Though I am not fond of these macros for our core code (it makes the
code more cumbersome especially for using private data in derivable
types), this definitely makes sense for public API, since it would allow
easier modifications with less chances of messing API/ABI stability.
The various information (width, height, image type and number of layers) are
those of the full image, not of the thumbnail. Make it clear in the docs of
GimpRunThumbnailFunc.
Additionally:
- file-xmc was returning the proper information but variables were wrongly
named, which was confusing.
- Fix file-ico thumbnail proc which was returning the thumbnail width/height.
- In file-darktable, initialize width/height to 0 so that we just don't show any
size when we don't get the information. It's better not to show anything than
completely wrong information (the thumbnail target size).
… than a GimpValueArray.
Similar to other GimpProcedure, move to using a config object. A difference is
that thumbnail procedures are always run non-interactively.
Also fixing WMF load thumbnail procedure: the dimension computation was wrong
when the image was wider than tall.