At the end of GtkImage css validation (during style-updated) when the
css properties (like the icon size) are valid we call _gtk_icon_helper_preload
which does an async icon theme lookup and load. This will happen on a thread
in parallel with the rest of the css machinery, and hopefully by the
time we need the icon it will be ready. If not we will block when we need
it, but during that blocking all the other icons will be loaded.
Testing widget-factory this changes the time of snapshot() from 31 to
25 msec, but on the other hand we also load a few more icons that we
didn't before causing the css validation phase to be about 8 msec slower.
This is because we're preloading all the images in the window, not only
the ones that are visible.
Unfortunately we still load a bunch of icons in snapshot(), from
GtkCssImageIconTheme, and ideally we should try to preload those also.
This happens when we first get the theme for a display, or then the
icon theme setting changes.
This means we don't have to do this scan in the first snapshot
and can do the i/o it in parallel with other stuff. This moves
a 10msec block from the first snapshot cycle to early setup.
If some other thread is lock the icon or icon theme locks they are likely
to do so for a long time, doing i/o. So, switch to trylock() for the
nonblocking part of _async(). This way we can return directly if the
result is available, but do a thread otherwise, never blocking the
calling (main) thread.
Move the lru cache under the global cache lock to avoid some ABBA
style deadlocks when going from icon_theme->icon lock an icon->icon_theme.
We also move all the icon lock uses to a small part of code and make
sure that code never calls out or blocks with any locks held.
Rename the GtkIcon->cache_lock to texture_lock to avoid confusion withe
the global cache_lock.
Removed any mentions of threadsafety from the API docs, we don't
want apps to rely on this, but rather use it outselves internally.
This was added in 0b1c9b7cc2 to protect
against reentrancy from the theme-changed signal, but we only emit this
from an idle these days, so thats not necessary anymore, and the recursion
check was causing issues with the async operations where a different
thread loading the theme caused the calling thread to thing the
theme is valid.
This makes GtkIconInfo directly implement paintable by loading
the icon as needed. This is done in a blocking fashion for now, but
could be made more async in the future.
It also means we can't return errors to the called, but I doubt
anyone actually does anything useful with them other than showing
nothing (which we already do).
This also changes a fringe behaviour for unthemed icons. They used to
be never scaled down, but that means we can't tell without i/o the
size of the paintable. Since this is the only case we can't know the
size i took an executive decision and removed that behaviour. I don't
think picking some arbitrary much larger than requested size is ever
right, nor do i think using GtkIconTheme with unthemed icons is overly
useful. If you want to display some random non-iconish image, use
GtkImage instead.
Replace uses of gtk_css_style_get_value with direct access,
throughout the tree. We don't replace all uses, just those
where we are dealing with a fixed property. Be careful to
handle the currentColor special case for color properties.
Introduce refcounted structs for groups of related css properties,
and use them to store the style values. Both GtkCssStaticStyle and
GtkCssAnimatedStyle fill in the structs in GtkCssStyle, and we
can avoid vfuncs for value access, which should be much faster.
We can even start accessing style->core->color directly.
