Re: [Gegl-developer] Journal for changes to a GEGL graph

[gfxuser <gfx user online de>]

Am 08.06.12 15:00, schrieb Jon Nordby:
> Also at LGRU (http://www.piksel.no/pulse/lgru), Øyvind allowed me to
> pick his brain about recording, storing and replaying changes done to
> a GEGL graph.
>
> == Usecases ==
> * Base for undo/redo stacks in GEGL based applications
> * Automated testing of GEGL graph manipulation API and interactive view widgets
> * Sharing and manipulation of a GEGL graph between multiple programs
>
> The brain picking was quite fruitful and together we came up with an
> initial specification for this feature, including the file format and
> API:http://git.gnome.org/browse/gegl/tree/docs/journal.txt
>
> This is kind-of a hot feature which can enable a lot of cool things,
> so I am hoping that someone may be interested in helping to implement
> it!
Hi,

I read it, but I'm not sure to have understood the goal behind. I don't 
see yet the necessity to have transactions for the usecases 1 and 2, but 
maybe I'm blocked. What's the purpose of transactions here?
Usecase 3: do you mean to let multiple programs work with the same GEGL 
graph at the same time?

One usecase is 'Base for undo/redo stacks':
A tree-like GEGL graph offers more than a simple history _stack_. Why 
not provide a undo/redo tree like K-3D? GIMP artists could ' jump 
back-and-forth among multiple "branches" of modifications to their 
scene' (see 
http://www.k-3d.org/wiki/FAQ#How_does_K-3D_compare_to_Blender.3F). This 
would give them more creative possibilities. I think a GEGL tree is a 
very good data structure for this and if an application decided not to 
use it, the possibility to use a stack based history is still included.

> This is kind-of a hot feature which can enable a lot of cool things,
Which cool things do you think of?

Best regards,

grafxuser

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