mirror of
https://github.com/emilk/egui.git
synced 2026-06-26 22:53:14 -04:00
cd3c38cf2a
## Summary * Closes #5229 * Closes #7776 On Windows, once a window is hidden with `ViewportCommand::Visible(false)`, two problems occur: 1. **Window can never be shown again** — Windows stops sending `RedrawRequested` events to invisible windows, and viewport commands are only processed during `run_ui_and_paint`, which is triggered by `RedrawRequested`. This creates a deadlock: ``` Visible(false) → window hidden → no RedrawRequested → run_ui_and_paint never called → Visible(true) stuck in queue → window stays hidden forever ``` 2. **High CPU usage** — The event loop spins at full speed with `ControlFlow::Poll` even for invisible windows, and repaint requests are scheduled immediately, causing a tight loop that burns CPU. ## Fix **For #5229:** In `check_redraw_requests`, after calling `window.request_redraw()`, detect invisible windows via `window.is_visible() == Some(false)` and call `run_ui_and_paint` directly for them. This ensures pending viewport commands (including `Visible(true)`) are still processed even when the OS doesn't send redraw events. **For #7776:** Three layers of throttling for invisible windows: - **Heartbeat scheduling:** After painting an invisible window, schedule the next repaint 100ms in the future (instead of immediately). This keeps viewport commands flowing while limiting to ~10 repaints/sec. - **Event throttling:** In `user_event`, throttle `RequestRepaint` events for invisible windows to at least 100ms delay, preventing egui's repaint callback from bypassing the heartbeat. - **ControlFlow fix:** Only set `ControlFlow::Poll` for visible windows. Invisible windows use `WaitUntil` instead of spinning. - **Backend sleep:** Add `is_visible() == Some(false)` alongside the existing `is_minimized()` sleep check in both wgpu and glow backends (defense in depth). The fix is platform-agnostic: `is_visible()` returns `Some(false)` only when the platform can confirm invisibility, so it won't trigger on platforms where invisible windows still receive `RedrawRequested`. ## Test plan - [x] `cargo fmt` passes - [x] `cargo clippy -p eframe --all-features` passes with no warnings - [x] Manual test on Windows: window reappears after `Visible(true)` when hidden - [x] Manual test on Windows: CPU stays near 0% while window is invisible (was ~16% before fix) --------- Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>