Commit Graph

239 Commits

Author SHA1 Message Date
Adel Gadllah
3d8445807a backend-glx: Remove redundant glFlush()
As noted in commit ce3f55292a an explict glFlush is needed for
both glBlitFramebuffer and glXCopySubBuffer.

_clutter_backend_glx_blit_sub_buffer was already doing an explicit
flush when using glBlitFramebuffer, so just do it unconditonally
and remove the call from clutter_stage_glx_redraw.

http://bugzilla.clutter-project.org/show_bug.cgi?id=2558
2011-02-14 12:55:49 +00:00
Emmanuele Bassi
3a378b849b stage/glx: Code clean ups 2011-02-14 12:00:31 +00:00
Robert Bragg
ce3f55292a glx: Make sure to glFlush if blitting to frontbuffer.
Unlike glXSwapBuffers, glXCopySubBuffer and glBlitFramebuffer don't
issue an implicit glFlush() so we have to flush ourselves if we want the
request to complete in finite amount of time since otherwise the driver
can batch the command indefinitely.

http://bugzilla.clutter-project.org/show_bug.cgi?id=2551
2011-02-09 19:12:20 +00:00
Emmanuele Bassi
56d133f908 backend: Move event translators to the base class
In the future, we want event translators to be the way to handle events
in backends. For this reason, they should be a part of the base abstract
ClutterBackend class, and not an X11-only concept.
2011-02-09 13:29:30 +00:00
Emmanuele Bassi
224280be22 backend: Invoke ClutterStageWindow::redraw by default
Instead of asking all backends to do that for us, we can call
ClutterStageWindow::redraw ourselves by default.

This changeset fixes all backends to actually do the right thing, and
move the stage implementation redraw inside the ClutterStageWindow
implementation itself.
2011-02-09 13:29:30 +00:00
Emmanuele Bassi
9be4cfe8a9 x11/stage: Use a global Window ↔ Stage relationship
Since we need to find the stage from the X11 Window, it's better to use
a static hashmap that gets updated every time the ClutterStageX11:xwin
member is changed, instead of iterating over every stage handled by the
global ClutterStageManager singleton.
2011-01-28 18:19:49 +00:00
Emmanuele Bassi
acf51259d2 x11: Store a back pointer to the backend in the stage
Since we access it in order to get the X11 Display pointer, it makes
sense to have the ClutterBackendX11 already available inside the
ClutterStageX11 structure, and avoid the pattern:

  ClutterBackend *backend = clutter_get_default_backend ();
  ClutterBackendX11 *backend_x11 = CLUTTER_BACKEND_X11 (backend);

which costs us a function call, a type cast and an unused variable.
2011-01-28 18:19:08 +00:00
Emmanuele Bassi
86c786aaad Merge branch 'xi2'
* xi2: (41 commits)
  test-devices: Actually print the axis data
  device-manager/xi2: Sync the stage of source devices
  event: Clean up clutter_event_copy()
  device: unset the axes array pointer when resetting
  device-manager/xi2: Fix device hotplugging
  glx: Clean up GLX implementation
  device/x11: Store min/max keycode in the XI device class
  x11: Hide all private symbols
  docs: More documentation fixes for InputDevice
  */event: Never manipulate the event queue directly
  win32: Update DeviceManager device creation
  device: Allow enabling/disabling non-master devices
  backend/eglx: Add newly created stages to the translators
  device: Add more doc annotations
  device: Use a double for translate_axis() argument
  test-devices: Clean up and show axes data
  event: Fix up clutter_event_copy()
  device/xi2: Translate the axis data after setting devices
  device: Add more accessors for properties
  docs: Update API reference
  ...
2011-01-21 20:22:32 +00:00
Robert Bragg
142b229c5c cogl: Adds _cogl_swap_buffers_notify for clutter backends
This adds a stop-gap mechanism for Cogl to know when the window system
is requested to present the current backbuffer to the frontbuffer by
adding a _cogl_swap_buffers_notify function that backends are now
expected to call right after issuing the equivalent request to OpenGL
vie the platforms OpenGL binding layer. This (blindly) updates all the
backends to call this new function.

For now Cogl doesn't do anything with the notification but the intention
is to use it as part of a planned read-pixel optimization which will
need to reset some state at the start of each new frame.
2011-01-21 16:18:10 +00:00
Emmanuele Bassi
7514f5fe92 glx: Clean up GLX implementation
Like commit a277b4091a, but targeted at
the GLX backend.
2011-01-21 10:49:12 +00:00
Emmanuele Bassi
a277b4091a x11: Hide all private symbols
The x11 backend exposes a lot of symbols that are meant to only be used
when implementing a subclassed backend, like the glx and eglx ones.

The uninstalled headers are also filled with cruft declarations of
functions long since removed.

Let's try to clean up this mess.
2011-01-21 10:25:46 +00:00
Emmanuele Bassi
de93f721c1 Clean up the copyright and licensing blurbs 2011-01-21 10:25:43 +00:00
Emmanuele Bassi
1b1e77b469 event/x11: Rework the way we translate X11 events
This is a lump commit that is fairly difficult to break down without
either breaking bisecting or breaking the test cases.

The new design for handling X11 event translation works this way:

  - ClutterBackend::translate_event() has been added as the central
    point used by a ClutterBackend implementation to translate a
    native event into a ClutterEvent;

  - ClutterEventTranslator is a private interface that should be
    implemented by backend-specific objects, like stage
    implementations and ClutterDeviceManager sub-classes, and
    allows dealing with class-specific event translation;

  - ClutterStageX11 implements EventTranslator, and deals with the
    stage-relative X11 events coming from the X11 event source;

  - ClutterStageGLX overrides EventTranslator, in order to
    deal with the INTEL_GLX_swap_event extension, and it chains up
    to the X11 default implementation;

  - ClutterDeviceManagerX11 has been split into two separate classes,
    one that deals with core and (optionally) XI1 events, and the
    other that deals with XI2 events; the selection is done at run-time,
    since the core+XI1 and XI2 mechanisms are mutually exclusive.

All the other backends we officially support still use their own
custom event source and translation function, but the end goal is to
migrate them to the translate_event() virtual function, and have the
event source be a shared part of Clutter core.
2011-01-21 10:25:43 +00:00
Emmanuele Bassi
cd96e631f1 glx: Deprecate ClutterGLXTexturePixmap
Since 1.4 the ClutterGLXTexturePixmap is just a wrapper around
ClutterX11TexturePixmap, so we can safely deprecate it. All the
functionality it provided is now effectively available from the
superclass or directly from Cogl.
2011-01-20 13:21:50 +00:00
Robert Bragg
5f181f7265 stage-window: tweak has_redraw_clips semantics
This tweaks the semantics of the has_redraw_clips vfunc so we can assume
that at the start of a new frame there is an implied, initial,
redraw_clip that clips everything (i.e. nothing would be redrawn) so in
that case we would expect the has_redraw_clips vfunc to return True at
the start of a new frame for backends that support clipping.

Previously there was an ambiguity when this function returned False
since it could either mean a full screen redraw had been queued or it
could mean that the clip state wasn't yet initialized for that frame.
This would result in _clutter_stage_has_full_redraw_queued() returning
True at the start of a new frame even before any actors have been
updated, which in turn meant we would incorrectly ignore queue_redraw
requests for actors, believing them to be redundant.
2010-11-24 15:09:47 +00:00
Emmanuele Bassi
46c597a1f6 Clean up clutter-private.h/6
Move all Actor private API to a separate file.
2010-10-21 12:22:17 +01:00
Emmanuele Bassi
8613013ab0 Clean up clutter-private.h/3
Move Stage private API to a separate header.
2010-10-21 11:33:26 +01:00
Emmanuele Bassi
e36cc40a49 Merge branch 'wip/non-recursive'
* wip/non-recursive:
  build: Start moving to a non-recursive layout
2010-09-29 15:55:58 +01:00
Robert Bragg
1e7f22db3b glx: queue full redraws for the first 2 frames
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.
2010-09-29 15:12:59 +01:00
Robert Bragg
771348b369 x11: minimize nasty artefacts when resizing windows
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.
2010-09-29 15:12:59 +01:00
Robert Bragg
b499696d83 Use paint volumes to do automatic culling
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.
2010-09-29 15:12:58 +01:00
Robert Bragg
f60703cb1d debug: CLUTTER_DEBUG_REDRAWS: disable clipped redraws
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.
2010-09-29 15:12:57 +01:00
Robert Bragg
3540d222e1 paint volumes: another pass at the design
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.
2010-09-29 15:12:57 +01:00
Emmanuele Bassi
8dd8fbdbdf build: Start moving to a non-recursive layout
*** WARNING: THIS COMMIT CHANGES THE BUILD ***

Do not recurse into the backend directories to build private, internal
libraries.

We only recurse from clutter/ into the cogl sub-directory; from there,
we don't recurse any further. All the backend-specific code in Cogl and
Clutter is compiled conditionally depending on the macros defined by the
configure script.

We still recurse from the top-level directory into doc, clutter and
tests, because gtk-doc and tests do not deal nicely with non-recursive
layouts.

This change makes Clutter compile slightly faster, and cleans up the
build system, especially when dealing with introspection data.

Ideally, we also want to make Cogl part of the top-level build, so that
we can finally drop the sed trick to change the shared library from the
GIR before compiling it.

Currently disabled:

  ‣ OSX backend
  ‣ Fruity backend

Currently enabled but untested:

  ‣ EGL backend
  ‣ Windows backend
2010-09-29 14:40:15 +01:00
Robert Bragg
ad398d583b glx: Mark stage clip initialized even for NULL user clip
If a NULL clip is passed to clutter_stage_glx_add_redraw_clip then we
update the redraw clip to have width of 0, but we weren't setting
stage_glx->initialized_redraw_clip = TRUE. This could result in a full,
unclipped stage redraw being reduced to a clipped redraw.
2010-09-13 18:18:35 +01:00
Alexandros Frantzis
12e58c7813 Hide internal glx and egl(x) backend symbols.
The glx and egl(x) backends export some internal symbols. Hide these
symbols (using '_' prefix) to reduce ABI differentiation between the
glx and eglx flavours.

http://bugzilla.clutter-project.org/show_bug.cgi?id=2267

Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
2010-08-23 11:49:07 +01:00
Emmanuele Bassi
1943b8e544 glx: Depend on libdrm
DRM is available on more platforms than Linux (e.g. kFreeBSD), but
Clutter currently FTBFS there because of not being an alternative to
the __linux__ code (where it should be HAVE_DRM).

Instead of copying the DRM data structures, we should use libdrm when
falling back to directly requesting to wait for the vblank.

http://bugzilla.clutter-project.org/show_bug.cgi?id=2225

Based on a patch by: Emilio Pozuelo Monfort <pochu27@gmail.com>
Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
2010-08-09 11:29:03 +01:00
Emmanuele Bassi
24d1142ecf glx: Add more debugging notes
Should help debug the GLX visual selection.
2010-08-03 17:53:58 +01:00
Emmanuele Bassi
609560b1cb glx: Unconditionally select X11/GLX events
Currently, we select input events and GLX events conditionally,
depending on whether the user has disabled event retrieval.

We should, instead, unconditionally select input events even with event
retrieval disabled because we need to guarantee that the Clutter
internal state is maintained when calling clutter_x11_handle_event()
without requiring applications or embedding toolkits to select events
themselves. If we did that, we'd have to document the events to be
selected, and also update applications and embedding toolkits each time
we added a new mask, or a new class of events - something that's clearly
not possible.

See:

  http://bugzilla.clutter-project.org/show_bug.cgi?id=998

for the rationale of why we did conditional selection. It is now clear
that a compositor should clear out the input region, since it cannot
assume a perfectly clean slate coming from us.

See:

  http://bugzilla.clutter-project.org/show_bug.cgi?id=2228

for an example of things that break if we do conditional event
selection on GLX events. In that specific case, the X11 server ≤ 1.8
always pushed GLX events on the queue, even without selecting them; this
has been fixed in the X11 server ≥ 1.9, which means that applications
like Mutter or toolkit integration libraries like Clutter-GTK would stop
working on recent Intel drivers providing the GLX_INTEL_swap_event
extension.

This change has been tested with Mutter and Clutter-GTK.
2010-08-03 16:11:52 +01:00
Emmanuele Bassi
eae4561929 Clean up the private flags for ClutterActor
Provide macros to quickly query a flag, and remove all namespacing
except the initial 'CLUTTER'.
2010-07-21 16:10:46 +01:00
Nate Stedman
fff5558ad2 Fixes build with GLX on Mac OS X.
Moves preprocessor #ifdef __linux_ above else statement, avoiding the
lack of an else block if __linux__ is not defined.

http://bugzilla.clutter-project.org/show_bug.cgi?id=2212

Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
2010-07-15 00:31:23 +01:00
Neil Roberts
5d860a9978 clutter-{glx,x11}-texture-pixmap: Use CoglTexturePixmapX11
The pixmap handling of both of the texture pixmap actors in Clutter is
now removed and instead it just creates a CoglTexturePixmapX11. Both
actors are now equivalent so there is no need to choose between the
two.
2010-06-22 12:22:48 +01:00
Neil Roberts
6ca13e54d8 Add -DCOGL_ENABLE_EXPERIMENTAL_API to Makefiles for Cogl and x11/glx
Cogl and Clutter should be able to use the experimental API so this
adds the required define to the CPPFLAGS in the Makefiles.
2010-06-22 12:22:47 +01:00
Robert Bragg
56315d92bd stage-glx: Never promote clipped redraws to full redraws.
When clipped redraws were first supported in Clutter a heuristic was
added to promote tall clipped redraws into full redraws due to a concern
that using glXCopySubBuffer for tall rectangles would block the GPU for
too long waiting for the vtrace to be in a suitable position so that
tearing isn't seen. We've so far been unable to measure any impact from
this blocking even with full height windows so we are removing the
arbitrary threshold of 300px that was originally "plucked out of thin
air".

http://bugzilla.o-hand.com/show_bug.cgi?id=2136
2010-06-16 01:04:35 +01:00
Robert Bragg
b1f7d2fea8 material: Avoid redundant glBindTexture calls
This adds a _cogl_bind_gl_texture_transient function that should be used
instead of glBindTexture so we can have a consistent cache of the
textures bound to each texture unit so we can avoid some redundant
binding.
2010-06-09 17:26:15 +01:00
Robert Bragg
30296a3307 backend-glx: Avoid vblank waits/glFinish calls when throttling blits
If we have the GLX_SGI_video_sync extension then it's possible to always
keep track for the video sync counter each time we call glXSwapBuffers
or do a sub stage blit. This then allows us to avoid waiting before
issuing a blit if we can see that the counter has already progressed.

Also since we expect that glXCopySubBuffer is synchronized to the vblank
we don't need to use glFinish () in conjunction with the vblank wait
since the vblank wait's only purpose is to add a delay.
2010-06-09 02:11:17 +01:00
Robert Bragg
1b31ac465d backend-glx: only check for GLX_SGI_video_sync for direct contexts
The GLX_SGI_video_sync spec explicitly says that it's only supported for
direct contexts so we don't setup up the function pointers if
glXIsDirect () returns GL_FALSE.
2010-06-09 02:10:08 +01:00
Robert Bragg
f37de23dec backend-glx: Make sure to throttle sub region blits
Neither glXCopySubBuffer or glBlitFramebuffer are integrated with the
swap interval of a framebuffer so that means when we do partial stage
updates (as Mutter does in response to window damage) then the blits
aren't throttled which means applications that throw lots of damage
events at the compositor can effectively cause Clutter to run flat out
taking up all the system resources issuing more blits than can even be
seen.

This patch now makes sure we use the GLX_SGI_video_sync or a
DRM_VBLANK_RELATIVE ioctl to throttle blits to the vblank frequency as
we do when using glXSwapBuffers.
2010-06-09 02:10:08 +01:00
Adel Gadllah
630a2c5edc backend-glx: Provide copy_sub_buffer fallback
Currently glXCopySubBufferMESA is used for sub stage redraws, but in case
a driver does not support GLX_MESA_copy_sub_buffer we fall back to redrawing
the complete stage which isn't really optimal.

So instead to directly fallback to complete redraws try using GL_EXT_framebuffer_blit
to do the BACK to FRONT buffer copies.

http://bugzilla.openedhand.com/show_bug.cgi?id=2128
2010-06-09 02:10:08 +01:00
Damien Lespiau
ec59af290c analysis: None used in pointer context
While this is totally fine (None is 0L and, in the pointer context, will
be converted in the right internal NULL representation, which could be a
value with some bits to 1), I believe it's clearer to use NULL instead
of None when we talk about pointers.
2010-06-01 12:08:18 +01:00
Owen W. Taylor
d8e1bd989c Ignore unexpected GLX_BufferSwapComplete
A server that supports GLX_BufferSwapComplete will always send
these events, so we should just silently ignore them if we've
chosen not to take advantage of the INTEL_swap_event GLX
extension.

http://bugzilla.openedhand.com/show_bug.cgi?id=2102

Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
2010-05-05 12:00:40 +01:00
Robert Bragg
62ac3b312e glx: handle spurious GLX_BufferSwapComplete events gracefully
Instead of simply aborting we now print out a warning, when a spurious
GLX_BufferSwapComplete event is handled since it seems that people are
coming across the problem (perhaps due to a buggy driver) and making
apps crash in this situation is a bit extreme.
2010-04-19 11:24:42 +01:00
Adel Gadllah
5de85051c3 Make sure GLX_SGI_swap_control is set up correctly
glXSwapIntervalSGI only affects buffer swaps to the
current GLX drawable.

That means that calling it once in clutter_backend_glx_get_features
isn't sufficent, so set it up in clutter_backend_glx_ensure_context to
make sure it affects buffer swaps for the current drawable.

http://bugzilla.openedhand.com/show_bug.cgi?id=2044

Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
2010-03-22 11:23:55 +00:00
Owen W. Taylor
2fc8ecdb92 glx: Clean up the clip area conditions
Move the size check after the NULL check, add the clip height into the
check logic and fix up the comment.

http://bugzilla.openedhand.com/show_bug.cgi?id=2040

Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
2010-03-19 18:23:03 +00:00
Emmanuele Bassi
a39cef41b8 glx: Do not access stage_clip without checking it
The stage_clip parameter for add_redraw_clip() can be NULL, so we need
to check before accessing its members.
2010-03-19 11:41:12 +00:00
Owen W. Taylor
d21b7522f8 Fix errors in keeping track of the stage bounding rectangle
* Add new clutter_geometry_union(), because writing union intersection
  is harder than it looks. Fixes two problems with the inline code in
  clutter_stage_glx_add_redraw_clip().

  1) The ->x and ->y of were reassigned to before using them to
     compute the new width and height.
  2) since ClutterGeometry has unsigned width, x + width is unsigned,
     and comparison goes wrong if either rectangle has a negative
     x + width. (We fixed width for GdkRectangle to be signed for GTK+-2.0,
     this is a potent source of bugs.)

* Use in clutter_stage_glx_add_redraw_clip()

* Account for the case where the incoming rectangle is empty, and don't
  end up with the stage being entirely redrawn.

* Account for the case where the stage already has a degenerate
  width and don't end up with redrawing only the new rectangle and not
  the rest of the stage.

The better fix here for the second two problems is to stop using a 0
width to mean the entire stage, but this should work for now.

http://bugzilla.openedhand.com/show_bug.cgi?id=2040

Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
2010-03-19 10:29:53 +00:00
Emmanuele Bassi
54504b7ac4 glx: Remove unnecessary call to create_stage()
If we are in the stage realization sequence we already have a GLX
context set in the backend; there is no need to call create_backend().
2010-03-17 17:41:52 +00:00
José Dapena Paz
6bd1846d6c Fix argb initialisation.
Fix clutter initialisation if argb visuals are enabled, setting a border
color on creating the dummy window. This should avoid BadMatch happening
when the depth of the root window visual is not the same of the depth
of the argb visual.

http://bugzilla.openedhand.com/show_bug.cgi?id=2011

Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
2010-03-10 00:13:37 +00:00
Robert Bragg
38a2414498 glx tfp: make clutter_glx_texture_pixmap_update_area cheap
This changes clutter_glx_texture_pixmap_update_area so it defers the
call to glXBindTexImageEXT until our pre "paint" signal handler which
makes clutter_glx_texture_pixmap_update_area cheap to call.

The hope is that mutter can switch to reporting raw damage updates to
ClutterGLXTexturePixmap and we can use these to queue clipped redraws.
2010-03-02 17:19:11 +00:00
Robert Bragg
c0d5af5de5 Adds initial clipped redraw support to Clutter
A new (internal only currently) API, _clutter_actor_queue_clipped_redraw
can be used to queue a redraw along with a clip rectangle in actor
coordinates. This clip rectangle propagates up to the stage and clutter
backend which may optionally use the information to optimize stage
redraws. The GLX backend in particular may scissor the next redraw to
the clip rectangle and use GLX_MESA_copy_sub_buffer to present the stage
subregion.

The intention is that any actors that can naturally determine the bounds
of updates should queue clipped redraws to reduce the cost of updating
small regions of the screen.

Notes:
» If GLX_MESA_copy_sub_buffer isn't available then the GLX backend
  ignores any clip rectangles.

» queuing multiple clipped redraws will result in the bounding box of
  each clip rectangle being used.

» If a clipped redraw has a height > 300 pixels then it's promoted into
  a full stage redraw, so that the GPU doesn't end up blocking too long
  waiting for the vsync to reach the optimal position to avoid tearing.

  » Note: no empirical data was used to come up with this threshold so
    we may need to tune this.

» Currently only ClutterX11TexturePixmap makes use of this new API. This
  is done via a new "queue-damage-redraw" signal that is emitted when
  the pixmap is updated. The default handler queues a clipped redraw
  with the assumption that the pixmap is being painted as a rectangle
  covering the actors transformed allocation. If you subclass
  ClutterX11TexturePixmap and change how it's painted you now also
  need to override the signal handler and queue your own redraw.

  Technically this is a semantic break, but it's assumed that no one
  is currently doing this.

This still leaves a few unsolved issues with regards to optimizing sub
stage redraws that need to be addressed in further work so this can only
be considered a stepping stone a this point:

» Because we have no reliable way to determine if the painting of any
  given actor is being modified any optimizations implemented using
  _clutter_actor_queue_redraw_with_clip must be overridable by a
  subclass, and technically must be opt-in for existing classes to avoid
  a change in semantics. E.g. consider that a user connects to the paint
  signal for ClutterTexture and paints a circle instead of a rectangle.
  In this case any original logic to queue clipped redraws would be
  incorrect.

» Currently only the implementation of an actor has enough information
  with which to queue clipped redraws. E.g. It is not possible for
  generic code in clutter-actor.c to queue a clipped redraw when hiding
  an actor because actors have no way to report a "paint box". (remember
  actors can draw outside their allocation and actors with depth may
  also be projected outside of their allocation)

  » The current plan is to add a actor_class->get_paint_cuboid()
    virtual so actors can report a bounding cube for everything they
    would draw in their current state and use that to queue clipped
    redraws against the stage by projecting the paint cube into stage
    coordinates.

» Our heuristics for promoting clipped redraws into full redraws to
  avoid blocking the GPU while we wait for the vsync need improving:

  » vsync issues aren't relevant for redirected/composited applications
    so they should use different heuristics. In this case we instead
    need to trade off the cost of blitting when using glXCopySubBuffer
    vs promoting to a full redraw and flipping instead.
2010-03-02 17:19:11 +00:00