Re: [Gimp-developer] Cage transform and Warp transform

[Jehan Pagès <jehan marmottard gmail com>]

Hi!

On Tue, Nov 28, 2017 at 5:32 PM, Elle Stone
<ellestone ninedegreesbelow com> wrote:
> On 11/28/2017 10:32 AM, Jehan Pagès wrote:
> > Hi!
> >
> > On Tue, Nov 28, 2017 at 3:54 PM, Elle Stone
> > <ellestone ninedegreesbelow com> wrote:
>
>
> > > I wanted to somewhat reshape some curved lines in a drawing, and tried
> > > the
> > > Cage transform, which I remember using a long time ago. After selecting
> > > the
> > > points, it took a long time for the cage transform to calculate the cage.
> > > But when trying to move a point on the cage, nothing happened. During all
> > > of
> > > this calculating plus "nothing happened", these lines were printed over
> > > and
> > > over to the terminal:
> > >
> > > (gimp-2.9:30657): GEGL-CRITICAL **: gegl_buffer_get: assertion
> > > 'GEGL_IS_BUFFER (buffer)' failed
> > >
> > > Is there a bug?
> >
> >
> > Well if it doesn't work and if there is a GEGL-critical, yes there is
> > definitely a bug. ;-)
> > You should run gimp with --gtk-g-fatal-warnings to force it to crash
> > when it gets a warning. Doing this inside gdb will get you a
> > stacktrace which led to this warning so that you can copy-paste it in
> > a bug report. :-)
>
>
> Hi Jehan,
>
> What is the actual command to type to get GIMP to run with
> --gtk-g-fatal-warnings? I kept getting terminal output that indicated that
> GIMP couldn't find the file "--gtk-g-fatal-warnings".

The command is:
$ gimp-2.9 --gtk-g-fatal-warnings

GIMP will crash as soon as it gets any warning.

To run this into gdb, you run first:
$ gdb gimp-2.9
Then inside gdb prompt:
(gdb) run --gtk-g-fatal-warnings

> Though in this case it really doesn't matter as I haven't been able to
> produce the same terminal output as before. Sorry for the noise!
>
> I still think I'm not doing something correctly with Cage transform. But as
> Warp worked perfectly for the task at hand, I'm very glad that the cage
> transform didn't work as expected, because otherwise I wouldn't have tried
> the Warp tool.

Well maybe you are not using cage transform tool correctly. Yet even
though no critical warnings are meant to happen! That is a definite
bug.
Also even if you were not using it correctly, then it would mean there
may be a design flaw. Cage tool should not be that complicated to
operate.

> > > Jehan, is there any possibility that this warp transform could be made to
> > > work symmetrically, perhaps via the symmetric painting dialog? Or maybe
> > > it
> > > already does, but somehow I did something wrong?
> >
> >
> > No. The symmetries work for paint tools (children of GimpPaintTool
> > class), but the warp transform is not a paint tool (I mean, not in our
> > code; it is derived directly from GimpDrawTool, which is lower level
> > class).
> > Of course, in theory, that could be changed. But this is not how it is
> > implemented currently.
>
>
> Thanks! for letting me know. I had a feeling the Warp tool wasn't code-wise
> related to the Paint tools, but wanted to ask to make sure. Whhether it can
> work symmetrically or not, it's a wonderful way to transform portions of an
> image.

Yep. Warp is cool indeed. :-)

Jehan

> Best,
> Elle



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