GNOME Bugzilla – Bug 160005
Channels are not taken into account in plug-in previews
Last modified: 2018-05-24 11:17:41 UTC
Plug-ins' preview display shows all color channels even if some or all are disabled or hidden.
The plug-ins don't know anything about the visibility state of the channels in the core and I don't think we want to change this. It would make the preview widget unnecessarily complex. I am not saying that it can't be done but I think it's not worth the effort. I'd vote to close as WONTFIX unless you can come up with a good argument why this feature is absolutely needed.
I came across this when I tried to use selective gaussian blur on only the red channel. The preview was basically useless in this case. I was trying to remove noise by blurring the red and the green channels separately. I basically had to do this by trial and error.
That sounds like a reasonable use case. This would have to be implemented in the preview widget then. Changing Component to libgimp.
I do not think of this as an enhancement. If there are cases in which the preview is not previewing, then it is buggy.
Joao, please open your eyes. The severity of this bug report had been changed to minor before you added your comment.
Ok. I just did not want to overturn your decision. Anyway, I've taken a look at the preview widget file. Indeed, it doesn't know from which image the image it's drawing came from - so the API will need to be changed. Having everything that uses the preview to check wich channels are active/visible seems me to be simply stupid - ultimately, the preview should get to "know" from which image it came from, so it can checkk by itself which channels are visible. Moreover, if there are inactive but visible channels, the easier thing I can think of is for the preview to fetch the bitmap from the image itself. And it goes getting more complicated - this is for channels. What about selections, or other things that could chabnge the affected data on an image? So here is my question: would it be viable that the source of the image displayed on a preveiw widget would be a GimpImage itself? - Maybe it would be easier to copy all attributes, selection from the original image, and copy only the subject layer.
No API change needed, there is gimp_drawable_get_image()
Joao, please stop adding such confusing comments here. The problem has been confirmed and I already outlined that the fix can be done entirely in the GimpPreview widget and that the existing API is sufficient. Your comments in #6 don't make any sense.
*** Bug 588993 has been marked as a duplicate of this bug. ***
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