Struct FocusHandle 

pub struct FocusHandle { /* private fields */ }

A way to put keyboard focus on one widget. Compose’s FocusRequester.

Make one with use_focus_handle, give it to a widget with .focus_handle(&handle), and call FocusHandle::request from a handler or an effect. Cloning is cheap: every clone is the same handle. The handle follows its widget’s node across re-renders, and when the widget is replaced by a new node, it follows the new one.

A drawer that takes focus when it opens and gives it back to the control that opened it when Escape closes it:

use compose_rust::runtime::*;
use compose_rust::ui::*;

#[Composable]
fn Screen() {
    let open = remember(|| mutable_state_of(false));
    let opener = use_focus_handle();
    let drawer = use_focus_handle();
    Column().content(|| {
        Button("Menu")
            .focus_handle(&opener)
            .on_click(move || open.set(true));
        if open.get() {
            let back = opener.clone();
            Column()
                .focus_handle(&drawer)
                .on_key_down(move |key| {
                    if key.text() == "Escape" {
                        key.consume();
                        open.set(false);
                        back.request();
                    }
                })
                .content(|| {
                    Text("Drawer");
                });
        }
    });
    // The drawer's node exists once the composition that opened it is applied, so
    // the request runs as an effect of that composition rather than in the click.
    let take = drawer.clone();
    let is_open = open.get();
    launched_effect(is_open, move || async move {
        if is_open {
            take.request();
        }
    });
}

A request made while the handle’s node is not on screen does nothing and is not kept for later, which is why the drawer above asks from an effect.

Implementations

impl FocusHandle

pub fn new() -> Self

A handle bound to nothing yet.

pub fn request(&self)

Asks for keyboard focus on the node this handle is bound to. The next batch carries one RequestFocus for it, however many times this is called before then.

A handle that is bound to no node on screen, because its widget has not been composed yet or has left, asks for nothing.

pub fn is_bound(&self) -> bool

Whether the handle is bound to a node. A node that has since left the screen still counts until another widget takes the handle.

Trait Implementations

impl Clone for FocusHandle

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for FocusHandle

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for FocusHandle

fn default() -> Self

Returns the “default value” for a type.

impl PartialEq for FocusHandle

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.