Instead of determining the focus item through item tree traversal and
pointer comparison and storing the intermediate indices in the
components in the tree, remember the focus item by a pair of
VWeak<ComponentVTable, Dyn> and item_index: usize.
This speeds up determining the focus item as well as delivering events,
which can now be done directly after retrieving an ItemRef with
get_item_ref.
This also fixes the duplicate line edit focus in the 7gui cells
test case.
This is in preparation for allowing the run-time / items to clone VRc's
of the component.
ComponentVTable functions like visit_children_item contine to take a
ComponentRefPin as "self" parameter type, as a VRc would not be
supported by rust right now. That means the implementation then uses
self_weak to obtain a strong self-reference.
Centralize the self_weak setup to be emitted only once, in the create()
function. create() is now always emitted and equipped with a parent
parameter, for non-root components. This allows slightly simplifying the
generic repeater code.
Move the layout constraint tracker into the window where we can apply
the constraints right before drawing, instead of doing that from within
the event loop. This allows to remove the component parameter from the
run function.
Similar to the mouse_grabber, we use a VisitChildrenResult field to
track the focus item within a component. Unlike the mouse grabber
however, it is set/cleared using dedicated focus events.
The key event now routes the key event directly to the focus item.
The focus can be requested via set_focus_item on a window, which the
TextItem does.
In the future the TextInput will request focus on mouse click,for
example.
Pass the outer-most component through to ItemVTable's input_event.
For the purpose of disambiguating this component from any nested
component instantiated by a repeater or so, it's called the
app_component.
The ComponentVTable takes a reference to a ComponentRefPin instead of a
ComponentRefPin by value, as the vtable macro gets confused otherwise
and thinks it's a self argument.
Unfortunately something is wrong with the Qt style, it looks like the Qt style
does not respect the rect given for the sub components
Also Input is not handled yet.
