main.rs

//! Shows how to render simple primitive shapes with a single color.

use bevy::{
    prelude::*,
    window::{CursorGrabMode, PresentMode, WindowLevel},
};

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .insert_resource(ClearColor(Color::BLACK))
        .add_plugins(DefaultPlugins.set(WindowPlugin {
            primary_window: Some(Window {
                title: "I am a window!".into(),
                resolution: (1008., 567.).into(),
                // Tells wasm to resize the window according to the available canvas
                fit_canvas_to_parent: true,
                // Tells wasm not to override default event handling, like F5, Ctrl+R etc.
                prevent_default_event_handling: false,
                ..default()
            }),
            ..default()
        }))
        //.add_plugins(DefaultPlugins)
        .add_startup_system(setup)
        .add_system(rectangle)
        .add_system(Update, keyboard_input)
        .run();
}

fn setup(
    mut commands: Commands,
) 
{
    commands.spawn(Camera2dBundle::default());
}

fn rectangle(mut cmd: Commands)
{
    cmd.spawn(SpriteBundle {
        sprite: Sprite {
            color: Color::hex("7700FF").unwrap(),
            custom_size: Some(Vec2::new(100.0, 100.0)),
            ..default()
        },
        transform: Transform::from_translation(Vec3::new(-50., 0., 0.)),
        ..default()
    });
}

fn keyboard_input_system(keyboard_input: Res<Input<KeyCode>>) {
    if keyboard_input.pressed(KeyCode::A) {
        info!("'A' currently pressed");
    }

    if keyboard_input.just_pressed(KeyCode::A) {
        info!("'A' just pressed");
    }

    if keyboard_input.just_released(KeyCode::A) {
        info!("'A' just released");
    }
}

The Example Code.rs

//! Demonstrates handling a key press/release.

use bevy::prelude::*;

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_systems(Update, keyboard_input_system)
        .run();
}

/// This system prints 'A' key state
fn keyboard_input_system(keyboard_input: Res<Input<KeyCode>>) {
    if keyboard_input.pressed(KeyCode::A) {
        info!("'A' currently pressed");
    }

    if keyboard_input.just_pressed(KeyCode::A) {
        info!("'A' just pressed");
    }

    if keyboard_input.just_released(KeyCode::A) {
        info!("'A' just released");
    }
}