Re: [Gimp-developer] fix gimp

[Boudewijn Rempt <boud valdyas org>]

On Wed, 27 Dec 2017, Michael Schumacher wrote:

> Planned, but not as easy as you might think -
> https://bugzilla.gnome.org/show_bug.cgi?id=138373 has more details.

Maybe I can add some observations... Krita has had autosave (and backup
savefiles) since 2004, so we've got a bit of experience there. It came
with the KOffice framework libraries that KImageShop was built on back
before I joined the project. 

Up to Krita 3.x, saving happens synchronously, so autosave blocks the users. 
But autosave only happens during natural intervals, because if the timer
for autosaving goes off while the user is drawing, it gets restarted. 
Saving to the native file format doesn't take minutes, though.

Still, this sometimes blocks the user, and we have had complaints about
that. For 4.x, we save a shallow copy of the image: i.e, when autosaving 
kicks in, we make a copy of the image and save that in the background. No
fuss, no interruption, but a bit of added user security.

This, actually, is also how Photoshop works: one Krita developer spoke to 
a Photoshop developer during a recent conference and picked his brain...
Photoshop makes a copy of the image for _every_ state. Any undo state is a 
shallow copy of the document. They do not save action data -- only copies
of the image. This also explains how they created the history brush.

-- 
Boudewijn Rempt | http://www.krita.org, http://www.valdyas.org