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Jonas Ådahl 1818d21da5 Introduce virtual monitors
Virtual monitors are monitors that isn't backed by any monitor like
hardware. It would typically be backed by e.g. a remote desktop service,
or a network display.

It is currently only supported by the native backend, and whether the
X11 backend will ever see virtual monitors is an open question. This
rest of this commit message describes how it works under the native
backend.

Each virutal monitor consists of virtualized mode setting components:

 * A virtual CRTC mode (MetaCrtcModeVirtual)
 * A virtual CRTC (MetaCrtcVirtual)
 * A virtual connector (MetaOutputVirtual)

In difference to the corresponding mode setting objects that represents
KMS objects, the virtual ones isn't directly tied to a MetaGpu, other
than the CoglFramebuffer being part of the GPU context of the primary
GPU, which is the case for all monitors no matter what GPU they are
connected to. Part of the reason for this is that a MetaGpu in practice
represents a mode setting device, and its CRTCs and outputs, are all
backed by real mode setting objects, while a virtual monitor is only
backed by a framebuffer that is tied to the primary GPU. Maybe this will
be reevaluated in the future, but since a virtual monitor is not tied to
any GPU currently, so is the case for the virtual mode setting objects.

The native rendering backend, including the cursor renderer, is adapted
to handle the situation where a CRTC does not have a GPU associated with
it; this in practice means that it e.g. will not try to upload HW cursor
buffers when the cursor is only on a virtual monitor. The same applies
to the native renderer, which is made to avoid creating
MetaOnscreenNative for views that are backed by virtual CRTCs, as well
as to avoid trying to mode set on such views.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1698>
2021-03-12 15:09:45 +00:00
.gitlab/issue_templates gitlab: Add missing < in markdown comment tag 2020-02-14 03:10:28 +00:00
.gitlab-ci ci: Install Xwayland from git 2021-01-25 15:14:35 +00:00
clutter clutter: Ensure we always call handle_event_post for processed events 2021-03-10 13:56:54 +00:00
cogl cogl/onscreen/egl: Remove platform pointer 2021-03-08 15:02:30 +00:00
data data: Updated exposed keybindings 2021-02-04 00:09:57 +01:00
doc Add MetaGravity and replace X11 equivalent with it 2020-02-29 21:01:50 +00:00
meson build: Add postinstall script 2019-08-27 09:57:54 +00:00
po Update Friulian translation 2021-03-10 13:03:01 +00:00
src Introduce virtual monitors 2021-03-12 15:09:45 +00:00
subprojects build: bump ABI to sysprof-capture-4 2020-07-28 11:13:30 -07:00
tools tools: Remove obsolete ppa-magic.py 2018-11-30 11:12:12 +08:00
.gitignore build: bump ABI to sysprof-capture-4 2020-07-28 11:13:30 -07:00
.gitlab-ci.yml tests: Add headless native backend test 2021-03-12 15:09:45 +00:00
config.h.meson xwayland: Check for listenfd option 2021-01-22 11:40:30 +01:00
COPYING Updated obsolete FSF postal address in COPYING 2014-01-12 08:44:30 +07:00
meson_options.txt tests: Add headless native backend test 2021-03-12 15:09:45 +00:00
meson.build tests: Add headless native backend test 2021-03-12 15:09:45 +00:00
mutter.doap mutter.doap: Add marge-bot as a maintainer 2020-11-16 11:59:45 +01:00
NEWS Tag release 40.beta 2021-02-22 15:44:43 +01:00
README.md README: Fix list paragraphs 2021-03-10 09:01:50 +03:00

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.

It can be useful to look at the documentation available at the Wiki.

Coding style and conventions

The coding style used is primarily the GNU flavor of the GNOME coding style with some additions:

  • Use regular C types and stdint.h types instead of GLib fundamental types, except for gboolean, and guint/gulong for GSource ids and signal handler ids. That means e.g. uint64_t instead of guint64, int instead of gint, unsigned int instead of guint if unsignedness is of importance, uint8_t instead of guchar, and so on.

  • Try to to limit line length to 80 characters, although it's not a strict limit.

  • Usage of g_autofree and g_autoptr are encouraged. The style used is

      g_autofree char *text = NULL;
      g_autoptr (MetaSomeThing) thing = NULL;
    
      text = g_strdup_printf ("The text: %d", a_number);
      thing = g_object_new (META_TYPE_SOME_THING,
                            "text", text,
                            NULL);
      thinger_use_thing (rocket, thing);
    
  • Declare variables at the top of the block they are used, but avoid non-trivial logic among variable declarations. Non-trivial logic can be getting a pointer that may be NULL, any kind of math, or anything that may have side effects.

  • Instead of boolean arguments in functions, prefer enums or flags when they're more expressive. The naming convention for flags is

    typedef _MetaSomeThingFlags
    {
      META_SOME_THING_FLAG_NONE = 0,
      META_SOME_THING_FLAG_ALTER_REALITY = 1 << 0,
      META_SOME_THING_FLAG_MANIPULATE_PERCEPTION = 1 << 1,
    } MetaSomeThingFlags;
    
  • Use g_new0() etc instead of g_slice_new0().

  • Initialize and assign floating point variables (i.e. float or double) using the form floating_point = 3.14159 or ratio = 2.0.

Git messages

Commit messages should follow the GNOME commit message guidelines. We require an URL to either an issue or a merge request in each commit. Try to always prefix commit subjects with a relevant topic, such as compositor: or clutter/actor:, and it's always better to write too much in the commit message body than too little.

License

Mutter is distributed under the terms of the GNU General Public License, version 2 or later. See the COPYING file for detalis.