This was adopted from #12878. I rebased the changes resolved the
following merge conflicts:
- moved over the changes originally done in bevy_winit/src/lib.rs's
`handle_winit_event` into bevy_winit/src/state.rs's `window_event`
function
- moved WinitEvent::KeyboardFocusLost event forwarding originally done
in bevy_winit/src/winit_event.rs to the equivalent in
bevy_winit/src/state.rs
Tested this by following the modified keyboard_input example from the
original PR.
First, I verified I could reproduce the issue without the changes. Then,
after applying the changes, I verified that when I Alt+Tabbed away from
the running example that the log showed I released Alt and when I tabbed
back it didn't behave like Alt was stuck.
The following is from the original pull request by @gavlig
# Objective
This helps avoiding stuck key presses after switching from and back to
Bevy window. Key press event gets stuck because window loses focus
before receiving a key release event thus we end up with false positive
in ButtonInput.
## Solution
I saw two ways to fix this:
1. add bevy_window as dependency and read WindowFocus events
2. add a KeyboardFocusLost event specifically for this.
I chose the latter because adding another dependency felt wrong, but if
that is more preferable changing this pr won't be a problem. Also if
someone sees another way please let me know.
To test the bug use this small modification over
examples/keyboard_input.rs: (it will work only if you have Alt-Tab
combination for switching between windows in your OS, otherwise change
AltLeft accordingly)
```
//! Demonstrates handling a key press/release.
use bevy::{prelude::*, input:⌨️:KeyboardInput};
fn main() {
App::new()
.add_plugins(DefaultPlugins)
.add_systems(Update, keyboard_input_system)
.run();
}
/// This system prints 'Alt' key state
fn keyboard_input_system(keyboard_input: Res<ButtonInput<KeyCode>>, mut
keyboard_input_events: EventReader<KeyboardInput>) {
for event in keyboard_input_events.read() {
info!("{:?}", event);
}
if keyboard_input.pressed(KeyCode::AltLeft) {
info!("'Alt' currently pressed");
}
if keyboard_input.just_pressed(KeyCode::AltLeft) {
info!("'Alt' just pressed");
}
if keyboard_input.just_released(KeyCode::AltLeft) {
info!("'Alt' just released");
}
}
```
Here i made a quick video with demo of the fix:
https://youtu.be/qTvUCk4IHvo In first part i press Alt and Alt+Tab to
switch back and forth from example app, logs will indicate that too. In
second part I applied fix and you'll see that Alt will no longer be
pressed when window gets unfocused
## Migration Guide
`WinitEvent` has a new enum variant: `WinitEvent::KeyboardFocusLost`.
Co-authored-by: gavlig <gavlig@gmail.com>
bd6acc6119