GLib has a specific type for byte arrays: `GBytes` (and it's underlying
GType `G_TYPE_BYTES`).
By using this type, we can avoid having a `GimpUint8Array` which is a
bit cumbersome to use for both the C API, as well as bindings. By using
`GBytes`, we allow other languages to pass on byte arrays as they are
used to, while the bindings will make sure to do the right thing.
In the end, it makes the API a little bit simpler for everyone, and
reduces confusion for people who are used to working with byte arrays
in other C/GLib based code (and not having 2 different types to denote
the same thing).
Related: https://gitlab.gnome.org/GNOME/gimp/-/issues/5919
GLib has a specific type of NULL-terminated string arrays:
`G_TYPE_STRV`, which is the `GType` of `char**` aka `GStrv`.
By using this type, we can avoid having a `GimpStringArray` which is a
bit cumbersome to use for both the C API, as well as bindings. By using
`GStrv`, we allow other languages to pass on string lists as they are
used to, while the bindings will make sure to do the right thing.
In the end, it makes the API a little bit simpler for everyone, and
reduces confusion for people who are used to working with string arrays
in other C/GLib based code (and not having 2 different types to denote
the same thing).
Related: https://gitlab.gnome.org/GNOME/gimp/-/issues/5919
While we do have quite a few gimp_pdb_run_procedure*() functions now, I
always felt that one based on a config file was missing, even more as we
are getting further and further into using config objects in plug-ins.
In C, the gimp_pdb_run_procedure() function is without a doubt the
easiest one. But such variable arg functions are not available on
bindings, and having to deal with GValue and GimpValueArray is a real
pain.
Also using a config file has the very great advantage that we don't need
to care about order. For instance, if I need to set the 10th argument of
a PDB call (and leave the rest to default values), I don't have to set
all 9 previous arguments. I can set only this one if I want. This
advantage is useful also for C code by the way.
For the record, here is how you could load then export an image with the
"file-png-*" PDB procedures in Python:
> c = Gimp.get_pdb().lookup_procedure('file-png-load').create_config()
> c.set_property('file', Gio.file_new_for_path('/path/sample.png'))
> r = Gimp.get_pdb().run_procedure_config('file-png-load', c)
> d = Gimp.Display.new(r.index(1)) # Give it a display to work on it.
Now exporting:
> img = r.index(1)
> c = Gimp.get_pdb().lookup_procedure('file-png-save').create_config()
> c.set_property('image', img)
> c.set_property('file', Gio.file_new_for_path('/path/exported.png'))
> layers = img.get_layers()
> c.set_property('drawables', Gimp.ObjectArray.new(Gimp.Drawable, layers, False))
> c.set_property('num-drawables', len(layers))
> r = Gimp.get_pdb().run_procedure_config('file-png-save', c)
Plug-ins that work from different bindings probably want to use their
own list-type to specify arguments, rather than working with a more
cumbersome `GimpValueArray`.
This new API should make it less verbose. For example:
```
args = Gimp.ValueArray.new(5)
args.insert(0, GObject.Value(Gimp.RunMode, Gimp.RunMode.NONINTERACTIVE))
args.insert(1, GObject.Value(Gimp.Image, image))
args.insert(2, GObject.Value(Gimp.Drawable, mask))
args.insert(3, GObject.Value(GObject.TYPE_INT, int(time.time())))
args.insert(4, GObject.Value(GObject.TYPE_DOUBLE, turbulence))
Gimp.get_pdb().run_procedure('plug-in-plasma', args)
```
becomes
```
Gimp.get_pdb().run_procedure('plug-in-plasma', [
GObject.Value(Gimp.RunMode, Gimp.RunMode.NONINTERACTIVE),
GObject.Value(Gimp.Image, image),
GObject.Value(Gimp.Drawable, mask),
GObject.Value(GObject.TYPE_INT, int(time.time())),
GObject.Value(GObject.TYPE_DOUBLE, turbulence),
])
```
for procedure arguments. This implies creating a new value array in
gimp_procedure_run() if the passed array is too short, instead of
just appending to the passed array, which was ugly anyway.
The idea is that we already have a GimpProcedure object in libgimp
which has name, help, blurb, arguments, return values and everything,
so we really don't need a parallel API to query PDB procedures for
their properties.
- make run() a virtual function of GimpProcedure
- move GIMP_PDB_ERROR to GimpPDB
- GimpPDBProcedure is a trivial subblass which populates
GimpProcedure's members by querying the PDB.
- make "plug-in", "procedure-type" and "name" construct-only
properties of GimpProcedure.
This is all work in progress.
Niels De Graef