This updates Wayland support in line with upstream changes to the Wayland
API and protocol.
This update means we no longer use the Cogl stub winsys so a lot of code
that had to manually interact with EGL and implement a swap_buffers
mechanism could be removed and instead we now depend on Cogl to handle
those things for us.
This update also adds an input device manager consistent with other
clutter backends.
Note: to use the client side "wayland" clutter backend you need to have
built Cogl with --enable-wayland-egl-platform. If Cogl has been built
with support for multiple winsys backends then you should run
applications with COGL_RENDERER=EGL in the environment.
Reviewed-by: Emmanuele Bassi <ebassi@linux.intel.com>
Generate a .bat file to generate the clutter-enum-types.[ch] for use
during the Visual C++ build process, which will greatly simplify the
maintenanace of the VS build files as public headers are added or removed
during the development process.
Instead of piggybacking on the EGL backend, let's create a small
ClutterBackend for the CEx100 platforms. This allows us to handle the
CEx100-specific details in a much cleaner way.
All the functionality that ClutterBackendCogl provided has been moved
into ClutterBackend itself, so there is no need to have this class
around in the source.
Cogl-based backends can derive directly from ClutterBackend.
The clutter-stage.h header still has a bunch of macros that have, for
reasons unknown[*], survived the 1.0 API cut and have long since been
deprecated. Let's hide them under the deprecated/ carpet and let us
never speak of them ever again.
[*] pretty sure alcohol or other psychotropic substances were involved
but I take the 5th on that.
The Clutter backend split is opaque enough that should allow us to just
build all possible backends inside the same shared object, and select
the wanted backend at initialization time.
This requires some work in the build system, as well as the
initialization code, to remove duplicate functions that might cause
conflicts at build and link time. We also need to defer all the checks
of the internal state of the platform-specific API to run-time type
checks.
Previously, the Cogl backend was at times a subclass of the X11
backend, and at times a standalone one. Now it is the other way
round, with GDK and X11 backends providing the concrete classes,
layered on top of the generic Cogl backend. A new EglNative backend
was introduced for direct to framebuffer rendering. This greatly
simplifies the API design (at the expense of some casts needed)
and reduces the amount of #ifdefs, without duplicating code.
https://bugzilla.gnome.org/show_bug.cgi?id=657434
This commit introduces a new flavour for Clutter, that uses GDK
for handling all window system specific interactions (except for
creating the cogl context, as cogl does not know about GDK), including
in particular events. This is not compatible with the X11 (glx)
flavour, and this is reflected by the different soname (libclutter-gdk-1.0.so),
as all X11 specific functions and classes are not available. If you
wish to be compatible, you should check for CLUTTER_WINDOWING_X11.
Other than that, this backend should be on feature parity with X11,
including XInput 2, XSettings and EMWH (with much, much less code)
https://bugzilla.gnome.org/show_bug.cgi?id=657434
The number of deprecations in clutter-main.h makes the header harder to
parse, and more confusing. We can use a separate header under the
deprecated subdirectory to hold all the deprecated symbols.
The code that has been deprecated should live into its own directory,
both in the repository and when installed. This should make it clear
which functionality is actually maintained and which is not.
We start with an oldie: the frame source API.
ClutterSettings should be able to load its initial state by using
configuration files in SYSCONFDIR and XDG_CONFIG_HOME. This allows
Clutter to have a system (and user) configuration on platforms that
do not have XSETTINGS bridges.
It was already the intention that the ClutterGLXTexturePixmap API should
be built and made available on any X11 based platforms since there was
nothing specific about the API and it is useful to have for
compatibility. There was a mistake in the Makefile.am though which meant
only the header was getting installed but the code wasn't being built.
Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
Since GLX and EGL are abstracted by Cogl the two backends are both
implementing everything using the Cogl API and they are almost
identical.
This updates the egl backend to support everything that the glx backend
supports. Now that EGL and GLX are abstracted by Cogl, the plan is that
we will squash the clutter-egl/glx backends into one. Since the EGL
backend in clutter can conditionally not depend on X11 we will use the
EGL backend as the starting point of our common backend.
https://bugzilla.gnome.org/show_bug.cgi?id=649826
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.
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.
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.
This backend hasn't been used for years now and so because it is
untested code and almost certainly doesn't work any more it would be a
burdon to continue trying to maintain it. Considering that we are now
looking at moving OpenGL window system integration code down from
Clutter backends into Cogl that will be easier if we don't have to
consider this backend.
This makes it possible to build Clutter against a standalone build of
Cogl instead of having the Clutter build traverse into the clutter/cogl
subdirectory.
This adds an autogen.sh, configure.ac and build/autotool files etc under
clutter/cogl and makes some corresponding Makefile.am changes that make
it possible to build and install Cogl as a standalone library.
Some notable things about this are:
A standalone installation of Cogl installs 3 pkg-config files;
cogl-1.0.pc, cogl-gl-1.0.pc and cogl-2.0.pc. The second is only for
compatibility with what clutter installed though I'm not sure that
anything uses it so maybe we could remove it. cogl-1.0.pc is what
Clutter would use if it were updated to build against a standalone cogl
library. cogl-2.0.pc is what you would use if you were writing a
standalone Cogl application.
A standalone installation results in two libraries currently, libcogl.so
and libcogl-pango.so. Notably we don't include a major number in the
sonames because libcogl supports two major API versions; 1.x as used by
Clutter and the experimental 2.x API for standalone applications.
Parallel installation of later versions e.g. 3.x and beyond will be
supportable either with new sonames or if we can maintain ABI then we'll
continue to share libcogl.so.
The headers are similarly not installed into a directory with a major
version number since the same headers are shared to export the 1.x and
2.x APIs (The only difference is that cogl-2.0.pc ensures that
-DCOGL_ENABLE_EXPERIMENTAL_2_0_API is used). Parallel installation of
later versions is not precluded though since we can either continue
sharing or later add a major version suffix.
if cross compiling clutter using mingw using an out of tree build
directory then a pre-requisite for creating the resources.o file
containing the transparent cursor is for the win32 directory itself to
be created at $(top_builddir)/clutter/win32.
The table we use for converting between keysyms and Unicode should be
static and constified, so that it can live in the .rodata section of
the ELF shared object, and be shared among processes.
This change moves the table to a source file, instead of an header; the
change also requires the clutter_keysym_to_unicode() function to be
moved from clutter-event.c into this new source file. The declaration is
still in clutter-event.h, so we don't need to do anything special.
Since the FBO target might have a different size than the mere paint box
of the actor, we need API to get it out of the ClutterOffscreenEffect
private data structure and on to sub-classes.
Since we cannot add new API in a stable cycle, we need a private
function; we'll leave it there even when opening 1.7, since it's useful
for internal purposes.
Implementation of event loop which works with GLib events, native OS X
events and Clutter events.
The event loop source code comes from the equivalent code in the Quartz
GDK backend from GTK+ 2.22.1, which is LGPL v2.1+ and thus compatible
with Clutter's licensing terms.
The code has been tested with libsoup, which did not work before together
with Clutter.
Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
http://bugzilla.clutter-project.org/show_bug.cgi?id=2490
This is a lump commit that is fairly difficult to break down without
either breaking bisecting or breaking the test cases.
The new design for handling X11 event translation works this way:
- ClutterBackend::translate_event() has been added as the central
point used by a ClutterBackend implementation to translate a
native event into a ClutterEvent;
- ClutterEventTranslator is a private interface that should be
implemented by backend-specific objects, like stage
implementations and ClutterDeviceManager sub-classes, and
allows dealing with class-specific event translation;
- ClutterStageX11 implements EventTranslator, and deals with the
stage-relative X11 events coming from the X11 event source;
- ClutterStageGLX overrides EventTranslator, in order to
deal with the INTEL_GLX_swap_event extension, and it chains up
to the X11 default implementation;
- ClutterDeviceManagerX11 has been split into two separate classes,
one that deals with core and (optionally) XI1 events, and the
other that deals with XI2 events; the selection is done at run-time,
since the core+XI1 and XI2 mechanisms are mutually exclusive.
All the other backends we officially support still use their own
custom event source and translation function, but the end goal is to
migrate them to the translate_event() virtual function, and have the
event source be a shared part of Clutter core.
Clutter has some platform-specific API that is accessible only if the
right backend has been compiled in. Third party applications that wish
to be portable across backends might want to use defines and other
pre-processor tricks to determine header inclusion and API usage.
While Clutter has an internal set of symbols it can use, third party
applications don't have the luxury of being able to access the config.h
generated by Clutter's configure script.
For this reason, Clutter should install a configuration header with a
series of namespaced defines that can be picked up by applications and
other third party code.
The device manager now fully owns the GSources corresponding to the
devices it manages. This will allow not only to remove the source when
udev signals a device removal but also handle read() errors gracefully
by removing the faulty device from the manager.
This backend is a event backend that can be enabled for EGL (for now).
It uses udev (gudev) to query input devices on a linux system, listens to
keyboard events from input devices and xkbcommon to translate raw key
codes into key keysyms.
This commit only supports key events, more to follow.
The wayland client code has support for translating raw linux input
device key codes coming from the wayland compositor into key symbols
thanks to libxkbcommon.
A backend directly listening to linux input devices (called evdev, just
like the Xorg one) could use exactly the same code for the translation,
so abstract it a bit in a separate file.
Since EGA colors are apparently all the rage in other toolkits, Clutter
should not be left out. On top of the usual CGA/EGA palette the static
colors also include the Tango Icon palette, which at least is more
pleasant to the eye.
Static colors are accessed through an enumeration by using
clutter_color_get_static(), or using the short-hand pre-processor
macros.
http://bugzilla.clutter-project.org/show_bug.cgi?id=2066
The profiling support was broken - probably during the restructuring of
the build environment, but I'm too lazy to bisect that.
The fix is trivial, and everything works as it should.
* private-cleanup:
Add copyright notices
Clean up clutter-private.h/6
Clean up clutter-private.h/5
Clean up clutter-private.h/4
Clean up clutter-private.h/3
Clean up clutter-private.h/2
Clean up clutter-private.h/1
ClutterPathConstraint is a simple Constraint implementation that
modifies the allocation of the Actor to which is has been applied using
a progress value and a ClutterPath.
Move the private Backend API to a separate header.
This also allows us to finally move the class vtable and instance
structure to a separate file and plug the visibility hole that left
the Backend class bare for everyone to poke into.
After commit 8dd8fbdb some errors appear if you try work directly
against cally:
* cally.pc.in removed some elements. After install clutter, doing
pkg-config --cflags cally-1.0
fails due missing winsys
* cally headers were moved from clutter-1.0/cally to
clutter-1.0/clutter/cally. Applications using it (yes I know,
nobody is officially using it) would require to:
* Change their include.
* Add directly a dependency to cally, in order to use the cally.pc
file with the correct directory include.
Note: Take into account that accessibility support still works (ie:
clutter_get_accessibility_enabled). This bug only prevents
applications to work directly against cally (ie: create a CallyActor
subclass)
http://bugzilla.clutter-project.org/show_bug.cgi?id=2353
Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
Like we do for the Quartz backend, we should turn on the -xobjective-c
compiler flag for the Fruity backend.
This does not mean that the backend actually works.
The internal copy of JSON-GLib was meant to go away right after the 1.0
release, given that JSON-GLib was still young and relatively unknown.
Nowadays, many projects started depending on this little library, and
distributions ship it and keep it up to date.
Keeping a copy of JSON-GLib means keeping it up to date; unfortunately,
this would also imply updating the code not just for the API but for the
internal implementations.
Starting with the 1.2 release, Clutter preferably dependend on the
system copy; with the 1.4 release we stopped falling back automatically.
The 1.6 cycle finally removes the internal copy and requires a copy of
JSON-GLib installed on the target system in order to compile Clutter.
This splits out all the clutter_paint_volume code from clutter-actor.c
into clutter-paint-volume.c. Since clutter-actor.c and
clutter-paint-volume.c both needed the functionality of
_fully_transform_vertices, this function has now been moved to
clutter-utils.c as _clutter_util_fully_transform_vertices.
*** WARNING: THIS COMMIT CHANGES THE BUILD ***
Do not recurse into the backend directories to build private, internal
libraries.
We only recurse from clutter/ into the cogl sub-directory; from there,
we don't recurse any further. All the backend-specific code in Cogl and
Clutter is compiled conditionally depending on the macros defined by the
configure script.
We still recurse from the top-level directory into doc, clutter and
tests, because gtk-doc and tests do not deal nicely with non-recursive
layouts.
This change makes Clutter compile slightly faster, and cleans up the
build system, especially when dealing with introspection data.
Ideally, we also want to make Cogl part of the top-level build, so that
we can finally drop the sed trick to change the shared library from the
GIR before compiling it.
Currently disabled:
‣ OSX backend
‣ Fruity backend
Currently enabled but untested:
‣ EGL backend
‣ Windows backend
Instead of doing the shlib trick, build ClutterJson (if needed) inside
the top-level clutter/ directory - similar to a non-recursive layout.
Hopefully, one day, we'll be able to do this with a real non-recursive
layout.
The keysyms defines in clutter-keysyms.h are generated from the X11 key
symbols headers by doing the equivalent of a pass of sed from XK_* to
CLUTTER_*. This might lead to namespace collisions, down the road.
Instead, we should use the CLUTTER_KEY_* namespace.
This commit includes the script, taken from GDK, that parses the X11
key symbols and generates two headers:
- clutter-keysyms.h: the default included header, with CLUTTER_KEY_*
- clutter-keysyms-compat.h: the compatibility header, with CLUTTER_*
The compat.h header file is included if CLUTTER_DISABLE_DEPRECATED is
not defined - essentially deprecating all the old key symbols.
This does not change any ABI and, assuming that an application or
library is not compiling with CLUTTER_DISABLE_DEPRECATED, the source
compatibility is still guaranteed.
Make sure we don't use deprecated API internally by adding
CLUTTER_DISABLE_DEPRECATED to the AM_CPPFLAGS.
This requires adding -UCLUTTER_DISABLE_DEPRECATED to the introspection
scanner CFLAGS, otherwise the deprecated API will never be introspected
and the data generated will not be compatible.
If we're depending on an uninstalled .gir, use --include-uninstalled.
We need to explicitly specify Cogl to let the scanner know it's also
uninstalled.
Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
This patch merges in substantial work from
Emmanuele Bassi <ebassi@linux.intel.com>
* Use new introspection --include-uninstalled API since we don't want
to try to find the clutter-1.0.pc file before it's installed.
* Use --pkg-export for Clutter-1.0.gir, since we want the .gir file to
contain the associated pkg-config file.
* Drop the use of --pkg for dependencies; those come from the associated
.gir files. (Actually, --pkg is almost never needed)
* Add --quiet
http://bugzilla.clutter-project.org/show_bug.cgi?id=2292
--quiet has been added to g-ir-scanner in the 0.9.1 cycle. We really
want to be able to compile clutter with 0.6.14 to be able to reuse
gir files that are distributed in current distributions.
Use the INTROSPECTION_SCANNER_ARGS (previously unused) variable to
convey --quiet when necessary.
Fixes: http://bugzilla.clutter-project.org/show_bug.cgi?id=2265
A TableLayout is a layout manager that allocates its children in rows
and columns. Each child is assigned to a cell (or more if a cell span
is set).
The supported child properties are:
• x-expand and y-expand: if this cell with try to allocate the
available extra space for the table.
• x-fill and y-fill: if the child will get all the space available in
the cell.
• x-align and y-align: if the child does not fill the cell, then
where the child will be aligned inside the cell.
• row-span and col-span: number of cells the child will allocate for
itself.
Also, the TableLayout has row-spacing and col-spacing for specifying
the space in pixels between rows and between columns.
We also include a simple test of the layout manager, and the
documentation updates.
The TableLayout was implemented starting from MxTable and
ClutterBoxLayout.
http://bugzilla.clutter-project.org/show_bug.cgi?id=2038
Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
The introspection scanner does not include '.' by default, so it was
always using the installed copy of Clutter-1.0.gir. Which obviously
wouldn't work if we didn't have one.
Toolkits and applications not written in C might still need access to
the Cally API to write accessibility extensions based on it for their
own native elements.
The Clutter Accessibility Library is an implementation of the ATK,
the Accessibility Toolkit, which exposes Clutter actors to accessibility
tools. This allows not only writing accessible user interfaces, but also
allows testing and verification frameworks based on A11Y technologies to
inspect and test a Clutter scene graph.
http://bugzilla.clutter-project.org/show_bug.cgi?id=2097
Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
The -Bsymbolic-functions linker flag allows to avoid intra-library
PLT jumps on ELF platforms. It is similar to the aliasing hack in
GLib and GTK+, but definitely less messy.
The configure script should look for the flags, in order to support
platforms/linkers that do not have it.
This adds a separate variable name "CLUTTER_SONAME_INFIX" to define the
infix for the clutter library that gets linked. Currently the WINSYS
corresponds to the directory we enter when building to compile the
window system and input support, but it is desirable to be able to
define multiple flavours that use the same WINSYS but should result in
different library names.
For example we are planning to combine the eglx and eglnative window
systems into one "egl" winsys but we will need to preserve the current
library names for the eglx and eglnative flavours.
* wip/deform-effect:
docs: Add DeformEffect and PageTurnEffect to the API reference
effect: Add PageTurnEffect
effect: Add DeformEffect
offscreen-effect: Traslate the modelview with the offsets
docs: Fix Effect subclassing section
The marshallers we use for the signals are declared in a private header,
and it stands to reason that they should also be hidden in the shared
object by using the common '_' prefix. We are also using some direct
g_cclosure_marshal_* symbol from GLib, instead of consistently use the
clutter_marshal_* symbol.
DeformEffect is an abstract class that should be used to write effects
that change the geometry of an actor before submitting it to the GPU.
Just like the ShaderEffect class, DeformEffect renders the actor to
which it has been applied into an FBO; then it creates a mesh and stores
it inside a VBO. Sub-classes can control vertex attributes like
position, texel coordinates and the color.
As with a351ff2af earlier, distributing headers generated at configure
time conflicts with out of tree builds as the distributed headers will
be included first instead of including the generated ones.
clutter-jon.h is generated at configure time, we should not distribute it.
This caused a build issue when compiling from a tarballs and out of tree
builds as we ended up with two clutter-json.h one in $(top_srcdir)/json
and the other in $(top_builddir)/json and picked up the wrong one
($(top_srcdir)/json is included first in the include search path).
A simple, GLSL shader-based blur effect.
The blur shader is taken straight from the test-shader.c interactive
test case. It's a fairly clunky, inefficient and visually incorrect
implementation of a box blur, but it's all we have right now until I
figure out a way to do multi-pass shading with the current API.
The ShaderEffect class is an abstract base type for shader-based
effects. GLSL-based effects should be implemented by sub-classing
ShaderEffect and overriding ActorMeta::set_actor() to set the source
code of the shader, and Effect::pre_paint() to update the uniform
values, if any.
The ShaderEffect has a generic API for sub-classes to set the values
of the uniforms defined by their shaders, and it uses the shader
types we defined for ClutterShader, to avoid re-inventing the wheel
every time.
The OffscreenEffect class is meant to be used to implement Effect
sub-classes that create an offscreen framebuffer and redirect the
actor's paint sequence there. The OffscreenEffect is useful for
effects using fragment shaders.
Any shader-based effect being applied to an actor through an offscreen
buffer should be used before painting the resulting target material and
not for every actor. This means that doing:
pre_paint: cogl_program_use(program)
set up offscreen buffer
paint: [ actors ] → offscreen buffer → target material
post_paint: paint target material
cogl_program_use(null)
Is not correct. Unfortunately, we cannot really do:
post_paint: cogl_program_use(program)
paint target material
cogl_program_use(null)
Because the OffscreenEffect::post_paint() implementation also pops the
offscreen buffer and re-instates the previous framebuffer:
post_paint: cogl_program_use(program)
change frame buffer ← ouch!
paint target material
cogl_program_use(null)
One way to fix it is to allow using the shader right before painting
the target material - which means adding a new virtual inside the
OffscreenEffect class vtable in additions to the ones defined by the
parent Effect class.
The newly-added paint_target() virtual allows the correct sequence of
actions by adding an entry point for sub-classes to wrap the "paint
target material" operation with custom code, in order to implement the
case above correctly as:
post_paint: change frame buffer
cogl_program_use(program)
paint target material
cogl_program_use(null)
The added upside is that sub-classes of OffscreenEffect involving
shaders really just need to override the prepare() and paint_target()
virtuals, since the pre_paint() and post_paint() do all that's needed.
ClutterEffect is an abstract class that should be used to apply effects
on generic actors.
The ClutterEffect class just defines what an effect should implement; it
could be defined as an interface, but we might want to add some default
behavior dependent on the internal state at a later point.
The effect API applies to any actor, so we need to provide a way to
assign an effect to an actor, and let ClutterActor call the Effect
methods during the paint sequence.
Once an effect is attached to an actor we will perform the paint in this
order:
• Effect::pre_paint()
• Actor::paint signal emission
• Effect::post_paint()
Since an effect might collide with the Shader class, we either allow a
shader or an effect for the time being.
We need to tell the introspection scanner all the dependencies we
require, including the pkg-config name to use when compiling the
GIR file into a typelib object.
ClickAction adds "clickable" semantics to an actor. It provides all
the business logic to emit a high-level "clicked" signal from the
various low-level signals inside ClutterActor.
* wip/state-machine:
Do not use wildcards in test-state
script: Implement State deserialization
state: added a "target-state" property
state: documented data structures
Add State interactive tests to the ignore file
state: Documentation and introspection annotation fixes
state: Minor coding style fixes
state: Clean up the header's documentation
state: Constify StateKey accessors
Do not include clutter.h from a Clutter header file
state-machine: made clutter_state_change take a boolean animate argument
state-machine: use clutter_timeline_get_progress
state-machine: add completed signal
state machine: added state machine
Conflicts:
.gitignore
* wip/constraints: (24 commits)
Add the Cogl API reference to the fixxref extra directories
Document the internal MetaGroup class
Remove the construct-only flag from ActorMeta:name
doc: Remove gtk-doc annotations from the json-glib copy
doc: Fix parameter documentation
Add named modifiers for Action and Constraint
Remove a redundant animation
Set the stage resizable in test-constraints
Use a 9 grid for the constraints test
Miscellaneous documentation fixes
docs: Document animating action and constraint properties
docs: Document BindConstraint and AlignConstraint
constraint: Rename BindConstraint:bind-axis
constraints: Add AlignConstraint
tests: Add a constraints interactive test
constraint: Add BindConstraint
actor: Implement Animatable
animation: Use the new Animatable API for custom properties
animatable: Add custom properties to Animatable
constraint: Add ClutterConstraint base class
...
Conflicts:
configure.ac
AlignConstraint is a simple constraint that keeps an actor's position
aligned to the width or height of another actor, multiplied by an
alignment factor.
The Constraint base, abstract class should be used to implement Actor
modifiers that affect the way an actor is sized or positioned inside a
fixed layout manager.
DragAction is an Action sub-class that provides dragging capabilities to
any actor. DragAction has:
• drag-begin, drag-motion and drag-end signals, relaying the event
information like coordinates, button and modifiers to user code;
• drag-threshold property, for delaying the drag start by a given
amount of pixels;
• drag-handle property, to allow using other actors as the drag
handle.
• drag-axis property, to allow constraining the dragging to a specific
axis.
An interactive test demonstrating the various features is also provided.
ClutterAction is an abstract class that should be used as the ancestor
for objects that change how an actor behaves when dealing with events
coming from user input.
ClutterActorMeta is a base, abstract class that can be used to derive
classes that are attached to a ClutterActor instance in order to modify
the way an actor is painted, sized/positioned or responds to events.
A typed container for ActorMeta instances is also provided to the
sub-classes can be attached to an Actor.
