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.
* 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.
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.
