Re: [Gegl-developer] Is gegl_buffer_* aware of source color profile?

[Øyvind Kolås <pippin gimp org>]

On Sat, Jan 25, 2020 at 2:58 PM JonnyRobbie via gegl-developer-list
<gegl-developer-list gnome org> wrote:
> It is true that I might do away with a gegl operation to get the auto constructed parameter UI. But I would 
> need more than one input image. In my mind/design, there's this main layer which would get this filter 
> applied on, but there need to be one or two user selectable secondary layers for additional input. Is it 
> possible to do that with the design you have in mind?

Have a look at the displacement map filter in GIMP, which is using a
UI created based on introspection of property meta-data annotations in
GEGL. When you create your own GEGL operations they appear as part of
the list of the GIMP GEGL tool, I have long flagged having GEGL ops
turn up in the GIMP menus in other locations than here as a high
priority with the GIMP developers; but for now the capabilities that
exist treat this as a staging area - and additional GIMP coding has to
be done to bind it to the PDB (needed for compatibility with old
plug-ins, and giving the action a menu option).

> But the bigger problem is the desperate lack of any guides/tutorials, etc. I started the development in the 
> current way simply because there's basically only one source of how to do a plugin development and that is 
> https://developer.gimp.org/plug-ins.html. And that guide is over ten years old and I got tons of 
> depreciated warnings etc. And I spent extremely long tracking and jumping through all gimp/gegl/babl C 
> documentation to get to the current point where it somehow works - in sRGB only.
>
> The only "guide" on how to create a gegl operation is 
> https://www.wiki.gimp.org/wiki/Hacking:Porting_filters_to_GEGL and that one is extremely sparse and imho 
> quite laughable for anyone but core gimp developers. I simply could not find any starting points on how to 
> create a gimp filter (plug-in alike) using a gegl operations (and XML for example).

The advice in the past was always finding a GIMP plug-in that does
close to what you want already and adapt it, this still stands - the
code is more up to date and better documentation than possibly decades
old developer documentation - some of which is outdated enough that it
is more harmful than, that said; more proper documentation of writing
new ops in both GEGL and GIMP would be welcomed by both projects.

/pippin