Re: [Gimp-developer] marking a document/image as dirty/changed in a plugin

On Fri, Nov 8, 2019 at 7:53 PM Liam R E Quin <liam holoweb net> wrote:

On Fri, 2019-11-08 at 18:40 -0800, Dan Hitt via gimp-developer-list
 But i don't
how you can mark an image as dirty.

Write some data to the image?

E.g. read a pixel and write it back again?

I'm using gimp 2.10.8 on debian 10.
You might want to update to 2.10.14. the current version.

slave ankh

Liam Quin - web slave for
with fabulous vintage art and fascinating texts to read.

Hi Liam,

Thanks for your mail.

Your method sounds like it should work, and i absolutely have to be able to
read and write pixels in order for my plugin to do what i want.

Now, for the limited purpose of just having the image show up as dirty when
metadata is written as a parasite, i eventually discovered that it suffices
to pass in the flag GIMP_PARASITE_UNDOABLE in when the parasite is created
by gimp_parasite_new(....).  And the comments in the internals
(gimpimage.c) advise you to never call (in all caps) gimp_image_dirty()
directly, and that instead, push an undo operation on the stack.  It makes
sense i guess, and certainly explains why there seems to be no external
interface to directly set the image dirty.

So that leaves me with two holes.  One is that although i've declared my
parasite to be undoable, i haven't provided any means to actually undo it.
So that's kind of bad, although the parasite info is not the main event
that i hope to do in my plugin.

The other hole is that i find that so far i cannot read and write a pixel.
The obvious looking calls, for example, as used in the basic tutorial, are now marked
deprecated.  So to properly do this simple operation of reading and writing
a pixel, one should go through the gegl interface.  That i have not done,
but obviously i need to.

Anyhow, thanks again for your help, and if you or anybody knows of some
easy tutorials on using the gegl apparatus, please let me know and tia.

(And glad you get to mess around with scanning and enjoying old books ---
the mustiness may not be so great, but it sounds like a great way to be in
touch with your roots!)


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