Use theme based on color scheme

[Siilwyn]

Start at solving #2158, I hope this can eventually land in master, otherwise I'm happy to share this branch for others to use.

• This uses the freedesktop portal to read the color-scheme preference.
• At the moment this only reads the color scheme on startup.
• zbus supports watching a property but I'm unsure where in the codebase to start this process, I'd love help with this: any pointers welcome!
• Thinking of removing the theme_light in favor of using the "normal" theme when the color scheme is: not found, has no preference or is set to prefer light. This simplifies things a bit and matches more with most distros that don't communicate prefer light when dark mode is off.

[archseer]

This pulls in hundreds of dependencies just to read a single value. Could this be done by a wrapper script on the user side that's executed when the editor starts?

[Siilwyn]

Yes that's quite unfortunate, this is the impact on the binary size: 26MB > 30MB. I'm going to add functionality that watches the dbus as well so a wrapper script won't cut it.

Will look into using a more lightweight way, maybe the dbus crate or using the dbus cli tools.

[jesse-c]

As someone who's invested in this sort of behaviour [1], I'm curious about this feature! I primarily use macOS, and as far as I can see, the proposed solution so far wouldn't support macOS? If that's true, I'm happy to do some thinking about how this could feature could be supported for macOS.

[1] https://github.com/jesse-c/AppearanceNotifier

[pascalkuthe]

Concerns like this is why I personally belive something like this does not belong in core. There is no standard solution/its highly platform specific and all that platform-specific code pulls in a huge number of dependencies. If this could be implemented in a couple lines of code plus a simple wrapper script that could be ok but I don't think that's the case.

Something like this could be a plugin (which could reasonably be a platform-specific so you have one plugin for mac and one for linux) once we have ar plugin system. Until then you could implement a rimple daemon to symlinks a different config file depending on whether dark/light theme is active and send a signal (pkill -USR1 hx) to reload the config.

[jesse-c]

That makes sense, @pascalkuthe!

If this could be implemented in a couple lines of code plus a simple wrapper script that could be ok but I don't think that's the case.

For macOS, if with performance, and other points, allowed, it can be done with a timer that runs every n milliseconds (or even every 1-3 seconds tbh), that checks the output of the terminal command defaults read -g AppleInterfaceStyle, which will tell you what the current macOS theme setting is (light vs dark).

Something like this could be a plugin (which could reasonably be a platform-specific so you have one plugin for mac and one for linux) once we have ar plugin system.

That sounds very reasonable.

Until then you could implement a rimple daemon to symlinks a different config file depending on whether dark/light theme is active and send a signal (pkill -USR1 hx) to reload the config.

This is what I have at the moment! [1] I was happy when I discovered this recently, haha.

[1] jesse-c/AppearanceNotifier@6e4cb4f

[swsnr]

As an alternative, most major xterm-compatible support the OSC 11 escape sequence to query the current background colour and correctly reply with the RGB value of the current background colour. From this value one can derive the luminance and determine whether the background colour is light or dark.

This approach works with raw IO, ie stdlib only without any additional dependencies, and detects the appropriate colour theme even if the terminal itself does not honour the desktop dark mode settings (some people do use a dark terminal even if the overall desktop appearance is light).

It does not allow monitoring (though helix could also just poll the background colour at certain intervals), but a simple command to change the background colour could help here.

I believe that this is how (neo)vim detects the terminal background colour.

[malobre]

@Siilwyn You may be interested in https://github.com/udoprog/tokio-dbus which only depends on tokio and libc.

[pascalkuthe]

closing this one out as I don't see us adding this to core (see discussion above). Thank you for contributing!