We may have the situation of multiple touchpoints in the same
widget, or combinations with other devices. Stack those ::active
states are preserved on widgets on all but the last pointer/touch
going away.
Some widgets have different accessible roles depending on some
parameter, so we cannot set the role at class init time. For those
widgets, we add an "accessible-role" property to GtkAccessible, and we
allow setting it (only) at construction time.
Each widget type has an accessible role associated to its class, as
roles cannot change during the life time of a widget instance.
Each widget is also responsible for creating an ATContext, to proxy
state changes to the underlying accessibility infrastructure.
To build a better world sometimes means having to tear the old one down.
-- Alexander Pierce, "Captain America: The Winter Soldier"
ATK served us well for nearly 20 years, but the world has changed, and
GTK has changed with it. Now ATK is mostly a hindrance towards improving
the accessibility stack:
- it maps to a very specific implementation, AT-SPI, which is Linux and
Unix specific
- it requires implementing the same functionality in three different
layers of the stack: AT-SPI, ATK, and GTK
- only GTK uses it; every other Linux and Unix toolkit and application
talks to AT-SPI directly, including assistive technologies
Sadly, we cannot incrementally port GTK to a new accessibility stack;
since ATK insulates us entirely from the underlying implementation, we
cannot replace it piecemeal. Instead, we're going to remove everything
and then incrementally build on a clean slate:
- add an "accessible" interface, implemented by GTK objects directly,
which describe the accessible role and state changes for every UI
element
- add an "assistive technology context" to proxy a native accessibility
API, and assign it to every widget
- implement the AT context depending on the platform
For more information, see: https://gitlab.gnome.org/GNOME/gtk/-/issues/2833
Crossing events are now detached from widget state, all tricky consequences
from getting multiple crossing events are now somewhat moot. Resort to sending
all generated crossing events, and drop this barely (ever?) used API.
Add a variant of gtk_widget_add_controller that
inserts the controller at the beginning, instead
of the end. This will be used in entry completion
to make sure the entry completion key event handling
supersedes the entry one while the popup is open.
Keep this private for now, until we determine if
it needs to be public api.
It feels slightly wrong to have GtkOrientable operate on widgets, but at
least what happens when an orientable widget changes orientation should
be part of GtkWidget.
This will allow to add more state changes without accessing widget state
from the outside of gtkwidget.c.
The tooltip handling in GtkWidget is "special":
- the string is stored inside the qdata instead of the private
instance data
- the accessors call g_object_set() and g_object_get(), and the
logic is all inside the property implementation, instead of
being the other way around
- the getters return a copy of the string
- the setters don't really notify all the involved properties
The GtkWidgetAccessible uses the (escaped) tooltip text as a source for
the accessible object description, which means it has to store the
tooltip inside the object qdata, and update its copy at construction and
property notification time.
We can simplify this whole circus by making the tooltip properties (text
and markup) more idiomatic:
- notify all side-effect properties
- return a constant string from the getter
- if tooltip-text is set:
- store the text as is
- escape the markup and store it separately for the markup getter
- if tooltip-markup is set:
- store the markup as is
- parse the markup and store it separately for the text getter
The part of the testtooltips interactive test that checks that the
getters are doing the right thing is now part of the gtk testsuite, so
we ensure we don't regress in behaviour.
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.
