'kms/impl-device/simple: Get the buffer handle from MetaDrmBuffer'
changed how fb ids are generated, but it only made it fully work with
atomic mode setting. For legacy/simple mode setting, it only handled the
primary plane buffer, not the hardware cursor.
Fix this by making sure the fb id is generated also in the legacy mode
setting case.
Fixes: ea39142da2
Closes: https://gitlab.gnome.org/GNOME/mutter/-/issues/2250
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2397>
When an X11 window becomes an all-workspace window its `workspace` is
set to NULL before `meta_window_x11_current_workspace_changed()` is
called. The latter then checks for `workspace` being NULL (which also
happens when unmanaging) and then returns early. So this does not update
`_NET_WM_DESKTOP` to 0xFFFFFFFF. Instead it remains at the workspace the
window was on before. This was causing programs like `wmctrl` to switch
to this old workspace when activating such a window.
Fix this by checking if the window is unmanaging instead.
Fixes: https://gitlab.gnome.org/GNOME/mutter/-/issues/2242
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2387>
Simply signal preedit string changes from/to NULL once, in order
to avoid unwanted activity in the client side. We do still need to
send the preedit once each .done event, if there is one, in order
to behave according to the protocol when it matters the most.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2395>
With the unthrottled input emission, we ended up often getting the
cursor updates long before any damage had been posted, meaning that if
you moved around the mouse pointer where the mouse had a high enough
refresh rate, we'd effectively stall the screen cast stream by only
sending cursor updates and nothing else.
Fix this by scheduling an update when we get a cursor update, then
sending a cursor-only frame after any damage and relayout has been
processed, but only if there is no queued damage that will cause an
actual repaint.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2393>
This handle is used by the legacy KMS API; lets avoid having to have GBM
specific code where this is done by letting the MetaDrmBuffer API, that
already has this information, expose it.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2275>
We'd put the message in a variable called `message`. If something passed
to meta_topic() was called `message`, it'd end up being `NULL` in the
log entry. Avoid this by making the local message variable a bit more
"on topic".
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2391>
Unfortunately we cannot do this generically since the target of the
button/touch press does matter, e.g. tapping on the OSK, or clicking
the IBus candidates window. These situations should not trigger a
reset.
So be more selective about the situations where button/touch presses
trigger an IM reset, in the case of ClutterText these are still clicks
inside the actor, for Wayland's text-input it is when clicking the
surface that has text_input focus.
For all other situations where clicking anywhere else might make
sense to trigger an IM reset are covered by the focus changing paths,
that also ensure a reset before changing focus between surfaces/actors.
Fixes: https://gitlab.gnome.org/GNOME/mutter/-/issues/1961
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2384>
Focus changes should trigger an IM reset, as some engines do want
to maybe commit the preedit string before changing focus. In addition,
we do not want the preedit string to be able to move between
windows/applications.
Ensure that the commit string is committed when the IM deems so, and
ensure we send a .done event disntinct to the .leave event, so that
the client doesn't miss the commit.
Fixes: https://gitlab.gnome.org/GNOME/mutter/-/issues/2030
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2384>
DMA buffers might be allocatable, but it doesn't mean the driver doesn't
fail when we try to allocate a buffer with an implicit modifier. Using
the proprietary NVIDIA driver for example, it will fail. Lets catch this
up front and avoid advertising DMA buffer support when we know it won't
work.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2383>
As of currently, we only emit .done() on actual changes coming from the
ClutterInputMethod/ClutterInputFocus. With the recent changes in the
interpretation of serials, it becomes more important now that the
compositor acknowledges every .commit done by the client, in order to
keep them feeding future IM state updates.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2365>
Compensate the protocol statelessness with our ClutterInputFocus
statefulness. This becomes more necessary now, since sending
consecutive .done() events is now considered acceptable behavior.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2365>
MetaCursorRendererNative only updates the cursor state when the
underlying texture changes. The cursor scale and transform do not
trigger updates. This results in wrong cursor orientations on rotated
displays. Use both texture changes and scale and transformation changes
to figure out when to update the cursor state.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2363>
When switching between the existence and not of a stage ClutterGrab, we
would correctly attempt to synchronize key focus from the perspective of
the Wayland clients.
But this synchronization should do its own checks about existing stage
grabs before determining a client window has key focus or not.
Add that check, so that grabs correctly unfocus the keyboard in Wayland
clients, in addition to pointers and touch.
Fixes: https://gitlab.gnome.org/GNOME/mutter/-/issues/2194
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2366>
When we get passed a "snippet" to the shaped texture, it's added as a
pipeline layer snippet to change how the source texture is sampled. When
we draw from a texture tower however we have allocated regular textures
which doesn't need any special layer snippet, so create separate
pipelines for those that doesn't use that snippet.
Closes: https://gitlab.gnome.org/GNOME/mutter/-/issues/528
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2278>
With Xwayland on demand, a number of maintenance X11 applications need
to be run first, before Xwayland starts accepting requests from the
normal clients, as soon as the WM_S0 selection is acquired by mutter.
On startup, mutter also sets a number of X11 properties that can be
queried by X11 clients.
Unfortunately, mutter acquires the WM_S0 selection before setting those
properties, so mutter and the first regular X11 client will race on
startup.
As a result, the X11 properties set by mutter on startup may not be
available to the very first X11 client when Xwayland starts.
To avoid that issue, make sure to take the WM_S0 selection last when
opening the display.
Closes: https://gitlab.gnome.org/GNOME/mutter/-/issues/2176
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2336>
Currently, meta_xwayland_shutdown_dnd() is called from the handler
on_x11_display_closing() triggered from the signal "x11-display-closing"
hooked up from meta_xwayland_init_display().
Once the signal has been triggered, on_x11_display_closing() removes the
signal handler, disconnecting from the signal.
As meta_xwayland_init_display() is called from meta_display_new() which
is issued only once, the signal handler is not restored again.
As a result, meta_xwayland_shutdown_dnd() is not called anymore after
Xwayland has been restarted, but meta_xwayland_init_dnd() will check and
assert that the manager's DND object is NULL.
Basically, restarting Xwayland more that once will trigger an assertion
failure in mutter. That's even more of a problem with autoclose-xwayland
where Xwayland is expected to terminate when there is no meaningful X11
client remaining, which can happen multiple times during the lifetime
of a user session.
To make sure that meta_xwayland_init_display() is called for every new
instance of Xwayland, simply keep the signal hooked in place by not
disconnecting it when triggered.
This reverts commit 9a10b8ff94.
Even though, originally, this issue was first introduced with commit
b4fe1fdd95 ("xwayland: Make setup/teardown
a bit more symmetrical") which didn't actually kept 'x11-display-setup'
and 'x11-display-closing' connected.
Closes: https://gitlab.gnome.org/GNOME/mutter/-/issues/2168
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2339>
For wayland meta_window_move_to_monitor sends a configure to the client
without actually moving the window, yet and the
meta_display_queue_check_fullscreen call won't detect any changes.
Checking for fullscreen in meta_window_update_monitor fixes the problem
because it is called whenever the window actually changed the monitor it
is on.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2325>
We rather confusingly still call a secondary display card that is
GPU-less (DisplayLink or other basic KMS device) a "secondary GPU",
so just because secondary_gpu_state is non-NULL doesn't mean we
can use it for rendering. The clearest indication of this is when
there is no EGL surface.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2341>
Since devices may be multiple things now, check all capabilities in order
to ensure all aspects of the device are correctly configured.
This change does the following observations:
- Devices that have TOUCHPAD | POINTER capabilities prefer the 'touchpad'
settings path. The regular pointer settings path is left for all
non-touchpads.
- Devices that are both a tablet and a touchscreen prefer the tablet
relocatable schema. This works for both aspects as the touchscreen
schema is a subset of the tablet one.
Other than that it's a rather boring, even if verbose search and replace.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2331>
We do not need to open code the ClutterInputDeviceType fetching from a
libinput_device, since we already created a native ClutterInputDevice that
has the right type.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2331>
We use meta_workpace_focus_default_window() to sync the input focus back
to a window after it was on shell UI, this is not really necessary on
Wayland, but it is on X11. What this function does internally is ask
MetaWindowStack about the topmost window and focus+raise that window.
In gnome-shell we set the input focus to the default window every time
the key-focus changes to NULL (see shell-global.c ->
sync_stage_window_focus()). Now when closing the alt-tab switcher and
activating a window while there's an always-on-top window on the
workspace, meta_workspace_focus_default_window() will focus that
always-on-top window right after closing the alt-tab switcher, making it
impossible to focus another window using alt-tab.
To fix this, make meta_workspace_focus_default_window() check if there's
an existing focus_window first, if there is, use that, and if there
isn't, resort to just focusing the topmost one.
Fixes: https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/5162
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2328>
This will allow us to reuse the keys and values more easily, as later
commits will rely on being able to iterate over the keys and values to
construct explict env strings for passing into special test cases.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2152>
We use get_window_for_event() to check whether an event happened on top
of a window or on top of shell UI to decide whether to bypass delivering
the event to Clutter. In case of crossing events though, we can't just
use the device actor to determine whether to forward the event to
Clutter or not: We do want to forward CLUTTER_LEAVE events which
happened on top of shell UI. In that case the device actor is already a
window actor (the pointer already is on top of a window), but the shell
still needs to get the LEAVE crossing event.
Since the event source actor got removed from the detail of
ClutterEvent, the context we're looking for (which actor did the pointer
leave) is now the target actor that the event gets emitted to. Since the
last commit, we also made event filters aware of this context by passing
the target actor to them, so use this context now to determine whether
we're on top of a window or not.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2321>
We'll need the additional context of which actor the event will be
emitted to in mutters event filter (see next commit), so pass that
target actor to the event filters that are installed.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2321>
Before scanning out the surface of a native client we have
to check the following attributes that influence the
relationship between buffer and the defined result on screen:
- buffer scale
- buffer transform
- viewport
In the future we can loose these checks again in cases where the
display hardware supports the required operations (scaling, cropping
and rotating).
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2276>
Prior to 67033b0a mutter was accidentally including sizes for
configurations that were just focus state changes. This was not leading
to any known problems on the client side, but it was causing issues in
mutter itself when detecting whether a resize originated from the client
or the server.
Not including sizes in focus change configurations anymore however
revealed a bug in gtk. It was storing the window size when in a fixed
size mode (tiled/maximized/fullscreen), but not on any other server side
resizes. It was then restoring this stored size whenever there was a new
configuration without a size while in floating mode, i.e. the focus
change configurations generated by mutter after 67033b0a.
This change now addresses the issue 67033b0a was fixing in a way that
restores the previous behavior of always including the size whenever
sending a configuration.
Fixes: https://gitlab.gnome.org/GNOME/mutter/-/issues/2091
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2238>
If the remote desktop service emits absolute input events (e.g. absolute
pointer events) before the stream has started streaming, we don't have a
virtual monitor, as the size has not been negotiated yet. When this
happens, just drop the event. Remote desktop services should probably
make sure not to send events before the streaming has started, but them
doing so anyway shouldn't trigger a crash, which would be the case
otherwise.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2270>
This test resizes the stream by updating the PipeWire stream properties.
This triggers a format negotiation, that results in the buffers being
reallocated with the new size. The test makes sure we eventually
receive this new size.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2270>
Keep the virtual monitor around if it's being resized. This reduces the
number of unnecessary object rebuilding that happen during monitor
rebuilding.
This changes finalize() vfunc into a dispose() vfunc in the abstract
stream source object implementation, as it needs the abstract stream
source object to close the stream early, so that various signal
listeners get disconnected early.
Closes: https://gitlab.gnome.org/GNOME/mutter/-/issues/1904
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2270>
We'll change mode's on-demand so using IDs identical to the virtual
monitor ID would mean IDs didn't change when changing mode, and that is
rather unintuitive. IDs don't mean much anyhow, just make them grow
within the realm of a 63 bit unsigned integer, as the 64th bit means its
a virtual mode ID. Making sure the ID is in the virtual mode namespace
is handled by meta_crtc_mode_virtual_new().
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2270>
In some configurations (e.g. NVIDIA driver 470) Xwayland may use DMA
buffer for passing buffers around. When this is done, we might attempt
to scanout these buffers when they are fullscreen, and to do so we
import them using gbm.
However, for the mentioned configuration, there is no gbm device
available for importing. This was not handled, and resulted in a crash;
avoid this crash by checking whether we have a gbm device and fail
gracefully if we don't.
Closes: https://gitlab.gnome.org/GNOME/mutter/-/issues/2098
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2318>
This aims to replace the x,y arguments in wl_surface.attach(); meaning
it can be used more sanely together with EGL, and at all when using
Vulkan.
The most common use case for the offset is setting the hotspot of DND
surfaces.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1905>
This implements the new 'bounds' event that is part of the xdg_toplevel
interface in the xdg-shell protocol. It aims to let clients create
"good" default window sizes that depends on e.g. the resolution of the
monitor the window will be mapped on, whether there are panels taking up
space, and things like that.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2167>
We'd guess the initial monitor before it was actually calculated by
looking at the initial geometry. For Wayland windows, this geometry was
always 0x0+0+0, thus the selected monitor was always the primary one.
This is problematic if we want to provide initial more likely
configurations to Wayland clients. While we're not doing that yet, it'll
be added later, and this is in preparation for that.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2167>
This will later be used to tell Wayland clients about a size they
shouldn't exceed.
If the window doesn't have a main monitor, this function does nothing
and returns FALSE.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2167>
gnome-desktop is used to retrieve the monitor vendor name which in some
use cases is not needed as it brings a bunch of gnome-desktop unwanted
dependencies.
The change makes mutter fallback to an "Undefined" vendor name if it is
built without gnome-desktop
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2317>
Return in meta_egl_choose_all_configs() the actual number of
configurations returned by eglChooseConfig(), which are not
necessarily the same number as those from eglGetConfigs().
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2303>
Since the introduction of ClutterGrabs, MetaDnd now no longer gets
notified about input events on the stage during grabs (for example while
the alt-tab popup is shown) and thus can't move the grab feedback actor
anymore.
To fix this, forward events to MetaDnD directly from
meta_display_handle_event() when a ClutterGrab is in effect.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2308>
We get the MetaWaylandCompositor a bunch of times, but we can do with
getting it only once and then also replace the is_wayland_compositor()
checks with a if (wayland_compositor).
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2308>
The XDG activation support was missing interoperability with other
startup sequences, notably those coming from other means than XDG
activation.
In order to play nice with X11 startup sequence IDs, we not just
have to check for the startup ID being in the general pool, but
we also need to fallback into X11-style timestamp comparison so the
window ends up properly focused.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2314>
When a drag and drop occurs from an X11 client to a Wayland native
client, mutter uses an internal X11 window as a peer for the DnD drop
site.
That internal X11 window is moved and resized to match the Wayland
native windows as the drag destination moves.
When moving from one Wayland native window to another Wayland native
window, the same X11 window is used, and as a result no DND enter/leave
events is emitted.
In that case, the drop may occur on the wrong Wayland native window,
because no new XdndEnter/XdndLeave event were emitted.
To avoid that issue, use a pair of X11 windows instead of just one and
alternate between the two when repicking a new drop surface, so that
moving from a Wayland surface to another will always generate the
expected enter/leave events that we rely on.
Closes: https://gitlab.gnome.org/GNOME/mutter/-/issues/2136
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2305>
When generating the action label, we expect both directions of these
features to have consistent settings (either both get a keycombo, or
they don't) or these just return NULL altogether.
Since one of the directions has an action associated, this is
misleading, so be more lenient at the time of generating the action
label.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2001>
If we happen to handle a CLUTTER_TOUCH_BEGIN without a corresponding
CLUTTER_TOUCH_END at MetaWaylandTouch, we would still attempt to
reuse the older MetaWaylandTouchInfo, resulting in an assert triggered
as there is a stale touch reference on the previous surface.
Warn in place and create a new touch info struct to still fix the
broken surface accounting, instead of finding out the hard
way after the surface is destroyed. The assert is preserved to ensure
the accounting does not sneakily break anymore/further.
Closes: https://gitlab.gnome.org/GNOME/mutter/-/issues/584
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2251>
It passes a MetaLogicalMonitor, which isn't introspected right now, so
skip it completely. The entry point to the UI is handled via
MetaDisplay, so it isn't needed.
This fixes the following warning:
<unknown>:: Warning: Meta: (Signal)monitor-privacy-screen-changed: argument object: Unresolved type: 'MetaLogicalMonitor'
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2287>
Structure tests in a list of dictionaries, instead of requiring each
test to have its own executable(...) and test(...) statement. The
intention of this is to make it easier to add more test cases.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2262>
It already was built into it without any symbols exported, but also
duplicated in test cases that used it. Make it so that the built in
functions are exported, with prefixes, and make all tests use the
exported functions. While at it, make things go via MetaContext or
MetaBackend depending on how early in initialization things are run.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2262>
We update some details like the last used device and pointer visibility
from events, but this is done inconsistently on X11 since the
ClutterEvents are created and pushed from an additional place.
Make these updates happen on a private call, that will be called from
these places in X11.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/285>
Even though it's great that XI2 has an event to notify about device
changes, this is something we can let the MetaBackend code handle
consistently for all backends, since looking for the source device
works everywhere.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/285>
Instead of relying in the device being updated from different parts of our
machinery for different backends, hook this up to our own event dispatching.
This will allow dropping all other places where this is done.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/285>
We create a cursor renderer per device for those at
meta_seat_native_handle_event_post() with PROXIMITY_IN events, but
the MetaWaylandTabletTool handles the event before that, and goes
with a NULL cursor renderer.
Make MetaBackend::get_cursor_renderer() on the native backend create
those cursor renderers on demand, and only handle PROXIMITY_OUT in
handle_event_post() to dispose those. This makes MetaWaylandTabletTool
happily get a cursor renderer again.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/285>
We now only enable DMA buffer based PipeWire screen casting if a
format/modifier has been negotiated. This practically means a consumer
is aware about what is needed, and we should not try to predict that it
uses the DMA buffer the right way (i.e. not mmap:ing directly).
However, in case we're not hardware accelerated, we never want to
attempt to use DMA buffer screen sharing, as we want to avoid
compositing into a DMA buffer on such hardware as doing so can be very
slow.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2086>
meta_window_(un)queue() was implemented with global arrays in window.c
that managed MetaLater handle IDs and lists of window queues. In order
to rely less on scattered static variables and making it clearer that
we're dealing with per display window management and not something
specific to a single window, move the window resize/calc-showing queue
management to MetaDisplay.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2264>
It's still used by e.g. GNOME Shell to produce fallback icons for X11
applications that doesn't come with a .desktop file. Geometry stays in
the generic class because it's used for minimize animations and is
configured by the panel (e.g. the one in gnome-shell-extensions).
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2264>
The comments in this function tells a story of C programmer self
reflecting about data types and Perl. While that can be nice, the rest
consisted mostly of repeating what the code line below did, with the end
result being that the function didn't fit on screen, resulting in worse
readability overall.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2264>
When handling lid state, we used to update the idle time right after
opening the lid. This behavior changed in commit 14b6c8780d due
to a typo/thinko, "if (lid_is_closed)" used to be an early return
condition before updating idle time, now it only updates in that
case.
Restore the original behavior, since this idle time update is key
in having gsd-power light up the display again, this presumably
fixes situations that required extra "light up" hints after suspend.
What it does surely fix is "ninja test" in g-s-d against recent
mutter, since the behavioral change induced a test timeout there.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2272>
The `ensure_x11_unix_perms` function tries to detect systems on which
/tmp/.X11-unix is owned by neither root nor ourselves because in that
case the owner can take over the socket we create (symlink races are
fixed in linux 800179c9b8a1e796e441674776d11cd4c05d61d7). This should
not be possible in the first place and systems should come with some way
to ensure that's the case (systemd-tmpfiles, polyinstantiationm …). That
check however only works if we see the root user namespace which might
not be the case when running in e.g. toolbx.
This change relaxes the requirements such that in the root user
namespace we detect and abort if a vulnerable system is detected but
unconditionally run in toolbx.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2261>
Add some debug logging that allows checking whether we're using DMA
buffers for screencasting or system memory buffers. This can be useful
for debugging screencasting performance and CPU usage.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2256>
