Enum TouchSourceV2Request 

pub enum TouchSourceV2Request {
    AcknowledgeEvents {
        last_acknowledged_event_stamp: u64,
        control_handle: TouchSourceV2ControlHandle,
    },
    #[non_exhaustive]
    _UnknownMethod {
        ordinal: u64,
        control_handle: TouchSourceV2ControlHandle,
        method_type: MethodType,
    },
}

A push-based reader protocol for a client to receive touch events.

Does not support cooperative gesture disambiguation (always-consume model). If Scenic has a mix of V1 and V2 clients contesting the same touch interaction in the view tree, Scenic’s gesture arena will implicitly treat the V2 client as if it immediately responded YES (claim ownership) to all pointer samples. Gesture ownership is then resolved using standard priority rules against other V1 clients’ explicit responses (like YES, MAYBE, or HOLD).

Clients requiring cooperative gesture disambiguation or augmentation (such as the accessibility subsystem using LocalHit) must continue using the pull-based [TouchSource] protocol instead.

Flow control and acknowledgment rules:

• The server will not push more than TOUCH_SOURCE_V2_MAX_UNACKNOWLEDGED_EVENTS (or a product-configured maximum) events without receiving an acknowledgment from the client. The server (Scenic) will throttle event delivery when unacknowledged events in flight reach this limit.
• Clients should send acknowledgments periodically (e.g. before reaching the limit, such as within 20 remaining credits) to avoid being throttled.
• No head-of-line blocking: Because channels and credit limits are independent per-view, a slow client that fails to acknowledge terminal events only blocks its own channel. Scenic can immediately start pushing events to other views on their own channels.

Like [TouchSource], Scenic only dispatches touch events to the TouchSourceV2 channel if the touch coordinate successfully intersects one of the view’s active hit regions (determined via Scenic’s global hit testing). If the hit test fails or targets a different view, no touch events are routed to this client’s TouchSourceV2 channel, preserving the security containment boundaries of the Fuchsia UI system.

The position of a touch event is defined in the context of a viewport, situated in the view, identical to [TouchSource].

Variants

AcknowledgeEvents

Acknowledges receipt of events up to last_acknowledged_event_stamp.

This grants the server “credits” to send more events. All events sent with a last_event_stamp less than or equal to last_acknowledged_event_stamp are considered acknowledged.

The server (Scenic) will throttle event delivery when unacknowledged events in flight reach TOUCH_SOURCE_V2_MAX_UNACKNOWLEDGED_EVENTS (or a product-configured maximum). Clients should send acknowledgments periodically (e.g. before reaching the limit, such as within 20 remaining credits) to avoid being throttled.

last_acknowledged_event_stamp must be strictly increasing. Non-compliance results in channel closure.

Fields

last_acknowledged_event_stamp: u64

control_handle: TouchSourceV2ControlHandle

#[non_exhaustive]

_UnknownMethod

An interaction was received which does not match any known method.

Fields

Non-exhaustive enum variants could have additional fields added in future. Therefore, non-exhaustive enum variants cannot be constructed in external crates and cannot be matched against.

ordinal: u64

Ordinal of the method that was called.

control_handle: TouchSourceV2ControlHandle

method_type: MethodType

Implementations

impl TouchSourceV2Request

pub fn into_acknowledge_events( self, ) -> Option<(u64, TouchSourceV2ControlHandle)>

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

Name of the method defined in FIDL

Trait Implementations

impl Debug for TouchSourceV2Request

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

Formats the value using the given formatter.