Struct EventTime 

pub struct EventTime(/* private fields */);

When an input event happened, on the engine’s monotonic clock.

The epoch is the contract

A timestamp whose origin is unspecified is worth nothing: you cannot subtract two of them across subsystems, and you cannot compare one to “now”. So this type states its epoch and makes matching it a backend obligation:

An EventTime is a duration measured from the same origin as the TimeSource driving FrameClock::update — that is, from MonotonicTime::new (process start) in a real run, and from ManualTime’s zero in a deterministic one.

That makes event.time and clock.render_dt() live on one timeline, which is what the P2 input pipeline needs to age an input against the tick it belongs to, and what topic 26’s client prediction needs to compute input-to-photon latency.

What backends have to do about it

No window system hands us this directly, so rebasing is part of writing a backend, not an optimization:

• Wayland stamps events with CLOCK_MONOTONIC milliseconds (microseconds under wp_presentation and the high-resolution input protocols). Subtract the clock reading taken when the shell was created.
• X11 stamps events with the X server’s time: a 32-bit millisecond counter with an unspecified origin that wraps every 49.7 days. The backend estimates the offset once at connection time and must detect the wrap; a backend that forwards the raw value produces an input pipeline that silently breaks after a month and a half of uptime.
• Win32 has GetMessageTime (a GetTickCount sample, also wrapping) and raw input’s QPC timestamps.
• The browser gives event.timeStamp, already a performance.now()-relative double.

When a backend genuinely has no timestamp for an event — a synthesized focus-loss key release, for instance — it stamps the event with the current time rather than EventTime::ZERO, because a zero timestamp reads as “this happened at process start” to every consumer downstream.

Implementations

impl EventTime

pub const ZERO: EventTime

The clock’s origin.

pub const fn from_duration(since_epoch: Duration) -> EventTime

Wraps a duration measured from the epoch described in the type docs.

pub const fn from_micros(micros: u64) -> EventTime

Microseconds since the epoch — the unit Wayland’s high-resolution input protocols and libinput both use.

pub const fn from_millis(millis: u64) -> EventTime

Milliseconds since the epoch — the unit core Wayland and X11 use.

pub const fn as_duration(self) -> Duration

Time since the epoch.

pub fn as_secs_f64(self) -> f64

Time since the epoch in seconds.

pub fn saturating_since(self, earlier: EventTime) -> Duration

How long after earlier this timestamp is, saturating at zero.

Saturating rather than panicking because event queues are not perfectly ordered in practice — a compositor can deliver a relative-motion event stamped fractionally before the absolute-motion event it accompanies — and an input pipeline must not die of it.

pub const fn saturating_add(self, delta: Duration) -> EventTime

This timestamp moved forward by delta.

Trait Implementations

impl Clone for EventTime

fn clone(&self) -> EventTime

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for EventTime

impl Debug for EventTime

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

Formats the value using the given formatter.

impl Default for EventTime

fn default() -> EventTime

Returns the “default value” for a type.

impl Display for EventTime

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

Formats the value using the given formatter.

impl Eq for EventTime

impl From<Duration> for EventTime

fn from(since_epoch: Duration) -> EventTime

Converts to this type from the input type.

impl Hash for EventTime

fn hash<__H>(&self, state: &mut __H)

where __H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for EventTime

fn cmp(&self, other: &EventTime) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

fn clamp_to<R>(self, range: R) -> Self

where Self: Sized, R: ClampBounds<Self>,

🔬This is a nightly-only experimental API. (clamp_to)

Restrict a value to a certain range.

impl PartialEq for EventTime

fn eq(&self, other: &EventTime) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PartialOrd for EventTime

fn partial_cmp(&self, other: &EventTime) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl StructuralPartialEq for EventTime