Function run_app 

pub fn run_app<P, A>(
    config: WindowConfig,
    presenter: P,
    app: A,
) -> Result<(), EventLoopError>
where
    P: Presenter + 'static,
    A: App<WindowBackend<P>> + 'static,

Drive an App from the windowed event loop.

This is the inverted driver: winit owns the event loop and calls back into the app on each redraw, rather than the app owning a while loop.

Each frame builds a Frame with a wall-clock dt measured via web_time::Instant: a plain std::time::Instant re-export on native, backed by the browser’s Performance.now() on wasm32 (where std::time::Instant itself is unavailable). Calls App::update.

On Flow::Exit the event loop exits gracefully (via [ActiveEventLoop::exit]) instead of force-exiting the process, so the stack unwinds normally and Drop impls up the call chain (unflushed writes, GPU/surface teardown, app-level RAII) run before the process exits. This works the same on wasm: winit’s web backend implements ActiveEventLoop::exit by stopping its requestAnimationFrame-driven runner rather than leaving it a no-op.

See https://main.retroglyph.dev/book/explanation/architecture.html#presenting-is-automatic: this driver presents automatically after each App::update call, except on Flow::Idle.

Resizing applies before update runs

This driver resizes the Terminal itself on every window resize, before the next App::update call, so Terminal::size is never stale from the app’s point of view even if it never reacts to input. It also pushes Event::Resize with the new cell dimensions, for an app that wants to react to the change itself (reflow a layout, regenerate a world) rather than just read the new size on its next draw.

Return contract differs on wasm32

On native this call blocks and only returns once the loop reaches Flow::Exit. On wasm32 it returns Ok(()) immediately after handing the app to the browser’s requestAnimationFrame-driven runner: the app keeps running after this call returns, so code that follows it executes concurrently with a live app rather than after it exits. retroglyph_core::app::run_on_with has no such split; it always blocks until the app exits, on every target.

Errors

Returns EventLoopError if the event loop cannot be created or fails while running.