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use std::{convert::Infallible, time::Instant};
use rxrust::prelude::{Observer, Subject};
/// Frame ticker emit message when new frame need to draw.
#[derive(Default, Clone)]
pub struct FrameTicker {
subject: Subject<'static, FrameMsg, Infallible>,
}
/// Message emitted at different status of a frame.
#[derive(Clone)]
pub enum FrameMsg {
/// This msg emit when all event has processed and framework begin to do
/// layout & paint of the frame.
///
/// only the first frame of continuous frames that do not need to be drawn
/// will be sent this message.
NewFrame(Instant),
/// This Msg emit when performed layout finished, and widget tree ready to
/// draw.
/// # Notice
/// - this message may emit more than once, if someone listen this message and
/// do some stuff to lead to some widget need relayout, be careful to modify
/// widget in the listener of this message.
LayoutReady(Instant),
/// This msg emit after render data has submitted that mean all stuffs of
/// current frame need to processed by framework done.
///
/// only the first frame of continuous frames that do not need to be drawn
/// will be sent this message.
Finish(Instant),
}
impl FrameTicker {
#[inline]
pub(crate) fn emit(&self, msg: FrameMsg) { self.subject.clone().next(msg) }
#[inline]
pub fn frame_tick_stream(&self) -> Subject<'static, FrameMsg, Infallible> { self.subject.clone() }
}