A Quicksilver Chanukah, Day 4: Blinds

With the recent update to winit, it gained web support! This is great, and it means that Quicksilver doesn’t need to have its own parallel implementation of windowing. However, there is room for an abstraction that’s a little simpler than Winit, and takes advantage of async/.await, which is where blinds comes in.

blinds is based on winit, but focused on Quicksilver’s specific use case of single-window games on desktop and web. It also integrates gilrs for gamepad support (though this could be provided directly by winit later), without exposing either in its external API. Additionally, blinds has optional support for OpenGL, via glow for uniform bindings across web and desktop.

The async API works via the LocalPool and the winit event loop, allowing you to write code that almost looks like a synchronous event loop.

use blinds::{run, Event, EventStream, Key, Settings, Window};

run(Settings::default(), app);

async fn app(_window: Window, mut events: EventStream) {
    loop {
        while let Some(ev): events.next_event().await {
            // Process your events here!
        }
        // Process your frame here!
    }
}

The use of .await here is a bit of a hack, as it allows the event loop to wrest control away from the user and return it to the browser without blocking. Compare this to the comparable snippet from the legacy Quicksilver API:

use quicksilver::{
    Result,
    geom::Vector,
    lifecycle::{Event, Settings, State, Window, run},
};

struct HelloWorld;

impl State for HelloWorld {
    fn new() -> Result<HelloWorld> {
        Ok(HelloWorld)
    }
    
    fn event(&mut self, window: &mut Window, event: &Event) -> Result<()> {
        // Process events here
        Ok(())
    }
    
    fn update(&mut self, window: &mut Window) -> Result<()> {
        // Update here
        Ok(())
    }

    fn draw(&mut self, window: &mut Window) -> Result<()> {
        // Draw here
        Ok(())
    }
}

fn main() {
    run::<HelloWorld>("Hello World", Vector::new(800, 600), Settings::default());
}

The async API isn’t just way more convenient than the previous, trait-based system. It also allows you to use other async APIs (like day 2’s platter), which is important for web support.

blinds isn’t quite ready for a full release yet: there are a few more window APIs I do want to expose before it leaves alpha. However, you can still try it out, just be aware that the API is fairly unstable and likely to change between multiple times before the first non-alpha release!

With blinds today, tomorrow will be the last new crate: golem!