Previously ClutterText was just reporting the allocation as the paint
volume. The preferred size of a ClutterText is just the logical
rectangle of the layout. A pango layout can sometimes draw outside of
its logical rectangle for example with an italicised font with large
serifs. Additionally, ClutterText doesn't make any attempt to clip the
text if the actor gets allocated a size too small for the text so it
would also end up drawing outside of the paint volume in that case. To
fix this, the paint volume is now reported as the ink rect of the
Pango layout. The rectangle for the cursor and selection is also
unioned into that because it won't necessarily be within the ink
rectangle.
The function for drawing the selection rectangles has been split up
into a generic function that calculates the rectangles that need to be
drawn and a function that draws them. That way the get_paint_volume
virtual can share the code to calculate the rectangles.
http://bugzilla.clutter-project.org/show_bug.cgi?id=2599
When the cursor is at the leftmost position in the text the drawn
pixel position is moved to the left by the size of the cursor. There's
no explanation for why this happens and it doesn't seem to make any
sense so this patch removes it. It makes multi-line texts looks odd
because the cursor ends up at a different horizontal position when it
is on the first line from any other line. It also makes using
priv->cursor_pos difficult in any other part of the code because the
paint function modifies it.
The original patch that added this can be traced back to Tidy commit
c356487c15. There's no explanation in the commit message either.
http://bugzilla.clutter-project.org/show_bug.cgi?id=2599
A long press is a special form of click action; the default
implementation uses a single signal with multiple states: query, action
and cancel. On click we use the "query" state to check whether the
ClutterClickAction supports long presses; if the callback returns TRUE
then we install a timeout and we either emit the "activate" state when
the timeout expires or we emit the "cancel" state if the pointer leaves
the actor, or if the pointer moves outside a certain threshold. If the
long press reached the "activate" state then we skip the clicked signal
emission.
A property to control the minimum time that has to elapse before a press
is recognized as a long press. This will be used by ClutterClickAction,
but it can be shared across touch-based gestures.
The G_CONST_RETURN define in GLib is, and has always been, a bit fuzzy.
We always used it to conform to the platform, at least for public-facing
API.
At first I assumed it has something to do with brain-damaged compilers
or with weird platforms where const was not really supported; sadly,
it's something much, much worse: it's a define that can be toggled at
compile-time to remove const from the signature of public API. This is a
truly terrifying feature that I assume was added in the past century,
and whose inception clearly had something to do with massive doses of
absynthe and opium — because any other explanation would make the
existence of such a feature even worse than assuming drugs had anything
to do with it.
Anyway, and pleasing the gods, this dubious feature is being
removed/deprecated in GLib; see bug:
https://bugzilla.gnome.org/show_bug.cgi?id=644611
Before deprecation, though, we should just remove its usage from the
whole API. We should especially remove its usage from Cally's internals,
since there it never made sense in the first place.
If an actor or the stage to which it belongs are being destroyed then
there is no point in queueing a redraw that will not be seen anyway.
Bailing out early also avoids the case in which a redraw is queued
during destruction wil cause redraw entries will be added to the Stage,
which will take references on it and cause the Stage never to be
finalized.
http://bugzilla.clutter-project.org/show_bug.cgi?id=2652
With the instantiatable ClutterShaderEffect, the only reason for
ClutterShader to exist is to make the ClutterActor::paint implementation
miserable.
Yes, ClutterShader doesn't use a FBO, so it's "more efficient" on
ClutterTextures. It's also generally wrong unless you know *exactly* how
the actor's pipeline is set up — something we cannot even guarantee
internally unless we start doing lame type checks.
ClutterShaderEffect doesn't require to be sub-classed in order to be
useful. It is possible to just create an instance, set the source and
the uniforms, and attach it to an actor. This should effectively replace
ClutterShader for good.
We were mistakenly using the constant 4 to determine the number of
vertices that need to be culled for a paint-volume to be considered
fully culled too. This is only ok for 2d volumes and was resulting in
some 3d volumes being considered culled whenever 4 out of 8 vertices
were culled. This fix is simply to reference the vertex_count variable
instead of assuming 4.
_clutter_stage_do_pick called by interactive picking and
clutter_stage_get_actor_at_pos could be accidentally reading back the wrong
actor id's if an other stage has had a more recent render due to animation.
This should resolve some multi stage / ClutterGtk related pick id warnings.
Commit 13ac1fe7 purported to extend the _clutter_id_pool_lookup()
warning to the case where the id referred to a deleted actor, but did
not actually do so, because _clutter_id_pool_remove() set deleted IDs
to 0xdecafbad, not NULL. Fix this.
https://bugzilla.gnome.org/show_bug.cgi?id=650597
Those were added on the old "just for automatic testing" times. That was
somewhat silly on that moment. Now is just silly (ie: having the stage
returning as default name "Stage").
The real description should be set by the app, or provided by the
context of a specific actor feature (like the tooltip on StWidget).
The current information provided by the default description can be
mostly obtained from the ATK_ROLE, and the indirect debugging
advantage of having always a meaningful description is just not enough
to justify them, and you can solve that by proper debug logging.
Fixes: http://bugzilla.clutter-project.org/show_bug.cgi?id=2482
In Cogl, cogl-pango.h has moved to <cogl-pango/cogl-pango.h>. When
using the experimental 2.0 API (which Clutter does) it is no longer
possible to include it under the old name of <cogl/cogl-pango.h> so we
need to update the include location.
In _clutter_actor_queue_redraw_with_clip, there was the possibility that
the actor will add itself to the stage's redraw queue without keeping track
of the allocated list member.
In clutter_actor_unparent, the redraw queue entry was being invalidated
before the mapped notify signal was being fired, meaning that queueing a
redraw of an unmapped actor in the mapped notification callback could
cause a crash.
http://bugzilla.clutter-project.org/show_bug.cgi?id=2621
Since ClutterText has overlapping primitives when selecting, or a
visible cursor, then we need to report that to Clutter, to avoid
bleeding colors through when a Text actor is non-fully opaque.
_clutter_stage_queue_actor_redraw returns a pointer to the
ClutterStageQueueRedrawEntry struct which it allocates. The actor is
expected to store a pointer to this so that it doesn't need to search
the list of queued redraws next time a queue redraw is called. However
_clutter_actor_queue_redraw_full wasn't storing this pointer which
meant that it thought every queue redraw was the first queue
redraw. That meant that queueing a redraw with a clip or an effect
would override any previous attempts to queue a redraw instead of
trying to combine them.
I think this happened because the old queue_redraw_with_clip also
didn't store the pointer and queue_redraw_full was based on that.
This adds a virtual to ClutterActor so that an actor subclass can
report whether it has overlapping primitives. ClutterActor uses this
to determine whether it needs to use ClutterFlattenEffect to implement
the opacity property. The default implementation of the virtual
returns TRUE which means that most actors will end up being redirected
offscreen when the opacity != 255. ClutterTexture and ClutterRectangle
override this to return FALSE because they should never need to be
redirected. ClutterClone overrides it to divert to the source.
The values for the ClutterOffscreenRedirect enum have changed to:
AUTOMATIC_FOR_OPACITY
The actor will only be redirected if has_overlaps returns TRUE and
the opacity is < 255
ALWAYS_FOR_OPACITY
The actor will always be redirected if the opacity < 255 regardless
of the return value of has_overlaps
ALWAYS
The actor will always be redirected offscreen.
This means that the property can't be used to prevent the actor from
being redirected but only to increase the likelihood that it will be
redirected.
ClutterActor now adds and removes the flatten effect depending on
whether flattening is needed directly in clutter_actor_paint(). There
are new internal versions of add/remove_effect that don't queue a
redraw. This means that ClutterFlattenEffect is now just a no-op
subclass of ClutterOffscreen. It is only needed because
ClutterOffscreen is abstract. Removing the effect also makes it so
that the cached image will be freed as soon as an actor is repainted
without being flattened.
This adds a property which can be used to redirect the actor through
an FBO before painting so that it becomes flattened in an image. The
image can be used as a cache to avoid having to repaint the actor if
something unrelated in the scene changes. It can also be used to
implement correct opacity even if the actor has overlapping
primitives. The property is an enum that takes three values:
CLUTTER_OFFSCREEN_REDIRECT_NEVER: The default behaviour which is to
never flatten the actor.
CLUTTER_OFFSCREEN_REDIRECT_ALWAYS: The actor is always redirected
through an FBO.
CLUTTER_OFFSCREEN_REDIRECT_ONLY_FOR_OPACITY: The actor is only
redirected through an FBO if the paint opacity is not 255. This
value would be used if the actor wants correct opacity. It will
avoid the overhead of using an FBO whenever the actor is fully
opaque.
The property is implemented by installing a ClutterFlattenEffect.
ClutterFlattenEffect is a new internal class which subclasses
ClutterOffscreen to redirect the painting to an FBO. When
ClutterOffscreen paints, the effect sets an opacity override on the
actor so that the image will always contain the actor at full
opacity. The opacity is then applied to the resulting image before
painting it to the stage. This means the actor does not need to be
redrawn while the opacity is being animated.
The effect has a high internal priority so that it will always occur
before any other effects and it gets hidden from the application.
When calling clutter_actor_clear_constraints the layout of the actor
may change so we need to queue a relayout. Similarly when the effects
are cleared we need to queue a redraw.
This adds a priority property to all ClutterActorMetas. The
ClutterMetaGroup keeps the list sorted so that higher priority metas
remain at the beginning of the list. The priority is a signed integer
with the default as zero. An actor meta can therefore be put before
all default metas with a positive number, or after with a negative
number.
There are constants to set an 'internal' priority. The intention is
that applications wouldn't be allowed to use these values so that we
can keep special internal metas to that are before or after all
application metas.
The property isn't a real GObject property because for now it is
completely internal and only used to implement the 'transparency'
property of ClutterActor. ClutterMetaGroup doesn't currently resort
the list if the property changes so if we wanted to make it public we
should either make it construct-only or make the meta group listen for
changes on the property and resort accordingly.
The methods in ClutterActor that get the list of metas now use a new
function that filters out internal metas from the meta
group. Similarly for clearing the metas, the internal metas are left
in.
This adds a new public function to queue a rerun of an effect. If
nothing else queues a redraw then when the effect's actor is painted
the effect will be run without the CLUTTER_EFFECT_RUN_ACTOR_DIRTY
flag. This allows parametrised offscreen effects to report that they
need to redraw the image without having to redraw the underlying
actor. This will be used to implement the 'transparency' effect of
ClutterActor.
If multiple redraws are queued with different effects then redrawing
is started from the one that occurs last in the list of effects.
Internally the function is a wrapper around the new function
_clutter_actor_queue_redraw_full. This is intended to be the sole
point of code for queuing redraws on an actor. It has parameters for
the clip and the effect. The other two existing functions to queue a
redraw (one with a clip and one without) now wrap around this function
by passing a NULL effect.
When painting an actor, it now tries to determine if the last paint of
the offscreen was using the same matrix and the actor isn't dirty. If
so, it can skip calling clutter_actor_continue_paint and avoid
actually painting the actor. Instead just the offscreen image will be
painted.
This adds a new virtual to ClutterEffect which is intended to be a
more flexible replacement for the pre and post_paint functions. The
implementation of a run virtual would look something like this:
void
effect_run (ClutterEffect *effect,
ClutterEffectRunFlags flags)
{
/* Set up state */
/* ... */
/* Chain to the next item in the paint sequence */
clutter_actor_continue_paint (priv->actor);
/* Clean up state */
/* ... */
}
ClutterActor now just calls this virtual instead of the pre_paint and
post_paint functions. It keeps track of the next effect in the list so
that it knows what to do when clutter_actor_continue_paint is
called. clutter_actor_continue_paint is a new function added just for
implementing effects.
The default implementation of the run virtual just calls pre_paint and
post_paint so that existing effects will continue to work.
An effect is allowed to conditionally skip calling
clutter_actor_continue_paint(). This is useful to implement effects
that cache the image of an actor. The flags parameter can be used to
determine if the actor is dirty since the last paint. ClutterActor
sets this flag whenever propagated_one_redraw is TRUE which means that
a redraw for this actor or one of its children was queued.
The id pool used for the actor's id should be a per-stage field. At some
point, we might have a Stage mapped to multiple framebuffers, or each
Stage mapped to a different framebuffer; also, on backend with low
color precision we don't want to exhaust the size of the available ids
with a global pool. Finally, it's yet another thing we can remove from
the global Clutter context.
Having the id pool allocated per-stage, and the pick id assigned on
Actor:mapped will make the whole pick-id more reliable and future proof.
http://bugzilla.clutter-project.org/show_bug.cgi?id=2633https://bugzilla.gnome.org/show_bug.cgi?id=647876
In test-pixmap.c instead of using the GdkPixbuf API to load the
redhand.png image we now use the cairo API to load the png into a xlib
surface which wraps our Pixmap.
This test was the last thing that depended on the gdk API and since
it's more concise to use Cairo here which is a hard dependency for
Clutter this change means we avoid depending on GdkPixbuf directly.
Cogl has now been split out into a standalone project with a separate
repository at git://git.gnome.org/cogl. From now on the Clutter build
will now simply look for a cogl-1.0 pkg-config file to find a suitable
Cogl library to link against at build time.
Do not use GdkPixbuf just for getting image data down into a PNG; Cairo
is perfectly capable of doing the same, at least just for debugging
purposes.
https://bugzilla.gnome.org/show_bug.cgi?id=647875
It stands to reason that any piece of code using Cairo and Cogl at the
same time, and dealing with texture data, will want to use the same
logic Clutter uses to determine the compatible pixel format between the
two.
https://bugzilla.gnome.org/show_bug.cgi?id=647875
When comparing the wrap modes of two pipeline layers it now considers
COGL_WRAP_MODE_AUTOMATIC to be equivalent to CLAMP_TO_EDGE. By the
time the pipeline is in the journal, the upper primitive code is
expected to have overridden this wrap mode with something else if it
wants any other behaviour. This is important for getting text to batch
together with textures because the text explicitly sets the wrap mode
to CLAMP_TO_EDGE on its pipeline.
The material cache will now only set the special combine mode if the
texture only has an alpha component. The atlased textures will have
all four components so it will leave the combine functions at the
default. This increases the chances of batching between glyphs and
images.
When using the global atlas, the glyph from cairo is now rendered into
an ARGB surface rather than an alpha-only surface.
Instead of creating just two materials (one for texturing and one for
solid primitives) the pango renderer now maintains a cache of
pipelines. The display list can request a pipeline for a texture from
the cache. The same pipeline cache is used by all display lists so
that the pipelines can be shared. This avoids changing the texture on
the material during a paint run.
It now avoids trying to reserve space for zero-sized glyphs. That
happens for example when the layout contains a space. This was causing
the regular glyph cache to be used because the global atlas does not
support zero-sized images. That would then break up the
batching. Instead it now still reserves an entry in the cache but
leaves the texture as COGL_INVALID_HANDLE.
When rendering a glyph from a texture, instead of adding the glyph's
texture handle to the display list it now retrieves the base texture
using _cogl_texture_foreach_subtexture_in_region and adds that
instead. That way the display can recognise that glyphs in the global
atlas are sharing the same texture and combine them into one VBO.
Whenever the glyph cache puts a glyph in the global atlas it will now
register for notifications of reorganisation of the global
atlases. When this happens it will forward this on as a notification
of reorganisation of the glyph cache.
This adds cogl_atlas_texture_* functions to register a callback that
will get invoked whenever any of the CoglAtlas's the textures use get
reorganized. The callback is global and is not tied to any particular
atlas texture.
If mipmapping is disabled, it will now try to create a standalone
atlas texture for a glyph rather than putting it in the atlas.
If the atlas texture can't be created then it will fallback to the
glyph cache.
This adds a new function called _cogl_atlas_texture_new_with_size. The
old new_from_bitmap function now just calls this and updates the
texture with the data.
If the texture can't be hardware repeated (ie, if it is sliced or it
has waste) then Cogl will reject the layer when rendering with a
VBO. In this case we should always fall back to rendering with
cogl_rectangle.
This commit is only needed temporarily because Cogl will end up
putting atlas textures in the display list. A later commit in the
series will make it so that the display list always has primitive
textures in it so this commit can be reverted.
This reverts the changes in 54d8aadf which combined the two glyph
caches into one. We want to start using separate caches again so that
we can non-mipmapped textures into the global atlas.
This extends cogl_onscreen_x11_set_foreign_xid to take a callback to a
function that details the event mask the Cogl requires the application
to select on foreign windows. This is required because Cogl, for
example, needs to track size changes of a window and may also in the
future want other notifications such as map/unmap.
Most applications wont need to use the foreign xwindow apis, but those
that do are required to pass a valid callback and update the event mask
of their window according to Cogl's requirements.
This adds Cogl API to show and hide onscreen framebuffers. We don't want
to go too far down the road of abstracting window system APIs with Cogl
since that would be out of its scope but the previous idea that we would
automatically map framebuffers on allocation except for those made from
foreign windows wasn't good enough. The problem is that we don't want to
make Clutter always create stages from foreign windows but with the
automatic map semantics then Clutter doesn't get an opportunity to
select for all the events it requires before mapping. This meant that we
wouldn't be delivered a mouse enter event for windows mapped underneath
the cursor which would break Clutters handling of button press events.
When building on windows for example we need to ensure we pass
-no-undefined to the linker. Although we were substituting a
COGL_EXTRA_LDFLAGS variable from our configure.ac we forgot to
reference that when linking cogl-pango.
For compatibility with the way we build Cogl as part of Clutter we now
substitute an empty MAINTAINER_CFLAGS variable. When building Cogl
standalone all our extra CFLAGS go through COGL_EXTRA_CFLAGS so the
separate MAINTAINER_CFLAGS aren't used, but automake will get confused
if a substitution isn't made.
This fixes the gdk-pixbuf check to not mistakenly check for the "xi"
package instead of gdk-pixbuf and remove a spurious listing "gl" in
COGL_PKG_REQUIRES which should only be there when we are using using
opengl not if we are using gles.
When building on windows for example we need to ensure we pass
-no-undefined to the linker. Although we were substituting a
COGL_EXTRA_LDFLAGS variable from our configure.ac we forgot to
reference that when linking cogl.
Until Cogl gains native win32/OSX support this remove the osx and win32
winsys files and instead we'll just rely on the stub-winsys.c to handle
these platforms. Since the only thing the platform specific files were
providing anyway was a get_proc_address function; it was trivial to
simply update the clutter backend code to handle this directly for now.
This is a workaround for a bug on OSX for some radeon hardware that
we can't verify and the referenced bug link is no longer valid.
If this is really still a problem then a new bug should be opened and we
can look at putting the fix in some more appropriate place than
cogl-gl.c
We want to be able to split Cogl out as a standalone project but there
are still some window systems that aren't natively supported by Cogl.
This allows Clutter to support those window systems directly but still
work with a standalone Cogl library.
This also ensures we set the SUPPORT_STUB conditional in clutter's
configure.ac when building for win32/osx and wayland.
For now we are going for the semantics that when a CoglOnscreen is first
allocated then it will automatically be mapped. This is for convenience
and if you don't want that behaviour then it is possible to instead
create an Onscreen from a foreign X window and in that case it wont be
mapped automatically.
This approach means that Cogl doesn't need onscreen_map/unmap functions
but it's possible we'll decide later that we can't avoid adding such
functions and we'll have to change these semantics.
Instead of using AC_DEFINE for the various COGL_HAS_PLATFORM defines
this now adds them to the COGL_DEFINES_SYMBOLS variable which gets
substituted into the public cogl-defines.h header.
This adds a simple standalone Cogl application that can be used to
smoke test a standalone build of Cogl without Clutter.
This also adds an x11-foreign app that shows how a toolkit can ask Cogl
to draw to an X Window that it owns instead of Cogl being responsible
for automatically creating and mapping an X Window for CoglOnscreen.
This allows more detailed control over the driver and winsys features
that Cogl should have. Cogl is designed so it can support multiple
window systems simultaneously so we have enable/disable options for
the drivers (gl vs gles1 vs gles2) and options for the individual window
systems; currently glx and egl. Egl is broken down into an option
for each platform.
The GDL API is used for example on intel ce4100 (aka Sodaville) based
systems as a way to allocate memory that can be composited using the
platforms overlay hardware. This updates the Cogl EGL winsys and the
support in Clutter so we can continue to support these platforms.
So that we can dynamically select what winsys backend to use at runtime
we need to have some indirection to how code accesses the winsys instead
of simply calling _cogl_winsys* functions that would collide if we
wanted to compile more than one backend into Cogl.
This moves the GLX specific code from cogl-texture-pixmap-x11.c into
cogl-winsys-glx.c. If we want the winsys components to by dynamically
loadable then we can't have GLX code scattered outside of
cogl-winsys-glx.c. This also sets us up for supporting the
EGL_texture_from_pixmap extension which is almost identical to the
GLX_texture_from_pixmap extension.
As was recently done for the GLX window system code, this commit moves
the EGL window system code down from the Clutter backend code into a
Cogl winsys.
Note: currently the cogl/configure.ac is hard coded to only build the GLX
winsys so currently this is only available when building Cogl as part
of Clutter.
The "DRM_SURFACELESS" EGL platform was invented when we were adding the
wayland backend to Clutter but in the end we added a dedicated backend
instead of extending the EGL backend so actually the platform name isn't
used.
Commit b061f737 moved _cogl_winsys_has_feature to the common winsys
code so there's no need to define it in the stub winsys any more. This
was breaking builds for backends using the stub winsys.
The comparison for finding onscreen framebuffers in
find_onscreen_for_xid had a small thinko so that it would ignore
framebuffers when the negation of the type is onscreen. This ends up
doing the right thing anyway because the onscreen type has the value 0
and the offscreen type has the value 1 but presumably it would fail if
we ever added any other framebuffer types.
The dispose function may be called multiple times during destruction
so it needs to be resilient against destroying any resources
twice. This wasn't the case for the reference to the Cogl context.
The code for _cogl_winsys_has_feature will be identical in all of the
winsys backends for the time being, so it seems to make sense to have
it in the common cogl-winsys.c file.
Previously the mask of available winsys features was stored in a
CoglBitmask. That isn't the ideal type to use for this because it is
intended for a growable array of bits so it can allocate extra memory
if there are more than 31 flags set. For the winsys feature flags the
highest used bit is known at compile time so it makes sense to
allocate a fixed array instead. This is conceptually similar to the
CoglDebugFlags which are stored in an array of integers with macros to
test a bit in the array. This moves the macros used for CoglDebugFlags
to cogl-flags.h and makes them more generic so they can be shared with
CoglContext.
Instead of having cogl_renderer_xlib_add_filter and friends there is
now cogl_renderer_add_native_filter which can be used regardless of
the backend. The callback function for the filter now just takes a
void pointer instead of an XEvent pointer which should be interpreted
differently depending on the backend. For example, on Xlib it would
still be an XEvent but on Windows it could be a MSG. This simplifies
the code somewhat because the _cogl_xlib_add_filter no longer needs to
have its own filter list when a stub renderer is used because there is
always a renderer available.
cogl_renderer_xlib_handle_event has also been renamed to
cogl_renderer_handle_native_event. This just forwards the event on to
all of the listeners. The backend renderer is expected to register its
own event filter if it wants to process the events in some way.
ClutterAnimation uses the weak ref machinery of GObject when associated
to ClutterActor by clutter_actor_animate() and friends - all the while
taking a reference on the actor itself. In order to trigger the weak ref
callback, external code would need to unref the Actor at least twice,
which has slim chance of happening. Plus, the way to destroy an Actor is
to call destroy(), not call unref().
The destruction sequence of ClutterActor emits the ::destroy signal, which
should be used by classes to release external references the might be
holding. My oh my, this sounds *exactly* the case!
So, let's switch to using the ::destroy signal for clutter_actor_animate()
and friends, since we know that the object bound to the Animation is
an Actor, and has a ::destroy signal.
This change has the added benefit of allowing destroying an actor as the
result of the Animation::completed signal without getting a segfault or
other bad things to happen.
Obviously, the change does not affect other GObject classes, or Animation
instances created using clutter_animation_new(); for those, the current
"let's take a reference on the object to avoid it going away in-flight"
mechanism should still suffice.
Side note: it would be interesting if GObject had an interface for
"destructible" objects, so that we could do a safe type check. I guess
it's a Rainy Day Project(tm)...
Do not use the generic GType class name: we have a :name property on
ClutterActor that is generally used for debugging purposes — so we
should use it when creating debugging spew in a consistent way.
The Cogl rework removed the Window creation from realize and its
relative destruction from unrealize; the two vfuncs also managed
the mapping between Window and Stage implementation that we use
when dealing with event handling. Sadly, the missing unrealization
left entries in the mapping dangling.
Since ClutterStageX11 already provides a ::realize implementation
that sub-classes are supposed to chain up to, and the Window ↔ Stage
mapping is private to clutter-stage-x11.c, it seems only fair that
the ClutterStageX11 should also provide an ::unrealize implementation
matching the ::realize.
This implementation just removes the StageX11 pointer from the X11
Window ↔ ClutterStageX11 mapping we set up in ::realize, since the
X11 Window is managed by Cogl, now.
