This reverts commit 246f9d284f.
This only reverts the part modifying libgimp* headers. All the part
switching to #pragma once in app/ was kept. See #14668.
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
By default the new API will be used. But if we build with
GIMP_DEPRECATED_REPLACE_NEW_API macro, then the same function names will
call the old API with ids.
This way, we don't have to update all our plug-ins at once (which I
tried and is very tedious work).
Note that bindings won't have access to the deprecated API at all.
This means that all functions which were returning or taking as
parameter an image id (as gint32) are now taking a GimpImage object
instead.
The PDB is still passing around an id only over the wire. But we create
an object for plug-ins to work on.
This is quite a huge API break, but is probably the best bet for the
future quality. It will make nicer API instrospection (and nicer API in
binding), will fix the issues with pspec on GimpImageID in Python
bindings (which makes the current Python API unusable as soon as we need
to work on images, which is most of our plug-ins!), etc.
Also it will allow to use signals on images, which will be a great asset
when we will finally have bi-directionnal communications (i.e. plug-ins
would be able to connect to image changes, destructions, and whatnot).
