Struct zng_task::UiTask

pub struct UiTask<R>(/* private fields */);

Represents a Future running in sync with the UI.

The future Waker, wakes the app event loop and causes an update, in an update handler of the task owner update is called, if this task waked the app the future is polled once.

Implementations

impl<R> UiTask<R>

pub fn new_raw<F>(event_loop_waker: Waker, task: F) -> Self

where F: Future<Output = R> + Send + 'static,

New task with already build event-loop waker.

App crate provides an integrated UiTaskWidget::new that creates the waker for widgets.

pub fn update(&mut self) -> Option<&R>

Polls the future if needed, returns a reference to the result if the task is done.

This does not poll the future if the task is done.

App Update

This method must be called only once per app update, if it is called more than once it will cause execution bugs, futures like task::yield_now will not work correctly, variables will have old values when a new one is expected and any other number of hard to debug issues will crop-up.

In debug builds this is validated and an error message is logged if incorrect updates are detected.

pub fn is_ready(&self) -> bool

Returns true if the task is done.

This does not poll the future.

pub fn into_result(self) -> Result<R, Self>

Returns the result if the task is completed.

This does not poll the future, you must call update to poll until a result is available, then call this method to take ownership of the result.

Trait Implementations

impl<R: Debug> Debug for UiTask<R>

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

Formats the value using the given formatter.