de610a13f1
Since commit eb9cd3857d we initialize the allocation of ClutterActors to an UNINITIALIZED ClutterActorBox. We do that to ensure the actor even emits notify::allocation in case it got a new valid allocation of 0,0,0,0. Now there's still the case where an actor gets removed from the scenegraph and added again to a different parent, in this case we still don't emit notify::allocation right now in case the new allocation equals the old one. There's two good reasons to do so though: 1) To Clutter, there's no difference between a newly created actor and an actor which got removed from the scenegraph, it's not consistent to always notify the allocation property in the former situation, but not always notify it in the latter situation. 2) When an allocation changes, Clutter notifies the subtree of that actor about an absolute geometry change (see the call to transform_changed() in clutter_actor_set_allocation_internal()). Now when an actor gets reparented, obviously the absolute geometry might change, so to make sure transform_changed() is always called in that case we need to make sure an allocation change happens. So simply reset the allocation property of the actor to an UNINITIALIZED ClutterActorBox as soon as it gets unrealized. https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1498
Mutter
Mutter is a Wayland display server and X11 window manager and compositor library.
When used as a Wayland display server, it runs on top of KMS and libinput. It implements the compositor side of the Wayland core protocol as well as various protocol extensions. It also has functionality related to running X11 applications using Xwayland.
When used on top of Xorg it acts as a X11 window manager and compositing manager.
It contains functionality related to, among other things, window management, window compositing, focus tracking, workspace management, keybindings and monitor configuration.
Internally it uses a fork of Cogl, a hardware acceleration abstraction library used to simplify usage of OpenGL pipelines, as well as a fork af Clutter, a scene graph and user interface toolkit.
Mutter is used by, for example, GNOME Shell, the GNOME core user interface, and by Gala, elementary OS's window manager. It can also be run standalone, using the command "mutter", but just running plain mutter is only intended for debugging purposes.
Contributing
To contribute, open merge requests at https://gitlab.gnome.org/GNOME/mutter.
The coding style used is primarily the GNU flavor of the GNOME coding
style
with some minor additions such as preferring stdint.h types over GLib
fundamental types, and a soft 80 character line limit. However, in general,
look at the file you're editing for inspiration.
Commit messages should follow the GNOME commit message guidelines. We require an URL to either an issue or a merge request in each commit.
License
Mutter is distributed under the terms of the GNU General Public License, version 2 or later. See the COPYING file for detalis.