Struct ScreencastPump 

pub struct ScreencastPump { /* private fields */ }

A CDP screencast attached to one page, fanned out to any number of consumers.

Attaching pins the viewport but does not start capture — capture begins on the first Self::subscribe and ends only when Self::stop is called, which stops delivery to every consumer at once. There is deliberately no per-consumer unsubscribe: consumers are meant to be centrally gated (a future privacy blackout stops the whole pump, not each consumer individually).

Implementations

impl ScreencastPump

pub async fn attach( page: &Page, quality: i64, every_nth_frame: i64, max_width: u32, max_height: u32, ) -> Result<Self, BrowserError>

Attach to page and pin its viewport. Does not start capturing — call Self::subscribe to begin.

every_nth_frame throttles Chrome’s emission at the source — cheaper than capturing everything and dropping frames later.

pub async fn subscribe(&self) -> Result<(FrameReceiver, Instant), BrowserError>

Register a consumer. The first subscription starts CDP capture; a pump already capturing just gains another fan-out target — the running capture is untouched. Returns the receiver plus the instant capture started, so a consumer can compute frame durations on the same clock the frames themselves are timestamped against.

pub async fn stop(&self)

Stop CDP capture for every consumer at once.

Safe to call even if nobody ever subscribed — but NOT a no-op then: attach already pinned the page’s device metrics, so the override has to come back regardless of whether a capture ever ran.

Trait Implementations

impl Drop for ScreencastPump

fn drop(&mut self)

Dropping a pump must end its capture, not orphan it.

Dropping a tokio JoinHandle detaches its task rather than aborting it, so without this the pump loop survived its own pump: it kept acking and fanning out frames, kept its consumers’ senders alive (so “zero consumers” never tripped anywhere above), and Page.stopScreencast was never sent — leaving Chrome capturing for the life of the process. Two live paths reach this: a RecordingHandle dropped without stop(), and FrameFanout::set_quality, which abort()s the supervisor task that owns the pump as a task local.

fn pin_drop(self: Pin<&mut Self>)

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

Execute the destructor for this type, but different to Drop::drop, it requires self to be pinned.