fuchsia.ui.focus

PROTOCOLS

FocusChainListener

Defined in fuchsia.ui.focus/focus_chain.fidl

A FocusChainListener receives an updated FocusChain when focus changes.

OnFocusChange

Sent when a focus change occurs. Since focus_chain may contain an empty update, every handler MUST respond to the message even if its contents are not immediately useful.

Request

Name	Type
`focus_chain`	`FocusChain`

Response

Name	Type

FocusChainListenerRegistry

Defined in fuchsia.ui.focus/focus_chain.fidl

A FocusChainListenerRegistry allows listening to FocusChain updates.

Register

Request

Name	Type
`listener`	`FocusChainListener`

STRUCTS

TABLES

FocusChain

Defined in fuchsia.ui.focus/focus_chain.fidl

A FocusChain tracks the status of the View hierarchy as View focus changes.

Reception. Only certain components may receive a FocusChain, as it captures global information about the scene graph.

Ordinal Name Type Description

Ordinal	Name	Type	Description
1	`focus_chain`	`vector<fuchsia.ui.views/ViewRef>`	The `focus_chain` is reported in order of dominance in the View hierarchy; each adjacent pair of elements represents a parent-child relationship. The `focus_chain` MAY be unset when `FocusChain` message is received, if the message is sent very early in the scene setup, before the first view is available. When `focus_chain` is set, however, the root View is always present and occupies slot 0 in the `focus_chain`. The newly-focused View receives a `fuchsia.ui.input.FocusEvent` and occupies the final slot in the vector. If a View gets destroyed, a `FocusChain` holder that listens will receive a `ZX_EVENTPAIR_PEER_CLOSED` signal on the corresponding `ViewRef`. Invalidation. A FocusChain is invalid if any one if its ViewRefs is invalid.

focus_chain

vector<fuchsia.ui.views/ViewRef>

The focus_chain is reported in order of dominance in the View hierarchy; each adjacent pair of elements represents a parent-child relationship.

The focus_chain MAY be unset when FocusChain message is received, if the message is sent very early in the scene setup, before the first view is available.

When focus_chain is set, however, the root View is always present and occupies slot 0 in the focus_chain. The newly-focused View receives a fuchsia.ui.input.FocusEvent and occupies the final slot in the vector.

If a View gets destroyed, a FocusChain holder that listens will receive a ZX_EVENTPAIR_PEER_CLOSED signal on the corresponding ViewRef.

Invalidation.

A FocusChain is invalid if any one if its ViewRefs is invalid.