The `get_child_at_index()` API model comes from AT-SPI, and it's not an
efficient design, especially when coupled with large widgets.
Replace `get_child_at_index()` with `get_first_accessible_child()` and
`get_next_accessible_sibling()`.
That allows efficiently retrieving all the children, simplifies the
implementation of GtkAccessible in GtkWidget and closely resembeles the
GtkWidget API.
Getting the last child and previous sibling for iterating backwards is
not a part of the interface at the moment, but they can be added at a
later date.
Note that this change required tracking the next stack page in
GtkStackPage.
Reduce our dependency on linked lists; pointer arrays are better at
cache locality.
Additionally, we can avoid quadratic behaviors when finding a child at a
given index.
Those property features don't seem to be in use anywhere.
They are redundant since the docs cover the same information
and more. They also created unnecessary translation work.
Closes#4904
When the stack is homogeneous in only one direction, the other direction
may produce min sizes to small for all children. Make sure to query at
least the min size for those.
This makes sure that the `GListModel` returned by
`gtk_stack_get_pages()` actually has the items removed before
`items-changed` is emitted.
Fixes: https://gitlab.gnome.org/GNOME/gtk/-/issues/4255
Remove a boatload of "or %NULL" from nullable parameters
and return values. gi-docgen generates suitable text from
the annotation that we don't need to duplicate.
This adds a few missing nullable annotations too.
When there is no visible child, gtk_selection_model_is_selected()
was returning TRUE for any invalid position.
So check if the page is non-NULL and match
Unparent the child widget before tearing down its
stack page. This is necessary so a11y can still access
the stack page accessible to emit change notification
when it learns that the child is removed.
This requires some cleanup to remove assumptions
about accessibles being widgets in the backend,
and some code to navigate the tree with these
extra objects in between widgets.
The accessibles for stack pages have the role
GTK_ACCESSIBLE_ROLE_TAB_PANEL. This is the first
step towards implementing the tabs patterns
as described in the aria authoring guidelines
for GtkStack.
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
The stack wasn't updating its visible-child when
the stack pages visible property changes. This
showed up in the inspector, when showing the details
for a list model item.
