Setting a field on a class structure is not always an easy task from
languages other than C. While bindings can provide access to the class
pointer, twiddling the fields in the class structure can be awkward.
Additionally, signal ids are not always readily available.
We can paper over the direct access to the class structure, as well as
the "signal name to id" mapping with a simple couple of setter
functions.
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.
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.
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().
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.
Similar to GtkShortcutTrigger, GtkShortCutAction provides all the
different ways to activate a shortcut.
So far, these different ways are supported:
- do nothing
- Call a user-provided callback
- Call gtk_widget_activate()
- Call gtk_widget_mnemonic_activate()
- Emit an action signal
- Activate an action from the widget's action muxer
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.
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.
Similar to GtkShortcutTrigger, GtkShortCutAction provides all the
different ways to activate a shortcut.
So far, these different ways are supported:
- do nothing
- Call a user-provided callback
- Call gtk_widget_activate()
- Call gtk_widget_mnemonic_activate()
- Emit an action signal
- Activate an action from the widget's action muxer
- Activate a GAction
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.
