Struct HeadlessApp 

pub struct HeadlessApp { /* private fields */ }

A headless app controller.

Headless apps don’t cause external side-effects like visible windows and don’t listen to system events. They can be used for creating apps like a command line app that renders widgets, or for creating integration tests.

You can start a headless app using AppBuilder::run_headless.

Implementations

impl HeadlessApp

pub fn renderer_enabled(&mut self) -> bool

If headless rendering is enabled.

When enabled windows are still not visible but frames will be rendered and the frame image can be requested.

Note that UiNode::render is still called when a renderer is disabled and you can still query the latest frame from WINDOWS.widget_tree. The only thing that is disabled is the actual renderer that converts display lists to pixels.

pub fn update(&mut self, wait_app_event: bool) -> AppControlFlow

Does updates.

If wait_app_event is true the thread sleeps until at least one app event is received or a timer elapses, if it is false only responds to app events already in the buffer.

pub fn update_observe( &mut self, on_pre_update: impl FnOnce() + Send + 'static, ) -> bool

Does updates and calls on_pre_update on the first update.

pub fn run_task<R, T>( &mut self, task: impl IntoFuture<IntoFuture = T>, ) -> Option<R>

where R: Send + 'static, T: Future<Output = R> + Send + 'static,

Execute the async task in the UI thread, updating the app until it finishes or the app shuts-down.

Returns the task result if the app has not shutdown.

pub fn run_task_deadline<R, T>( &mut self, task: impl IntoFuture<IntoFuture = T>, deadline: impl Into<Deadline>, ) -> Option<R>

where R: Send + 'static, T: Future<Output = R> + Send + 'static,

Does run_task with a deadline.

Returns the task result if the app has not shutdown and the deadline is not reached.

If the deadline is reached an error is logged. Note that you can use with_deadline to create a future with timeout and handle the timeout error.

pub fn run_test<R, T>( &mut self, task: impl IntoFuture<IntoFuture = T>, ) -> Option<R>

where R: Send + 'static, T: Future<Output = R> + Send + 'static,

Does run_task with a deadline, panics on timeout.

pub fn exit(self)

Requests and wait for app exit.

Forces deinit if exit is cancelled.

pub fn has_exited(&self) -> bool

If the app has exited.

Exited apps cannot update anymore. The app should be dropped to unload the app scope.