freeze/thaw_notify () showed up on the perf trace for rapid ColumnView
scrolling. Track the three properties manually to make it a little
faster.
Related: https://gitlab.gnome.org/GNOME/gtk/-/issues/3334
Instead of 6 vfuncs, we now have 3 and rely on the factory keeping track
of what it needs to do.
We're doing lots of dancing from one object to another here, but this
will hopefully get simpler with further commits.
Make sure the APIs follow a predictable path:
setup
bind
rebind/update (0-N times)
unbind
teardown
This is the first step towards providing multiple different factories.
This is implemented by using actions, which are a neat trick to get to
allow the ListItem to call functions on the ListView without actually
needing to be aware of it.
We now don't let the functions create widgets for the item from the
listmodel, instead we hand out a GtkListItem for them to add a widget
to.
GtkListItems are created in advance and can only be filled in by the
binding code by gtk_container_add()ing a widget.
However, they are GObjects, so they can provide properties that the
binding code can make use of - either via notify signals or GBinding.
Also refactor the whole list item management yet again.
Now, list item APIs doesn't have bind/unbind functions anymore, but only
property setters.
The item factory is the only one doing the binding.
As before, the item manager manages when items need to be bound.
Thisis the abstraction I intend to use for creating widgets and binding
them to the item out of the listview.
For now this is a very dumb wrapper around the functions that exist in
the API.
But it leaves the freedom to turn this into public API, make an
interface out of it and most of all write different implementations, in
particular one that uses GtkBuilder.
