome-hackers] Widget delete_event and destroy_event

[Jeffrey M. <ku...@zo...>]

You are right.  We would have to change the listener class
to return a boolean, gather this in the fire* method and
return it to the native layer.  Then the native layer would
have to return this to gtk.  Should we try to get this in
before the freeze?

-Jeff

On Sat, 2004-02-28 at 16:47, Mark Howard wrote:
> One final thing to panic about before the api freeze..
> 
> I've always been confused about this so it could just be a case of me
> not understanding.
> 
> If the user closes a window, how does the application pop up a window
> saying "unsaved changed : save/discard/cancel" ?
> 
> AFAICT, we can't do this in java-gnome.
> 
> In the past, I thought we needed to send a boolean return value to
> either delete_event or destroy_event - indeed, they are boolean
> functions. In Widget.java, we just return true and false (why?) - I
> suspect this is wrong
> 
> I can't find any documentation about these signals at the moment though.
> grep -r delete_event gtk/* finds two functions which I don't really
> understand
> grep for destroy_event returns nothing!

Re: [java-gnome-hackers] Widget delete_event and destroy_event

[Mark H. <mh...@ca...>]

On Sat, Feb 28, 2004 at 04:38:09PM -0500, Jeffrey Morgan wrote:
> You are right.  We would have to change the listener class
> to return a boolean, gather this in the fire* method and
> return it to the native layer.  Then the native layer would
> have to return this to gtk.  Should we try to get this in
> before the freeze?

I think so.

Most of the lifeCycleEvent's have void callbacks though - should we have
separate listener methods for these? 

-- 
  .''`. Mark Howard
 : :' :
 `. `'  http://www.tildemh.com 
   `-   mh...@de... | mh...@ti... | mh...@ca... 

Re: [java-gnome-hackers] Widget delete_event and destroy_event

[Mark H. <mh...@ca...>]

Gtk Tutorial to the rescue: (but we still need to make a major change
and test it)

<quote>
static gboolean delete_event( GtkWidget *widget,
                              GdkEvent  *event,
                              gpointer   data )
{
    /* If you return FALSE in the "delete_event" signal handler,
     * GTK will emit the "destroy" signal. Returning TRUE means
     * you don't want the window to be destroyed.
     * This is useful for popping up 'are you sure you want to quit?'
     * type dialogs. */

    g_print ("delete event occurred\n");

    /* Change TRUE to FALSE and the main window will be destroyed with
     * a "delete_event". */

    return TRUE;
}

/* Another callback */
static void destroy( GtkWidget *widget,
                     gpointer   data )
{
    gtk_main_quit ();
}
</quote>

How should we fix this?

Possibly add a new method to the LifeCycleListener:
boolean lifeCycleQuestion( LifeCycleEvent )
(please think of a better name for it)
to be used by delete events.

Then in Widget.java modify the handleDelete/Destroy methods and
fireLifeCycleEvent to be more like fireFocusEvent - i.e. return a
boolean.

I'm not sure about the semantics of it though. Do we stop calling
handlers when we first get a true returned?

One final question: why is our destory event boolean when the one in the
gtk tutorial is void?  

-- 
  .''`. Mark Howard
 : :' :
 `. `'  http://www.tildemh.com 
   `-   mh...@de... | mh...@ti... | mh...@ca...