[bug #23336] NSWindow initWithContentRect:sytleMask... apparently called twice when loading from .gorm file

[Gregory John Casamento]

Follow-up Comment #1, bug #23336 (project gnustep):

Follow ups..

I'm apparently missing something,... I get an error trying to compile that.

Gregory Casamento -- Principal Consultant - OLC, Inc
# GNUstep Chief Maintainer


----- Original Message ----
From: Fred Kiefer <fredkiefer@gmx.de>
To: Gregory John Casamento <greg_casamento@yahoo.com>
Cc: GNUstep Developer <gnustep-dev@gnu.org>
Sent: Tuesday, May 20, 2008 4:34:53 AM
Subject: Re: NSWindow & NSGraphicsContext issue

Strange, I get the log message as soon as I open an image from the
ToyViewer open menu entry.

The ToyViewer version I am using is this one:
http://www.sonappart.net/TV.tar.bz2

Hope this helps
Fred

Gregory John Casamento wrote:
> I've tried to recreate this issue.  I am not seeing the NSLog that was
added come up once during my tests either when running the application
(ToyViewer) or any other apps.
>
> I'm continuuing to look into it.  I'm going to open a bug on this so that
the progress can be tracked there.
>
> GC
>
>  Gregory Casamento -- Principal Consultant - OLC, Inc
> # GNUstep Chief Maintainer
>
>
> ----- Original Message ----
> From: Gregory John Casamento <greg_casamento@yahoo.com>
> To: Fred Kiefer <fredkiefer@gmx.de>; GNUstep Developer
<gnustep-dev@gnu.org>
> Sent: Monday, May 19, 2008 4:34:49 PM
> Subject: Re: NSWindow & NSGraphicsContext issue
>
> Fred,
>
> I will take a look at this as soon as possible.    The solution should
allow existing gorm files to be handled properly as well as correct the
problem going forward.
>
> GJC
>
> Gregory Casamento -- Principal Consultant - OLC, Inc
> # GNUstep Chief Maintainer
>
>
> ----- Original Message ----
> From: Fred Kiefer <fredkiefer@gmx.de>
> To: GNUstep Developer <gnustep-dev@gnu.org>
> Sent: Sunday, May 18, 2008 7:26:06 PM
> Subject: Re: NSWindow & NSGraphicsContext issue
>
> I was able to resolve most of the problems I listed below by not using
> autorelease objects.
>
> There still is one issue and it is an important one. When creating an
> NSWindow from a Gorm file the initialization is called twice. This will
> result in two backend objects being created for the window and one of
> them would leak and the window map would stay in an inconsistent state,
> after the window is freed. I was able to hack around this, by adding a
> check for an already existing _windowNum into
> initWithContentRect:styleMask:backing:defer:screen:. This only prevents
> part of the problem and a real fix would be not to have an NSWindow (or
> a subclass) in a Gorm file at all. For NIB files we already us
> NSWindowTemplate instead of GSWindowTemplate and this prevents the
problem.
> Could somebody with a deeper understanding of Gorm please look into this
> issue?
>
> Fred
>
> Fred Kiefer wrote:
>> Last week I tried to resolve a circular refernce problem between
>> NSWindow and NSGraphicsContext.
>>
>> The source of the problem is that when an NSWindow gets displayed it
>> generates an NSGraphicsContext (or rather a subclass) which will then
>> manage all the actual drawing. The window retain the context and the
>> context has an info dictionary which includes the window. That way we
>> already start off with a circular reference. To break this I released
>> the window once, to adjust the retain count. Now when the window gets
>> deallocated I first do a retain on it and then release the graphics
>> context which will in turn result in a release on the window. Or so I
>> hoped. There were a few issues with my original code. The graphics
>> context and the dictionary where autorelease objects, so I had to
>> postpone the deallocation of the window by returning from dealloc and
>> let it be called again. This also needed a bit of isa sizzling as
>> subclasses will not be aware of that reference counting trick and wont
>> be prepared to get dealloc called twice. (And the code in NSWindow
>> dealloc needed to be reentrant as well)
>>
>> With that all resolved I expected my code now to work correctly, but
>> this still isn't the case. As it turns out, calling retain on an object
>> that already was about to get released wont have the expected result.
>> When a release is send to an object with a retain count of 1, that count
>> wont be changed! Now this means that I have to differentiate between
>> calls to _termianteWindow that come from dealloc, where I don't call the
>> retain and calls for oneShot windows, where I need to increase the
>> retain count before freeing the context.
>>
>> All of this now looks like an even bigger mess then the one I started
>> with and now any help on how to clearly solve this would be welcome.
>>
>> Cheers,
>> Fred
>>
>> PS: Some of the code I talk about above is still not committed.



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