Context for this PR: bevyengine#8745 .

Dynamic key mapping to rely on physical key rather than only logical key

Problem description

winit 0.29 logical key with modifiers (shift) is hard to use cache with, because winit can send pressed('A'), and then released('a').

So Res::<Key>::is_pressed('A') returns true when pressing 'A' then releasing 'a'. That's not correct!

Details

A branch without the Dynamic key mapping can be tried there: https://github.com/Vrixyz/bevy/tree/update-winit-without-dynamic-key-mapping

KeyEvent {
    physical_key: ShiftRight,
    logical_key: Shift,
    text: None,
    location: Right,
    state: Pressed,
    repeat: false,
    platform_specific: KeyEventExtra {
        text_with_all_modifers: None,
        key_without_modifiers: Shift,
    },
}

KeyEvent {
    physical_key: KeyQ,
    logical_key: Character(
        "A", // <--- We store cache["A"] = pressed
    ),
    text: Some(
        "A",
    ),
    location: Standard,
    state: Pressed,
    repeat: false,
    platform_specific: KeyEventExtra {
        text_with_all_modifers: Some(
            "A",
        ),
        key_without_modifiers: Character(
            "a",
        ),
    },
}

KeyEvent {
    physical_key: ShiftRight,
    logical_key: Shift,
    text: None,
    location: Right,
    state: Released,
    repeat: false,
    platform_specific: KeyEventExtra {
        text_with_all_modifers: None,
        key_without_modifiers: Shift,
    },
}

KeyEvent {
    physical_key: KeyQ,
    logical_key: Character(
        "a", // <--- We store cache["a"] = released;
    ),
    text: None,
    location: Standard,
    state: Released,
    repeat: false,
    platform_specific: KeyEventExtra {
        text_with_all_modifers: None,
        key_without_modifiers: Character(
            "a",
        ),
    },
}

New aggregated resource Res<Input<KeyLogic>>

This is less necessary, but I noticed a lot of duplicated code between Res<Input<KeyCode>> and Res<Input<Key>>, this is an attempt to simplify the API and improve maintainability.

Resources impacts

Breaking: removed Res<Input<KeyCode>> and Res<Input<ScanCode>>, in favor of Res<Input<KeyLogic>>

• ScanCode information can be inferred within KeyLogic::PhysicalKey.
• a new concept of LogicalKey (depending on OS software layout) can be accessed through KeyLogic::Key.

API impacts

These key snippets assume a keys: Res<Input<KeyLogic>>

You can now query for physical or logical key codes with:

• Physical: keys.pressed(KeyLogic::Physical(KeyCode::KeyA))
• Logical: keys.pressed(KeyLogic::Logic(Key::Character(SmollStr::new("a")))

Through From trait impls, ergonomics are still good:

• Physical: keys.pressed(KeyCode::KeyA)
• Logical: keys.pressed("a")
  • or keys.pressed(KeyLogic::Logic("a"))
  • or keys.pressed(Key::Character("a"))