Sometimes it is necessary for third party code to have a
function called during the redraw process, so that you can
update the scenegraph before it is painted.
The stencil buffer is always cleared the first time a clip is used
that needs it and the stencil test is disabled otherwise so there is
no need to clear before a paint.
When the stage state changes between active/deactive, send out
key-focus-in/key-focus-out signal for the current key focused
actor on the stage.
Fixes bug:
http://bugzilla.openedhand.com/show_bug.cgi?id=1503
Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
When showing a Stage for the first time we end up realizing the stage
implementation before realizing the wrapper. This leads to segmentation
faults or errors coming from the backend because we're fumbling the
state and realization sequence.
The fix for bug 1138 broke multi-stage support on GLX, causing
X11 to segfault with the following stack trace:
Backtrace:
0: /usr/X11R6/bin/X(xf86SigHandler+0x7e) [0x80c91fe]
1: [0xb7eea400]
2: /usr/lib/xorg/modules/extensions//libglx.so [0xb7ae880c]
3: /usr/lib/xorg/modules/extensions//libglx.so [0xb7aec0d6]
4: /usr/X11R6/bin/X [0x8154c24]
5: /usr/X11R6/bin/X(Dispatch+0x314) [0x808de54]
6: /usr/X11R6/bin/X(main+0x4b5) [0x8074795]
7: /lib/i686/cmov/libc.so.6(__libc_start_main+0xe5) [0xb7c75775]
8: /usr/X11R6/bin/X(FontFileCompleteXLFD+0x21d) [0x8073a81]
which I can only track down to clutter_backend_glx_ensure_current()
being passed a NULL stage -- something that happens when a stage
is not correct realized. That should lead to a glXMakeCurrent(None)
and not to a segmentation fault, though.
The stage is chaining up to the ClutterGroup::paint instead of
the ClutterGroup::pick method. This works anyway because we
detect the stage by default, but it's not a reliable solution
in case we decide to change the picking further on.
The master clock is currently advanced using a frame source driven
by the default frame rate. This breaks the sync to vblank because
the vblanking rate could be different than 60 Hz -- or it might be
completely disabled (e.g. with CLUTTER_VBLANK=none).
We should be using the main loop to check if we have timelines
playing, and if so queue a redraw on the stages we own.
We should also prepare the subsequent frame at the end of the redraw
process, so if there are new redraw we will have the scene already
in place.
This makes Clutter redraw at the maximum frame rate, which is
limited by the vblanking frequency.
Commit 515350a7 renamed ::focus-in and ::focus-out to ::key-focus-in
and ::key-focus-out respectively. One signal emission for ::focus-out
escaped the renaming in ClutterStage.
For consistency, and since those signals are key-related, the
::focus-in signal is not ::key-focus-in and the ::focus-out
signal is now ::key-focus-out.
With the recent change to internal floating point values, ClutterUnit
has become a redundant type, defined to be a float. All integer entry
points are being internally converted to floating point values to be
passed to the GL pipeline with the least amount of conversion.
ClutterUnit is thus exposed as just a "pixel with fractionary bits",
and not -- as users might think -- as generic, resolution and device
independent units. not that it was the case, but a definitive amount
of people was convinced it did provide this "feature", and was flummoxed
about the mere existence of this type.
So, having ClutterUnit exposed in the public API doubles the entry
points and has the following disadvantages:
- we have to maintain twice the amount of entry points in ClutterActor
- we still do an integer-to-float implicit conversion
- we introduce a weird impedance between pixels and "pixels with
fractionary bits"
- language bindings will have to choose what to bind, and resort
to manually overriding the API
+ *except* for language bindings based on GObject-Introspection, as
they cannot do manual overrides, thus will replicate the entire
set of entry points
For these reason, we should coalesces every Actor entry point for
pixels and for ClutterUnit into a single entry point taking a float,
like:
void clutter_actor_set_x (ClutterActor *self,
gfloat x);
void clutter_actor_get_size (ClutterActor *self,
gfloat *width,
gfloat *height);
gfloat clutter_actor_get_height (ClutterActor *self);
etc.
The issues I have identified are:
- we'll have a two cases of compiler warnings:
- printf() format of the return values from %d to %f
- clutter_actor_get_size() taking floats instead of unsigned ints
- we'll have a problem with varargs when passing an integer instead
of a floating point value, except on 64bit platforms where the
size of a float is the same as the size of an int
To be clear: the *intent* of the API should not change -- we still use
pixels everywhere -- but:
- we remove ambiguity in the API with regard to pixels and units
- we remove entry points we get to maintain for the whole 1.0
version of the API
- we make things simpler to bind for both manual language bindings
and automatic (gobject-introspection based) ones
- we have the simplest API possible while still exposing the
capabilities of the underlying GL implementation
Redundant clearing of depth and stencil buffers every render can be very
expensive, so cogl now gives control over which auxiliary buffers are
cleared.
Note: For now clutter continues to clear the color, depth and stencil buffer
each paint.
Currently, all timelines install a timeout inside the TimeoutPool
they share. Every time the main loop spins, all the timeouts are
updated. This, in turn, will usually lead to redraws being queued
on the stages.
This behaviour leads to the potential starvation of timelines and
to excessive redraws.
One lesson learned from the games developers is that the scenegraph
should be prepared in its entirety before the GL paint sequence is
initiated. This means making sure that every ::new-frame signal
handler is called before clutter_redraw() is invoked.
In order to do so a TimeoutPool is not enough: we need a master
clock. The clock will be responsible for advancing all the active
timelines created inside a scene, but only when the stage is
being redrawn.
The sequence is:
+ queue_redraw() is invoked on an actor and bubbles up
to the stage
+ if no redraw() has already been scheduled, install an
idle handler with a known priority
+ inside the idle handler:
- advance the master clock, which will in turn advance
every playing timeline by the amount of milliseconds
elapsed since the last redraw; this will make every
playing timeline emit the ::new-frame signal
- queue a relayout
- call the redraw() method of the backend
This way we trade multiple timeouts with a single frame source
that only runs if a timeline is playing and queues redraws on
the various stages.
Bug 1138 - No trackable "mapped" state
* Add a VISIBLE flag tracking application programmer's
expected showing-state for the actor, allowing us to
always ensure we keep what the app wants while tracking
internal implementation state separately.
* Make MAPPED reflect whether the actor will be painted;
add notification on a ClutterActor::mapped property.
Keep MAPPED state updated as the actor is shown,
ancestors are shown, actor is reparented, etc.
* Require a stage and realized parents to realize; this means
at realization time the correct window system and GL resources
are known. But unparented actors can no longer be realized.
* Allow children to be unrealized even if parent is realized.
Otherwise in effect either all actors or no actors are realized,
i.e. it becomes a stage-global flag.
* Allow clutter_actor_realize() to "fail" if not inside a toplevel
* Rework clutter_actor_unrealize() so internally we have
a flavor that does not mess with visibility flag
* Add _clutter_actor_rerealize() to encapsulate a somewhat
tricky operation we were doing in a couple of places
* Do not realize/unrealize children in ClutterGroup,
ClutterActor already does it
* Do not realize impl by hand in clutter_stage_show(),
since showing impl already does that
* Do not unrealize in various dispose() methods, since
ClutterActor dispose implementation already does it
and chaining up is mandatory
* ClutterTexture uses COGL while unrealizable (before it's
added to a stage). Previously this breakage was affecting
ClutterActor because we had to allow realize outside
a stage. Move the breakage to ClutterTexture, by making
ClutterTexture just use COGL while not realized.
* Unrealize before we set parent to NULL in clutter_actor_unparent().
This means unrealize() implementations can get to the stage.
Because actors need the stage in order to detach from stage.
* Update clutter-actor-invariants.txt to reflect latest changes
* Remove explicit hide/unrealize from ClutterActor::dispose since
unparent already forces those
Instead just assert that unparent() occurred and did the right thing.
* Check whether parent implements unrealize before chaining up
Needed because ClutterGroup no longer has to implement unrealize.
* Perform unrealize in the default handler for the signal.
This allows non-containers that have children to work properly,
and allows containers to override how it's done.
* Add map/unmap virtual methods and set MAPPED flag on self and
children in there. This allows subclasses to hook map/unmap.
These are not signals, because notify::mapped is better for
anything it's legitimate for a non-subclass to do.
Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
Bug 1513 - Allow passing in ClutterPickMode to
clutter_stage_get_actor_at_pos()
At the moment, clutter_stage_get_actor_at_pos() uses CLUTTER_PICK_ALL
internally to find an actor. It would be useful to allow passing in
ClutterPickMode to clutter_stage_get_actor_at_pos(), so that the caller
can specify CLUTTER_PICK_REACTIVE as a criteria.
Since we have to do (z_far - z_near) and use it in a division we
should check that the user is not passing a value that would
cause a division by zero.
Bug 1454 - move queue_redraw virtualization to ClutterActor
The ClutterActor::queue-redraw signal allows parent containers to
track whether their children need a redraw.
Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
It's reasonably normal for a relayout of the stage to cause the stage
to be queued for drawing; for this reason we should do the relayout before
we clear stage->update_idle. (But want to clear update_idle() before actually
doing the redraw to handle the corner case where the draw queues another
redraw.)
The fog and perspective API is currently split in two parts:
- the floating point version, using values
- the fixed point version, using structures
The relative properties are using the structure types, since they
are meant to set multiple values at the same time. Instead of
using bare values, the whole API should be coalesced into two
simple calls using structures to match the GObject properties.
Thus:
clutter_stage_set_fog (ClutterStage*, const ClutterFog*)
clutter_stage_get_fog (ClutterStage*, ClutterFog*)
clutter_stage_set_perspective (ClutterStage*, const ClutterPerspective*)
clutter_stage_get_perspective (ClutterStage*, ClutterPerspective*)
Which supercedes the fixed point and floating point variants.
More importantly, both ClutterFog and ClutterPerspective should
using floating point values, since that's what get passed to
COGL anyway.
ClutterFog should also drop the "density" member, since ClutterStage
only allows linear fog; non-linear fog distribution can be achieved
using a signal handler and calling cogl_set_fog() directly; this keeps
the API compact yet extensible.
Finally, there is no ClutterStage:fog so it should be added.
Add annotations such as (transfer-none) (out) (element-type ClutterActor),
and so forth to the doc comments as appropriate.
The annotations added here are a combination of the annotations previously
in gir-repository for Clutter and annotations found in a review of all
return values with that were being parsed with a transfer of "full".
http://bugzilla.openedhand.com/show_bug.cgi?id=1452
Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
cogl_paint_init was a bit too miscellaneous; it mainly cleared the color, depth
and stencil buffers but arbitrarily it also disabled fogging and lighting.
It no longer disables lighting, since we know Cogl never enables lighting and
disabling of fog is now handled with a seperate function.
Since I noticed cogl_set_fog was taking a density argument documented as
"Ignored" I've also added a mode argument to cogl_set_fog which exposes the
exponential fog modes which can make use of the density.
The stage will usually be painted before the first ConfigureNotify
arrives so we need to set the SYNC_MATRICES flag to ensure that the
viewport will be correct for that paint. Unfortunately this means that
the viewport will be set again once the ConfigureNotify is received
but compared to rendering an initial invalid scene I think it is the
lesser of two evils.
The clutter_stage_get_resolution() and fixed-point API are just
shorthands for:
clutter_backend_get_resolution (default_backend);
And as such do not fit at all in the ClutterStage class. The only
reason for their existence was the ClutterUnit conversion macros,
which have now been fixed to use the default backend through a
function call instead.
Thus, we can safely remove the stage entry points.
The intention behind ::queue-redraw is to be able to block the
default handler by attaching a callback and calling one of the
g_signal_stop_emission variants.
However this doesn't work, because ::queue-redraw has the
G_SIGNAL_RUN_FIRST flag instead of G_SIGNAL_RUN_LAST.
This is the result of running a number of sed and perl scripts over the code to
do 90% of the work in converting from 16.16 fixed to single precision floating
point.
Note: A pristine cogl-fixed.c has been maintained as a standalone utility API
so that applications may still take advantage of fixed point if they
desire for certain optimisations where lower precision may be acceptable.
Note: no API changes were made in Clutter, only in Cogl.
Overview of changes:
- Within clutter/* all usage of the COGL_FIXED_ macros have been changed to use
the CLUTTER_FIXED_ macros.
- Within cogl/* all usage of the COGL_FIXED_ macros have been completly stripped
and expanded into code that works with single precision floats instead.
- Uses of cogl_fixed_* have been replaced with single precision math.h
alternatives.
- Uses of COGL_ANGLE_* and cogl_angle_* have been replaced so we use a float for
angles and math.h replacements.
Add a ClutterStage::queue-redraw signal.
The purpose of this signal is to allow combining the Clutter redraw
idle with another redraw idle such as gtk's (or any other one really;
this is desirable anytime Clutter is not the only thing drawing to
a toplevel window).
To override the default, you would connect to ::queue-redraw and then
stop the signal emission.
Since we only update the GL viewport when we receive a ConfigureNotify
event on X11, we also need a function to allow other toolkits to tell
a stage that the viewport should be updated.
This commit adds clutter_stage_ensure_viewport(), a function that simply
sets the private SYNC_MATRICES flag on the stage and then queues a
redraw.
This function should be called by libraries integrating Clutter with
other toolkits, like clutter-gtk or clutter-qt.
It was always reading one pixel lower than requested. If y was 0 then
it would try to read below the lowest line.
Thanks to Geoff Gustafson for spotting.
Since the CLUTTER_ACTOR_IN_PAINT private flag is set as part
of the paint process by clutter_actor_paint(), there is no
need to set it inside the ClutterStage paint function.
* clutter/clutter-entry.c:
* clutter/clutter-label.c:
* clutter/clutter-rectangle.c:
* clutter/clutter-script.c:
* clutter/clutter-stage.c: Use the ParamSpecColor and GValue
API for ClutterColor-based properties.
Bug 1210 - Add CoglColor API
* clutter/cogl/cogl-color.h:
* clutter/cogl/cogl.h.in:
* clutter/cogl/common/Makefile.am:
* clutter/cogl/common/cogl-color.c:
* clutter/cogl/gl/Makefile.am:
* clutter/cogl/gl/cogl.c:
* clutter/cogl/gles/Makefile.am:
* clutter/cogl/gles/cogl-texture.c:
* clutter/cogl/gles/cogl.c: Add a new color-type, to be used by
COGL. CoglColor is optimized to allow the minimum amount of
conversions possible for both GL and GLES implementations.
* clutter/clutter-actor.c:
* clutter/clutter-clone-texture.c:
* clutter/clutter-entry.c:
* clutter/clutter-main.c:
* clutter/clutter-rectangle.c:
* clutter/clutter-stage.c:
* clutter/clutter-texture.c: Use CoglColor when needed.
* clutter/pango/pangoclutter-render.c: Use CoglColor when needed.
* doc/reference/cogl/cogl-docs.sgml:
* doc/reference/cogl/cogl-sections.txt: Update the documentation.
* tests/test-cogl-offscreen.c:
* tests/test-cogl-primitives.c:
* tests/test-cogl-tex-convert.c:
* tests/test-cogl-tex-foreign.c:
* tests/test-cogl-tex-getset.c:
* tests/test-cogl-tex-polygon.c:
* tests/test-cogl-tex-tile.c:
* tests/test-paint-wrapper.c: Update the tests.
* README: Update release notes.
Bug 1209 - Move fixed point API in COGL
* clutter/cogl/cogl-fixed.h:
* clutter/cogl/cogl.h.in:
* clutter/cogl/common/Makefile.am:
* clutter/cogl/common/cogl-fixed.c: Add fixed point API, modelled
after the ClutterFixed. The CoglFixed API supercedes the ClutterFixed
one and avoids the dependency of COGL on Clutter's own API.
* clutter/cogl/common/cogl-clip-stack.c:
* clutter/cogl/common/cogl-primitives.c:
* clutter/cogl/common/cogl-primitives.h: Update internal usage of
ClutterFixed to CoglFixed.
* clutter/cogl/gl/Makefile.am:
* clutter/cogl/gl/cogl-primitives.c:
* clutter/cogl/gl/cogl-texture.c:
* clutter/cogl/gl/cogl.c: Ditto, in the GL implementation of the
COGL API.
* clutter/cogl/gles/Makefile.am:
* clutter/cogl/gles/cogl-fbo.c:
* clutter/cogl/gles/cogl-gles2-wrapper.c:
* clutter/cogl/gles/cogl-primitives.c:
* clutter/cogl/gles/cogl-texture.c:
* clutter/cogl/gles/cogl.c: Ditto, in the GLES implementation of
the COGL API.
* clutter/pango/pangoclutter-glyph-cache.c:
* clutter/pango/pangoclutter-glyph-cache.h: Ditto, in the Pango
renderer glyphs cache.
* clutter/clutter-fixed.c:
* clutter/clutter-fixed.h: ClutterFixed and related API becomes
a simple transition API for bindings and public Clutter API.
* clutter/clutter-actor.c:
* clutter/clutter-alpha.c:
* clutter/clutter-backend.c:
* clutter/clutter-behaviour-depth.c:
* clutter/clutter-behaviour-ellipse.c:
* clutter/clutter-behaviour-path.c:
* clutter/clutter-behaviour-rotate.c:
* clutter/clutter-behaviour-scale.c:
* clutter/clutter-clone-texture.c:
* clutter/clutter-color.c:
* clutter/clutter-entry.c:
* clutter/clutter-stage.c:
* clutter/clutter-texture.c:
* clutter/clutter-timeline.c:
* clutter/clutter-units.h: Move from the internal usage of
ClutterFixed to CoglFixed.
* doc/reference/clutter/clutter-sections.txt:
* doc/reference/cogl/cogl-docs.sgml:
* doc/reference/cogl/cogl-sections.txt: Update the documentation.
* tests/test-cogl-tex-tile.c:
* tests/test-project.c: Fix tests after the API change
* README: Add release notes.
* clutter/clutter-stage.c (clutter_stage_read_pixels): Use
OpenGL's coordinate system for the arguments to glReadPixels (so
that y zero is the bottom of the window). Use clutter_redraw
instead of clutter_stage_paint to ensure the right GL context is
selected. Set some of the glPixelStore parameters that might have
been changed by Cogl.
* tests/test-stage-read-pixels.c: Replace with a different test
that gets a sub-region of the stage around the cursor.
* clutter/clutter-stage.c (clutter_stage_dispose): Unrealize the
stage before removing the update idle handler. Otherwise
unrealizing causes another redraw to be queued and if the stage
object remains alive it will cause an assert and abort.
* clutter/clutter-main.c:
Destroy the debugging timer when the context is freed.
* clutter/clutter-stage.c:
Free the stage title when the stage is finalized.
* clutter/clutter-stage.c:
(clutter_stage_hide_cursor):
Fixed C&P bug that made it impossible to show cursor once hidden.
Stripped trailing whitespace.
Add a note to the clutter_stage_read_pixels doc that the alpha channel
isn't guaranteed to contain sensible data
* tests/test-stage-read-pixels.c: (update_snapshot):
Overwrite the alpha data when using clutter_stage_read_pixels; fixes
this test on non-nvidia drivers
* clutter/clutter-actor.c:
(clutter_actor_set_min_width),
(clutter_actor_set_min_height),
(clutter_actor_set_natural_width),
(clutter_actor_set_natural_height): Ignore any override of the
minimum and natural size of the stage on backends that only
support static stages.
* clutter/clutter-stage.c (clutter_stage_allocate): Use the
preferred size of the ClutterStage implementation instead of
the display size.
* clutter/clutter-backend.[ch]: Remove get_display_size() and
clutter_backend_get_display_size().
* clutter/eglnative/clutter-backend-egl.c:
* clutter/fruity/clutter-backend-fruity.c:
* clutter/osx/clutter-backend-osx.c:
* clutter/sdl/clutter-backend-sdl.c:
* clutter/win32/clutter-backend-win32.c:
* clutter/x11/clutter-backend-x11.c: Remove get_display_size()
implementations.
* clutter/clutter-main.h: Make the priority constants public.
* clutter/clutter-stage.c: Use CLUTTER_PRIORITY_REDRAW.
* clutter/clutter-timeline.c: Use CLUTTER_PRIORITY_TIMELINE.
* clutter/clutter-stage.c:
(clutter_stage_allocate): Minor optimization.
(clutter_stage_init): Do not set the minimum size of the
stage wrapper, and require that the backends set the size
themselves.
* clutter/clutter-backend.c:
(clutter_backend_get_display_size): Provide a fallback for
backends not implementing get_display_size().
* clutter/clutter-stage.c:
(clutter_stage_allocate): Add debug messages.
* clutter/sdl/clutter-backend-sdl.c:
(clutter_backend_sdl_get_display_size),
(clutter_backend_sdl_class_init): Implement get_display_size()
on the SDL backend.
* clutter/clutter-backend.h:
* clutter/clutter-backend.c:
(clutter_backend_get_display_size): Add a function for getting the
display size out of the backend.
* clutter/clutter-stage.c:
(clutter_stage_allocate): When allocating on a backend with a
static stage, we simply ignore the passed box and override it with
the size of the display.
* clutter/eglnative/clutter-backend-egl.c:
(clutter_backend_egl_get_display_size),
(clutter_backend_egl_class_init): Implement get_display_size() by
returning the size of the EGL surface.
* clutter/fruity/clutter-backend-fruity.c:
(clutter_backend_egl_get_display_size),
(clutter_backend_egl_class_init): Ditto as above.
* clutter/x11/clutter-backend-x11.c:
(clutter_backend_x11_get_display_size),
(clutter_backend_x11_class_init): Implement get_display_size() by
returning the DisplayWidth and DisplayHeight of the current
screen.
* clutter/clutter-stage.c:
(clutter_stage_allocate): Check if the stage provided by the
backend is static (i.e. a framebuffer that cannot be resized)
and interrupt the allocation chain there.
* clutter/eglnative/clutter-stage-egl.c:
(clutter_stage_egl_class_init): Remove the ::allocate empty
stub.
Bug 981 - clutter_stage_read_pixels temprow fix (Haakon Sporsheim)
* clutter/clutter-stage.c (clutter_stage_read_pixels): Allocate
the temporary row data used to flip the buffer from glReadPixels()
in order to fix compilation under MSVC. Also validate the input
parameters to avoid random segfaults.
Bug #815 - Split up request, allocation, and paint box
* clutter/clutter-actor.[ch]: Rework the size allocation,
request and paint area. Now ::request_coords() is called
::allocate(), and ::query_coords() has been split into
::get_preferred_width() and ::get_preferred_height(). See
the documentation and the layout test on how to implement
a container and layout manager with the new API. (#915,
based on a patch by Havoc Pennington, Lucas Rocha and Johan
Bilien)
* clutter/clutter-clone-texture.c: Port CloneTexture to
the new size negotiation API; it just means forwarding
the requests to the parent texture.
* clutter/clutter-deprecated.h: Add deprecated and replaced
API.
* clutter/clutter-entry.c: Port Entry to the new size
negotiation API.
* clutter/clutter-group.c: Port Group to the new size
negotiation API; the semantics of the Group actor do not
change.
* clutter/clutter-label.c: Port Label to the new size
negotiation API, and vastly simplify the code.
* clutter/clutter-main.[ch]: Add API for executing a
relayout when needed.
* clutter/clutter-private.h: Add new Stage private API.
* clutter/clutter-rectangle.c: Update the get_abs_opacity()
call to get_paint_opacity().
* clutter/clutter-stage.c:
(clutter_stage_get_preferred_width),
(clutter_stage_get_preferred_height),
(clutter_stage_allocate),
(clutter_stage_class_init): Port Stage to the new size
negotiation API.
* clutter/clutter-texture.c: Port Texture to the new size
negotiation API.
* clutter/clutter-types.h: Add ClutterRequestMode enumeration.
* clutter/x11/clutter-stage-x11.c: Port the X11 stage
implementation to the new size negotiation API.
* tests/Makefile.am: Add the layout manager test case.
* tests/test-opacity.c: Update.
* tests/test-project.c: Update.
* tests/test-layout.c: Test case for a layout manager implemented
using the new size negotiation API; the layout manager handles
both transformed and untransformed children.
* clutter/clutter-stage.c (clutter_stage_get_default): Don't grab
the floating reference when creating the default stage. The stage
manager will take a reference to it so it will behave as any other
stage.
(clutter_stage_new): Don't take the floating reference to the new
stage but let the stage manager keep it instead.
* clutter/clutter-stage-manager.c
(_clutter_stage_manager_add_stage): Take a reference to the stage
when it is added to the list.
(_clutter_stage_manager_remove_stage): Unref the stage when it is
removed from the list.
(clutter_stage_manager_dispose): Keep track of the 'next' pointer
as a separate variable so we can cope when the stage being
destroyed removes itself from the list as the list is being
iterated.
* clutter/clutter-actor.c (clutter_actor_destroy): Take a
reference at the beginning of the function even if there is no
parent container so that overall the reference count is not
changed when the actor is unref'd again at the bottom of the
function. Previously it would have a net effect of leaving the
reference count alone unless it is a top level actor in which case
it would unref it.
