ANNOUNCE - graphics package

Joe Armstrong <>
Tue Jan 20 13:58:39 CET 2004


On Tue, 20 Jan 2004, Peter-Henry Mander wrote:

> 
> Sounds like two distinct problems, please explain why they're the same (if they are).
> 
> I think Joe's problem is to maintain consistency between what is visible on screen, and what the Erlang data structures contain, i.e. the user kills a window (maybe forcefully) but ex11 isn't aware the window has gone. The windows don't unexpectedly vanish (I hope!)
>
 
Not quite. 

Lets suppose an application program creates several top level windows
to do this it opens (say) port 6000 and zaps off commands to the X server.
If the user kills an individual window then X closes the socket
and all windows vanish.

To avoid this I make a new connection for each top level window.

The problem is more in the other direction. The user can only kill
top level windows - not interior windows.

I associate a controlling process with each widget - if there is an error
in that process then I need to remove the window in a clean way
so that it does not effect the other windows. I also need to tidy up after
a window has been deleted and remove any event handlers which were installed
to take care of internal events. 

/Joe

 
> Am I correct Joe? I would expect some form of event or notification in this context. My knowledge of X11 is not all that good, so I'm probably babbling.
> 
> The erlang-gtk thing sounds like a garbage collection issue, i.e. how to keep window handles within the reachable memory set. If the window reference is no longer reachable, it get garbage collected and probably destroyed.
> 
> Pete.
> 
> 
> On Tue, 20 Jan 2004 13:23:32 +0200 (EET)
> Taavi Talvik <> wrote:
> 
> > On Tue, 20 Jan 2004, Joe Armstrong wrote:
> > 
> > > > The parent-child-sibling organisation of Xwindow maps neatly into
> > > > processes. If ex11 can become a concurrent set of loosly coupled
> > > > Xwindows mapped as processes, I reckon that designing new widgets will
> > > > become easy enough not to require a huge library if canned widgets
> > > > that we generally see in most windowing environments.
> > 
> > > Yes - this is *exactly* how I'm building things. The only problem is
> > > garbage collecting the windows and graphics context etc when you
> > > kill the windows.
> > 
> > I had similiar problem - garbage collecting destroyed gtk+ widgets,
> > when implementing yet another erlang-gtk+ binding with pipe driver
> > (http://home.uninet.ee/~taavi/files/erlang/xgs/).
> > 
> 




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