ferretro/ferretro_components/src/provided/stdlib/fps.rs

71 lines
2.0 KiB
Rust

use crate::base::ControlFlow;
use crate::prelude::*;
use std::time::{Duration, Instant};
use std::path::Path;
/// Uses [std::thread::sleep] to maintain the target FPS specified by the core.
///
/// The sleep occurs during either `video_refresh` or at the end of `run()`.
pub struct SleepFramerateLimitComponent {
did_sleep: bool,
started_video: bool,
fps: f64,
frame_begin: Instant,
}
impl RetroComponent for SleepFramerateLimitComponent {
fn post_load_game(&mut self, retro: &mut LibretroWrapper, _rom: &Path) -> crate::base::Result<()> {
self.fps = retro.get_system_av_info().timing.fps;
Ok(())
}
fn pre_run(&mut self, _retro: &mut LibretroWrapper) -> ControlFlow {
self.did_sleep = false;
ControlFlow::Continue
}
fn post_run(&mut self, _retro: &mut LibretroWrapper) -> ControlFlow {
if self.started_video && !self.did_sleep {
self.do_sleep();
}
ControlFlow::Continue
}
}
impl RetroCallbacks for SleepFramerateLimitComponent {
fn video_refresh(&mut self, _frame: &VideoFrame) {
self.started_video = true;
self.do_sleep();
}
fn set_system_av_info(&mut self, system_av_info: &SystemAvInfo) -> Option<bool> {
self.fps = system_av_info.timing.fps;
Some(true)
}
}
impl Default for SleepFramerateLimitComponent {
fn default() -> Self {
SleepFramerateLimitComponent {
did_sleep: false,
started_video: false,
fps: 60.0, // default until load_game
frame_begin: Instant::now(),
}
}
}
impl SleepFramerateLimitComponent {
pub fn do_sleep(&mut self) {
// similar hack to the sample rate, make sure we don't divide by zero.
let mut spf = 1.0 / self.fps;
if spf.is_nan() || spf.is_infinite() {
spf = 1.0 / 60.0;
}
Duration::from_secs_f64(spf)
.checked_sub(self.frame_begin.elapsed())
.map(std::thread::sleep);
self.did_sleep = true;
self.frame_begin = Instant::now();
}
}