If you add a widget to a parent, this will invalidate the css nodes
for parent/siblings. Afterwards, if the parent is mapped, we will
realize the new child. This calls gtk_widget_update_alpha() which
needs the css opacity, so it revalidates the css.
Thus, for each widget_add (while visible) will trigger a full
revalidation of each sibling. If you add N children to a parent that
leads to O(N^2) revalidations.
To demo this I changed gtk-demo to always double the count
(independent of the fps) and print the time it took. Here is the
results (after a bit):
Setting fishbowl count=256 took 3,4 msec
Setting fishbowl count=512 took 10,1 msec
Setting fishbowl count=1024 took 34,1 msec
Setting fishbowl count=2048 took 126,3 msec
Setting fishbowl count=4096 took 480,3 msec
Setting fishbowl count=8192 took 1892,7 msec
Setting fishbowl count=16384 took 7751,0 msec
Setting fishbowl count=32768 took 38097,7 msec
Setting fishbowl count=65536 took 191987,7 msec
To fix this we drop gtk_widget_update_alpha() and just
calculate it when needed (which is only in a single place).
It was really only necessary because we previously set
the alpha on the surface.
With this fix the above becomes:
Setting fishbowl count=256 took 1,0 msec
Setting fishbowl count=512 took 1,9 msec
Setting fishbowl count=1024 took 3,7 msec
Setting fishbowl count=2048 took 7,4 msec
Setting fishbowl count=4096 took 18,1 msec
Setting fishbowl count=8192 took 31,0 msec
Setting fishbowl count=16384 took 66,3 msec
Setting fishbowl count=32768 took 126,7 msec
Setting fishbowl count=65536 took 244,6 msec
Setting fishbowl count=131072 took 492,2 msec
Setting fishbowl count=262144 took 984,3 msec
It's private, no APIs, we don't talk about it. But we will start using
it very soon, so we can do size request caching in columns and avoid
sizegroups...
Add back a property that determines whether an individual
widget will accept focus or not. :can-focus prevents the
focus from ever entering the entire widget hierarchy
below a widget, and :focusable just determines if grabbing
the focus to the widget itself will succeed.
See #2686
This gives us a hook to walk the widget tree whenever a global
setting changes and do per-widget invalidations. This will
replace gtk_style_context_reset_widgets().
This is used for widgets that contain the focus widget,
reserving the focused state for the focus location itself.
This aligns our focus state handling with
https://www.w3.org/TR/selectors-4/
People should use shortcut controllers instead (global, capture).
A side effect of this is that GtkAccelLabel now lost its method to
magically look up accelerators to display. Somebody needs to add that
back later.
It's an outdated technology now that everybody is using GActionGroups.
If somebody wanted to support changeable shortcuts, they'd need to
reintroduce it in another way.
We want access to the private data from the action muxer so we can just
move the structures to the gtkwidgetprivate.h header. Alternatively we
could create accessors, but given that we'll probably need to use this
in other areas, seems reasonable to just put it there.
People should use shortcut controllers instead (global, capture).
A side effect of this is that GtkAccelLabel now lost its method to
magically look up accelerators to display. Somebody needs to add that
back later.
It's an outdated technology now that everybody is using GActionGroups.
If somebody wanted to support changeable shortcuts, they'd need to
reintroduce it in another way.
Emit crossing events - with a new GTK_CROSSING_DROP type - like we do
for motion events. There is no more special casing for them.
Note that the gesture has not been updated yet, so some obscure behavior
may occur.
We don't want to expose the GtkCrossingData struct, and manually
feeding events to event controllers is not something we want to
encourage, going forward.
Instead of relying on gdk's antiquated crossing events,
create a new GtkCrossingData struct that contains the
actual widgets, and a new event controller vfunc that
expects this struct. This also saves us from making sense
of X's crossing modes and details, and makes for a
generally simpler api.
The ::focus-in and ::focus-out signals of GtkEventControllerKey
have been replaced by a single ::focus-change signal that
takes GtkCrossingData as an argument. All callers have
been updated.
We want to make events readonly, so stop translating
their coordinates and instead pass the translated
coordinates separately, when propagating events.
1. Rename the thing
2. Turn it from a signal to a vfunc
3. Pass the GtkCssStyleChange to it
We don't export any public API about the GtkCssStyleChange yet, it's
just a boring opaque struct.
