The transitions we create implicitly should be removed from the set of
transitions associated to an actor; the transitions explicitly
associated to an actor, though, have to survive the emission of their
'stopped' signal.
We can remove the update_transition() private method, and move its
functionality inside the create_transition() private method, thereby
removing lots of duplicated code, as well as redundant checks on the
existence of a transition. This will allow handling transition updates
atomically in the future.
Another progress function from the CSS3 Transitions specification, using
a parametrices cubic bezier curve between (0, 0) and (1, 1) with two
control points.
(sadly, no ASCII art can approximate a cubic bezier, so no graph)
The cubic-bezier() progress function comes with a bunch of preset easing
modes: ease, ease-in, ease-out, and ease-in-out, that we can map to
enumeration values.
The CSS3 Transitions specification from the W3C defines the possibility
of using a parametrized step() timing function, with the following
prototype:
steps(n_steps, [ start | end ])
where @n_steps represents the number of steps used to divide an interval
between 0 and 1; the 'start' and 'end' tokens describe whether the value
change should happen at the start of the transition, or at the end.
For instance, the "steps(3, start)" timing function has the following
profile:
1 | x
| |
| x---|
| ' |
| x---' |
| ' |
0 |---' |
Whereas the "steps(3, end)" timing function has the following profile:
1 | x---|
| ' |
| x---' |
| ' |
x---' |
| |
0 | |
Since ClutterTimeline uses an enumeration for controlling the progress
mode, we need additional API to define the parameters of the steps()
progress; for this reason, we need a CLUTTER_STEPS enumeration value,
and a method for setting the number of steps and the value transition
policy.
The CSS3 Transitions spec helpfully also defines a step-start and a
step-end shorthands, which expand to step(1, start) and step(1, end)
respectively; we can provide a CLUTTER_STEP_START and CLUTTER_STEP_END
enumeration values for those.
This patch brings 'enter-event' and 'leave-event' generation for touch
based devices. This leads to adding a new API to retrieve coordinates
of a touch point.
https://bugzilla.gnome.org/show_bug.cgi?id=679797
We use floorf() for the allocation origin, and ceilf() for the
allocation size. Swapping the two introduces rounding errors if
the original allocation is not clamped to the nearest pixel.
This reverts commit 7f6b17bc50.
ClutterLayoutManager implementations should just defer the easing state
set up to the child, and not try to impose a global one.
This reverts commit 793bde9143.
ClutterLayoutManager implementations should just defer the easing state
set up to the child, and not try to impose a global one.
This reverts commit 320fb156b4.
ClutterLayoutManager implementations should just defer the easing state
set up to the child, and not try to impose a global one.
This reverts commit 58a1854b57.
ClutterLayoutManager implementations should just defer the easing state
set up to the child, and not try to impose a global one.
This reverts commit 03ec016faa.
ClutterLayoutManager implementations should just defer the easing state
set up to the child, and not try to impose a global one.
ClutterTexture is full of side effects that have been picked up over the
years; they make improving ClutterTexture harder than necessary, as well
as making subclassing impossible without introducing weird behaviours in
the child classes as well.
Since Clutter 1.10 we have the ClutterImage content type, which is
side-effects free, given that it just paints texture data using the
state of the actor.
Sadly, we still have subclasses of ClutterTexture, both deprecated and
not, so we cannot deprecate ClutterTexture right out; the type and
structures will still be available, like we do for ClutterGroup, but the
whole API should be moved to the deprecated section, waiting for the
time in which we can get rid of it all.
We need an alternative to the translation performed by the anchor point,
one that possibly applies to all three axes and is relative to the
pivot-point.
https://bugzilla.gnome.org/show_bug.cgi?id=677853
For some transformations we need to be able to set the Z component of
the pivot point.
Unlike :pivot-point, the Z coordinate is not normalized because actors
are 2D surfaces.
https://bugzilla.gnome.org/show_bug.cgi?id=677853
Given that the rotation transformations are now affected by the pivot
point, the Actor class should provide an accessors pair only for the
angle of rotation on a given axis.
https://bugzilla.gnome.org/show_bug.cgi?id=677853
The pivot point is a point in normalized coordinates space around which
all transformations revolve.
It supercedes the anchor point and the per-transformation center points
as well as the gravity settings, and tries to sort out the mess that
is the modelview matrix set up in ClutterActor.
https://bugzilla.gnome.org/show_bug.cgi?id=677853
The ClutterActor:depth property has always been a bit of a misnomer:
actors are 2D flat surfaces, so they cannot have "depth"; the property
defines the position on the Z axis.
Another side effect of the :depth property is that it decides the
default paint and allocation order on insertion, and that setting it
will call the ClutterContainer.sort_depth_order() method. This has
proven to be a fairly bad design decision that we strung along from the
0.x days, as it gives a false impression of being able to change the
paint and allocation order simply by changing the position on the Z
axis — something that, in reality, requires depth testing to be enabled
during the paint sequence of an actor's parent.
For 2.0 we need a clean break from the side effects, and a better
defined interface.
ClutterActor:z-position is essentially what ClutterActor:depth is, but
doesn't call into ClutterContainer, and has a more apt name.
https://bugzilla.gnome.org/show_bug.cgi?id=679465
The :position property on ClutterText clashes with the same property on
ClutterActor; it's also badly named, given that it represents the
cursor's position inside the text; finally, it does not match its
accessors, violating the API style conventions.
https://bugzilla.gnome.org/show_bug.cgi?id=679457
Overriding the default behaviour of ClutterDragAction::drag-motion is
currently a pain; you either need to subclass the ClutterDragAction and
override the class closure for the signal, or you need to connect to the
signal and call g_signal_stop_emission_by_name() - neither option being
particularly nice or clean. The established pattern for these cases
would be to have a boolean return value on the ::drag-motion signal, but
we cannot do that without breaking ABI.
To solve the issue in a backward compatible way, we should introduce a
new signal, ::drag-progress, with a boolean return value. If the signal
emission chain returns TRUE, the ::drag-motion signal will be emitted,
and the default behaviour will be honoured; if the signal emission chain
returns FALSE, instead, the ::drag-motion signal will not be emitted.
https://bugzilla.gnome.org/show_bug.cgi?id=679451
Acquiring the Clutter lock to mark critical sections is not portable,
and not recommended to implement threaded applications with Clutter.
The recommended pattern is to use worker threads, and schedule UI
updates inside idle or timeout handlers within the main loop. We should
enforce this pattern by deprecating the threads_enter()/leave()
functions. For compatibility concerns, we need internal API to acquire
the main lock during frame processing dispatch.
https://bugzilla.gnome.org/show_bug.cgi?id=679450
It can be useful to check whether a ClutterActorIter is currently valid,
i.e. if the iterator has been initialized *and* if the actor to which it
refers to hasn't been updated.
We can also use the is_valid() method in the conformance test suite to
check that initialization has been successful, and that changing the
children list through the ClutterActorIter API leaves the iterator in a
valid state.
The dispose sequence will keep the object alive, and we need to release
the last reference held by the StageManager before releasing control to
GObject.
The build should not add deprecated/ into the default INCLUDE paths, so
that deprecated headers are clearly separated; this will make it easier
to get rid of them when we branch out for 2.0.
Copy and paste of the implementation done at Gtk+ based on pango. This
should be moved to a common library, like the old GailTextUtil. Ideally
on pango itself.
https://bugzilla.gnome.org/show_bug.cgi?id=677221
It is possible that we get a DeviceChanged event for a device
that is not in the hash table yet. E.g. I've seen this when
using xrandr to change screen resolution. Prevent a crash in
this case.
https://bugzilla.gnome.org/review?bug=678439
* clutter/clutter-cairo-texture.c (clutter_cairo_texture_emit_draw):
Always update the Cogl texture after emitting ::draw, since we control
the dynamic extent in which drawing should happen on the cairo_t.
Fixes#677966.
If the Interval used has a different type than the property we are
animating through a PropertyTransition then we should transform the
interpolated value before applying it, to avoid warnings down the
line.
The compute() method will cache the result, to avoid multiple
allocations and copies; this means, though, that we need to unset the
GValue when destroying the Interval.
Now that the interval can transform the initial and final values to the
type declared when constructing it, there is no need to check for the
value type inside set_initial_value() and set_final_value().
It's possible that GValues passed to a ClutterInterval setter are not
of the same type as the interval - for instance, if they come from
language bindings, or from untrusted sources; we can use the same
transformation functions we already use inside ClutterTransition to
ensure that the ClutterInterval always stores values of the same type
used to create the interval itself.
The ::stopped signal should be emitted at the end of the Timeline, after
the last ::completed signal emission, in order to have a proper
chronological progress of signal emissions:
started → new-frame → [ ... ] → completed → stopped
This way, ::stopped can perform a proper teardown of the state set up
during ::started, without interfering with the potential cyclical
emission of ::completed.
Calling clutter_point_free(clutter_point_zero()) or calling
clutter_rect_free(clutter_rect_zero()) should be safe, exactly like it's
safe to call those functions with a NULL argument.
The implicit animations only apply to properties that are documented as
'animatable'; the explicit animations apply to any property defined
through GObject or ClutterAnimatable.
For 1.x, we still have a duration of 0 msecs, but we have a valid easing
state, so we can change the easing parameters without calling save and
restore.
By checking if the interval is valid inside compute_value() we can catch
the cases where the interval values of a PropertyTransition are set
after the transition has been added to an Animatable instance - i.e. the
following code:
let transition = new Clutter.PropertyTransition();
transition.set_property_name('opacity');
actor.add_transition('opacityAnim', transition);
transition.set_to_value(0);
should be equivalent to:
let transition = new Clutter.PropertyTransition();
transition.set_property_name('opacity');
transition.set_to_value(0);
actor.add_transition('opacityAnim', transition);
instead of emitting a warning.
Once a ClutterPropertyTransition is attached to a ClutterAnimatable, if
no interval is set we can simply use the current state of the property
to define the from and to values. This allows the creation of property
transitions from the current state of the Animatable instance without
excessive verbosity.
ClutterContent implementations may allow repeating their contents when
painting; we should provide the repeat policy on the actor, like we do
for scaling filters and content gravity.
ClutterActor's x-align and y-align properties should be used to control
the alignment of the PangoLayout when painting it within a larger
allocation, and the ClutterText has the x-expand or the y-expand flags
set.
Fixed positions are defined to be initialized at 0,0 whenever
enabled, by setting fixed_position_enabled to true, or by setting
just one of x/y. This normally happens in the defaults, but we need
to make sure it also happens if a fixed position was once set but
then disabled. We do this by always resetting it back to 0,0 when
fixed_position_set is unset.
Instead of showing the full timestamp for debugging messages that happen
within a second, showing the delta from the previous full timestamp can
be more useful when debugging; this allows immediately seeing the time
difference, instead of doing the math in our heads.
Only for debug builds, the debug name should include a) actor name, b)
type name, and c) pointer address.
For non-debug builds we can live with the actor/type name.
ClutterGridLayout is port of GtkGrid to a Clutter layout manager. All
the logic is taken from gtkgrid.c, so all the credits should go to
Matthias Clasen for writing this nice piece of code.
ClutterGridLayout supports adding children with it's own methods
GridLayout.attach() and GridLayout.attach_next_to() as well as
Actor.add_child() and friends. The latter adds children in a similar
fashion to ClutterBoxLayout
https://bugzilla.gnome.org/show_bug.cgi?id=677372
The plain C bytes array, while convenient from a C perspective, is not
well handled by language bindings: the length of the array is not
specified, and it's only just implied by the image data size, rowstride,
and pixel format.
GBytes is a read-only bytes buffer that has an implicit length; we can
use it as the storage medium so that language bindings can actually
function correctly.
This will ensure that we have a CoglContext, albeit the stub winsys one,
on Mac.
Tested-by: Roland Peffer <gdevel@clixxun.com>
Tested-by: Laszlo Pandy <laszlok2@gmail.com>
The ::stopped signal is emitted when the timeline has been completely
exhausted or when the timeline has been programmatically stopped by
using clutter_timeline_stop(); the notification at the end of the
timeline run allows to write handlers without having to check whether
the current repeat is the last one, like we are forced to do when using
the ::completed signal.
Based on the patch by: Jasper St. Pierre <jstpierre@mecheye.net>
https://bugzilla.gnome.org/show_bug.cgi?id=676854
Ensure that resizing transitions smoothly when switching between major
axis; the allocation aspect ratio is not important: it's the size of the
allocation that dictates the major axis.
It's similar to to the implicit animation API of ClutterActor and
compatible to deprecated API of ClutterBoxLayout and
ClutterTableLayout.
It adds :use-animations, :easing-mode, :easing-duration and
:easing-delay properties to control animations when allocation of a
child has changed. Layout manager implementers should call
use_animations = clutter_layout_manager_get_easing_state (manager,
&mode,
&duration,
&delay);
from the allocate() virtual function to access these values.
https://bugzilla.gnome.org/show_bug.cgi?id=676827
The z coordinate of the origin should be checked against the same
coordinate of the vertex behind it. Given that most actors are flat
surfaces, this check should always succeed.
https://bugzilla.gnome.org/show_bug.cgi?id=675396
Instead of going through clutter_event_get_state() and checking if the
modifier mask is set, we can provide simple convenience functions to do
it for us.
When creating a FlowLayout container, setting a specific size on it, and
adding a child to it, as per the attached testcase, it crashes. The line
on the backtrace doesn't really make sense, but from looking over it, it
appears that it's probably because priv->line_natural is NULL. The
attached patch makes it so in this case, priv->line_natural is
allocated.
https://bugzilla.gnome.org/show_bug.cgi?id=676068
Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
-Don't include unistd.h and stdint.h unconditionally as not all Windows
compilers have them around.
-Only include cogl/cogl-xlib.h when it is really supported by Cogl and GDK.
-sys/ioctl.h is not available on Windows (MinGW/MSVC).
-Correct the call to cogl_renderer_set_winsys_id:
(backend_cogl->cogl_renderer, COGL_WINSYS_ID_WGL) ->
(renderer, COGL_WINSYS_ID_WGL)
The property uses an array with the following CSS style syntax
[ top, right, bottom, left ] or
[ top, left/right, bottom ] or
[ top/bottom, left/right ] or
[ top/right/bottom/left ]
https://bugzilla.gnome.org/show_bug.cgi?id=676367
Passing a NULL buffer to clutter_text_set_text() does not behave the same
way as passing an empty string "" (as specified in the documentation).
This was working as expected previously, but somehow the behaviour changed
at some point and created 2 new issues:
- Passing a NULL pointer will not reset the string
- If the ClutterText is editable, it will segfault in strcmp
Validations have been added to prevent this.
https://bugzilla.gnome.org/show_bug.cgi?id=675890
This fixes drop_action_unregister() to not call g_object_get_data()
on priv->stage if not yet resolved. This can happen if the action's
actor was destroyed before ever being mapped.
When the transition was removed from the scroll-actor manually,
to cancel a not-finished animation, the transition struct member
wasn't reset to NULL.
This fixes this problem, and removes the need for the struct member
to be reset manually when animation has completed.
https://bugzilla.gnome.org/show_bug.cgi?id=676334
When setting up the transition manually by calling
clutter_keyframe_transition_set_key_frame (transition, n, keys);
clutter_keyframe_transition_set_values (transition, n, values);
clutter_keyframe_transition_set_modes (transition, n, modes);
the frame doesn't have a valid interval when calling set_keys(), so we
need to check its existence and create it if necessary.
https://bugzilla.gnome.org/show_bug.cgi?id=676031
Chaining up to the parent's implementation of pick() is not enough: we
need to paint our children explicitly because of the compatibility mode
checks we use to avoid breaking custom containers.
https://bugzilla.gnome.org/show_bug.cgi?id=676088
We need to clip the children during picking as well as we do when
painting, to avoid reactive children outside of the visible area
receiving events.
This also allows us to refactor some common code into proper functions.
-Add configuration in Clutter projects to add option to build Clutter with
the GDK3 backend in addition to the Win32 backend
-Add another preconfigured clutter-config.h.win32_GDK which contains
backend configs for both GDK3 and Win32 windowing and input.
When asking for the preferred width and height of an actor, in case
only one of either the minimum or the natural width is set, the margin
offsets should also be applied.
When getting touch events, the device manager would try
to pass an invalid device to translate_axes().
clutter_event_set_device() will only update event->touch.device
for touch events, not event->motion.device, as used.
Fixes Totem crashing on mouse motion/button press when using
a touchpad.
https://bugzilla.gnome.org/show_bug.cgi?id=675371
The drop-cancel signal allows the drop action to cleanup its
state if the can-drop signal is refused. This is especially
useful if the drop action (or its target actor) is managing
any drop target animations.
https://bugzilla.gnome.org/show_bug.cgi?id=675336
The example code that is meant to be XIncluded into the API reference
should not be part of the interactive test suite: it's code that it is
meant to be used as a reference implementation - whereas the interactive
test suite should be allowed to be lean and test behaviour even in nasty
ways. In short: the test suite should not be the place where we show off
idiomatic code for educational purposes.
The introspection scanner has become slightly more annoying, in the hope
that people start fixing their annotations. As it turns out, it was the
right move.
It's time. Now that we have clutter_actor_allocate() respecting the
easing state of an actor, and that the LayoutManager animation virtual
functions have been deprecated, we can put ClutterAlpha on the chopping
block, and be done with it, once and for all.
So long, ClutterAlpha; and thanks for all the fish.
This semi-aborted API was broken for various reasons:
- it strongly depended on ClutterAlpha, a class we're trying to
deprecate;
- it requires a lot of boilerplate and copy-and-paste code;
- it requires a full relayout of the actor tree for something
that ought to be automatically handled by ClutterActor.
Now that clutter_actor_allocate() handles transitions using the easing
state of the actor, we can deprecate the LayoutManager API for the 1.x
series, and remove it for the 2.x series.
BoxLayout will use the easing state of the children it's allocating; the
current API is re-implemented in terms of an implicit easing state
forced on each child prior to allocating it.
Calling clutter_actor_allocate() should transition between the current
allocation and the new allocation, by using the defined implementation
of the easing state.
This means that:
clutter_actor_save_easing_state (actor);
clutter_actor_allocate (actor, &new_alloc, flags);
clutter_actor_restore_easing_state (actor);
will cause "actor" to transition between the current allocation and the
desired new allocation.
The trick is to ensure that this happens without invalidating the
entire actor tree, but only the portion of the tree that has the
transitioned actor as the local root. For this reason, we just call the
allocate() implementation from within the transition frame advancement,
without invalidating flags: the actor, after all, *has* a valid
allocation for the duration of the transition.
The :x-expand and :y-expand flags on ClutterActor are used to signal
that an actor should expand horizontally and/or vertically - i.e. that
its parent's layout management policy should try to assign extra space
to the actor when allocating it.
The expand flags are automatic: when set on a leaf node in the actor
tree, they will bubble up through the parent and grandparents up to the
top level actor; during allocation, the actors with children will lazily
compute whether their children needs to expand.
The TransitionGroup class is a logical container for running multiple
transitions.
TransitionGroup is not a Score: it is a Transition that advances each
Transition it contains using the delta between frames, and ensures that
all transitions are in a consistent state; these transitions are not
advanced by the master clock.
There are cases when we want to advance a timeline from another time
source. We cannot use _clutter_timeline_do_tick() directly, as that
assumes that the timeline is already playing, so we'll need to create a
wrapper that toggles the playing flag around it.
Given that we can create a ClutterInterval without an initial and final
values using g_object_new(), it stands to reason that we ought to be
able to create an instance when passing NULL GValue pointers to the
new_with_values() constructor as well.
We tend to use float comparison for structured data types like Vertex,
Point, and Size; we should take into consideration fluctuations in the
floating point representation as well.
Instead of a single new() constructor that both allocates and
initializes, split the allocation and initialization into two separate
functions for types that are typically used on the stack, and rarely
allocated on the heap, like ClutterPoint and friends.
This is also applied retroactively to ClutterActorBox and ClutterVertex,
given that the same considerations on usage apply to them as well; we
can add a return value to clutter_actor_box_init() and
clutter_vertex_init() in an ABI-compatible way, so that
clutter_actor_box_new() and clutter_vertex_new() can be effectively
reimplemented as "init (alloc ())".
Using a compound type property for position and size has various
advantages: it reduces the amount of checks; it reduces the amount
of notify signals to connect to; it reduces the amount of transitions
generated.
The ClutterCanvas content implementation should be used instead, to
avoid stringing along the ClutterTexture API and implementation.
This change requires some minor surgery, as the deprecated section
already contains an header for the previously deprecated methods; plus,
we don't want to deprecate clutter_cairo_set_source_color(). This means
creating a new header to be used for Cairo-related API.
The get_distance() API uses machine integers to compute the distance;
this means that on 32bit we can overflow the integer size. This gets
hidden by the fact that get_distance() returns an unsigned integer as
well.
In reality, ClutterPath is an unmitigated mess, and the only way to
actually fix it is to break API.
https://bugzilla.gnome.org/show_bug.cgi?id=652521
This commit adds a further conditional check for calling
clutter_actor_show() when adding a child to an actor. We cannot
unconditionally change the value of the show-on-set-parent property like
the original solution of commit 81b19a78f5
as that breaks the document invariant that show-on-set-parent will be
changed iff an actor is without a parent.
The new ADD_CHILD_SHOW_ON_SET_PARENT flag is part of the default and
legacy flags, thus retaining the default behaviour when adding a child;
the flag is not passed when reordering the list of children, which means
we ignore the state of the show-on-set-parent property.
The conformance test suite fully passes, including the newly added test
to verify that changing the paint order does not trigger visibility.
https://bugzilla.gnome.org/show_bug.cgi?id=674510
This reverts commit 81b19a78f5.
The commit breaks the conformance test unit for the invariants we
guarantee for the 1.x API:
ERROR:actor-invariants.c:307:actor_show_on_set_parent: assertion failed: (show_on_set_parent)
It's possible to run Clutter with the 'null' input backend, which means
that clutter_device_manager_get_default() may return NULL. In the future
we may add a default dummy device manager, but right now it's safer to
just add a simple NULL check in the places where we ask for the device
manager.
I can't think of any reason why it would do this and there's no
comment explaining it so let's just remove it. The global fog state
has been removed in Cogl 2.0 so it will cause problems later.
Reviewed-by: Emmanuele Bassi <ebassi@linux.intel.com>
CoglVertexBuffer is deprecated so here is a fairly simple replacement
to use the experimental CoglPrimitive API.
Reviewed-by: Emmanuele Bassi <ebassi@linux.intel.com>
Drop a bunch of variables that are not meant to be used by Cally; also,
drop the wrong library name from the Libs key: Clutter has a single
shared library, now.
https://bugzilla.gnome.org/show_bug.cgi?id=674105
The interface looked like a good idea around the time Clutter 0.2 was
out, but in reality we never had a proper, and supported implementation
outside of clutter-gst - thus, ClutterMedia was acting like a wrapper
around GStreamer, leading to hilarious issues of impedence mismatch
between API and all sorts of indirection issues typical of wrong
abstractions.
In theory, ClutterMedia should have been deprecated and removed before
we hit 1.0, but we kept flip-flopping on the issue.
For 2.0, it's time to take it out.
And shoot it in the face.
It's been a year and change, and two stable releases, since we
introduced the paint volume mechanism to allow actors to paint outside
their allocation safely in environments that support clipped redraws.
The time has come to flip the switch, and return a valid paint volume,
matching the actor's allocation, by default - at least for Actor
instances from classes that do not override paint() and
get_paint_volume().
If an actor has a paint signal handler then it's the user responsability
not to paint outside the allocation - and to suffer the consequences of
doing so; in an ideal world, paint() would not be a signal in the first
place anyway. Plus, the idea that painting can happen at any time and
still have a valid surface greatly conflicts with the design goal of
making Clutter's rendering operations fully retained into a render tree.
We can still revert this commit before spinning 1.12, if need be.
When removing the last Action, Constraint, or Effect, we should also be
clearing the corresponding MetaGroup: code inside ClutterActor relies on
NULL checks, and changing them all to check for NULL && n_items == 0
would not be fun.
configure.ac defines XINPUT_2_2 if XI 2.2 support was found. The code
expects XINPUT_2_2 in the device manager, but HAVE_XINPUT_2_2 in the x11
backend.
On newer X servers, the latter causes a BadValue when XIQueryDevice sends a
different major/minor than gdk's device manager (gnome-control-center).
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
https://bugzilla.gnome.org/show_bug.cgi?id=673961
We need to remove the transition only if the current repeat is equal to
the number of repeats, and if the transition was marked as remove on
complete. Otherwise, the transition has to remain where it is.
The opacity internal setter will do it for us, and it will take into
consideration any eventual flatten effect applied to the actor.
This unbreaks the actor-offscreen-redirect conformance test.
The get_geometry() implementation is broken on multi-head systems; the
only solution is to use XRandR to get the size of the CRTC that contains
the stage.
In XInput 2, the proximity events of XInput 1 have been replaced by an
axis on a valuator class. This means that, on devices that support
proximity information, for instance pens of a tablet, you will start
receiving events with the distance as an axis value - similarly to how
the pressure and tilt are presented in the API.
We were using g_list_foreach() prior to the first Apocalypse, and that
function is resilient against changes to the list while iterating it;
since we are not using a GList any more, we need handle this case
ourselves.
This also avoids the warning
Cogl-WARNING **: ./cogl-buffer.c:215: GL error (1285): Out of memory
generated by cogl_buffer_map when the CoglBuffer has zero length.
When the easing state has a duration of zero milliseconds we can skip
the entire create_transition() call inside set_width() and set_height(),
to avoid what may be a costly call to get_preferred_*.
If we update a transition that is currently playing, we need to check
the current easing state, and look at the eventual duration, in case
the user wants to cancel the transition.
