I'll comment on this one here since I cannot attend the GimpCon.
Splitting up as discussed on the mailinglist before:
1. a completely passive widget that has no other function then to
visualize a preview image.
See bugzilla http://bugzilla.gnome.org/show_bug.cgi?id=144759.
The API for this one should only contain some primitive functions.
And could almost be a drop-in replacement for GtkPreview.
This goal should also be fairly easy be reached before next milestone.
2. a more actively involved preview widget would have that uses the first widget
and has the basic navigation lets say horizontal and vertical scroll bars.
Reaching a consensus on how this should be accomplished shouldn't be
that hard as is the implementation.
Probaly can also be reached before next milestone.
Question to ask : How much plugin-in's are covered with this functionality?
3. Other more advanced fearues :
Here I think there are different opinions all driven by the key
factors speed / accuracy and type of image. The choice for this
should IMO be made for each plugin seperatly.
Compromising here is not a good option.
I'll try to give some arguments.
- Computer generated images have more likely larger parts with the
same pixel values then photograhic images so I would say the plugin's
for the first should not be as accurate (risk of beeing flamed).
- Stuff like overall collor correction can be done on a scaled down
version of the image to gain speed in the preview.
- Sharpening should be done at the unscaled version of a image since
rescaling it would render the sharpening useless.
- Blurring is kind of a problem with small radius this act's more
like sharpening while with a large radiuses it's more an overall
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