This changes allocation of the widget trees to happen as a side effect
to the GdkSurface::layout signal, which first passes the GtkNative
instance where it is then forwarded to the implementations of the
GtkNative interface.
The implementations of GtkNative are the ones doing the actual
gtk_widget_allocate(), and they do so in their GtkNativeClass::layout
function.
In wayland, popup positioning and event handling are doubly async.
This makes it unreliable to figure out parent surface coordinates
out of the popup position and the events received. This results in
jumpy text handles there.
The best way to deal with parent surface coordinates is to handle
the events there. Make the handles transparent to input, and make
the drag gesture be set up on the parent widget's native.
The gesture is set up in the capture phase, setting it on the native
(as opposed to the parent widget) achieves a feeling similar to it
being a distinct surface, as it should take precedence over other
gestures in the emission chain (e.g. scrolledwindows).
As everything is in parent widget's native's coordinates, the drag
handles become smooth again.
Instead of being a GObject managing two GtkWidgets, make GtkTextHandle
a GtkWidget subclass, representing a single handle.
From the perspective of users (GtkText and GtkTextView), this is not a
big leap since they have to be aware of a great deal of text handles'
state. It actually makes things more direct and simple.
With text handles being widgets, those can be actual children of the
widget, and may have their own GdkSurface that we move around at will.
This is the second major aspect of this refactor.
Similar to previous removals of g_cclosure_marshal_VOID__VOID we can remove
other marshallers for which are a simple G_TYPE_NONE with single parameter.
In those cases, GLib will setup both a c_marshaller and va_marshaller for
us. Before this commit, we would not get a va_marshaller because the
c_marshaller is set.
Related to GNOME/Initiatives#10
GtkTextHandle was neglected by whoever removed the ::draw signal,
leaving it entirely broken. Update to using GtkGizmo so we can
implement snapshot of text handles.
Input has received a revamp too, handling is done through a
GtkGestureDrag and coordinate calculations simplified by storing
the delta to the hotspot on ::begin instead of ::update, as this
value is constant throughout the gesture. Widget state management
on crossing events happens implicitly, so no longer needs to be
done here.
Last but not least, CSS has also been updated so handles are
rendered at the correct size and proportion, and with the padding
that code expects of it.
We now rely on toplevels receiving and forwarding all the events
the windowing should be able to handle. Event masks are no longer a
way to determine whether an event is deliverable ot a widget.
Events will always be delivered in the three captured/target/bubbled
phases, widgets can now just attach GtkEventControllers and let those
handle the events.
Text handles use to connect to the first GtkScrollable up the hierarchy
so they can be repositioned when scrolling. It makes more sense to look
up the first child of a GtkScrolledWindow, it must be an scrollable too,
and will be the scrollable that can actually change the position of the
text handles.
https://bugzilla.gnome.org/show_bug.cgi?id=761676
It is assumed that border.top is the same than pointing_to.height (which
equals the strong cursor position), which is not since some time ago.
The border calculation has been move on top too, it is now used in the
Y position one, and doesn't depend on anything we calculate later.
Text handles are subsurfaces on wayland, so sort of their own toplevel.
This made gtk_widget_translate_coordinates() to bail out there, resulting
in text handles being mispositioned and jumpy. To fix this, translate to
toplevel GtkWindow coordinates manually, and translate coordinates from
there.
Along the way, the coordinates reported in ::handle-dragged have been
fixed so there is no small jumps in either axis (most noticeable in the
X axis when you started dragging, and in the Y axis when moving between
lines of different heights.
This behavior has been made optional on add_popover() time, text handles
will keep being able to overflow the window, in order to allow text
selection on views too close to the window edge.
Regular GtkPopovers are reinstaurated to the previous size positioning
logic though, that is, limited by the visible area of the window.
