FLT_MIN is the smallest *positive* number above 0 that can be
represented as floating point number. If this is used to initialize the
maximum x/y coordinates of a rectangle, this will always be used if all
x/y coordinates of the rectangle are negative. This means that picking
at 0,0 will always be a hit for such rectangles.
Since mutter creates such a window for server side decorations on X11,
this window will always be picked at 0,0 preventing clicking/hovering
the activities button in gnome-shell at that coordinate.
Fixes https://gitlab.gnome.org/GNOME/mutter/issues/893
When rendering on-stage, it might be necessary to push offscreen
framebuffers to the paint context by external consumers, such as
GNOME Shell effects.
Expose clutter_paint_context_push|pop_framebuffer().
https://gitlab.gnome.org/GNOME/mutter/merge_requests/955
They have been deprecated for a long time, and all their uses in clutter
and mutter has been removed. This also removes some no longer needed
legacy state tracking, as they were only ever excercised in certain
circumstances when there was sources (pipelines or materials) on the now
removed source stack.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/935
Stop using API that uses the implicit Cogl framebuffer stack, (e.g.
cogl_push_matrix()) and replace usage by the corresponding API taking an
explicit framebuffer (e.g. cogl_framebuffer_push_matrix()).
For offscreens etc, the offscreen framebuffer is still pushed to and
popped from the Cogl framebuffer stack, so that paint nodes still draw
to the right framebuffer.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/935
While we still push and pop to the Cogl framebuffer stack, as so is
still needed to render the actors correctly, don't use the API using the
implicit framebuffer stack ourself in the offscreen effect code.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/935
clutter_paint_node_get_framebuffer() fell back on
cogl_get_draw_framebuffer() when the root node didn't have a custom
get_framebuffer vfunc. As this relies on deprecated implicit Cogl stack
API, it needs to go away, so handle this in the caller that knows more
about the context.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/935
Instead of using the intermediate stage state "active framebuffer" to
find the framebuffer a paint eventually targets, use the "base
framebuffer" of the paint context, as this more correctly corresponds to
the end point of a paint. It also means we can then later remove this
intermediate state from the stage.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/935
Instead of pushing and popping the Cogl framebuffer stack, use the
framebuffer passed around using the pick context. This removes usage of
the deprecated framebuffer stack when picking.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/935
Rendering off stage we never cull, and previously this was checked by
comparing the "active framebuffer" of the stage, to the current
framebuffer in the cogl stack. Replace this by checking whether the
current paint context is currently drawing on stage or not.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/935
Just as with painting, add a pick context that carries pick related
temporary state when doing actor picking. It is currently unused, and
will at least at first still carry around a framebuffer to deal track
view transforms etc.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/935
When painting, actors rely on semi global state tracked by the state to
get various things needed for painting, such as the current draw
framebuffer. Having state hidden in such ways can be very deceiving as
it's hard to follow changes spread out, and adding more and more state
that should be tracked during a paint gets annoying as they will not
change in isolation but one by one in their own places. To do this
better, introduce a paint context that is passed along in paint calls
that contains the necessary state needed during painting.
The paint context implements a framebuffer stack just as Cogl works,
which is currently needed for offscreen rendering used by clutter.
The same context is passed around for paint nodes, contents and effects
as well.
In this commit, the context is only introduced, but not used. It aims to
replace the Cogl framebuffer stack, and will allow actors to know what
view it is currently painted on.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/935
We do check the clip area as an optimization to know which input devices
might need updating state after a relayout (Assuming that if a device is
under a non-painted area, it's actor beneath didn't change).
Use the clip region for this, and drop the last usage of the clip region
bounds.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/867
This commit was split out from `cleanup: Use g_clear_signal_handler()
where possible` as it fixes an actual signal leak and should therefore
get backported to stable releases.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/940
This is inspired by 98892391d7 where the usage of
`g_signal_handler_disconnect()` without resetting the corresponding
handler id later resulted in a bug. Using `g_clear_signal_handler()`
makes sure we avoid similar bugs and is almost always the better
alternative. We use it for new code, let's clean up the old code to
also use it.
A further benefit is that it can get called even if the passed id is
0, allowing us to remove a lot of now unnessecary checks, and the fact
that `g_clear_signal_handler()` checks for the right type size, forcing us
to clean up all places where we used `guint` instead of `gulong`.
No functional changes intended here and all changes should be trivial,
thus bundled in one big commit.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/940
CallyTexture is an accessibility object associated with ClutterTexture.
ClutterTexture is going away, so prepare by first removing the
accessibility object that would be constructed for it.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/932
clutter_event_get_scroll_finish_flags() should return a ClutterScrollFinishFlags
but due to what looks like a bad copy/paste it instead returns a
ClutterScrollSource on asserts.
The definitions of the enums are these:
typedef enum
{
CLUTTER_SCROLL_SOURCE_UNKNOWN,
CLUTTER_SCROLL_SOURCE_WHEEL,
CLUTTER_SCROLL_SOURCE_FINGER,
CLUTTER_SCROLL_SOURCE_CONTINUOUS
} ClutterScrollSource;
typedef enum
{
CLUTTER_SCROLL_FINISHED_NONE = 0,
CLUTTER_SCROLL_FINISHED_HORIZONTAL = 1 << 0,
CLUTTER_SCROLL_FINISHED_VERTICAL = 1 << 1
} ClutterScrollFinishFlags;
The asserts would only return CLUTTER_SCROLL_SOURCE_UNKNOWN. This
is equal to CLUTTER_SCROLL_FINISHED_NONE which this patch uses
instead. Thus no functional change is intended. This only fixes a
compile warning.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/931
Clutter has a draw debug mode that allows for painting
paint volumes. Right now, this debug mode uses the old
immediate paint mode.
Switch the painting of paint volumes to use paint nodes,
and sneak a few minor style cleanups.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/890
Now that we unconditionally use ClutterActorNode to
paint ClutterActors, move the PAINT private flag to
the ClutterActorNode. This way, we can run the paint
on the actor anywhere inside the paint tree.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/890
When setting the root node as child of a clip or transform node, we add a
new reference to it, without removing the one that we've previously added
when getting it from the actor node (and that won't ever be unset by the
auto-pointer since the root_node is re-associated).
So, once we add the root node as child and re-define it, unref it.
Fixes https://gitlab.gnome.org/GNOME/mutter/issues/908
Previously, we would use a single offscreen framebuffer for both
transformations and when a shadow framebuffer should be used, but that
can be dreadfully slow when using software rendering with a discrete GPU
due to bandwidth limitations.
Keep the offscreen framebuffer for transformations only and add another
intermediate shadow framebuffer used as a copy of the onscreen
framebuffer.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/877
A compositor is notably opaque (usually has nothing to be painted on!).
gnome-shell sets this hint, but there's no reason why we wouldn't want
it by default.
Also, the color buffer being cleared messes with stencil clips, as the
clear operation by definition ignores the stencil buffer. We want to
use these more extensively in the future, so just drop this API.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/911
This reverts commit 4918893326.
This commit prevented cogl_stage_cogl_redraw_view() from skipping
swap buffers entirely if the invalidation region ended up empty.
This meant we were actually swapping buffers when we didn't need to.
The source of the glitches was fixed more properly, so this just adds
extra work.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/898
This way, we can simply pop up the Looking Glass and run:
>>> Meta.add_clutter_debug_flags(Clutter.DebugFlag.PICK, 0, 0)
And measure specific actions or events on GNOME Shell.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/862
As we do not prevent the SwapBuffers call from happening, those also
do count. Results in clip area calculations to be right for monitors
that previously did not get invalidated.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/888
Make ClutterActor paint using ClutterTransformNode, ClutterClip
node, and ClutterActorNode. Essencially, the actor node is a
replacement for clutter_actor_continue_paint().
An interesting aspect of this commit is that the order of the
operations is reversed to be preserved.
Before being able to remove the dummy node hack, we'll need to
make ClutterEffects compatible with paint nodes first -- and
naturally, that's enough content for its own merge request.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/872
ClutterActorNode is a paint node that runs the 'paint'
function of an actor. It is a useful helper node to be
used during the transition to paint nodes.
The role of ClutterActorNode will change over time. For
now, it is just a call to clutter_actor_continue_paint(),
which also paints the effects. When ClutterEffect is
ported to paint nodes, ClutterActorNode will morph to
only notify the actor about the painting, and will become
a private node to Clutter.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/872
Previously picking was done on an int (x,y) to address a particular pixel.
While `int` was the minimum precision required, it was also an unnecessary
type conversion.
The callers (input events mainly) all provide float coordinates and the
internal picking calculations also have always used floats. So it was
inconsistent and unnecessary to drop to integer precision in between those.
ABI break: This changes the parameter types for public function
`clutter_stage_get_actor_at_pos`, but its documentation is already
sufficiently vague to not need changing.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/844
This is an extremely straightforward and minimalistic port of
CoglVector APIs to the corresponding Graphene APIs.
Make ClutterPlane use graphene_vec3_t internally too, for the
simplest purpose of keeping the patch focused.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/458
Mutter requires Clutter, which requires Cogl. That means
Clutter requires all Cogl dependencies, and Mutter requires
all Clutter dependencies as well.
However, currently, Clutter does not pull in its dependencies,
which means we need to link against Cogl manually.
Add Clutter dependencies to declare_dependency() so that the
graphene dependency only needs to be declared once, for Cogl,
and pulled together.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/458
This is a deprecated property that is not used anywhere
in the codebase. Not by GNOME Shell. Because it uses the
deprecated ClutterGeometry type, it's a good target for
cleaning up, given that ClutterGeometry will be dropped
later on.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/458
Fog is explicitly deprecated in favour of CoglSnippet API,
and in nowhere we are using this deprecated feature, which
means we can simply drop it without any sort of replacement.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/458
When clutter actors with key focus are destroyed we emit ::key-focus-out on
them just after their destruction. This is against our assumption that no
signal should be emitted after "::destroy" (see GNOME/mutter!769 [1]), and
in fact could cause the shell to do actions that we won't ever stop on
destroy callback.
To avoid this to happen, use a private function to set its key-state (so we
can avoid looking for the stage) and emit ::key-focus-in/out events and use
this value in both clutter_actor_has_key_focus(),
clutter_actor_grab_key_focus() and on unmap and destruction to unset the
stage key focus before we emit the ::destroy signal.
As result of this, we can now avoid to unset the key focus on actor
destruction in the stage.
[1] https://gitlab.gnome.org/GNOME/mutter/merge_requests/769
Fixes https://gitlab.gnome.org/GNOME/gnome-shell/issues/1704
Clutter had support for internal children in its early revisions, but they
were deprecated for long time (commit f41061b8df, more than 7 years ago) and
no one is using them in both clutter and in gnome-shell.
So remove any alternative code path that uses internal children.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/816
This is for all intents and purposes the same as
`cogl_object_ref/unref`, but still refers to handles rather than
objects (while we're trying to get rid of the former) so it's a bit of
unnecessary redundant API.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/451
The default value of the ClutterShaderEffect:shader-type
property is CLUTTER_FRAGMENT_SHADER. However, because the
struct field is not actually initialized to it, it ends
up assuming the value 0, which is CLUTTER_VERTEX_SHADER.
Properly initialize ClutterShaderEffect's shader_type to
CLUTTER_FRAGMENT_SHADER.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/846
ClutterActor took a reference in its transition 'stopped' handler,
aiming to keep the transition alive during signal emission even if it
was removed during. This is, however, already taken care of by
ClutterTimeline, by always taking a reference during its 'stopped'
signal emission, so no need to add another one.
This also has the bonus of making reference ownership simpler, as well
as avoidance of double free if an actor was destroyed before a
transition has finished.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/828
Implicit transitions had a referenced taken while emitting the
completion signals, but said reference would only be released if it was
had remove-on-complete set to TRUE.
Change this to instead remove the 'is_implicit' state and mark all
implicit transitions as remove-on-complete. This fixes a
ClutterPropertyTransition leak in gnome-shell triggered by e.g. showing
/ hiding menus.
Fixes: https://gitlab.gnome.org/GNOME/gnome-shell/issues/1740https://gitlab.gnome.org/GNOME/mutter/merge_requests/828
The final version of the function was changed to allow points that are
touching the edge of a quadrilateral to be counted as "inside". Update
the function documentation to refect this.
Also clarify that the function is written in such a way that it is
agnostic to clockwise or anticlockwise vertex ordering.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/783
In `clutter_stage_view_blit_offscreen()`, the given clipping rectangle
is in “view” coordinates whereas we intend to copy the whole actual
framebuffer, meaning that we cannot use the clipping rectangle.
Use the actual framebuffer size, starting at (0, 0) instead.
That fixes the issue with partial repainting with shadow framebuffer
when fractional scaling is enabled.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/820
Clutter actors might emit property changes in dispose, while unparenting.
However we assume that the ::destroy signal is the last one we emit for an
actor, and that starting from this moment the object is not valid anymore,
and so we don't expect any signal emission from it.
To avoid this, freeze the object notifications on an actor during its
disposition, just before the ::destroy signal emission.
Update the actor-destroy test to verify this behavior.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/769
Clutter actors unset their parent on dispose, after emitting the ::destroy
signal, however this could cause ::parent-set signal emission. Since we
assume that after the destruction has been completed the actor isn't valid
anymore, and that during the destroy phase we do all the signal / source
disconnections, this might create unwanted behaviors, as in the signal
callbacks we always assume that the actor isn't in disposed yet.
To avoid this, don't emit ::parent-set signal if the actor is being
destroyed.
Update the actor-destroy test to verify this behavior.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/769
If there is no transformation, use `cogl_blit_framebuffer()` as a
shortcut in `clutter_stage_view_blit_offscreen()`, that dramatically
improves performance when using a shadow framebuffer.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/809
Delayed clutter timelines might be removed while they are still in the
process of being executed, but if they are not playing yet their delay
timeout won't be stopped, causing them to be executed anyway, leading to a
potential crash.
In fact if something else keeps a reference on the timelines (i.e. gjs), the
dispose vfunc delay cancellation won't take effect, causing the timelines to
be started and added to the master clock.
To avoid this, expose clutter_timeline_cancel_delay() function and call it
if a timeline is not playing but has a delay set.
Fixes https://gitlab.gnome.org/GNOME/mutter/issues/815https://gitlab.gnome.org/GNOME/mutter/merge_requests/805
If a timeline is delayed and we request to stop or pause it, we are emitting
the "::paused" signal on it, however this has never been started, and so
nothing has really be paused.
So, just try to cancel the delay on pause and return if not playing.
No code in mutter or gnome-shell is affected by this, so it is safe to
change.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/805
Clutter stage used to compute the initial projection using a fixed z
translation which wasn't matching the one we computed in
calculate_z_translation().
This caused to have a wrong initial projection on startup which was then
correctly recomputed only at the first paint.
However, since this calculation doesn't depend on view, but only on viewport
size, perspective's fovy and z_near we can safely do this at startup and
only when any of those parameters change.
Then we can move the computation out _clutter_stage_maybe_setup_viewport()
since the cogl framebuffer viewport sizes aren't affecting this.
Fixes https://gitlab.gnome.org/GNOME/gnome-shell/issues/1639https://gitlab.gnome.org/GNOME/mutter/merge_requests/803
When suspending, the devices are removed and the virtual device
associated with the corresponding core pointer is disposed.
Add the pointer accessibility virtual device to the core pointer
on resume to restore pointer accessibility on resume if enabled.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/761
Currently, Clutter does picking by drawing with Cogl and reading
the pixel that's beneath the given point. Since Cogl has a journal
that records drawing operations, and has optimizations to read a
single pixel from a list of rectangle, it would be expected that
we would hit this fast path and not flush the journal while picking.
However, that's not the case: dithering, clipping with scissors, etc,
can all flush the journal, issuing commands to the GPU and making
picking slow. On NVidia-based systems, this glReadPixels() call is
extremely costly.
Introduce geometric picking, and avoid using the Cogl journal entirely.
Do this by introducing a stack of actors in ClutterStage. This stack
is cached, but for now, don't use the cache as much as possible.
The picking routines are still tied to painting.
When projecting the actor vertexes, do it manually and take the modelview
matrix of the framebuffer into account as well.
CPU usage on an Intel i7-7700, tested with two different GPUs/drivers:
| | Intel | Nvidia |
| ------: | --------: | -----: |
| Moving the mouse: |
| Before | 10% | 10% |
| After | 6% | 6% |
| Moving a window: |
| Before | 23% | 81% |
| After | 19% | 40% |
Closes: https://gitlab.gnome.org/GNOME/mutter/issues/154,
https://gitlab.gnome.org/GNOME/mutter/issues/691
Helps significantly with: https://gitlab.gnome.org/GNOME/mutter/issues/283,
https://gitlab.gnome.org/GNOME/mutter/issues/590,
https://gitlab.gnome.org/GNOME/mutter/issues/700
v2: Fix code style issues
Simplify quadrilateral checks
Remove the 0.5f hack
Differentiate axis-aligned rectangles
https://gitlab.gnome.org/GNOME/mutter/merge_requests/189
Add a function to check whether a point is inside a quadrilateral
by checking the cross product of vectors with the quadrilateral
points, and the point being checked.
If the passed quadrilateral is zero-sized, no point is ever reported
to be inside it.
This will be used by the next commit when comparing the transformed
actor vertices.
[feaneron: add a commit message and remove unecessary code]
https://gitlab.gnome.org/GNOME/mutter/merge_requests/189
This reverts commit f57ce7254d.
It causes crashes, https://gitlab.gnome.org/GNOME/mutter/issues/735, and
changes various expectations relied upon by the renderer code, and being
close to release, it's safer to revert now and reconsider how to remove
the pending swap counter at a later point.
Add a boolean parameter to the signal to inform the handler whether the
timeout completed successfully or not. This allows the shell to
gracefully end the pie timer animation and show a success animation when
the click happens.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/745
When a dwell click causes the pointer to move to another surface, a
synthetic event is generated which triggers another dwell click.
Make sure we ignore those to avoid dwell clicking twice in a raw.
Suggested-by: Carlos Garnacho <carlosg@gnome.org>
https://gitlab.gnome.org/GNOME/mutter/merge_requests/747
Restarting the dwell click immediately would result in a contant
animation showing.
Start dwell detection in its own timeout handler, which has the nice
effect of not constantly showing a dwell animation and also making sure
that the dwell click timeout is started when pointer movement stops.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/747
Sometimes the dwell timeout doesn't start again after quickly moving the
pointer. That happens if `should_stop_dwell` returns TRUE for the last
motion event we receive: It will stop the current timeout, but not start
a new one until we receive another event where the moved distance is
smaller than the threshold.
To fix this, always call `should_start_dwell` and `start_dwell_timeout`
instead of using an else-block, this makes sure we start a new dwell
timeout still during the same motion event that stopped the old one.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/746
And add the necessary glue so those initialize a X11 clutter backend.
This should get Clutter tests that are dependent on windowing to work
again, thus they were enabled back again.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/672
The end goal is to have all clutter backend code in src/backends. Input
is the larger chunk of it, which is now part of our specific
MutterClutterBackendNative, this extends to device manager, input devices,
tools and keymap.
This was supposed to be nice and incremental, but there's no sane way
to cut this through. As a result of the refactor, a number of private
Clutter functions are now exported for external backends to be possible.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/672
The end goal is to have all clutter backend code in src/backends. Input
is the larger chunk of it, which is now part of our specific
MutterClutterBackendX11, this extends to device manager, input devices,
tools and keymap.
This was supposed to be nice and incremental, but there's no sane way
to cut this through. As a result of the refactor, a number of private
Clutter functions are now exported for external backends to be possible.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/672
Mutter needs to know which framebuffer the paint nodes will be
drawn into, and using cogl_get_draw_framebuffer() directly is
not an option since ClutterRootNode only pushes the draw fb
at draw time.
Expose clutter_paint_node_get_framebuffer().
https://gitlab.gnome.org/GNOME/mutter/merge_requests/409
Incompressible events already pass through unmodified, so queuing them
just wasted time and memory.
We would however like to keep the ordering of events so we can only
apply this optimization if the queue is empty.
This reduces the input latency of incompressible events like touchpad
scrolling or drawing tablets by up to one frame. It also means the same
series of events now arrives at the client more smoothly and not in
bursts.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/711
Until now we would:
1. Enqueue modifier key event on the stage.
2. Update device modifier state.
3. Dequeue and process modifier key event with NEW device modifier state.
But if we consider optimizing out the queuing in some cases then there
will become a problem:
1. Process modifier key event with OLD device modifier state.
2. Update device modifier state.
To correct the above we now do:
1. Update device modifier state.
2. Queue/process modifier key event with NEW device modifier state.
It appears commit dd940a71 which introduced the old behaviour was correct
in the need to update the device modifier state, but is at least no longer
correct (if it ever was) that it should be done after queuing the event.
If queuing is working, as it is right now, then it makes no difference
whether the device modifier state is updated before or after. Because both
cases will come before the dequeing and processing.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/711
Thanks to the now removed global/context grabs, we can move pointer and
keyboard grabs back home to where they belong.
While at it, also add handling of CLUTTER_TABLET_DEVICE devices to
`on_grab_actor_destroy` and `clutter_input_device_get_grabbed_actor`.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/536
If possible, GLib will try to use the va_marshaller to pass the signal
arguments, rather than unboxing into and out of a `GValue`. This is much
more performant and especially good for often-thrown signals.
The original bug even mentions Clutter performance issues as a drive to
implement the va_marshaller in GLib (see
https://bugzilla.gnome.org/show_bug.cgi?id=661140).
https://gitlab.gnome.org/GNOME/mutter/merge_requests/700
Some of the marshallers we generate in `clutter-marshal.list` are also
available in GLib, so we don't need to generate them ourselves. Even
more, by passing NULL to `g_signal_new` in these cases will actually
internally optimize this even more by also setting the valist
marshaller, which is a little bit faster than the regular marshalling
using `GValue` and libffi.
https://gitlab.gnome.org/GNOME/mutter/merge_requests/700
