Struct WindowHandle 

pub struct WindowHandle<V> { /* private fields */ }

A handle to an open window whose root view has type V.

Use it to read or update the window’s root view from outside the window, such as from another window or from a task. Handles don’t keep the window open: if the window closes, the methods return an error. Get one from App::open_window, or convert an AnyWindowHandle with AnyWindowHandle::downcast. The handle derefs to AnyWindowHandle, so window_id() is available too.

Examples

struct Counter {
    count: usize,
}

impl Render for Counter {
    fn render(&mut self, _: &mut Window, _: &mut Context<Self>) -> impl IntoElement {
        div()
    }
}

let handle = window.handle();
app.update(|cx| {
    handle.update(cx, |counter, _, _| counter.count += 1).unwrap();
});
app.read(|cx| assert_eq!(handle.read(cx).unwrap().count, 1));

Implementations

impl<V: 'static + Render> WindowHandle<V>

pub fn new(id: WindowId) -> Self

Creates a handle for the window with id, assuming its root view has type V.

This does not check the live root. Reads and updates fail if its type does not match V. AnyWindowHandle::downcast checks the type recorded in that handle, which may be stale after Window::replace_root.

pub fn root<C>(&self, cx: &mut C) -> Result<Entity<V>>

where C: AppContext,

Returns the window’s root view as an entity.

Errors

Fails if the window is closed or if the root view’s type no longer matches V.

pub fn update<C, R>( &self, cx: &mut C, update: impl FnOnce(&mut V, &mut Window, &mut Context<'_, V>) -> R, ) -> Result<R>

where C: AppContext,

Updates the root view, and gives update the window and a context for the view.

Use it to change the view from outside the window. Calls to notify made in the update redraw the window on the next frame.

Errors

Fails if the window is closed or if the root view’s type no longer matches V.

pub fn read<'a>(&self, cx: &'a App) -> Result<&'a V>

Returns a reference to the root view for reading.

Errors

Fails if the window is closed or if the root view’s type no longer matches V.

pub fn read_with<C, R>( &self, cx: &C, read_with: impl FnOnce(&V, &App) -> R, ) -> Result<R>

where C: AppContext,

Passes the root view and the app to read_with and returns its result.

Errors

Fails if the window is closed or if the root view’s type no longer matches V.

pub fn entity<C>(&self, cx: &C) -> Result<Entity<V>>

where C: AppContext,

Returns the root view as an Entity, which you can clone and keep.

Errors

Fails if the window is closed or if the root view’s type no longer matches V.

pub fn is_active(&self, cx: &mut App) -> Option<bool>

Returns whether the window is active, or None if it is closed or currently borrowed.

See Window::is_window_active for what counts as active.

Methods from Deref<Target = AnyWindowHandle>

pub fn build_entity<V: Render + 'static>( &self, cx: &mut TestAppContext, build_view: impl FnOnce(&mut Window, &mut Context<'_, V>) -> V, ) -> Entity<V>

Creates an entity with build_view in this window.

Panics

Panics if the window has been closed.

pub fn window_id(&self) -> WindowId

Returns the WindowId of this window.

pub fn root_entity_type_name(&self) -> &'static str

Returns the root type name recorded when this handle was created.

This uses std::any::type_name. Replacing the window’s root does not change the name stored in an existing handle.

pub fn downcast<T: 'static>(&self) -> Option<WindowHandle<T>>

Converts this handle to WindowHandle<T> if its recorded root type is T.

This compares the stored type tag without querying the window. After Window::replace_root, a successful downcast can still yield a handle whose reads and updates fail. Use AnyWindowHandle::update to inspect the live root instead.

pub fn update<C, R>( self, cx: &mut C, update: impl FnOnce(AnyView, &mut Window, &mut App) -> R, ) -> Result<R>

where C: AppContext,

Updates the state of the root view of this window.

This will fail if the window has been closed.

pub fn read<T, C, R>( self, cx: &C, read: impl FnOnce(Entity<T>, &App) -> R, ) -> Result<R>

where C: AppContext, T: 'static,

Read the state of the root view of this window.

This will fail if the window has been closed.

Trait Implementations

impl<V> Clone for WindowHandle<V>

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<V> Copy for WindowHandle<V>

impl<V> Debug for WindowHandle<V>

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

Formats the value using the given formatter.

impl<V> Deref for WindowHandle<V>

type Target = AnyWindowHandle

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<V> DerefMut for WindowHandle<V>

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl<V> Eq for WindowHandle<V>

impl<V: 'static> From<WindowHandle<V>> for AnyWindowHandle

fn from(val: WindowHandle<V>) -> Self

Converts to this type from the input type.

impl<V> Hash for WindowHandle<V>

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl<V> PartialEq for WindowHandle<V>

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

Equality operator ==.

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

Inequality operator !=.