bevy_window_manager

A Bevy plugin for window state persistence and multi-monitor utilities.

Motivation

Originally created as a mechanism to restore a window to its last known position when launching. I quickly discovered that on my MacBook Pro with Retina display (scale factor 2.0) and my external monitor with a scale factor 1.0, there were numerous issues with saving. Especially painful is the situation that winit uses the scale factor of where you're typing (launching) the application so that when it lands on a different monitor, you cannot reliably restore the window to its last known position when launching from a monitor with a different scale factor than the application window's target monitor.

bevy_window_manager plugin works around these issues by using winit directly to capture actual window positions and compensate for scale factor conversions. See the documentation in src/lib.rs for technical details.

Windows has similar scale factor issues, plus additional quirks like invisible window borders that prevent precise placement. As of 0.17.1, this plugin includes workarounds for Windows multi-monitor setups with monitors at different scale factors (see Platform Support for testing notes).

Future directions include comprehensive multi-monitor lifecycle support.

Usage

use bevy::prelude::*;
use bevy_window_manager::WindowManagerPlugin;

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_plugins(WindowManagerPlugin)
        .run();
}

For a complete interactive example with fullscreen mode switching, run:

cargo run --example restore_window

API

This crate exposes several types for working with monitors and windows beyond the plugin itself. See docs.rs for full API documentation.

Monitors Resource

Query available monitors sorted by position:

• monitors.at(x, y) – Find the monitor containing a position
• monitors.by_index(index) – Get monitor by sorted index
• monitors.primary() – Get the primary monitor (index 0)
• monitors.closest_to(x, y) – Find the closest monitor to a position

MonitorInfo

Information about a single monitor: index, scale, position, and size.

WindowExt Extension Trait

Requires use bevy_window_manager::WindowExt:

• window.monitor(&monitors) – Get the monitor this window is currently on
• window.effective_mode(&monitors) – Detect effective window mode (handles macOS green button fullscreen)
• window.set_position_and_size(position, size) – Set both in one call

Plugin Configuration

• WindowManagerPlugin – Uses executable name for config directory
• WindowManagerPlugin::with_app_name("name") – Custom app name
• WindowManagerPlugin::with_path(path) – Full control over state file path

Version Compatibility

Platform Support

This plugin was originally created to handle a MacBook Pro with external monitors at different scale factors, which caused window position/size corruption. Windows multi-monitor setups with monitors at different scale factors are now supported as of 0.17.1 (see CHANGELOG).

Note on Windows testing: Windows support has been tested in a VMware virtual machine with multiple monitors at different scale factors. Native Windows installations may behave differently - if you encounter issues, please open an issue with details about your monitor configuration.

Note on Linux support: Linux support has begun with single-monitor testing on KDE Plasma (Asahi Linux). Multi-monitor setups with different scale factors are not yet tested. Wayland has an inherent limitation: clients cannot query or set window position, so only size and fullscreen state can be restored. If you encounter issues, please open an issue with details about your distribution, desktop environment, and monitor configuration.

Feature Flags (Platform Workarounds)

This plugin includes workarounds for known issues in winit and Bevy. Each workaround is behind a feature flag, and all are enabled by default.

This design allows:

• Easy testing of upstream fixes - disable a workaround to verify an upstream fix works
• Opt-out flexibility - if a workaround doesn't suit your setup, you can exclude it
• Minimal code when not needed - platform-specific workarounds are compiled out on other platforms

Available Feature Flags

Disabling Workarounds

To test without a specific workaround (e.g., to verify an upstream fix):

# Disable all workarounds
cargo run --example restore_window --no-default-features

# Disable only the macOS drag-back workaround
cargo run --example restore_window --no-default-features --features workaround-winit-4341,workaround-winit-3124,workaround-macos-scale-compensation,workaround-bevy-22060

In your Cargo.toml, you can selectively enable features:

[dependencies]
bevy_window_manager = { version = "0.17", default-features = false, features = ["workaround-winit-4341"] }

License

bevy_window_manager is free, open source and permissively licensed! Except where noted (below and/or in individual files), all code in this repository is dual-licensed under either:

• MIT License (LICENSE-MIT or http://opensource.org/licenses/MIT)
• Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)

at your option.

Your contributions

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.