PROTOCOLS

Listener

Defined in fuchsia.accessibility.virtualkeyboard/virtual_keyboard.fidl

Provides the ability to inform an interested party ("listener") of changes in virtual keyboard state (e.g. visibility).

Roles

This protocol will typically be:

• Implemented by platform components which implement accessibility. For example, a11y_manager.
• Consumed by components which provide a GUI affordance for text input.

Notes

When the consumer of this protocol observes that the channel is closed, it (the protocol consumer) should retry Registry.Register(), applying back-off logic to avoid tight loops.

OnVisibilityChanged

Informs the Listener of a change in keyboard visibility.

Consumers of this protocol should wait for each call to be acknowledged before calling again, to avoid queueing large numbers of updates.

Request

Name	Type
updated_visibility	bool

Response

<EMPTY>

Registry

Defined in fuchsia.accessibility.virtualkeyboard/virtual_keyboard.fidl

Provides the ability to register a virtual keyboard.

This protocol exists to bind Listeners to Views (via ViewRefs). The binding allows, e.g., the accessibility subsystem determine if an interaction with the View should result in a focus transfer.

Roles

This protocol will typically be:

• Implemented by platform components which implement accessibility. For example, a11y_manager.
• Consumed by components which provide a GUI affordance for text input.

Register

Registers the View referenced by view_ref as a View which may contain a virtual keyboard.

The presence or absence of a virtual keyboard within the View may change dynamically.

• The initial state is indicated by is_visible.
• The Registry consumer will update state by invoking methods on the provided server_end:Listener.

Notes

• The implementer may limit the number of simultaneous registrations allowed (e.g. only allowing a single registration at a time).
• The implementer should monitor the provided ViewRef for a ZX_EVENTPAIR_PEER_CLOSED signal (see documentation for fuchsia.ui.views.ViewRefControl).
• If the request would exceed the simultaneous registration limit, or when the ViewRef receives ZX_EVENTPAIR_PEER_CLOSED, the implementer should dispose of listener.

Request

Name	Type
view_ref	fuchsia.ui.views/ViewRef
is_visible	bool
listener	server_end:Listener