This is a quick implementation that avoids many
glyph cache lookups. We keep an array of direct
pointers in the text render node, and throw those
cached pointers away whenever any atlases have
been dropped (since that may invalidate the cached
glyphs).
We were putting big glyphs in the cache, in their
own texture, but forgetting to mark the texture
as permanent, so it could be reused, leading to
occasional misrendering. Fix this by marking these
textures as permanent, and explicitly freeing them
when the cache entry gets old.
There is no need for us to be very precise about
aging the glyph entries. It is enough to check
occasionally and mark old entries. This reduces
the overhead of work we do every frame on the
caches, at the cost of letting glyphs linger
a bit longer in the cache.
Make this function more similar to the icon
cache equivalent, and simplify it a bit. We
don't use the boolean return, and we don't need
to look at the age of entry when marking it
used.
Remember which atlases were removed, and only
check those when looking for icons or glyphs
to remove. For most frames, we don't have to
check at all since no atlases were removed.
Pass the glyph position into the glyph caching functions,
not just the glyph index. This allows us to cache different
images for different subpixel positions.
Use the same texture atlases to back both
the glyph and icon caches, and unify their
sizes and management. Store big glyphs
in separate textures, so all atlases have
the same size. Tweak some of the eviction
parameters.
We share the caches across all GL contexts
on a display, unless the GSK_NO_SHARED_CACHES
env var is set.
Add a setter for per-renderer debug flags, and use
them where possible. Some places don't have easy access
to a renderer, so this is not complete.
Also, use g_message instead of g_print throughout.
