bevy/crates/bevy_window/src/system.rs
Brezak 0c7df881e7
Properly handle repeated window close requests (#14573)
# Objective

Spamming the window close button on window may trigger a panic.

```
thread 'main' panicked at <Bevy repo>\crates\bevy_ecs\src\system\commands\mod.rs:1320:13:
error[B0003]: Could not insert a bundle (of type `bevy_window:🪟:ClosingWindow`) for entity 0v1#4294967296 because it doesn't exist in this World. See: https://bevyengine.org/learn/errors/b0003
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Encountered a panic when applying buffers for system `bevy_window::system::close_when_requested`!
2024-08-01T15:00:29.742612Z  WARN bevy_ecs::world::command_queue: CommandQueue has un-applied commands being dropped. Did you forget to call SystemState::apply?
Encountered a panic in system `bevy_app::main_schedule::Main::run_main`!
error: process didn't exit successfully: `target\debug\bevy.exe` (exit code: 101)
```

## Solution

Don't panic when trying to insert the `ClosingWindow` component into a
entity.

## Testing

Found and tested on windows. I haven't checked if this bug happens on
linux or macos.
For testing I ran this code:

```rust
use std::{thread, time::Duration};

use bevy::prelude::*;

fn lag() {
    thread::sleep(Duration::from_millis(300));
}

fn main() -> AppExit {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_systems(Update, lag)
        .run()
}
```

Then spammed the window close button. The panic no longer occurs.
2024-08-01 16:15:28 +00:00

58 lines
2.3 KiB
Rust

use crate::{ClosingWindow, PrimaryWindow, Window, WindowCloseRequested};
use bevy_app::AppExit;
use bevy_ecs::prelude::*;
/// Exit the application when there are no open windows.
///
/// This system is added by the [`WindowPlugin`] in the default configuration.
/// To disable this behavior, set `close_when_requested` (on the [`WindowPlugin`]) to `false`.
/// Ensure that you read the caveats documented on that field if doing so.
///
/// [`WindowPlugin`]: crate::WindowPlugin
pub fn exit_on_all_closed(mut app_exit_events: EventWriter<AppExit>, windows: Query<&Window>) {
if windows.is_empty() {
bevy_utils::tracing::info!("No windows are open, exiting");
app_exit_events.send(AppExit::Success);
}
}
/// Exit the application when the primary window has been closed
///
/// This system is added by the [`WindowPlugin`]
///
/// [`WindowPlugin`]: crate::WindowPlugin
pub fn exit_on_primary_closed(
mut app_exit_events: EventWriter<AppExit>,
windows: Query<(), (With<Window>, With<PrimaryWindow>)>,
) {
if windows.is_empty() {
bevy_utils::tracing::info!("Primary window was closed, exiting");
app_exit_events.send(AppExit::Success);
}
}
/// Close windows in response to [`WindowCloseRequested`] (e.g. when the close button is pressed).
///
/// This system is added by the [`WindowPlugin`] in the default configuration.
/// To disable this behavior, set `close_when_requested` (on the [`WindowPlugin`]) to `false`.
/// Ensure that you read the caveats documented on that field if doing so.
///
/// [`WindowPlugin`]: crate::WindowPlugin
pub fn close_when_requested(
mut commands: Commands,
mut closed: EventReader<WindowCloseRequested>,
closing: Query<Entity, With<ClosingWindow>>,
) {
// This was inserted by us on the last frame so now we can despawn the window
for window in closing.iter() {
commands.entity(window).despawn();
}
// Mark the window as closing so we can despawn it on the next frame
for event in closed.read() {
// When spamming the window close button on windows (other platforms too probably)
// we may receive a `WindowCloseRequested` for a window we've just despawned in the above
// loop.
commands.entity(event.window).try_insert(ClosingWindow);
}
}