Re: [Gimp-developer] How to call gimp_export_image() from Pythonplugin

On 19.06.2014 22:09, Ed . wrote:
It is not a PDB function, but a libgimp (C) function. Since pygimp can do gimpui stuff (also C functions), there is no conceptual reason why pygimp shouldn't also handle gimpexport (which is where gimp_export_image lives).

Which functions in GIMP goes to PDB, and which stays only in libgimp?

As I understand, libgimp should contain _all_ functionality, that may be needed for external C plugins. So it's "low-level" library.

PDB functions are designed to be called from scripts for automation and easer writing custom plugins in Scheme/Python/Perl scripts. So there mostly should be "high-level" functions, since there is no point in calling "low-level" operations, like set_pixel(), due to performance overhead of PDB.

gimp_export_image() is "high-level" function: it does several operations on image as whole and optionally asks user for some input. If gimp_export_image() would be available though PDB, it could be called from any "fu"-script, that can call PDB functions, and there would be no need to export it specifically in Python, Perl, Ruby, C#...

Correct me if I'm wrong, since I'm new to PDB and GIMP development.

I thought that in Python it was straightforward to access C functions? This is simply a function that returns an integer, albeit one that uses the GIMP UI - which pygimp already can initialise.

Best way to use C functions from Python is to write wrapper module in C that will export methods as Python functions/classes (just as GIMP-Python does). Also you can load shared object and call C-function directly using libffi library (presented as ctypes module in Python), but this error-prone and really hackish way.

-----Original Message----- From: Vladimir Rutsky
Sent: Thursday, June 19, 2014 6:24 PM
To: João Sebastião de Oliveira Bueno
Cc: Ed . ; gimp-developer
Subject: Re: [Gimp-developer] How to call gimp_export_image() from Pythonplugin

On Wed, Jun 18, 2014 at 9:52 PM, Joao S. O. Bueno <gwidion gmail com> wrote:
IS it available throught the PDB?
Most GIMP - Python functions are done via PDB, except pixel-region
manipulation stuff.
If it is not in the PDB, it is not availabl in GIMP 2.8 - the current
GIMP Python structure has to
special cases a lot of things to work aside from the PDB, and doing so
is not minor stuff
done inside a release cycle.

Making the 3-4 above calls are straightforward - I see no reason to
violate the principle of no new features inside a release to add this.
In GIMP 2.10, the export feature will also have to deal with precision
management, and besides this export function, a class of PDB calls
dealing with precision needs
to be added as well.

Joao, Ed,

so gimp_export_image() should be exported to Python though PDB (to all
plugins) or by writing custom export code as done for some functions
to export it only to Python?

Vladimir Rutsky

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