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|
use std::thread;
use std::time::{Duration, Instant};
use sdl2::pixels::Color;
use sdl2::rect::Rect;
use sdl2::render::WindowCanvas;
use sdl2::video::{Window, WindowContext};
use specs::prelude::*;
use crate::components::{Pos, StaticDrawable};
use crate::texture_manager::TextureManager;
/// The minimum time in micro a frame should take to limit the number of
/// frames drawn to the screen. 5000 microseconds for a maximum of 200 frames
/// per second.
pub const FRAME_TIME_MIN_US: u64 = (1_000_000. / 200.) as u64;
pub struct SysDraw
{
last_frame_time: Instant,
canvas: WindowCanvas,
texture_manager: TextureManager<WindowContext>,
}
impl SysDraw
{
pub fn new(window: Window) -> Self
{
let mut canvas = window
.into_canvas()
.build()
.expect("Unable to create canvas");
canvas.set_draw_color(Color::RGB(255, 255, 0));
let texture_manager = TextureManager::new(canvas.texture_creator());
Self {
last_frame_time: Instant::now(),
canvas,
texture_manager,
}
}
pub fn delay_for_min_frametime(&mut self)
{
let frame_duration_us = (Instant::now() - self.last_frame_time).as_micros() as u64;
if frame_duration_us < FRAME_TIME_MIN_US {
thread::sleep(Duration::from_micros(FRAME_TIME_MIN_US - frame_duration_us));
}
self.last_frame_time = Instant::now();
}
}
impl<'a> System<'a> for SysDraw
{
type SystemData = (ReadStorage<'a, Pos>, ReadStorage<'a, StaticDrawable>);
fn run(&mut self, (pos, drawable): Self::SystemData)
{
self.canvas.clear();
/* XXX: This is so slow.. yaaaawn. Replace with ids and texture manager
* lifetime? */
for (pos, drawable) in (&pos, &drawable).join() {
let texture = self
.texture_manager
.get(&drawable.texture_name)
.expect("Unable to load texture");
self.canvas
.copy(
&texture,
Some(drawable.source_rect),
Rect::new(
pos.0.x as i32,
pos.0.y as i32,
drawable.source_rect.width(),
drawable.source_rect.height(),
),
)
.expect("Unable to draw texture");
}
self.delay_for_min_frametime();
self.canvas.present();
}
}
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