Trait accesskit::ActivationHandler

pub trait ActivationHandler {
    // Required method
    fn request_initial_tree(&mut self) -> Option<TreeUpdate>;
}

Handles activation of the application’s accessibility implementation.

Required Methods

fn request_initial_tree(&mut self) -> Option<TreeUpdate>

Requests a TreeUpdate with a full tree. If the application can generate the tree synchronously within this method call, it should do so and return the TreeUpdate. Otherwise, it must send the update to the platform adapter asynchronously, no later than the next display refresh, even if a frame would not normally be rendered due to user input or other activity. The application should not return or send a placeholder TreeUpdate; the platform adapter will provide one if necessary until the real tree is sent.

The primary purpose of this method is to allow the application to lazily initialize its accessibility implementation. However, this method may be called consecutively without any call to DeactivationHandler::deactivate_accessibility; this typically happens if the platform adapter merely forwards tree updates to assistive technologies without maintaining any state. A call to this method must always generate a TreeUpdate with a full tree, even if the application normally sends incremental updates.

The thread on which this method is called is platform-dependent. Refer to the platform adapter documentation for more details.

Implementors