Implement way to automatically detect dark/light terminal

[cmer]

I'd like to propose the following:

If MCFLY_LIGHT is set to TRUE or FALSE, force McFly to display in the specified mode.

If MCFLY_LIGHT is NOT set, make a best effort guess to determine which mode to display in, otherwise fall back to dark mode. I was able to detect light/dark mode in some terminals (but not all) with the following Fish script:

  if string match -r '\;15$' $COLORFGBG &> /dev/null
    set -gx MCFLY_LIGHT TRUE
  end

It'd be awesome if McFly could perform this check every time it is triggered when MCFLY_LIGHT is not set to any particular value.

The COLORFGBG environment variable is set by many terminals such as iTerm2, Rxvt and Konsole. macOS Terminal does NOT set it, however.

[jltml]

Totally agreed; this would be wonderful! For anyone stumbling upon this who uses zsh on Mac with Terminal.app, this is what I have in the interim:

mcfly_auto_light_mode() {
  if [[ $(defaults read -g AppleInterfaceStyle) != 'Dark' ]]; then
    export MCFLY_LIGHT=TRUE
  fi
}
zsh-defer mcfly_auto_light_mode

(the zsh-defer is from this plugin)

[cantino]

I'm game if you want to make this change @cmer. I think the determination should be in the mcfly.bash / mcfly.zsh / mcfly.fish scripts that then set the ENV.

[cmer]

I have submitted a PR.

[vtmocanu]

This would apply only to new terminal/tabs right? ie it would not apply for existing ones.
I have hacked my .p10k so this gets set on each prompt iteration:

POWERLEVEL9K_RIGHT_PROMPT_ELEMENTS+=(mcfly_theme)
function prompt_mcfly_theme() {
  if grep -q 'light' ~/.theme_status; then
    export MCFLY_LIGHT=TRUE
  else unset MCFLY_LIGHT
  fi
}

i update ~/.theme_status dinamically with dark-notify

would love for mcfly to have a config where i could set this (so it checks for the theme on each run) and i could update that file with https://github.com/cormacrelf/dark-notify

[Tealk]

For Gnome 43 it works like this:

colorscheme="$(gsettings get org.gnome.desktop.interface color-scheme)"
if [ ! "$colorscheme" = "'prefer-dark'" ]; then
  export MCFLY_LIGHT=TRUE
fi

[rhersel]

dconf read /org/gnome/desktop/interface/color-scheme
'default' --> light theme
'prefer-dark' --> dark theme