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
We don't want wrapping labels to cause tooltips to
have excessive height, so we need to set a reasonable
value for width-chars, without forcing short tooltips
into a full line length. Also be careful to respect
preexisting line breaks (we have such examples in
widget factory).
FIXME: Is this necessary?
Could the surfaces just clamp to 1x1 themselves?
We recently declared that surfaces can decide on whatever size they want
so natives need to inspect the size they requested anyway.
Replace the gdk_surface_move_to_rect() API with a new GdkSurface
method called gdk_surface_present_popup() taking a new GdkPopupLayout
object describing how they should be laid out on screen.
The layout properties provided are the same as the ones used with
gdk_surface_move_to_rect(), except they are now set up using
GdkPopupLayout.
Calling gdk_surface_present_popup() will either show the popup at the
position described using the popup layout object and a new unconstrained
size, or reposition it accordingly.
In some situations, such as when a popup is set to autohide, presenting
may immediately fail, in case the grab was not granted by the display
server.
After a successful present, the result of the layout can be queried
using the following methods:
* gdk_surface_get_position() - to get the position relative to its
parent
* gdk_surface_get_width() - to get the current width
* gdk_surface_get_height() - to get the current height
* gdk_surface_get_rect_anchor() - to get the anchor point on the anchor
rectangle the popup was effectively positioned against given
constraints defined by the environment and the layout rules provided
via GdkPopupLayout.
* gdk_surface_get_surface_anchor() - the same as the one above but for
the surface anchor.
A new signal replaces the old "moved-to-rect" one -
"popup-layout-changed". However, it is only intended to be emitted when
the layout changes implicitly by the windowing system, for example if
the monitor resolution changed, or the parent window moved.
We do get events on the tooltip window too, and
we better ignore them, or bad things may happen,
such as widgets that are their own parents and
cause infinite loops.
Fixes: https://gitlab.gnome.org/GNOME/gtk/issues/2339
In order to make tooltip positioning portable, make use of the
move_to_rect API. Some semantical changes are made, as identical
semantics cannot be implemented using the move-to-rect API.
Primarily the implemented semantics are:
Position the tooltip in the center pixels slightly below (defaults to 4
units below) the tooltipped widget. This is always the case for keyboard
driven tooltips; the case where it tries to avoid the pointer cursor is
not implemented.
For pointer position triggered tooltips, implement the following
additional semantics:
Use the current cursor size to determine the padding used to enlarge the
anchor rectangle. This is to try to avoid the cursor overlapping the
tooltip.
If the anchor rectangle is too tall (meaning if we'd be constrained
and flip on the Y axis, it'd flip too far away from the originally
intended position), rely only on the pointer position to position the
tooltip. The approximate pointer cursor rectangle is used as a anchor
rectangle. Ideally we should use the actual pointer cursor rectangle
(image used as well as hotspot coordinate), but we don't have API to
get that information.
If the anchor rectangle isn't to tall, just make sure the tooltip isn't
too far away from the pointer position on the X axis.
Closes: #134Closes: #432Closes: #574Closes: #579Closes: #878
Instead, add a function gtk_image_set_icon_size() for the cases where
overriding the icon size is necessary.
Treat icon sizes the same way as pixel sizes, too. So gtk_image_clear()
no longer unsets the icon size.
It's not a hugely complicated file, but it's easier to deal with some of
the details of tooltip windows styling if we have a UI file to edit,
instead of source code.
