Struct Timer 

#[repr(C)]
pub struct Timer {
    pub data: RefAny,
    pub node_id: OptionDomNodeId,
    pub created: Instant,
    pub last_run: OptionInstant,
    pub run_count: usize,
    pub delay: OptionDuration,
    pub interval: OptionDuration,
    pub timeout: OptionDuration,
    pub callback: TimerCallback,
}

A Timer is a function that is run on every frame.

There are often a lot of visual Threads such as animations or fetching the next frame for a GIF or video, etc. - that need to run every frame or every X milliseconds, but they aren’t heavy enough to warrant creating a thread - otherwise the framework would create too many threads, which leads to a lot of context switching and bad performance.

The callback of a Timer should be fast enough to run under 16ms, otherwise running timers will block the main UI thread.

Fields

data: RefAny

Data that is internal to the timer

node_id: OptionDomNodeId

Optional node that the timer is attached to - timers attached to a DOM node will be automatically stopped when the UI is recreated.

created: Instant

Stores when the timer was created (usually acquired by Instant::now())

last_run: OptionInstant

When the timer was last called (None only when the timer hasn’t been called yet).

run_count: usize

How many times the callback was run

delay: OptionDuration

If the timer shouldn’t start instantly, but rather be delayed by a certain timeframe

interval: OptionDuration

How frequently the timer should run, i.e. set this to Some(Duration::from_millis(16)) to run the timer every 16ms. If this value is set to None, (the default), the timer will execute the timer as-fast-as-possible (i.e. at a faster framerate than the framework itself) - which might be performance intensive.

timeout: OptionDuration

When to stop the timer (for example, you can stop the execution after 5s using Some(Duration::from_secs(5))).

callback: TimerCallback

Callback to be called for this timer

Implementations

impl Timer

pub fn new( data: RefAny, callback: TimerCallbackType, get_system_time_fn: GetSystemTimeCallback, ) -> Self

Create a new timer

pub fn tick_millis(&self) -> u64

pub fn is_about_to_finish(&self, instant_now: &Instant) -> bool

Returns true ONCE on the LAST invocation of the timer This is useful if you want to run some animation and then when the timer finishes (i.e. all animations finish), rebuild the UI / DOM (so that the user does not notice any dropped frames).

pub fn instant_of_next_run(&self) -> Instant

Returns when the timer needs to run again

pub fn with_delay(self, delay: Duration) -> Self

Delays the timer to not start immediately but rather start after a certain time frame has elapsed.

pub fn with_interval(self, interval: Duration) -> Self

Converts the timer into a timer, running the function only if the given Duration has elapsed since the last run

pub fn with_timeout(self, timeout: Duration) -> Self

Converts the timer into a countdown, by giving it a maximum duration (counted from the creation of the Timer, not the first use).

pub fn invoke( &mut self, callback_info: CallbackInfo, frame_start: Instant, get_system_time_fn: GetSystemTimeCallback, ) -> TimerCallbackReturn

Crate-internal: Invokes the timer if the timer should run. Otherwise returns Update::DoNothing

Trait Implementations

impl Clone for Timer

fn clone(&self) -> Timer

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Timer

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

Formats the value using the given formatter.

impl Hash for Timer

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

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 PartialEq for Timer

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for Timer

impl StructuralPartialEq for Timer