Commit Graph

7588 Commits

Author SHA1 Message Date
Carlos Garnacho
4fb968af76 clutter: Remove reentrancy checks at emit_event_chain()
When using alt-tab to switch between windows, on a key handler we
undo the compositor grab, which triggers a repick, which generates
crossing events, which are handled in place, and trigger these
reentrancy checks.

On one hand, we do intend these crossings to take effect in place,
rather than being queued (possibly after a number of already queued
events). On the other hand, we now outright discourage generating
events from random places (and hope to make it just not possible,
eventually) thus we can afford not to protect against reentrancy
caused by API misuse.

So just drop these checks, and let these crossing events be
properly handled.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1657>
2020-12-28 19:11:26 +01:00
Carlos Garnacho
b04e326572 clutter/main: Add clutter_stage_repick_device() call
This is the very same code than meta_wayland_pointer_repick(),
made part of Clutter, so triggering repicks on the same pointer
coordinates is made easy.

The intention is to remove meta_wayland_pointer_repick() in favor
of this call.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1654>
2020-12-23 12:54:49 +01:00
Carlos Garnacho
794962327e clutter/main: Change picked actor before emitting crossing events
Updating the state before emitting the CLUTTER_LEAVE event allows its
handlers to query the pointer actor, and avoid getting the same actor
again. Conceptually, this makes picking more "atomic", and the events a
notification of the change.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1654>
2020-12-22 18:27:37 +01:00
Jonas Dreßler
3a8b714e72 clutter: Use G_PARAM_EXPLICIT_NOTIFY for actor and stage properties
Turns out GObject implicitly notifies all properties by default as soon
as a property setter is called, no matter if the property actually
changed or not. One can opt-out of this behavior by setting the
G_PARAM_EXPLICIT_NOTIFY flag.

So since almost all our properties get notified explicitely (well,
except ClutterActors deprecated show-on-set-parent property), set this
flag for all properties of ClutterActor and ClutterStage now. This
significantly reduces the number of notify:: signals emitted on
ClutterActors, because in gnome-shell javascript we usually set GObject
properties directly, not by going through the extra setter method.

More cleanups can be done in the future, since this flag is suitable for
almost every property in Clutter and even Mutter.

This fixes a crash where we'd hit a newly introduced assertion in
on_device_actor_reactive_changed() of ClutterStage because
notify::reactive got emitted multiple times.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1651>
2020-12-20 12:37:34 +01:00
Jonas Dreßler
ad65c89d3c clutter/stage: Use own list of pointer devices to find updated devices
Due to a few reasons currently the updating of input devices after stage
relayouts isn't working right now. Since we now have a list of pointer
devices in ClutterStage, we can simply use that list and can avoid
asking the input thread. Also we no longer need to check whether the
devices are pointer devices, since our list only consists of pointer
devices.

So switch to ClutterStages private list of pointer devices, which also
includes the core pointer (as opposed to the list returned by
clutter_seat_peek_devices()). This fixes picking after relayouts.

Note that this doesn't catch every possible change that might need a
repick, actors might also need a repick after transformation changes or
in case their custom clip has been changed.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1634>
2020-12-18 18:32:05 +00:00
Jonas Dreßler
ae6d83fb47 clutter: Switch to storing device->actor associations in ClutterStage
As planned and prepared with the last commits, let ClutterStage take
care of tracking input devices and their respective actors. This means
we now can remove the old infrastructure for this from
ClutterInputDevice.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1633>
2020-12-18 16:17:00 +01:00
Jonas Dreßler
a9a9d27ead clutter: Add function to update input device actors to clutter-main
We're moving keeping track of input devices and their associated actors
out of ClutterInputDevice, this commit basically adds replacements for
clutter_input_device_update() and clutter_input_device_set_actor() to
clutter-main and shuffles the internals of those functions around a bit
for clarity.

clutter_stage_update_device() is made available in clutter-mutter.h
because we need to update the actor of input devices not only from
ClutterStage (when repicking after relayout), but also from
MetaWaylandPointer (inside meta_wayland_pointer_repick()).

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1633>
2020-12-18 15:13:48 +01:00
Jonas Dreßler
98a5cb37d9 clutter/stage: Add infrastructure to track devices and their actors
With the introduction of the input thread, we want to avoid modifying
ClutterInputDevices from the main thread, since they're owned and
updated by the thread.

There's one part of ClutterInputDevice that's still modified from the
main thread though, that is device-actors of pointer devices, and we're
going to move that state-tracking into ClutterStage instead.

So start that by adding the infrastructure to ClutterStage to keep track
of those things. It consists of two hashtables which associate devices
and touch sequences with actors, those hashtables get updated using
clutter_stage_update_device_entry() and
clutter_stage_remove_device_entry(), they can be queried by calling
clutter_stage_get_device_actor(), which will replace
clutter_input_device_get_actor().

clutter_stage_get_device_coords() is added and made available in
clutter-mutter.h because we need to get the coordinates when repicking
in meta_wayland_pointer_repick().

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1633>
2020-12-18 15:09:48 +01:00
Georges Basile Stavracas Neto
49653b0b0a clutter/blur: Select a better n_steps
The n_steps variable corresponds to the number of *pairs* of
texture lookups that the blur shader does. For example, when
n_steps = 1, the for-loop reads 1 pixel before and 1 pixel
after the current one.

Our blur shader is heavily inspired in WebRender's blur shader,
the biggest difference being that we calculate the gaussian
samples in the fragment shader itself, and not in the vertex
shader. (This could be an improvement in performance for the
future though!)

WebRender's blur shader calculates n_steps differently than what
we currently do, though. It calculates n_step in such a way that
at least 2 steps are performed for evey non-zero sigma value.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1646>
2020-12-17 13:21:50 +00:00
Georges Basile Stavracas Neto
5fca8f231a clutter/blur: Fix shader loop
We must iterate at least once, and i starts at 1, so use
less-or-equal in the for-loop.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1646>
2020-12-17 13:21:50 +00:00
Georges Basile Stavracas Neto
0b4b341e6c clutter/blur: Make sigma a float
The shader already operates on floating point sigma, and
there's just no reason for us to force it to be an unsigned
integer. It's still important that sigma must be positive
though.

Make sigma a float, and make sure it's a positive number.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1646>
2020-12-17 13:21:50 +00:00
Georges Basile Stavracas Neto
925809ea75 clutter/blur: Pass direction as vec2
Yet another way to reduce the instruction count of the fragment
shader. Passing a pair of floats once is virtually free, compared
to computing horizontal and vertical on each fragment run.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1646>
2020-12-17 13:21:50 +00:00
Georges Basile Stavracas Neto
8588352d1d clutter/blur: Remove uniform locations from BlurPass
They're not used anywhere except when setting up the pipeline, so
make them local variables.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1646>
2020-12-17 13:21:50 +00:00
Daniel van Vugt
261447a498 clutter/stage: Steal and manually free pending_queue_redraw entries
New entries indirectly added to `pending_queue_redraw` during the loop
would make our iterator invalid and cause `g_hash_table_iter_next` to
fail without having visited all elements. That was seen as assertion
failures but also likely resulted in incomplete paint clips.

Now we steal the iterator's entry before such corruption can happen,
free it manually, and reset the iterator to the beginning on every
iteration. This is actually safe and efficient because we're removing each
entry we visit. So no time is wasted in resuming from the (new) beginning
of the hash table.

Fixes: https://gitlab.gnome.org/GNOME/mutter/-/issues/1557
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1615>
2020-12-17 16:21:17 +08:00
Georges Basile Stavracas Neto
2f01ef69e3 clutter/paint-node: Add multi-rect operations
Add a new pair of APIs corresponding to CoglFramebuffer's draw_rectangles()
and draw_textured_rectangles(). They're generally more performance compared
to adding multiple single-rect operations. These variants are heavily used
by GNOME Shell's CSS implementation.

The op array is built to match cogl_framebuffer_draw_textured_rectangles()
always, which means it's a series of 8 floats composed (x1 y1 x2 y2) and
(s1 t1 s2 t2). To avoid adding new struct fields to ClutterPaintOperation,
which is a performance and memory sensitive structure, simply divide the
array length by 8 (which is guaranteed to be correct).

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1637>
2020-12-17 03:04:03 +00:00
Georges Basile Stavracas Neto
2cef2b6b1e clutter/paint-node: Rename multitex_coords to coords
The array will be used not only for multitexture, but also for
multirectangle operations. Rename it to be generic enough to
cover both cases.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1637>
2020-12-17 03:04:03 +00:00
Georges Basile Stavracas Neto
d717cc9231 clutter/blur: Shortcircuit when sigma is 0
When there's no blur to be performed, don't do any; instead,
return the original texture, and don't run the vertical and
horizontal blur pipelines.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1637>
2020-12-17 03:04:03 +00:00
Jonas Dreßler
7de5f79ddb Revert "clutter/offscreen-effect: Use the paint volume origin as the FBO offset"
This change broke the color picker in gnome-shell, let's revert it for
now until a correct solution can be figured out.

This reverts commit 0bace8dbde.

Closes https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/3494

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1645>
2020-12-16 23:08:25 +00:00
Georges Basile Stavracas Neto
53f7b6c149 clutter: Simplify framebuffer setup using ortho projection
Setting an ortho projection gives us pretty much the same result as
manually calculating the projection matrix. The ortho projection is
actually more "complete" than the custom projection we've been using,
as it also considers z-near and z-far, but in practice the generated
pixels are exactly equal.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1642>
2020-12-16 11:46:26 -03:00
Georges Basile Stavracas Neto
431bde921c clutter/effect: Move ClutterEffect creation to ClutterActor
As so paint node creation is centralized in a single function.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1355>
2020-12-15 12:07:57 -03:00
Georges Basile Stavracas Neto
46c68f368f clutter/offscreen-effect: Document paint nodes
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1355>
2020-12-15 12:07:57 -03:00
Georges Basile Stavracas Neto
4898408404 clutter/effect: Add paint nodes to all paint vfuncs
In the purely paint node based rendering future, ClutterEffects
simply add more paint nodes to the tree when painting the actor.

This is the leap to achieve that future.

Add paint nodes to pre_paint, paint, and post_paint, and move the
ClutterEffectNode creation to _clutter_effect_paint().

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1355>
2020-12-15 11:48:28 -03:00
Georges Basile Stavracas Neto
ea20076bad clutter/offscreen-effect: Implement paint_node()
The paint node tree that ClutterOffscreenEffect generates is
simple:

  Root
    |------------+
    |            |
  Layer        Pipeline
    |
  Actor

Right now, both pre-paint and ClutterLayerNode push the offscreen
to the framebuffer stack. That's harmless, and will go away soon
anyway.

The actor node is created and added in a separate function because
it'll be reused by the next commit.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1355>
2020-12-15 11:48:28 -03:00
Georges Basile Stavracas Neto
26c1a5eedf clutter/offscreen-effect: Use paint nodes to paint target
Add a new ClutterPaintNode parameter to the paint_target() vfunc.
For now, create a temporary ClutterEffectNode that is passed to
paint_target() and immediately painted; next commits will move
this to upper layers.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1355>
2020-12-15 10:36:34 -03:00
Georges Basile Stavracas Neto
691d31748a clutter/desaturate-effect: Switch to create_pipeline vfunc
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1355>
2020-12-15 10:36:34 -03:00
Georges Basile Stavracas Neto
b3641e0833 clutter/colorize-effect: Switch to create_pipeline vfunc
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1355>
2020-12-15 10:36:34 -03:00
Georges Basile Stavracas Neto
5c628083b6 clutter/brightness-contrast-effect: Switch to create_pipeline vfunc
Pretty much the exact same steps and constraints of the previous
commit.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1355>
2020-12-15 10:36:34 -03:00
Georges Basile Stavracas Neto
5587c70c6a clutter/blur-effect: Switch to create_pipeline vfunc
The blur pipeline is still cached on ClutterBlurEffect, and we
simply update the uniforms when asked to create the pipeline.

Now that ClutterOffscreenEffect will use the blur pipeline, it
doesn't need to override the paint_target() vfunc anymore.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1355>
2020-12-15 10:36:34 -03:00
Georges Basile Stavracas Neto
5794871977 clutter/offscreen-effect: Add new create_pipeline() vfunc
The most annoying aspect of ClutterOffscreenEffect right now, and
the reason for all its subclasses to override pre-paint, is that
the pipeline creation isn't under subclasses' control. That means
all subclasses must ask ClutterOffscreenEffect to run pre-paint
and create the pipeline, then they all create their own pipelines
to paint.

To reduce this complexity, add a new create_pipeline() vfunc to
ClutterOffscreenEffect. Next commits will port effects to use this
new vfunc.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1355>
2020-12-15 10:36:34 -03:00
Georges Basile Stavracas Neto
6654053250 clutter/paint-nodes: Make ClutterLayerNode always push/pop
ClutterLayerNode currently skips pushing the offscreen framebuffer when
no operations are set. This was added at the time because pushing and
popping was a synchronization point in Cogl, slow enough to force the
layer node to have this protective measure. Nowadays, pushing and
popping on the paint context is free.

Make ClutterLayerNode always push and pop in pre and post paint.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1355>
2020-12-15 10:36:34 -03:00
Georges Basile Stavracas Neto
15f5087135 Introduce ClutterBlurNode
ClutterBlurNode is a paint node based on ClutterLayerNode
that draws all children in an offscreen framebuffer, blurs
this framebuffer, and finally paints the blurred contents
according the the paint operations added.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1627>
2020-12-14 09:45:50 -03:00
Georges Basile Stavracas Neto
3440fbd358 clutter: Add private ClutterBlur
ClutterBlur is a small helper structure that implements
blurring a texture.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1627>
2020-12-14 09:43:08 -03:00
Georges Basile Stavracas Neto
3a3eaf5ad3 clutter/paint-nodes: Fix blit node oversights
Copy-paste error sneaked ClutterTransformNodeClass in
clutter_blit_node_class_init(). It wasn't problematic
because they both typedef to ClutterPaintNodeClass, but
fix it anyway.

Also switch to g_object_ref() in clutter_blit_node_new().

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1627>
2020-12-14 09:21:30 -03:00
Daniel van Vugt
ebf9f18080 clutter/text: Make update_cursor_location() operate in stage coordinates
Until now we would `clutter_input_focus_set_cursor_location` with
cursor-rectangle-in-physical-pixels + actor-location-in-stage-coordinates.
But those use different scaling factors so it only got the right answer
when the framebuffer scale was 1.0.

This directly determines the geometry of the invisible dummy cursor in
gnome-shell ibusCandidatePopup.js:

```
  panelService.connect('set-cursor-location', (ps, x, y, w, h) => {
      this._setDummyCursorGeometry(x, y, w, h);
  });
```

And because it's invisible it wasn't obvious that it was wrong until you
enable `CLUTTER_PAINT=damage-region` and you can see its ghost at the wrong
offset and scale.

So now we `clutter_input_focus_set_cursor_location` using purely unscaled
stage coordinates. And `CLUTTER_PAINT=damage-region` shows that
gnome-shell's `_dummyCursor` is placed precisely over the visible cursor.

Fixes: https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/3399
and probably other IBus issues that arise when using framebuffer scaling.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1576>
2020-12-12 08:18:49 +00:00
Daniel van Vugt
db30a4d7b4 clutter/text: Scale down clutter_text_get_cursor_rect to actor coordinates
`priv->cursor_rect` is stored in physical pixels, not local coordinates.
So unscale it before returning from `clutter_text_get_cursor_rect`, which
is explicitly documented as returning "actor-relative coordinates".

This went missed with fractional scaling support, and unnoticed as nobody
uses `clutter_text_get_cursor_rect` yet. But that will soon change.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1576>
2020-12-12 08:18:49 +00:00
Daniel van Vugt
0bace8dbde clutter/offscreen-effect: Use the paint volume origin as the FBO offset
Before now it was assumed that the only negative local coordinates would
be those introduced by `_clutter_actor_box_enlarge_for_effects`, and we
used the difference for `fbo_offset_x/y`. But that was misguided (of me)
because gnome-shell can give us paint volumes at negative coordinates too,
like when rendering `box-shadow` on the top or left edge of an actor.

The maximum extents of negative coordinates we might need to render are
in fact the (enlarged) left and top edges of the paint volume. So use
those as the FBO offset. This places the actor's local origin correctly
within the FBO and thus also ensures it's not over-clipped at the edges
of the FBO, which now line up with the enlarged extents of the paint
volume.

This fixes one third of
https://gitlab.gnome.org/GNOME/gnome-shell/issues/1090
The other fixes required are !1053 and gnome-shell!1417.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1538>
2020-12-12 00:27:46 +00:00
Jonas Dreßler
9693462f32 clutter/actor: Use different view list when picking frame clock of stage
Apparently it can happen that a timeline tries to pick a frame clock
from an actor that's on a stage, but the actor still doesn't find a
frame clock and returns NULL.

This probably is the case when starting a timeline right after attaching
an actor to a newly created stage, so before the first stage-update
cycle. In this case clutter_actor_update_stage_views() will not have run
and the stage-actor will have priv->stage_views set to NULL even though
there are stage views.

To prevent this from happening, use the complete list of stage views
maintained by the backend when picking a frame clock for the stage.

This doesn't fix any issue appearing on master, but is correct
nonetheless.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1631>
2020-12-11 22:51:44 +00:00
Carlos Garnacho
e21929be82 clutter: Do not poke backend code for motion compression
We now have all info available in ClutterEvent, use it and stop poking
backend internals.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1623>
2020-12-08 15:37:38 +00:00
Carlos Garnacho
0842ac936f clutter: Drop infrastructure to copy/free platform event data
This is now unused, all information belongs to ClutterEvents.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1623>
2020-12-08 15:37:38 +00:00
Carlos Garnacho
b88790554b clutter: Move relative motion information to ClutterEvent
Instead of using native backend platform data specifically, store
this info in ClutterMotionEvent. This includes time in usec since
it's just used for motion events, in the future it could make sense
to make these general to all events again, but it could make sense
to make ClutterEvent structs private before.

In order to express that a motion event has relative motion info,
the CLUTTER_EVENT_FLAG_RELATIVE_MOTION event flag has been added
for it.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1623>
2020-12-08 15:37:38 +00:00
Carlos Garnacho
eaa04ecee5 backends: Unify touch sequence to slot conversion
We had code in both backends that sort of independently associated
sequences to slots. Make both transform slots to sequences the same
way, so they may share the implementation convert those back to slots.

This helper now lives in Clutter API.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1623>
2020-12-08 15:37:38 +00:00
Carlos Garnacho
9f5c453fc7 clutter: Move evdev evcode data to Clutter button/key events
We have this as platform-dependent data in the native backend, and
a bunch of fallback code done in place in the evcode users. Stop
making this platform-dependent data, and move it to the relevant
ClutterEvents.

The fallback code for the X11 backend case is about the same, but
now it is done directly by the X11 backend.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1623>
2020-12-08 15:37:38 +00:00
Carlos Garnacho
4a0c56f928 clutter: Simplify stage state management
Making this an event is overly convoluted, accounting that we
emit the event, then convert it to a ClutterStage signal, then
its only consumer (a11y) sets the active ATK state.

Take the event out of the equation, unify activation/deactivation
of the stage in MetaStage, and use it from the X11 backend too.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1623>
2020-12-08 15:37:38 +00:00
Carlos Garnacho
96e320ba5a clutter: Drop CLUTTER_DESTROY_NOTIFY event
Stop propagating this as a Clutter event. DestroyNotify is only
relevant on nested X11 sessions, so handle it specifically in place.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1623>
2020-12-08 15:37:38 +00:00
Carlos Garnacho
49b3ac2f86 clutter: Drop CLUTTER_CLIENT_MESSAGE event
This is used nowhere and emitted nowhere. We can do without it.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1623>
2020-12-08 15:37:38 +00:00
Georges Basile Stavracas Neto
033423f6db Introduce ClutterBlitNode
It is not possible to express a blit operation using paint
nodes as of now. This is a requirement for GNOME Shell, e.g.,
to implement its blur effect.

Add a new ClutterBlitNode node that takes two framebuffers as
input, and blits the source framebuffer into the current one
according to added rectangles.

Because this paint node uses the rectangles in a different way
compared to all the other nodes, add an auxiliary method to
ensure all blit operations are valid.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1340>
2020-12-08 15:14:04 +00:00
Georges Basile Stavracas Neto
4c75389baa clutter/paint-nodes: Add serialization to layer node
It's useful to know which framebuffer the layer node is holding,
so serialize that too.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1340>
2020-12-08 15:14:04 +00:00
Georges Basile Stavracas Neto
63ea2dacc4 clutter/paint-nodes: Add new ClutterLayerNode API
ClutterLayerNode is the "offscreen framebuffer" node, that paints it's
child nodes in a separate framebuffer, and then copies that framebuffer
to the parent one.

It'll be useful to hand ClutterLayerNode which framebuffer and pipeline
to use, as this is a requirement for porting e.g. ClutterOffscreenEffect
and subclasses.

Add a new clutter_layer_node_new_to_framebuffer() API.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1340>
2020-12-08 15:14:04 +00:00
Georges Basile Stavracas Neto
89f9be0dd1 clutter/paint-nodes: Add opacity overriding to ClutterActorNode
Some effects, such as ShellBlurEffect and ClutterOffscreenEffect, need
to make sure the actor is painted fully opaque. With ClutterActorNode,
however, that is currently not possible.

Add a new 'opacity' parameter to clutter_actor_node_new(). It follows
the opacity override heuristic, where -1 means disable, and anything
else is clamped to [0, 255].

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1340>
2020-12-08 15:14:04 +00:00
Georges Basile Stavracas Neto
5c772a634e clutter/effect: Add paint_node vfunc
Introduce a new paint_node vfunc that, if implemented, allows
the effect to add nodes to a transient paint node that is
immediately painted. This is a transitional step until we
have fully delegated paint node rendering.

The most basic implementation of a ClutterEffect.paint_node
vfunc, and also the default implementation, is with an actor
node, as follows:

```
static void
foo_bar_paint_node (ClutterEffect           *effect,
                    ClutterPaintNode        *node,
                    ClutterPaintContext     *paint_context,
                    ClutterEffectPaintFlags  flags)
{
  g_autoptr (ClutterPaintNode) actor_node = NULL;

  actor_node = clutter_actor_node_new (effect->actor);
  clutter_paint_node_add_child (node, actor_node);
}
```

This example gives the exact same behavior of simply calling
clutter_actor_continue_paint(). In the future, the paint node
itself will be a parameter of clutter_actor_continue_paint()
and we'll be able to simplify it event more.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1340>
2020-12-08 15:14:03 +00:00
Georges Basile Stavracas Neto
e45d1c6ea6 Introduce ClutterEffectNode
ClutterEffectNode is a private ClutterPaintNode implementation
that does effectively nothing, but helps organizing the paint
node tree. It also helps debugging, since it can output the
effect class and name to the JSON debugging routines.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1340>
2020-12-08 15:14:03 +00:00
Georges Basile Stavracas Neto
3c8bfc1482 clutter/paint-node: Walk up paint node tree to find framebuffer
The idea of having a paint node tree is that we don't really need
to retrieve the framebuffer from ClutterPaintContext. For example,
ClutterLayerNode draws into an offscreen framebuffer; if any child
of a layer node needs to retrieve a framebuffer to draw, the layer
node's offscreen framebuffer should be used.

However, clutter_paint_node_get_framebuffer() goes straight to the
root node of the tree, skipping any potential paint nodes with a
custom framebuffer.

Modify clutter_paint_node_get_framebuffer() to walk up the paint
node tree until a node with a custom framebuffer appears. In many
cases, this will end up either in dummy or layer node's custom
framebuffer implementations.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1340>
2020-12-08 15:14:03 +00:00
Carlos Garnacho
14ab90eeba clutter/actor: Initialize out variable
Fixes a compiler warning with -Wmaybe-uninitialized enabled:

  ../../../../Source/gnome/mutter/clutter/clutter/clutter-actor.c: In function ‘clutter_actor_paint’:
  ../../../../Source/gnome/mutter/clutter/clutter/clutter-actor.c:3808:50: warning: ‘result’ may be used uninitialized in this function [-Wmaybe-uninitialized]
   3808 |       else if (result == CLUTTER_CULL_RESULT_OUT && success)
        |                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~

Which might presumably happen in the unlikely case that there's no clip
frusta.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1624>
2020-12-08 13:35:50 +00:00
Daniel van Vugt
e91062aaec clutter/pick-stack: Add a copyright for Canonical
Where much of the logic was introduced in commit 14c706e51b

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1619>
2020-12-01 12:54:41 +00:00
Carlos Garnacho
424f3b702e clutter: Do not emit signals during ClutterBackend finalization
Missed because nobody does that ATM.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:34 +00:00
Carlos Garnacho
2ff5bb4299 backends/native: Update keyboard a11y status in seat impl
Instead of going through the event queue, stage handling code, and
back to the input device via a vmethod call, do this directly in the
MetaSeatImpl. This is not too different from X11, where everything
happens inside the backend.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:34 +00:00
Carlos Garnacho
f117a157dc clutter: Add vmethod to find out group for pad features
Do it so the wayland bits don't have to access native input devices
internals. The data is still readonly, idempotent, etc.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:34 +00:00
Carlos Garnacho
e0444a3d35 clutter: Move ClutterInputDevice fields to private struct
All that is left in the "public" struct is all state that ClutterStage
delegates on ClutterInputDevice. That should move somewhere else, but
not here, not now.

All private fields belong to construct-only properties, with only getter
API, and idempotent vmethods (except keyboard a11y, atm). This should
be enough to make ClutterInputDevice obviously thread safe, outside the
backend.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:34 +00:00
Carlos Garnacho
71b4c0ee02 clutter: Drop keycode_to_evdev vmethod
This is just used in the native backend, move it to an utility
function there.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:34 +00:00
Carlos Garnacho
c7f989c1e2 clutter: Drop ClutterInputDevice private tool maintenance API
This is just used in the native backend (with the X11 going its own
way). Just keep a HT of tools there, and drop this API.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:34 +00:00
Carlos Garnacho
06d577fdf3 clutter: Move scroll valuator accounting to backends/x11
This is just used there. Another X11 detail that got open coded.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:34 +00:00
Carlos Garnacho
d7d92b0ddc clutter: Drop ClutterInputDevice axis API
Most of this comes from X11 peculiarities that were open coded in
the Clutter ABI. We don't need this except in X11, so move this axis
handling there.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:34 +00:00
Carlos Garnacho
5689a843c7 clutter: Drop internal update_from_tool() vmethod
This is kinda pointless now, and will be made completely unneeded
by dropping device axes.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:33 +00:00
Carlos Garnacho
168ceb9905 backends: Forward event axes as array of ClutterInputAxes elements
Instead of encoding arrays in ways that we need the ClutterInputDevice
to decode them, use ClutterInputAxes as the array index.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:33 +00:00
Carlos Garnacho
e772f62ea7 clutter: Make axes part of the device tool
This info can be construct-only there, as opposed to devices.
Move this info to tools, so we can drop it from devices.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:33 +00:00
Carlos Garnacho
be9c531ab9 clutter: Drop clutter_input_device_get_associated_device()
And the private setter. One may ask the seat for the pointer/keyboard
instead of asking the device for its counterpart.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:33 +00:00
Carlos Garnacho
c4fa5ef88a clutter: Drop clutter_input_device_get_physical_devices() API
This is unused, we have the seat for this kind of stuff.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:33 +00:00
Carlos Garnacho
699da157c7 clutter: Drop clutter_input_device_get_key()/n_keys API
And the corresponding setters. This is completely unused, and
unrecommended. In xkb we trust.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:33 +00:00
Carlos Garnacho
d58e082500 clutter: Drop clutter_input_device_get_modifier_state() API
This is using ClutterSeat state queries underneath, let the only
caller do that, and drop this call.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:33 +00:00
Carlos Garnacho
c6849a66e8 clutter: Drop clutter_input_device_get_coords() method
This is not device state anymore. It uses ClutterSeat API underneath,
so let callers do that instead.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:33 +00:00
Carlos Garnacho
b789d38f68 clutter: Switch to GAsyncQueue for ClutterMainContext event queue
We will be moving to having events produced in one thread and consumed
in another. Make this an async event queue in preparation for that.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:33 +00:00
Carlos Garnacho
2c1558ddbd backends: Make device tracking at MetaInputSettings ad-hoc API
Depending on the backend, we want to integrate this object at different
levels. It will sit close to the MetaBackendX11/MetaSeatX11 in X11, but
it will be put deep down with MetaSeatImpl in the native backend, in a
separate thread.

Since we can't depend on a single object type, nor are able to track
ClutterSeat signals neatly, make this API something to be called
explicitly by backends.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:33 +00:00
Carlos Garnacho
c601a824e9 clutter: Update device for the current tool in backends
This should happen deeper in backends, not here in clutter-main.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:33 +00:00
Carlos Garnacho
2ceac4a296 clutter: Make ClutterSeat::handle_device_event vfunc more generic
Make it able to handle not just device added/removed events, but perform
any kind of post-processing that needed to be done on ClutterEvents at
the seat level.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:33 +00:00
Carlos Garnacho
c3acaeb251 backends: Move keyboard a11y into backends
And out of Clutter API. This is mainly set via settings, or the windowing
itself, so we don't need to leak these details up our own backend.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:33 +00:00
Carlos Garnacho
b1d12a994d clutter: Drop ClutterInputDevice::enabled and setter/getter
This is unused now, and not something we generally allow.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:33 +00:00
Carlos Garnacho
dea909aea7 clutter: Simplify backend-independent touch accounting
Coordinates are tracked by the ClutterSeat backends, we just need to
track the target actor at this level.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:33 +00:00
Carlos Garnacho
2411460cff clutter: Drop clutter_input_device_set_coords()
Input devices aren't "updated" anymore, but their state queried to the
seat. This goes nowhere.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:33 +00:00
Carlos Garnacho
3234ae2993 clutter: Drop clutter_input_device_update_from_event()
Input devices aren't "updated" anymore, but their state queried to
the seat instead. This API was only meant for embedders of Clutter,
and is pointless to us.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:33 +00:00
Carlos Garnacho
730da1dbe1 clutter: Pass base event to clutter_input_device_update()
So we may fetch coordinates without necessarily querying the device
state.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:33 +00:00
Carlos Garnacho
932a5cab09 clutter: Drop clutter_input_device_set_state()
Nothing uses it anymore.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:33 +00:00
Carlos Garnacho
cb7794c19c clutter: Use ClutterSeat underneath coords/modifiers input device getters
This is not device state, but belonging to seat guts.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:33 +00:00
Carlos Garnacho
fba1122a3c clutter: Add ClutterSeat::query_state() vmethod
This will query a device state; position and modifiers.
Note that ClutterSeat subclasses don't implement the vmethod yet,
so calling clutter_seat_query_state() may crash ATM.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1403>
2020-11-27 15:14:33 +00:00
Daniel van Vugt
17dbb98811 clutter/stage: Remove fps_timer
It's unused since a9a9a0d1c5.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1603>
2020-11-26 11:03:08 +00:00
Georges Basile Stavracas Neto
6c4b897d74 clutter/actor: Cull out when picking
Testing points and rays against boxes is substantially cheaper - in
fact, almost trivial - compared to triangles. Check if the actor's
paint volume doesn't intersect with the current pick point / ray,
and skip recursing altogether in those cases.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1520>
2020-11-25 16:34:29 +00:00
Georges Basile Stavracas Neto
1fdde25b3e clutter/paint-volume: Add new API to convert to graphene_box_t
Will be used to cull when picking based on the actor's projected
paint volume.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1520>
2020-11-25 16:34:29 +00:00
Georges Basile Stavracas Neto
c3534d3390 clutter/pick-context: Store point and ray on construction
It'll be used to do a quick box test to cull out while picking.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1520>
2020-11-25 16:34:29 +00:00
Georges Basile Stavracas Neto
1b29d265a8 clutter/stage: Remove cached pick mode
The cached pick mode never actually cached anything, since it is
always, unconditionally reset when painting. Furthermore, next
commits will cull out actors during pick, which makes the pick
stack uncacheable.

Remove the cached pick mode.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1520>
2020-11-25 16:34:29 +00:00
Georges Basile Stavracas Neto
3073aee7c8 clutter/pick-stack: Add autoptr support
It'll allow us use g_autoptr (ClutterPickStack) when removing the pick stack
cache, making the code a bit more modern.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1520>
2020-11-25 16:34:29 +00:00
Simon McVittie
1a1f1eccba clutter/frame-clock: Schedule a frame at least once per second
Users of Debian arm64 (aarch64) report that on at least some GPUs
or screens, after time-based screen blanking has occurred, it is not
possible to unlock the screen. Bisection indicates that this regressed
in commit 209b1ba3, so presumably this is because a refresh rate of 0
is reported while the screen is blanked, leading to the frame clock
pausing forever.

Fixes: 209b1ba3 "clutter/frame-clock: Adapt refresh rate from to frame info"
Closes: https://gitlab.gnome.org/GNOME/mutter/-/issues/1536
Bug-Debian: https://bugs.debian.org/974172
Signed-off-by: Simon McVittie <smcv@debian.org>
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1601>
2020-11-25 10:14:10 +00:00
Jonas Dreßler
58930e9e1f clutter/actor: Use a variable to check if culling is allowed
Since we now want to check whether culling is force-disabled using a
debug flag in two places, let's factor this out into a separate
variable.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1591>
2020-11-25 01:08:02 +01:00
Jonas Dreßler
0320649a1c clutter/actor: Always update last_paint_volumes during painting
It's currently possible that some last_paint_volumes don't get updated
during a paint cycle, this can happen when a ClutterOffscreenEffect is
used: The offscreen effect might skip painting the content and the
children of an actor because it uses its own offscreened texture
instead. This means the offscreen effect doesn't call
clutter_actor_continue_paint(), and thus the the last_paint_volumes of
the children won't be updated.

Now one might think that isn't a problem, because as soon as a child
changes it's size or position, the offscreened texture would get
invalidated and clutter_actor_continue_paint() would get called. It's
not that easy though: Because the last_paint_volume includes all the
transformation matrices up to eye-coordinates, it has to be updated on
any changes to matrices, which includes position/transformation changes
to any actor up the hierarchy.

Now that's where get into problems with the offscreen effect: In case of
transformation changes to the offscreened actor or an actor up the
hierarchy, the offscreened texture won't get invalidated (that makes
sense, we can simply paint it transformed) and the last_paint_volumes
won't get updated even though they should.

This leaves us around with outdated last_paint_volumes where
last_paint_volume_valid is still set to TRUE. It can cause issues with
culling and clipped redraws.

So fix that by ensuring that all children that would get painted by
Clutter get their last_paint_volumes updated in case a ClutterEffect
decided not to call clutter_actor_continue_paint().

This ignores the case where a paint() vfunc override does the same and
doesn't call clutter_actor_paint() on children. Let's ignore this case
for now, there shouldn't be any implementation which does that and
ideally in a world that's painted solely by ClutterContent, we can get
rid of that vfunc in the future.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1591>
2020-11-25 01:07:32 +01:00
Jonas Dreßler
0da8a49719 clutter/stage: Clarify comments in add_to_stage_clip() a bit
The first comment isn't really needed anymore since
the is_full_stage_redraw_queued() underneath is quite self-explaining.

Also rephrase the second comment a bit, including that
_clutter_paint_volume_get_stage_paint_box() does the aligning to the
pixel grid.

Finally, the last comment also looks out of date since we do that
rounding inside _clutter_paint_volume_get_stage_paint_box(), so remove
it.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1511>
2020-11-24 18:30:19 +00:00
Jonas Dreßler
906124b09f clutter/stage: Don't pass QueueRedrawEntries to actors
We currently pass actors a reference to their associated
ClutterStageQueueRedrawEntry when queueing a redraw. This "splitting" of
the ownership of the entry has introduced quite a few bugs in the past
and is hard to follow.

So give up the "splitting" of the ownership and exclusively handle those
entries inside ClutterStage. To still allow removing the entry when an
actor gets unrealized introduce clutter_stage_dequeue_actor_redraw()
similar to what we already have for relayouts.

To be able to efficiently find entries when actors queue redraws, make
pending_queue_redraws a GHashTable, which fits quite nicely and also
allows removing the QueueRedrawEntries actor pointer in favour of the
key of the hashtable.

Since the struct is now private to ClutterStage, we can also rename it
to QueueRedrawEntry.

While at it, also sneak in the removal of the leading underscore from
clutter_stage_queue_actor_redraw().

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1511>
2020-11-24 18:30:19 +00:00
Jonas Dreßler
1cd386551d clutter/actor: Remove the queue-redraw signal
The "queue-redraw" signal is not used anywhere in Clutter and we now
also removed the vfunc implementation of the stage. So stop emitting it
and remove it, but keep the propagate_queue_redraw infrastructure to
make sure clones still get their redraws queued.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1511>
2020-11-24 18:30:19 +00:00
Jonas Dreßler
ce4c297cea clutter/actor: Emit the queue-redraw signal right away
Since we now decoupled the "queue-redraw" signal from creating the stage
clip, we can move signal emission into
_clutter_actor_queue_redraw_full() and emit the signal right away when
queueing a redraw on an actor. With that we now no longer have to
accommodate for the stage pending_queue_redraws list changing while
iterating over it.

To ensure we don't emit the signal too often when multiple redraws are
queued on one actor, use the propagated_one_redraw flag to limit the
number of emissions to a single one for every update cycle.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1511>
2020-11-24 18:30:19 +00:00
Jonas Dreßler
9b16eff784 clutter: Move assembling the redraw clip out of "queue-redraw" signal
Putting together the redraw clip of the stage never really fitted nicely
with the "queue-redraw" signal emission, it forces us to emit the
signals in a batch and we also use a weird trick to get the old paint
volume that's already on-screen into the final redraw clip (we call
_clutter_actor_propagate_queue_redraw() on the stage).

So start breaking up this association by making the stage explicitely
request the redraw clip from the actor and removing the
ClutterPaintVolume argument from _clutter_actor_finish_queue_redraw().
This is done by adding a private function
clutter_actor_get_redraw_clip() which returns our old (currently
visible) paint volume and the new paint volume.

This also allows removing the check whether a full stage redraw has been
queued in clutter_actor_real_queue_redraw() and we can now just stop the
signal emission if a propagation happened at least once.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1511>
2020-11-24 18:30:19 +00:00
Georges Basile Stavracas Neto
3cf11f77b3 clutter/pick-stack: Move triangle check to else block
Just to improve the legibility of this part of the code. We
go either through box, or triangle, but never both.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1599>
2020-11-23 13:34:28 -03:00
Georges Basile Stavracas Neto
d2feaa8d67 clutter/pick-stack: Use graphene_box_t for axis-aligned rectangles
The most common case for Clutter is 2D axis-aligned actors, which
maintain these properties even after projecting to eye coordinates.
In those cases, we can use a simpler hit test by checking against
boxes.

Not only this is simpler, but this maintains an important aspect
of picking that is a requirement for Clutter: watertightness. Even
though the triangles checks do work on x86_64, they do not guarantee
watertightness. This breaks tests on ARM.

Use graphene_box_t to hit-test axis-aligned 2D actors.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1599>
2020-11-23 13:34:28 -03:00
Jonas Dreßler
b5a7fe4b23 clutter/actor: Handle clips correctly when building paint volume
clutter_actor_paint() implements a clear preference for custom clips
over clip_to_allocation: If a custom clip is set, clip_to_allocation is
ignored.

Since the paint volume reflects what Clutter is going to paint, we
should handle it the same when putting together our paint volume: So
first handle custom clips, and if one is set, use that. Then handle
clip_to_allocation, and if that's set, use that. And finally, if both
aren't set, union our allocation with the children paint volumes to get
the building volume.

clutter_actor_paint() also doesn't check whether the custom clip is
empty: If that's the case, it will simply not paint anything. Given that
that's allowed by clutter_actor_paint(), the paint volume should also
follow here and return an empty paint volume in case the custom clip is
empty.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1592>
2020-11-23 14:06:13 +00:00