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>
eframe: the egui framework
eframe is the official framework library for writing apps using egui. The app can be compiled both to run natively (for Linux, Mac, Windows, and Android) or as a web app (using Wasm).
To get started, see the examples.
To learn how to set up eframe for web and native, go to https://github.com/emilk/eframe_template/ and follow the instructions there!
There is also a tutorial video at https://www.youtube.com/watch?v=NtUkr_z7l84.
For how to use egui, see the egui docs.
eframe defaults to using wgpu for rendering (with an option to change to glow), and on native it uses egui-winit.
To use on Linux, first run:
sudo apt-get install libxcb-render0-dev libxcb-shape0-dev libxcb-xfixes0-dev libxkbcommon-dev libssl-dev
You need to either use edition = "2024", or set resolver = "2" in the [workspace] section of your to-level Cargo.toml. See this link for more info.
You can opt-in to the using egui_glow for rendering by enabling the glow feature and setting NativeOptions::renderer to Renderer::Glow.
Alternatives
eframe is not the only way to write an app using egui! You can also try egui-miniquad, bevy_egui, egui_sdl2_gl, and others.
You can also use egui_glow and winit to build your own app as demonstrated in https://github.com/emilk/egui/blob/main/crates/egui_glow/examples/pure_glow.rs.
Limitations when running egui on the web
eframe and egui compiles to Wasm using either WebGPU (when available) or WebGL2 for rendering, and almost nothing else from the web tech stack. This has some benefits, but also produces some challenges and serious downsides.
- Rendering: Getting pixel-perfect rendering right on the web is very difficult.
- Search: you cannot search an egui web page like you would a normal web page.
- Bringing up an on-screen keyboard on mobile: there is no JS function to do this, so
eframefakes it by adding some invisible DOM elements. It doesn't always work. - Mobile text editing is not as good as for a normal web app.
- No integration with browser settings for colors and fonts.
- Accessibility: There is an experimental screen reader for
eframe, but it has to be enabled explicitly. There is no JS function to ask "Does the user want a screen reader?" (and there should probably not be such a function, due to user tracking/integrity concerns).eguisupports AccessKit, but as of early 2024, AccessKit lacks a Web backend.
In many ways, eframe is trying to make the browser do something it wasn't designed to do (though there are many things browser vendors could do to improve how well libraries like egui work).
The suggested use for eframe are for web apps where performance and responsiveness are more important than accessibility and mobile text editing.
Companion crates
Not all rust crates work when compiled to Wasm, but here are some useful crates have been designed to work well both natively and as Wasm:
Name
The frame in eframe stands both for the frame in which your egui app resides and also for "framework" (eframe is a framework, egui is a library).