Input backends are, in some cases, independent from the windowing system
backends; we can initialize input handling using a model similar to what
we use for windowing backends, including an environment variable and
compile-/run-time checks.
This model allows us to remove the backend-specific init_events(), and
use a generic implementation directly inside the base ClutterBackend
class, thus further reducing the backend-specific code that every
platform has to implement.
This requires some minor surgery to every single backend, to make sure
that the function exposed to initialize the event loop is similar and
performs roughly the same operations.
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.
The g_atexit() function has been deprecated in GLib as it is a fairly
bad idea in basically all cases.
We could probably use a GCC destructor if we didn't care about
portability, but for the time being we just remove the atexit() handler
that disposed the backend.
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.
This gives us a way to clearly track the internal Cogl API that Clutter
depends on. The aim is to split Cogl out from Clutter into a standalone
3D graphics API and eventually we want to get rid of any private
interfaces for Clutter so its useful to have a handle on that task.
Actually it's not as bad as I was expecting though.
eglGetProcAddress() returns non-null function pointers
whether or not they're actually supported by the driver,
since it can be used before any driver gets loaded. So
we have to check if the extensions are advertised first,
which requires having an initialized display, so we split
the display creation code into its own function.
The exception to extension-checking is EGL_MESA_drm_display,
since by definition it's needed before any display is even
created.
Adapt to changes from this Wayland commit:
"Update surface.attach and change surface.map to surface.map_toplevel"
(82da52b15b49da3f3c7b4bd85d334ddfaa375ebc)
Adapt to changes from these wayland commits:
35fd2a8cc68c42d90756330535de04cbbb4d2613
2bb3ebe1e437acf836449f0a63f3264ad29566f2
f8fc08f77187f6a5723281dab66841e5f3c24320
http://bugzilla.clutter-project.org/show_bug.cgi?id=2474
Always use pageflipping, but avoid full repaint by copying back dirty
regions from front to back. Additionally, we dealy copying back until
we're ready to paint the new frame, so we can avoid copying areas that
will be repainted anyway.
This is the least amount of copying per frame we can get away with at all
and at the same time we don't have to worry about stalling the GPU on
synchronized blits since we always pageflip.
