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Quite often there are situations where multiple gestures try to recognize, keeping track of the same set of points (for example an edge drag gesture on the stage and a click gesture somewhere in the scenegraph). Usually what's wanted here is that the first gesture to move to RECOGNIZING wins over all other active gestures and "claims" the point for itself. We implement this by introducing a concept called "influencing". It works by making all gestures operating on a shared set of points aware of each other using ClutterAction->register_sequence(). ClutterGesture uses this vfunc to keep track of all other ClutterGestures that are potentially conflicting, and keeps a list (priv->cancel_on_recognizing) of those. As soon as the move to RECOGNIZING happens, all gestures inside this list get moved to CANCELLED. To allow fine-grained control over this behavior, two APIs are introduced: 1) on the implementation level (should_influence() and should_be_influenced_by()): This is a vfunc that gets called as soon as a potential conflict is detected. It's helpful when a specific gesture always behaves the same towards another gesture, for example to make sure a LongPress gesture never cancels a DragGesture. 2) on the gesture user level, clutter_gesture_can_not_cancel() is introduced: This allows control for the user of a gesture to specify that a specific instance of a gesture won't cancel another gesture. Calling this twice so that both gestures can't cancel each other allows for things like simultaneous recognition of a pinch-to-zoom and rotate gesture. Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2389>
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 of 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.
It can be useful to first look at the GNOME Handbook and the documentation and API references below first.
Documentation
- Coding style and conventions
- Git conventions
- Code overview
- Building and Running
- Debugging
- Monitor configuration
API Reference
- Meta: https://mutter.gnome.org/meta/
- Clutter: https://mutter.gnome.org/clutter/
- Cally: https://mutter.gnome.org/cally/
- Cogl: https://mutter.gnome.org/cogl/
- CoglPango: https://mutter.gnome.org/cogl-pango/
- Mtk: https://mutter.gnome.org/mtk/
License
Mutter is distributed under the terms of the GNU General Public License, version 2 or later. See the COPYING file for detalis.