Also:
- renaming gimp_layer_group_new() to gimp_group_layer_new() in order to keep the
same name as in core code (i.e. GimpGroupLayer, not GimpLayerGroup).
- renaming gimp_image_merge_layer_group() to gimp_group_layer_merge()
- new functions: gimp_procedure_add_group_layer_argument(),
gimp_procedure_add_group_layer_aux_argument() and
gimp_procedure_add_group_layer_return_value().
This can be tested, e.g. in Python with these calls:
```py
i = Gimp.get_images()[0]
g = Gimp.GroupLayer.new(i, "hello")
i.insert_layer(g, None, 1)
g2 = Gimp.GroupLayer.new(i, "world")
i.insert_layer(g2, g, 1)
g.merge()
```
This was work started long ago, stored in an old stash which I finally
finish now! :-)
… test-color-parser.c file.
The file libgimpcolor/test-color-parser.c was compiled but never actually called
by the build. Now that we have a nice infrastructure to test libgimp API, I am
moving it there with the new format. Doing this also allowed me to discover some
bugs in CSS parsing, as well as discover Python binding was failing here (cf.
the few previous commits).
Only one test is disabled so far, the one where 4 digits are used per channel in
hexadecimal notation: "#64649595eded". This format simply doesn't appear
anywhere in the spec, and also the result values in the samples listing don't
even fit. So far, I'm just unsure what to do with it, if we want to keep this
support (of some kind of higher precision hex notation, but not specified, so is
it even used by anyone?) or not.
All the other tests just work in both C and Python!
The comment I had written back then was wrong. Meson in fact can create an env
object from another with a simple assignment (which copies the object, rather
than pointing to a same object), per the answer which has been given to me in:
https://github.com/mesonbuild/meson/issues/13045
This allows to have a properly separate environment (when using GIMP as a build
tool, we don't want to load the test files).
Calling gimp_selection_float from a Python plug-in could make it crash
with an error like Calling error for procedure 'gimp-selection-float':
Item x cannot be used because it is not a group item.
This is caused by an incorrect check for group layers.
gimp_pdb_item_is_group returns an error when the condition is False,
while we only want an error when a group layer is selected (True).
Thus we need to use gimp_pdb_item_is_not_group, which returns an error
when the item is a group, which is what we want.
These function names are a little confusing, we might need to think
about better naming sometime.
I added C/Python tests for this function, so that we can test whether
this works correctly.
Most of the C boiler-plate code is generated so that all you have to do is
implement the run() function with test code in it.
Also adding a README to make it all very clear and easy to add new tests.
With Python binding, it gets very easy to test new functions. I've been
wondering if we need C counterparts, but really since it's a GObject
Introspection binding, if a function succeeds there, it should also succeed in C
code.
For now, I'm testing a few of GimpPalette API. Not all of it yet. Also I test
both the direct C binding and PDB procedure since in some cases, one or the
other may not properly working. See #10885.
