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

Am 08.06.12 15:00, schrieb Jon Nordby:
Also at LGRU (, √ėyvind 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

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


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 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,



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