Trait kas::WidgetChildren[−][src]

pub trait WidgetChildren: WidgetCore {
    fn first_id(&self) -> WidgetId;

    fn num_children(&self) -> usize;

    fn get_child(&self, index: usize) -> Option<&(dyn WidgetConfig + 'static)>;

    fn get_child_mut(
        &mut self, 
        index: usize
    ) -> Option<&mut (dyn WidgetConfig + 'static)>;

    fn record_first_id(&mut self, _id: WidgetId) { ... }

    fn is_ancestor_of(&self, id: WidgetId) -> bool { ... }

    fn find_child(&self, id: WidgetId) -> Option<usize> { ... }

    fn find_leaf(&self, id: WidgetId) -> Option<&(dyn WidgetConfig + 'static)> { ... }

    fn find_leaf_mut(
        &mut self, 
        id: WidgetId
    ) -> Option<&mut (dyn WidgetConfig + 'static)> { ... }

    fn walk_children<F>(&self, f: F)
    where
        F: FnMut(&(dyn WidgetConfig + 'static)),
    { ... }

    fn walk_children_mut<F>(&mut self, f: F)
    where
        F: FnMut(&mut (dyn WidgetConfig + 'static)),
    { ... }
}
Expand description

Listing of a widget’s children

This trait is part of the Widget family and is derived by derive(Widget) unless #[widget(children = noauto)] is used.

Dynamic widgets must implement this trait manually, since derive(Widget) cannot currently handle fields like Vec<SomeWidget>.

Whenever the number of child widgets changes or child widgets are replaced, one must send TkAction::RECONFIGURE. (TODO: this is slow. Find an option for partial reconfigures. This requires better widget identifiers; see #91.)

Required methods

Get the first identifier of self or any children

Widget identifiers are assigned sequentially by depth-first-search, children before parents. Any widget thus has a range of identifiers, from the first assigned to any descendent (or self) to its own (WidgetCore::id). This method must return the first identifier.

Get the number of child widgets

Get a reference to a child widget by index, or None if the index is out of bounds.

For convenience, Index<usize> is implemented via this method.

Required: index < self.len().

Mutable variant of get

Warning: directly adjusting a widget without requiring reconfigure or redraw may break the UI. If a widget is replaced, a reconfigure must be requested. This can be done via Manager::send_action. This method may be removed in the future.

Provided methods

Record first identifier

This is called during WidgetConfig::configure_recurse with the first identifier. This may be used to implement WidgetChildren::first_id, although in many cases the first identifier can be read directly from the first child. This method has a default implementation doing nothing.

This method should only be called from configure_recurse.

Check whether id is a descendant

This function assumes that id is a valid widget.

Find the child which is an ancestor of this id, if any

This child may then be accessed via Self::get_child or Self::get_child_mut.

This requires that the widget tree has already been configured by event::ManagerState::configure.

Find the leaf (lowest descendant) with this id, if any

This requires that the widget tree has already been configured by event::ManagerState::configure.

Find the leaf (lowest descendant) with this id, if any

This requires that the widget tree has already been configured by ManagerState::configure.

Walk through all widgets, calling f once on each.

This walk is iterative (nonconcurrent), depth-first, and always calls f on self after walking through all children.

Walk through all widgets, calling f once on each.

This walk is iterative (nonconcurrent), depth-first, and always calls f on self after walking through all children.

Implementations on Foreign Types

Implementors