On 3/5/07, geert.jordaens-CNXmb7IdZIWZIoH1IeqzKA@public.gmane.org wrote:

hello,

when brouwsing trough the bug reports Bug 378115 got my attention. I'm trying to figure out hou the buffer and tile's interact with each other. It seems to me that depending the call of gegl_buffer_get_scaled one pyramid level is calculated. Is there realy a image pyramid? Should the image pyramid not be included in the tiles? (As a consequence this would increase the tile size to 1 + 1/3.)

When gegl_buffer_get_scaled is called the tiles needed at the level to satisfy the request is computed (and cached). Thus the tiles are generated on demand (and cached for later use).

Level 0: is the base level, this level always exist (as things are currently implemented).
Level 1: the tile size here is the same as tiles of the ones on level 0, but contains data from 4 tiles on level 0. Level 2: one tile consists of data from 4 tiles on level 1.

This tile generation happens automatically within the tile architecture, gegl_buffer_get_scaled just requests tiles at the appropriate level, and retrieves either cached tiles or makes the tiles needed be generated. When tiles for level 2 is requested, tiles on level 1 are created and cached as well if needed.

/Øyvind K.