『ゲームプログラミングC++』の第一章をもとにrust-sdl2で書いたもの

main.rs

extern crate sdl2;
use sdl2::event::Event;
use sdl2::keyboard::Keycode;
use sdl2::pixels::Color;
use std::time::Duration;

struct Game {
    sdl_context: sdl2::Sdl, // SDL全体オブジェクト
    canvas: sdl2::render::Canvas<sdl2::video::Window>, // Rendererの代わり
}

impl Game {
    fn new() -> Result<Self, String> {
        let sdl_context = sdl2::init()?;
        let video_subsystem = sdl_context.video()?;
        let window = video_subsystem
            .window("えすでぃーえる！", 800, 600)
            .position_centered()
            .build()
            .map_err(|e| e.to_string())?;
        let canvas = window.into_canvas().build().map_err(|e| e.to_string())?;
        Ok(Self {
            sdl_context: sdl_context,
            canvas: canvas,
        })
    }

    fn run_roop(&mut self) -> Result<(), String> {
        let mut count: u8 = 0;
        'mainloop: loop {
            // イベント処理
            for event in self.sdl_context.event_pump()?.poll_iter() {
                match event {
                    Event::KeyDown {
                        keycode: Some(Keycode::Escape),
                        ..
                    }
                    | Event::Quit { .. } => break 'mainloop,
                    _ => {}
                }
            }
            self.draw(count);
            if count == 255 {
                count = 0;
            } else {
                count += 1;
            }
            ::std::thread::sleep(Duration::new(0, 1_000_000_000u32 / 30));
        }

        Ok(())
    }

    fn draw(&mut self, kido: u8) {
        self.canvas.set_draw_color(Color::RGB(kido, kido, kido));
        self.canvas.clear();
        self.canvas.present();
    }
}

fn main() -> Result<(), String> {
    let mut game = Game::new()?;
    game.run_roop()?;
    Ok(())
}