When ClutterGLXTexturePixmap uses GL_ARB_texture_rectangle,
it needs to pass the right internal format (GL_RGB or GL_RGBA)
when it initializes the texture with glTexImage2D() or later
handling won't recognize the alpha channel.
http://bugzilla.openedhand.com/show_bug.cgi?id=1586
Signed-off-by: Robert Bragg <robert@linux.intel.com>
Since it is convenient to use geometry with an opacity of 0 for input only
purposes it's a worthwhile optimization to avoid submitting anything
for such actors while painting.
Backface culling is enabled as part of cogl_enable so the different
rendering functions in Cogl need to explicitly opt-in to have backface
culling enabled. Cogl vertex buffers should allow backface culling so
they should check whether it is enabled and then set the appropriate
cogl_enable flag.
In order to cope with the situation where an application renders with
a PangoLayout, makes some changes and then renders again with the same
layout, CoglPangoRenderer needs to detect that the changes have
occured so that it can recreate the display list. This is acheived by
keeping a reference to the first line of the layout. When the layout
is changed Pango will clear the layout pointer in the first line and
create a new line. So if the layout pointer in the line becomes NULL
then we know the layout has changed. This trick was suggested by
Behdad Esfahbod in this email:
http://mail.gnome.org/archives/gtk-i18n-list/2009-May/msg00019.html
When a position is given to cogl_pango_render_layout_subpixel it
translates the GL matrix by the coordinates. However it was not
dividing by PANGO_SCALE so the coordinates were completely wrong.
Most of the operations involving the texture's allocated area require
floats -- either for computations or for setting the geometry into
COGL. So it doesn't make any sense to use get_allocation_coords() and
cast everything to floats.
Currently, COGL depends on defining debug symbols by manually
modifying the source code. When it's done, it will forcefully
print stuff to the console.
Since COGL has also a pretty, runtime selectable debugging API
we might as well switch everything to it.
In order for this to happen, configure needs a new:
--enable-cogl-debug
command line switch; this will enable COGL debugging, the
CoglHandle debugging and will also turn on the error checking
for each GL operation.
The default setting for the COGL debug defines is off, since
it slows down the GL operations; enabling it for a particular
debug build is trivial, though.
COGL has a debug message system like Clutter's own. In parallel,
it also uses a coupld of #defines. Spread around there are also
calls to printf() instead to the more correct g_log* wrappers.
This commit tries to unify and clean up the macros and the
debug message handling inside COGL to be more consistent.
ClutterTexture has many properties that can only be accessed using
the GObject API. This is fairly inefficient and makes binding the
class overly complicated.
The Texture class should have accessor methods for all its properties,
properly documented.
The code for the conversion of the GL error enumeration code
into a string is not following the code style and conventions
we follow in Clutter and COGL.
The GE() macro is also using fprintf(stderr) directly instead
of using g_warning() -- which is redirectable to an alternative
logging system using the g_log* API.
We use math routines inside Cogl, so it's correct to have it in
the LIBADD line. In normal usage something else was pulling in
-lm, but the introspection is relying on linking against the
convenience library.
Based on a patch by: Colin Walters <walters@verbum.org>
Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
The timeline created when calling set_timeline(NULL) is referenced
even though we implicitly own it. When the Animation is destroyed,
the timeline is then leaked.
Thanks to: Richard Heatley <richard.heatley@starleaf.com>
Fixes bug:
http://bugzilla.openedhand.com/show_bug.cgi?id=1548
Add a method for deleting the current selection inside a Text actor.
This is useful for subclasses.
See bug:
http://bugzilla.openedhand.com/show_bug.cgi?id=1521
Based on a patch by: Raymond Liu <raymond.liu@intel.com>
ClutterAnimation currently inherits the initial floating reference
semantics from GInitiallyUnowned. An Animation is, though, meant to
be used as a top-level object, like a Timeline or a Behaviour, and
not "owned" by another object. For this reason, the initial floating
reference does not make any sense.
Document that repeated calls to clutter_cairo_texture_create()
continue drawing on the same cairo_surface_t. Add
clutter_cairo_texture_clear() for when you don't want that behavior.
http://bugzilla.openedhand.com/show_bug.cgi?id=1599
Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
The cursor x position is already translated, so we do not need to take the
actors allocation into account when calculating scrolling.
Additionally, we need to update the text_x value before running
clutter_text_ensure_cursor_position.
Add any scrolling offset to the x value when in single line mode.
Now that the offset is taken into account in the position_to_coords
function, we do not need to adjust the cursor x manually in
clutter_text_paint.
If the cursor is already at the end of the Text contents then we
need to maintain its position when deleting the previous character
using the relative key binding.
The required "fake" libclutter-cogl.la upon with the main clutter
shared object depends is only built with introspection enabled
instead of being built unconditionally.
Passing:
--library=clutter-@CLUTTER_FLAVOUR@-@CLUTTER_API_VERSION@
to g-ir-scanner, when building Cogl was causing g-ir-scanner to
link the introspection program against the installed clutter library,
if it existed or fail otherwise. Instead copy the handling from
the json/ directory where we link against the convenience library
to scan, and do the generation of the typelib later in the
main clutter/directory.
Fixes bug:
http://bugzilla.openedhand.com/show_bug.cgi?id=1594
Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
If text is set, ClutterText should never return less than the layout
height for minimum and preferred heights.
This holds unless ellipsize and wrap are enabled, in which case the
minimum height should be the height of the first line -- which is
the height needed to at the very least show the ellipsization.
Based on a patch by: Thomas Wood <thomas@openedhand.com>
Fixes bug:
http://bugzilla.openedhand.com/show_bug.cgi?id=1598
Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
This is the another step into abstracting the backend operations
that are currently spread all across the board back into the
backend implementations where they belong.
The GL context creation, for instance, is demanded to the stage
realization which makes it a critical path for every operation
that is GL-context bound. This usually does not make any difference
since we realize the default stage, but at some point we might
start looking into avoiding the default stage realization in order
to make the Clutter startup faster.
It also makes the code maintainable because every part is self
contained and can be reworked with the minimum amount of pain.
The master clock is using the redraw priority to create the source
that will be used to spin the paint sequence if something is being
animated using a timeline.
Unfortunately, the priority is too high and this causes starvation
when embedding into other toolkits -- like gtk+.
Thanks to Havoc Pennington for catching this.
The XVisualInfo for GL is created when a stage is being realized.
When embedding Clutter inside another toolkit we might not want to
realize a stage to extract the XVisualInfo, then set the stage
window using a foreign X Window -- which will cause a re-realization.
Instead, we should abstract as much as possible into the X11 backend.
Unfortunately, the XVisualInfo for GL is requested using GLX API; for
this reason we have to create a ClutterBackendX11 method that we
override inside the ClutterBackendGLX implementation.
This also allows us to move a little bit of complexity from out of
the stage realization, which is currently a very delicate and hard
to debug section.
I was seeing clutter_text_get_selection trying to malloc up to 4Gb due to
unexpected negative arithmetic for the start/end offsets which resulted
in a crash.
This just tests for positions of -1 before deciding if the start/end
positions need to be swapped. The conversion from position to byte offset
already works with -1.
cogl_clip_push_window_rect is implemented using GPU scissoring which allows
the GPU to cull anything that falls outside a given rectangle. Since in the
case of picking we only ever care about a single pixel we can get the GPU to
ignore all geometry that doesn't intersect that pixel and only rasterize for
one pixel.
Previously clipping could only be specified in object coordinates, now
rectangles can also be pushed in window coordinates.
Internally rectangles pushed this way are intersected and then clipped using
scissoring. We also transparently try to convert rectangles pushed in
object coordinates into window coordinates as we anticipate the scissoring
path will be faster then the clip planes and undoubtably it will be faster
than using the stencil buffer.
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.
COGLenum, COGLint and COGLuint which were simply typedefs for GL{enum,int,uint}
have been removed from the API and replaced with specialised enum typedefs, int
and unsigned int. These were causing problems for generating bindings and also
considered poor style.
The cogl texture filter defines CGL_NEAREST and CGL_LINEAR etc are now replaced
by a namespaced typedef 'CoglTextureFilter' so they should be replaced with
COGL_TEXTURE_FILTER_NEAREST and COGL_TEXTURE_FILTER_LINEAR etc.
The shader type defines CGL_VERTEX_SHADER and CGL_FRAGMENT_SHADER are handled by
a CoglShaderType typedef and should be replaced with COGL_SHADER_TYPE_VERTEX and
COGL_SHADER_TYPE_FRAGMENT.
cogl_shader_get_parameteriv has been replaced by cogl_shader_get_type and
cogl_shader_is_compiled. More getters can be added later if desired.
Calling glReadPixels is bad enough in forcing us to synchronize the CPU with
the GPU, but glFinish has even stronger synchonization semantics than
glReadPixels which may negate some driver optimizations possible in
glReadPixels.
Commit 43fa38fcf5 broke out-of-tree builds by removing some of the
builddir directories from the include path. builddir/clutter/cogl and
builddir/clutter are needed because cogl.h and cogl-defines-gl.h are
automatically generated by the configure script. The main clutter
headers are in the srcdir so this needs to be in the path too.
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>
Setting the stage window using the set_stage_foreign() method will
lead to a re-realization. We need to make sure that the Drawable
currently associated to the GL context is set to None, to avoid a
BadDrawable error or, if we're unlucky, a segfault in the X server.
This commit reverts part of commit 5bcde25c - specifically the
part that forced a realization of the stage if we are ensuring
the GL context with it. This makes Clutter behave like it did
prior to commit 5bcde25c: if we are asked to ensure the GL context
with an unrealized stage we simply pass NULL to the backend
implementation.
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.
Since we are destroying any previously set VisualInfo we keep we know
for sure that stage->xvisinfo is going to be None; hence, no reason to
check this condition.
The verify_map_state() internal method is conditionally compiled
if we have CLUTTER_ENABLE_DEBUG set; for this reason, all calls to
that method should be made conditional.
When building Clutter with introspection enabled everything stops
at Cogl GIR generation because it depends on the installed library
to work. Since we still require some changes in the API to be able
to build the GIR and the typelib for Cogl we should disable the
generation of the GIR as well.
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.
When destroying a top-level actor we can actually relax the verification
of the map state, since it might be fully asynchronous and we might not
re-enter inside the mainloop in time to receive the unmap notification.
If the filter means that the there should be no rows left in the model,
clutter_model_get_iter_at_row (model, 0) should return NULL.
Howevever the currene implementation misbehaves and returns a bad iterator.
This change resolves the issue by tracking if we actually found any
non-filtered rows in our pass through the sequence.
OH Bugzilla: 1591
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.
Currently, picking in ClutterGroup pollutes the CLUTTER_DEBUG=paint
logs since it just calls the paint function. Reimplementing the pick
doesn't make us lose anything -- it might even be slightly faster
since we don't have to do a (typed) cast and a class dereference.
The timeline created when calling set_timeline(NULL) is referenced
even though we implicitly own it. When the Animation is destroyed,
the timeline is then leaked.
Thanks to: Richard Heatley <richard.heatley@starleaf.com>
Fixes bug:
http://bugzilla.openedhand.com/show_bug.cgi?id=1548
Currently, the conversion from em to units is done by using the
default font name inside the backend. For actors using their own
font/text layout we need a way to specify the font name along
with the quantity we wish to transform.
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.
Currently, the default screen guard value is 0, which is a valid
screen number on X11, and it might not be the default.
Patch suggested by: Owen W. Taylor <otaylor@redhat.com>
Currently, the introspection data for Cogl is built right into
Clutter's own typelib. This makes functions like:
cogl_path_round_rectangle()
Appear as:
Clutter.cogl_path_round_rectangle()
It should be possible, instead, to have a Cogl namespace and:
Cogl.path_round_rectangle()
This means building introspection data for Cogl alone. Unfortunately,
there are three types defined in Cogl that confuse the introspection
scanner, and make it impossible to build a typelib:
COGLint
COGLuint
COGLenum
These three types should go away before 1.0, substituted by int,
unsigned int and proper enumeration types. For this reason, we can
just set up the GIR build and wait until the last moment to create
the typelib. Once that has been done, we will be able to safely
remove the Cogl API from the Clutter GIR and typelib and let
people import Cogl if they want to use the Cogl API via introspection.
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.
Add a method for deleting the current selection inside a Text actor.
This is useful for subclasses.
See bug:
http://bugzilla.openedhand.com/show_bug.cgi?id=1521
Based on a patch by: Raymond Liu <raymond.liu@intel.com>
ClutterAnimation currently inherits the initial floating reference
semantics from GInitiallyUnowned. An Animation is, though, meant to
be used as a top-level object, like a Timeline or a Behaviour, and
not "owned" by another object. For this reason, the initial floating
reference does not make any sense.
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
When calling clutter_model_iter_next () / clutter_model_iter_prev () we need
to update the row for the iterator. In order to improve the peformance of
iterating this change adds a private row mutator and switches ClutterListModel
to use it.
In order to carry out various comparisons for e.g. identifying the first
iterator in the model we need a ClutterModelIter. This change switches from
creating a new iterator each time to reusing an existing iterator.
The flags field of ClutterActor should have accessor methods for,
language bindings.
Also, the set_flags() and unset_flags() methods should actively
emit notifications for the changed properties.
This is simply a wrapper around cogl_color_set_from_4f and
cogl_material_set_color. We already had a prototype for this, it was
an oversight that it wasn't already implemented.
There were several functions I believe no one is currently using that were
only implemented in the GL backend (cogl_offscreen_blit_region and
cogl_offscreen_blit) that have simply been removed so we have a chance to
think about design later with a real use case.
There was one nonsense function (cogl_offscreen_new_multisample) that
sounded exciting but in all cases it just returned COGL_INVALID_HANDLE
(though at least for GL it checked for multisampling support first!?)
it has also been removed.
The MASK draw buffer type has been removed. If we want to expose color
masking later then I think it at least would be nicer to have the mask be a
property that can be set on any draw buffer.
The cogl_draw_buffer and cogl_{push,pop}_draw_buffer function prototypes
have been moved up into cogl.h since they are for managing global Cogl state
and not for modifying or creating the actual offscreen buffers.
This also documents the API so for example desiphering the semantics of
cogl_offscreen_new_to_texture() should be a bit easier now.
These are necessary if nesting redirections to an fbo,
otherwise there's no way to know how to restore
previous state.
glPushAttrib(GL_COLOR_BUFFER_BIT) would save draw buffer
state, but also saves a lot of other stuff, and
cogl_draw_buffer() relies on knowing about all draw
buffer state changes. So we have to implement a
draw buffer stack ourselves.
Signed-off-by: Robert Bragg <robert@linux.intel.com>
It is valid in some situations to have a material layer with an invalid texture
handle (e.g. if you setup a texture combine mode before setting the texture)
and so _cogl_material_layer_free needs to check for a valid handle before
attempting to unref it.
Adds missing notices, and ensures all the notices are consistent. The Cogl
blurb also now reads:
* Cogl
*
* An object oriented GL/GLES Abstraction/Utility Layer
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.
The clutter frame source tries to average out the frame deltas so that
if one frame takes 1 interval plus a little bit of extra time then the
next frame will be 1 interval minus that little bit of extra
time. Therefore the deltas can sometimes be less than the frame
interval. ClutterTimeline should accumulate these small differences
otherwise it will end up missing out frames so the total duration of
the timeline will be a lot longer.
For example this was causing test-actors to appear to run very slow.
The method of ClutterTimeline that advances the timeline by a
delta (in millisecond) is going to be useful for testing the
timeline's behaviour -- and unbreak the timeline test suite that
was broken by the MasterClock merge.
With the introduction of the map/unmap flags and the split of the
visible state from the mapped state we require that every part of
a scene graph branch is mapped in order to be painted. This breaks
the ability of a ClutterClone to paint an hidden source actor.
In order to fix this we need to introduce an override flag, similar
in spirit to the current modelview and paint opacity overrides that
Clone is already using.
The override flag, when set, will force a temporary map on a
Clone source (and its children).
ClutterContainer provides a foreach_with_internals() vfunc for
iterating over all of a container's children, be them added using
the Container API or be them internal to the container itself.
We should be using the foreach_with_internals() function instead
of the plain foreach().
When replacing the fbo_handle with a new handle it first unrefs the
old handle. This was previously a call to cogl_offscreen_unref which
silently ignored attempts to unref COGL_INVALID_HANDLE. However the
new cogl_handle_unref does check for this so we should make sure the
handle is valid to avoid the warning.
Bug 1565 - test-fbo case failed in many platform
clutter_texture_new_from_actor was broken because it created the FBO
texture but then never attached it to the material so it was never
used for rendering. The old behaviour in Clutter 0.8 was to assign the
texture directly to priv->tex. In 0.9 priv->tex is replaced with
priv->material which has a reference to the tex in layer 0. So putting
the FBO texture directly in layer 0 more closely matches the original
behaviour.
When rendering a pango layout CoglPangoRenderer now records the
operations into a list called a CoglPangoDisplayList. The entries in
the list are either glyph renderings from a texture, rectangles or
trapezoids. Multiple consecutive glyph renderings from the same glyph
cache texture are combined into a single entry. Note the
CoglPangoDisplayList has nothing to do with a GL display list.
After the display list is built it is attached to the PangoLayout with
g_object_set_qdata so that next time the layout is rendered it can
bypass rebuilding it.
The glyph rendering entries are drawn via a VBO. The VBO is attached
to the display list so it can be used multiple times. This makes the
common case of rendering a PangoLayout contained in a single texture
subsequent times usually boil down to a single call to glDrawArrays
with an already uploaded VBO.
The VBOs are accessed via the cogl_vertex_buffer API so if VBOs are
not available in GL it will resort to a fallback.
Note this will fall apart if the pango layout is altered after the
first render. I can't find a way to detect when the layout is
altered. However this won't affect ClutterText because it creates a
new PangoLayout whenever any properties are changed.
Currently ClutterModel::get_iter_at_row() ignores whether we have
a filter in place. This also extends to the get_n_rows() method.
The more consistent, more intuitive and surely more correct way to
handle a Model with a filter in place is to take into account the
presence of the filter itself -- that is:
- get_n_rows() should take into account the filter and return the
number of *filtered* rows
- get_iter_at_row() should also take the filter into account and
get the first non-filtered row
These two changes make the ClutterModel with a filter function
behave like a subset of the original Model without a filter in
place.
For instance, given a model with three rows:
- [row 0] <does not match filter>
- [row 1] <matches filter>
- [row 2] <matches filter>
- [row 3] <does not match filter>
The get_n_rows() method will return "2", since only two rows will
match the filter; the get_first_iter() method will ask for the
zero-eth row, which will return an iterator pointing to the contents
of row 1 (but the :row property of the iterator will be set to 0);
the get_last_iter() method will ask for the last row, which will
return an iterator pointing to the contents of row 2 (but the :row
property of the iterator will be set to 1).
This changes will hopefully make the Model API more consistent
in its usage whether there is a filter in place or not.
Currently, there is no way for implementations of the ClutterModel
abstract class to know whether there is a filter in place. Since
subclasses might implement some optimization in case there is no
filter present, we need a simple (and public) API to ask the model
itself.
Setting the wrap mode on the PangoLayout seems to have disappeared
during the text-actor-layout-height branch merge so this brings it
back. The test for this in test-text-cache no longer needs to be
disabled.
We also shouldn't set the width on the layout if there is no wrapping
or ellipsizing because otherwise it implicitly enables wrapping. This
only matters if the actor gets allocated smaller than its natural
size.
Bug 1484 - Redraw ClutterClone when the source changes, even for
!visible sources
Connect to ::queue-redraw on the clone source and queue a redraw.
This allows redrawing the Clone when the source changes, even in
case of a non visible source actor.
http://bugzilla.openedhand.com/show_bug.cgi?id=1484
Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
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.
