Enum ViewRefInstalledRequest

pub enum ViewRefInstalledRequest {
    Watch {
        view_ref: ViewRef,
        responder: ViewRefInstalledWatchResponder,
    },
}

A method of enabling ViewRef holders to determine if a ViewRef has been “installed” in the view tree: the time it is first connected, transitively, to the root view. Typically, after installation, view focus may be transferred to that ViewRef.

Note: It’s important to distinguish between a ViewRef’s installed status and current connected-to-view-tree status. The former undergoes a state change once, from “no” to “yes”. The latter may change continuously, depending on view tree topology. As such, “installed” cannot imply “currently connected to view tree”; even a hypothetical “ViewRefConnected” protocol is fundamentally racy.

Variants

Watch

Sets up a callback to fire when the requested |view_ref| is installed.

• If |view_ref| has not already been installed, the |Watch| response will fire when it is.
• If |view_ref| has already been installed, the |Watch| response will fire immediately.
• If |view_ref| is invalid, or becomes invalid (perhaps because the view was destroyed), the |Watch| call returns with an error. The error is not guaranteed to be immediate, but a ViewRef holder can itself determine ViewRef validity by listening for ZX_EVENTPAIR_PEER_CLOSED.

Flow control: The caller is allowed multiple |Watch| calls on multiple ViewRefs. There is at most one response per call back to the client.

Note: Prior to installation, this |Watch| call is kept alive as long as the ViewRef is valid.

Fields

view_ref: ViewRef

responder: ViewRefInstalledWatchResponder

Implementations

impl ViewRefInstalledRequest

pub fn into_watch(self) -> Option<(ViewRef, ViewRefInstalledWatchResponder)>

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

Name of the method defined in FIDL

Trait Implementations

impl Debug for ViewRefInstalledRequest

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

Formats the value using the given formatter.