eframe: Automatically change theme when system dark/light mode changes #2750
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Really cool, thank you so much for working on this!
Since winit now has WindowEvent::ThemeChanged I wonder if we even need the dark-light feature. Can we detect the initial system theme with just winit? There is Window::theme but it seems to be Mac only (Windows not mentioned) and it's unclear if it reads it from system settings or just the previous call to window.set_theme.
In either case, I think we should listen for ThemeChanged regardless of whether or not the dark-light feature is enabled.
| #[cfg(feature = "dark-light")] | ||
| WindowEvent::ThemeChanged(winit_theme) if self.follow_system_theme => { |
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I don't see any reason to limit this on the dark-light feature.
dark-light pulls in a specific dependency for detecting the system theme on start-up. Maybe we can do that via winit instead?
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I have removed #[cfg(feature = "dark-light")] from all places where it's not necessary.
Detecting the theme via winit's theme function works for Windows and macOS—I have tested the latest change on both my Windows 11 and my macOS devices.
The theme is read from the system preferences when the window is created.
The theme function always returns None on Linux though (for both X11 and Wayland), so there we still have to rely on dark-light.
The NativeOptions::system_theme function has become a bit of a liar, since it no longer corresponds with the effectively used system theme on Windows and macOS.
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Interesting! Sounds like we maybe don't need dark-light at all then? (since it already doesn't work well on Linux)
emilk
added
web
Since #2750 we now get what we need straight from `winit`.
* Remove dark-light dependency Since #2750 we now get what we need straight from `winit`. * fix warning * Docstring formatting * fix typo in check.sh
I noticed that
eframedoes not change the theme when the system dark/light mode is changed while the app is running.For
winitreacting to the change is fairly easy: There's aThemeChangedevent. It's not supported everywhere, but I guess it's better than nothing :).For web, there's a
changeevent onMediaQueryList.dark_light_mode_change.mp4