A clutter actor might be painted on a stage view with a view scale
other than 1. In this case, to show the content in full resolution, the
actor must use a higher resolution resource (e.g. texture), which will
be down scaled to the stage coordinate space, then scaled up again to
the stage view framebuffer scale.
Use a 'resource-scale' property to save information and notify when it
changes.
The resource scale is the ceiled value of the highest stage view scale a
actor is visible on. The value is ceiled because using a higher
resolution resource consistently results in better output quality. One
reason for this is that rendering is often not perfectly pixel aligned,
meaning even if we load a resource with a suitable size, due to us still
scaling ever so slightly, the quality is affected. Using a higher
resolution resource avoids this problem.
For situations inside clutter where the actual maximum view scale is
needed, a function _clutter_actor_get_real_resource_scale() is provided,
which returns the non-ceiled value.
Make sure we ignore resource scale computation requests during size
requests or allocation while ensure we've proper resource-scale on
pre-paint.
https://bugzilla.gnome.org/show_bug.cgi?id=765011https://gitlab.gnome.org/GNOME/mutter/merge_requests/3
ad5555bf42