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Setting Emacs theme based on ambient light

matthewbilyeu.com

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Re: Setting Emacs theme based on ambient light

#3

Post by auxym »

I've had this in my vimrc for a little while:

  let hr = (strftime('%H'))
  if hr >= 17
      set background=dark
  elseif hr >= 7
      set background=light
  elseif hr >= 0
      set background=dark
  endif
Using a light sensor would be cool, but I actually work from a desktop PC most of the time, so no sensor. I guess the next best thing would be something like f.lux does: query some web service for the sunset time at your current location.

Re: Setting Emacs theme based on ambient light

#4

Post by gkya »

auxym wrote: post #3

I've had this in my vimrc for a little while: let hr = (strftime('%H')) if hr >= 17 set background=dark elseif hr >= 7 set background=light elseif hr >= 0 set background=dark endif Using a light sensor would be cool, but I actually work from a desktop PC most of the time, so no sensor. I guess the next best thing would be something like f.lux does: query some web service for the sunset time at your current location.

I have this old and slightly buggy vim plugin [1] which uses py-ephem to determine the correct moment to switch themes every day. It's been quite a while since I've used vim and I don't maintain this, but you may want to chech it out. BTW, if there's anybody that wants to take over it, please contact me via a github issue through the repo below.

[1] https://github.com/cadadr/vim-sunflower

Re: Setting Emacs theme based on ambient light

#6

Post by Scarbutt »

is the background color really the problem? I though screen brightness was a more issue, for example: continue using your light theme but lower down the brightness, most of your websites are going to be white backgrounds, switch between dark and light background frequently strains more the eyes, looking for the link where I read this.

Re: Setting Emacs theme based on ambient light

#7

Post by ddavis »

Thanks for sharing, this is really cool. I often struggle with my Emacs theme switching between light and dark traveling in and out of my windowless office which is filled with intense unnatural night. I once tried to write some Elisp for determining my theme based on the network I was connected to, didn’t work out. I’ll definitely try using this!

Re: Setting Emacs theme based on ambient light

#8

Post by kfoley »

I really like this idea, it's something I've been wanting to try out for a while now.

I'm curious if using `run-with-timer` causes any performance issues in emacs. If so one option is to watch the value outside of emacs and then change the theme using `emacsclient -d "(load-theme 'my-dark-theme t)"` from the script.

Re: Setting Emacs theme based on ambient light

#9

Post by rockymadden »

Scarbutt wrote: post #6

is the background color really the problem? I though screen brightness was a more issue, for example: continue using your light theme but lower down the brightness, most of your websites are going to be white backgrounds, switch between dark and light background frequently strains more the eyes, looking for the link where I read this.

Agreed, and for this reason I use Lumen: https://github.com/anishathalye/lumen

Re: Setting Emacs theme based on ambient light

#10

Post by TeMPOraL »

kfoley wrote: post #8

I really like this idea, it's something I've been wanting to try out for a while now. I'm curious if using `run-with-timer` causes any performance issues in emacs. If so one option is to watch the value outside of emacs and then change the theme using `emacsclient -d "(load-theme 'my-dark-theme t)"` from the script.

It looks like it could; the timer isn't the problem (they're just entries in a queue), but #'shell-command-to-string call might be. It's a synchronous, blocking call (at least on my Emacs 26, running (shell-command-to-string "sleep 5") hangs the whole Emacs nicely for 5 seconds).

Personally, I'd reimplement it the way you suggest - I'd put the timer loop in C code to save on repeatedly starting a process, and then make it run emacsclient -e "(change-theme-for-lighting %d)", where %d is a sensor value, whenever that value crosses a threshold.

Alternatively, if you want to keep the entire business logic within Emacs Lisp code, there's some way to make it work too. I'd look into documentation of #'make-process[0]. There's an argument :FILTER that would let you set a function that receives stdout from that process. Alternatively, #'start-process-shell-command with NIL for buffer, + #'set-process-filter should achieve the same thing. So the C program would be barfing out the sensor value every second or so, and the process filter would read it.

(You might also want to read through the sources of #'shell-command to see how it uses the above facilities to handle asynchronous shell processes - the ones you invoke with M-x async-shell-command - but I think it'll work out of the box, and the process filter will only be executed as new output arrives.)

--

[0] - in Emacs, type: C-h f make-process. Gotta love the self-documenting features of this editor. Actually, half of my comment is based on what I just read in docs of various Emacs functions. Also, hint: make sure you install Emacs with sources - then you can easily jump from help buffer directly into code implementing the thing you're reading about.

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