The internal copy of JSON-GLib was meant to go away right after the 1.0
release, given that JSON-GLib was still young and relatively unknown.
Nowadays, many projects started depending on this little library, and
distributions ship it and keep it up to date.
Keeping a copy of JSON-GLib means keeping it up to date; unfortunately,
this would also imply updating the code not just for the API but for the
internal implementations.
Starting with the 1.2 release, Clutter preferably dependend on the
system copy; with the 1.4 release we stopped falling back automatically.
The 1.6 cycle finally removes the internal copy and requires a copy of
JSON-GLib installed on the target system in order to compile Clutter.
Since re-working how redraws are queued it is no longer necessary to
dirty the pick buffer in _clutter_actor_real_queue_redraw since this
should now reliably be handled in _clutter_stage_queue_actor_redraw.
This adds two internal functions relating to explicit traversal of the
scenegraph:
_clutter_actor_foreach_child
_clutter_actor_traverse
_clutter_actor_foreach_child just iterates the immediate children of an
actor, and with a new ClutterForeachCallback type it allows the
callbacks to break iteration early.
_clutter_actor_traverse traverses the given actor and all of its
decendants. Again traversal can be stopped early if a callback returns
FALSE.
The first intended use for _clutter_actor_traverse is to maintain a
cache pointer to the stage for all actors. In this case we will need to
update the pointer for all descendants of an actor when an actor is
reparented in any way.
This adds a private getter to query the number of children an actor has.
One use planned for this API is to avoid calling get_paint_volume on
such actors. (It's not clear what the best semantics for
get_paint_volume are for actors with children, so we are considering
leaving the semantics undefined for the initial clutter 1.4 release)
We now explicitly track the list of children each actor has in a private
GList. This gives us a reliable way to know how many children an actor
has - even for composite actors that don't implement the container
interface. This also will allow us to directly traverse the scenegraph
in a more generalized fashion. Previously the scenegraph was
more-or-less represented implicitly according the implementation of
paint methods.
When using the CLUTTER_PAINT=paint-volumes debug option we try and show
when a paint volume couldn't be determined by drawing a blue outline of
the allocation instead. There was a typo though and instead we were
drawing an outline the size of the stage instead of for the given actor.
This fixes that and removes a FIXME comment relating to the blue outline
that is now implemented.
To allow Clutter to queue clipped redraws when a clone actor changes we
need to be able to report a paint volume for clone actors. This patch
makes ClutterClones query the paint volume of their source actor and
masquerade it as their own volume.
This reverts commit ca44c6a7d8abe9f2c548bee817559ea8adaa7a80.
In reality there are probably lots of actors that depend on the exact
semantics as they are documented so this change isn't really acceptable.
For example when the font changes in ClutterText we only queue a
relayout, and since it's possible that the font will have the same size
and the actor won't get a new allocation it wouldn't otherwise queue a
redraw.
Since queue_redraw requests now get deferred until just before a paint
run it is actually no longer a problem to queue the redraw here.
Instead of immediately, recursively emitting the "queue-redraw" signal
when clutter_actor_queue_redraw is called we now defer this process
until all stage updates are complete. This allows us to aggregate
repeated _queue_redraw requests for the same actor avoiding redundant
paint volume transformations. By deferring we also increase the
likelihood that the actor will have a valid paint volume since it will
have an up to date allocation; this in turn means we will more often be
able to automatically queue clipped redraws which can have a big impact
on performance.
Here's an outline of the actor queue redraw mechanism:
The process starts in clutter_actor_queue_redraw or
_clutter_actor_queue_redraw_with_clip.
These functions queue an entry in a list associated with the stage which
is a list of actors that queued a redraw while updating the timelines,
performing layouting and processing other mainloop sources before the
next paint starts.
We aim to minimize the processing done at this point because there is a
good chance other events will happen while updating the scenegraph that
would invalidate any expensive work we might otherwise try to do here.
For example we don't try and resolve the screen space bounding box of an
actor at this stage so as to minimize how much of the screen redraw
because it's possible something else will happen which will force a full
redraw anyway.
When all updates are complete and we come to paint the stage (see
_clutter_stage_do_update) then we iterate this list and actually emit
the "queue-redraw" signals for each of the listed actors which will
bubble up to the stage for each actor and at that point we will
transform the actors paint volume into screen coordinates to determine
the clip region for what needs to be redrawn in the next paint.
Note: actors are allowed to queue a redraw in reseponse to a
queue-redraw signal so we repeat the processing of the list until it
remains empty. An example of when this happens is for Clone actors or
clutter_texture_new_from_actor actors which need to queue a redraw if
their source queues a redraw.
For Clone actors we will need a way to report the volume of the source
actor as the volume of the clone actor. To make this work though we need
to be able to replace the reference to the source actor with a reference
to the clone actor instead. This adds a private
_clutter_paint_volume_set_reference_actor function to do that.
This adds a way to initialize a paint volume from another source paint
volume. This lets us for instance pass the contents of one paint volume
back through the out param of a get_paint_volume implementation.
This makes clutter_actor_queue_redraw simply bail out early if the actor
isn't a descendant of a ClutterStage since the request isn't meaningful
and it avoids a crash when trying to queue a clipped redraw against the
stage to clear the actors old location.
This splits out all the clutter_paint_volume code from clutter-actor.c
into clutter-paint-volume.c. Since clutter-actor.c and
clutter-paint-volume.c both needed the functionality of
_fully_transform_vertices, this function has now been moved to
clutter-utils.c as _clutter_util_fully_transform_vertices.
There are too many examples where the default assumption that an actor
paints inside its allocation isn't true, so we now return FALSE in the
base implementation instead. This means that by default we are saying
"we don't know the paint volume of the actor", so developers need to
implement the get_paint_volume virtual to take advantage of culling and
clipped redraws with their actors.
This patch provides very conservative get_paint_volume implementations
for ClutterTexture, ClutterCairoTexture, ClutterRectangle and
ClutterText which all explicitly check the actor's object type to avoid
making any assumptions about subclasses.
We were always explicitly checking priv->needs_allocation in
_clutter_actor_queue_redraw_with_clip, but we only need to do that if
the CLUTTER_REDRAW_CLIPPED_TO_ALLOCATION flag is used.
This initializes priv->last_paint_box with a degenerate box, so a newly
allocated actor added to the scenegraph and made visible only needs to
trigger a redraw of its initial position. If we don't have a valid
last_paint_box though we would instead trigger a full stage redraw.
To make comparing the performance with culling/clipped redraws
enabled/disabled fairer we now avoid querying the paint box when they
are disabled, so that results should reflect how the cost of
transforming paint volumes into screen space etc gets offset against the
benefit of culling.
In clutter_stage_allocate at the end we were always querying the latest
allocation set and using the geometry to assert the viewport and then
kicking a full redraw. These only need to be done when the allocation
really changes, so we now read the previous allocation at the start of
the function and compare at the end. This was stopping clipped redraws
from being used in a lot of cases.
To consider that we've see a number of drivers that can struggle to get
going and may produce a bad first frame we now force the first 2 frames
to be full redraws. This became a serious issue after we started using
clipped redraws more aggressively because we assumed that after the
first frame the full framebuffer was valid and we only redraw the
content that changes. With buggy drivers though, applications would be
left with junk covering a lot of the stage until some event triggered a
full redraw.
This is a workaround for a race condition when resizing windows while
there are in-flight glXCopySubBuffer blits happening.
The problem stems from the fact that rectangles for the blits are
described relative to the bottom left of the window and because we can't
guarantee control over the X window gravity used when resizing so the
gravity is typically NorthWest not SouthWest.
This means if you grow a window vertically the server will make sure to
place the old contents of the window at the top-left/north-west of your
new larger window, but that may happen asynchronous to GLX preparing to
do a blit specified relative to the bottom-left/south-west of the window
(based on the old smaller window geometry).
When the GLX issued blit finally happens relative to the new bottom of
your window, the destination will have shifted relative to the top-left
where all the pixels you care about are so it will result in a nasty
artefact making resizing look very ugly!
We can't currently fix this completely, in-part because the window
manager tends to trample any gravity we might set. This workaround
instead simply disables blits for a while if we are notified of any
resizes happening so if the user is resizing a window via the window
manager then they may see an artefact for one frame but then we will
fallback to redrawing the full stage until the cooling off period is
over.
Instead of triggering a full stage redraw for Expose events we use the
geometry of the exposed region given in the event to queue a clipped
redraw of the stage.
Clutter has now taken responsibility for managing its viewport,
projection matrix and view transform as part of ClutterStage so
_cogl_setup_viewport is no longer used by anything, and since it's quite
an obscure API anyway it's we've taken the opportunity to remove the
function.
Since clutter_actor_queue_redraw now automatically clips redraws
according to the paint volume of the actor we have to be careful to
ensure we really force a full redraw when the stage is allocated a new
size or the stage viewport changes.
We have bent the originally documented semantics a bit so now where we
say "Queueing a new layout automatically queues a redraw as well" it
might be clearer to say "Queuing a new layout implicitly queues a redraw
as well if anything in the layout changes".
This should be close enough to the original semantics to not cause any
problems.
Without this change then we we fail to take advantage of clipped redraws
in a lot of cases because queuing a redraw with priv->needs_allocation
== TRUE will automatically be promoted to a full stage redraw since it's
not possible to determine a valid paint-volume.
Also queuing a redraw here will end up registering a redundant clipped
redraw for the current location, doing quite a lot of redundant
transforms, and then later when re-allocated during layouting another
queue redraw would happen with the correct paint-volume.
This uses actor paint volumes to perform culling during
clutter_actor_paint.
When performing a clipped redraw (because only a few localized actors
changed) then as we traverse the scenegraph painting the actors we can
now ignore actors that don't intersect the clip region. Early testing
shows this can have a big performance benefit; e.g. 100% fps improvement
for test-state with culling enabled and we hope that there are even much
more compelling examples than that in the real world,
Most Clutter applications are 2Dish interfaces and have quite a lot of
actors that get continuously painted when anything is animated. The
dynamic actors are often localized to an area of user focus though so
with culling we can completely avoid painting any of the static actors
outside the current clip region.
Obviously the cost of culling has to be offset against the cost of
painting to determine if it's a win, but our (limited) testing suggests
it should be a win for most applications.
Note: we hope we will be able to also bring another performance bump
from culling with another iteration - hopefully in the 1.6 cycle - to
avoid doing the culling in screen space and instead do it in the stage's
model space. This will hopefully let us minimize the cost of
transforming the actor volumes for culling.
This makes clutter_actor_queue_redraw transparently use an actor's paint
volume to queue a clipped redraw.
We save the actors paint box each time it is painted so that when
clutter_actor_queue_redraw is called we can determine the old and new
location of the actor so we know the full bounds of what must be redrawn
to clear its old view and show the new.
This makes _clutter_actor_transform_and_project_box a static function
and removes the prototype from clutter-private.h since it is no longer
used outside clutter-actor.c
The base implementation for the actor queue_relayout method was queuing
an implicit redraw, but there shouldn't be anything implied from the
mere process of queuing a redraw that should force us to queue a redraw.
If actors are moved as a part of relayouting later then they will queue
a redraw. Also clutter_actor_queue_relayout() still also explicitly
queues a redraw so I think this may have been doubly redundant.
If clutter_actor_allocate finds it necessary to update an actors
allocation then it now also queue a redraw of that actor. Currently we
queue redraws for actors very early on when queuing a relayout instead
of waiting to determine the final outcome of relayouting to determine if
a redraw is really required. With this in place we can move away from
preemptive queuing of redraws.
clutter_actor_queue_relayout currently queues a relayout and a redraw,
but the plan is to change it to only queue a relayout and honour the
documentation by assuming that the process of relayouting will
result queuing redraws for any actors whos allocation changes.
This doesn't make that change it just adds an internal
_clutter_actor_queue_only_relayout function which
clutter_actor_queue_relayout now uses as well as calling
clutter_actor_queue_redraw.
This adds a private ->relayout_pending boolean similar in spirit to
redraw_pending. This will allow us to queue a relayout without
implicitly queueing a redraw; instead we can depend on the actions
of a relayout to queue any necessary redraw.
When clutter_texture_new_from_actor is use we need to track when the
source actor queues a redraw or a relayout so we can also queue a redraw
or relayout for the texture actor.
There is an internal _clutter_actor_queue_redraw_with_clip API that gets
used for texture-from-pixmap to minimize what we redraw in response to
Damage events. It was previously working in terms of a ClutterActorBox
but it has now been changed so an actor can queue a redraw of volume
instead.
The plan is that clutter_actor_queue_redraw will start to transparently
use _clutter_actor_queue_redraw_with_clip when it can determine a paint
volume for the actor.
For the blur effect we use a BLUR_PADDING constant to pad out the volume
of the source actor on the x and y axis. Previously we were offsetting
the origin negatively using BLUR_PADDING and then adding BLUR_PADDING
to the width and height, but we should have been adding 2*BLUR_PADDING
instead.
This ensures that clipped redraws are disabled when using
CLUTTER_PAINT=redraws. This may seem unintuitive given that this option
is for debugging clipped redraws, but we can't draw an outline outside
the clip region and anything we draw inside the clip region is liable to
leave a trailing mess on the screen since it won't be cleared up by
later clipped redraws.
This adds a debug option to visualize the paint volumes of all actors.
When CLUTTER_PAINT=paint-volumes is exported in the environment before
running a Clutter application then all actors will have their bounding
volume drawn in green with a label corresponding to the actors type.
This is a fairly extensive second pass at exposing paint volumes for
actors.
The API has changed to allow clutter_actor_get_paint_volume to fail
since there are times - such as when an actor isn't a descendent of the
stage - when the volume can't be determined. Another example is when
something has connected to the "paint" signal of the actor and we simply
have no way of knowing what might be drawn in that handler.
The API has also be changed to return a const ClutterPaintVolume pointer
(transfer none) so we can avoid having to dynamically allocate the
volumes in the most common/performance critical code paths. Profiling was
showing the slice allocation of volumes taking about 1% of an apps time,
for some fairly basic tests. Most volumes can now simply be allocated on
the stack; for clutter_actor_get_paint_volume we return a pointer to
&priv->paint_volume and if we need a more dynamic allocation there is
now a _clutter_stage_paint_volume_stack_allocate() mechanism which lets
us allocate data which expires at the start of the next frame.
The API has been extended to make it easier to implement
get_paint_volume for containers by using
clutter_actor_get_transformed_paint_volume and
clutter_paint_volume_union. The first allows you to query the paint
volume of a child but transformed into parent actor coordinates. The
second lets you combine volumes together so you can union all the
volumes for a container's children and report that as the container's
own volume.
The representation of paint volumes has been updated to consider that
2D actors are the most common.
The effect apis, clutter-texture and clutter-group have been update
accordingly.
Previously we used the transformed allocation but that doesn't take
into account actors with depth which may be projected outside the
area covered by the transformed allocation.
The blur effect will sample pixels on the edges of the offscreen buffer,
so we want to add a padding to avoid clamping the blur.
We do this by creating a larger target texture, and updating the paint
volume of the actor during paint to take that padding into account.
We should be using the real, on-screen, transformed size of the actor to
size and position the offscreen buffer we use to paint the actor for an
effect.
An Effect implementation might override the paint volume of the actor to
which it is applied to. The get_paint_volume() virtual function should
be added to the Effect class vtable so that any effect can get the
current paint volume and update it.
The clutter_actor_get_paint_volume() function becomes context aware, and
does the right thing if called from within a ClutterEffect pre_paint()
or post_paint() implementation, by allowing all effects in the chain up
to the caller to modify the paint volume.
