These are not usable by plug-ins anymore which should store their data between
runs as arguments or aux arguments (in case of values which should be stored
from one run to another but are not really usable for non-interactive scripts).
These are per-plug-in (not polluting the whole process space with just random
strings as identifiers which could be used by other plug-ins) and even survive
restarts of GIMP.
I still keep these functions, but only internally, as they are used to store
settings of GimpAspectPreview, GimpDrawablePreview and GimpZoomPreview across
plug-in runs. Still I changed their API to set and return a GBytes directly
(mimicking the private PDB functions' API).
Also I remove gimp_pdb_get_data_size() which is useless when exchanging GBytes
directly.
Note that the 2 functions are still exported in the library, and only not
advertized through headers (so they are not really internal, just hidden), on
purpose, because we need to call them in libgimpui. So it is still relatively
easy for a plug-in to use them. Nevertheless I made clear in the function
documentation that these must not be considered public and could end up deleted
at any time. Any plug-in still trying to call these takes the risk of having
their code relying on unreliable API.
The gimp_procedure_run() already existed, though it was with an ordered
GimpValueArray array of arguments. Its usage feels redundant to the series of
gimp_pdb_run_procedure*() functions (which is confusing), but
gimp_procedure_run() was actually a bit more generic, because it does not
necessarily calls GimpProcedure-s through the PDB! For instance, it can runs a
local GimpProcedure, such as the case of one procedure which would want to call
another procedure in the same plug-in, but without having to go through PDB. Of
course, for local code, you may as well run relevant functions directly, yet it
makes sense that if one of the redundant-looking function is removed, it should
be the more specific one. Also gimp_procedure_run() feels a lot simpler and
logical, API wise.
A main difference in usage is that now, plug-in developers have to first
explicitly look up the GimpPdbProcedure with gimp_pdb_lookup_procedure() when
they wish to call PDB procedures on the wire. This was done anyway in the
gimp_pdb_run_procedure*() code, now it's explicit (rather than calling by name
directly).
Concretely:
* gimp_pdb_run_procedure(), gimp_pdb_run_procedure_config() and
gimp_pdb_run_procedure_valist() are removed.
* gimp_procedure_run() API is modified to use a variable args list instead of a
GimpValueArray.
* gimp_procedure_run_config() and gimp_procedure_run_valist() are added.
* gimp_procedure_run_config() in particular will be the one used in bindings
which don't have variable args support through a (rename-to
gimp_procedure_run) annotation.
As far as plug-in API is concerned, at least the calling API, order of arguments
when calling PDB procedures doesn't matter anymore.
Order still matters for creating procedures with standard arguments (for
instance, "run-mode" is first, then image, or file, drawables or whatnot,
depending on the subtype of procedure), but not for calling with libgimp.
Concretely in this commit:
- gimp_pdb_run_procedure_argv() was removed as it's intrinsically order-based.
- gimp_pdb_run_procedure() and gimp_pdb_run_procedure_valist() stay but their
semantic changes. Instead of an ordered list of (type, value) couple, it's now
an unordered list of (name, type, value) triplets. This way, you can also
ignore as many args as you want if you intend to keep them default. For
instance, say you have a procedure with 20 args and you only want to change
the last one and keep the 19 first with default values: while you used to have
to write down all 20 args annoyingly, now you can just list the only arg you
care about.
There are 2 important consequences here:
1. Calling PDB procedures becomes much more semantic, which means scripts with
PDB calls are simpler (smaller list of arguments) and easier to read (when
you had 5 int arguments in a row, you couldn't know what they refer to,
except by always checking the PDB source; now you'll have associated names,
such as "width", "height" and so on) hence maintain.
2. We will have the ability to add arguments and even order the new arguments in
middle of existing arguments without breaking compatibility. The only thing
which will matter will be that default values of new arguments will have to
behave like when the arg didn't exist. This way, existing scripts will not be
broken. This will avoid us having to always create variants of PDB procedure
(like original "file-bla-save", then variant "file-bla-save-2" and so on)
each time we add arguments.
Note: gimp_pdb_run_procedure_array() was not removed yet because it's currently
used by the PDB. To be followed.
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.
Jehan