Enum ChildViewWatcherRequest

pub enum ChildViewWatcherRequest {
    GetStatus {
        responder: ChildViewWatcherGetStatusResponder,
    },
    GetViewRef {
        responder: ChildViewWatcherGetViewRefResponder,
    },
}

A protocol that provides information about a particular child View which is attached to the Viewport owned by the parent client; connections to this protocol are estabished in [CreateViewport]. Since a Flatland instance may contain any number of Viewports, each of which may or may not be attached to a transform, the client can maintain connections to an equal number of ChildViewWatcher instances.

Each ChildViewWatcher instance will remain connected as long as the corresponding child View exists; the connection will also be closed if the child’s ViewCreationToken is dropped without using it to create a View.

Variants

GetStatus

A hanging get for receiving the status of a View. This provides information to the parent, such as whether or not the child has successfully presented content through this View.

This hanging get will only fire when the ChildViewStatus is different than the previously returned ChildViewStatus. This can happen immediately, and even if the creator of the Viewport hasn’t yet called Present() after calling CreateViewport(). This allows the parent to know that the child has content ready to display before the parent modifies their own local scene graph to incorporate the child content.

It is invalid to call GetStatus while a previous call is still pending. Doing so will cause both this channel and the Flatland channel that handed out ChildViewWatcher to be closed.

Fields

responder: ChildViewWatcherGetStatusResponder

GetViewRef

Hanging get to receive the ViewRef of the child View. This will only fire when the View ref is different from the previously-returned View ref. Note: currently the View ref will not change after it is first received, but this will change if/when the API changes to allow relinking of views.

The ViewRef is not returned until the View is included in the View tree, in other words when there is a chain of ancestor transforms all the way back up to the root of the scene graph, i.e. the display.

It is invalid to call GetViewRef while a previous call is still pending. Doing so will cause both this channel and the Flatland channel that handed out ChildViewWatcher to be closed.

A GetViewRef call will hang if the View was created using CreateView, but returns the View if the View was created using CreateView2. This is because CreateView does not mint a ViewRef for that View.

Fields

responder: ChildViewWatcherGetViewRefResponder

Implementations

impl ChildViewWatcherRequest

pub fn into_get_status(self) -> Option<ChildViewWatcherGetStatusResponder>

pub fn into_get_view_ref(self) -> Option<ChildViewWatcherGetViewRefResponder>

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

Name of the method defined in FIDL

Trait Implementations

impl Debug for ChildViewWatcherRequest

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

Formats the value using the given formatter.