On 11/18/06, Martin Nordholts wrote:

I've been thinking about how an Undo/Redo implementation in an image manipulating program that uses GEGL would look. From what I can tell, most IMPs uses tiles for Undo/Redo implementations; after an operation, they store the changed tiles. On an undo, the changed tiles are reverted back.

If such an interface were to be provided it would be internal to the GeglBuffer implementation. And it is indeed possible to implement such a state information on a per GeglBuffer level. For many applications it will probably be more beneficial to store the history of actions as a sequence of operations, and rely on efficient caching to avoid re computation of the entire stroke/filter history.

However, the current gegl.h seems to offer no interface for tile access. Has there been any discussion about this, i.e. is a tile interface supposed to be available in GEGL?

A tile interface will most probably not be provided, as even the fact that sparse buffers are implemented by the means of tiles is an implementation detail of the current GeglBuffer implementation that should not be exposed to users of the interface.

/Øyvind K.