base16-nvim Set `vim.o.background`

It would be great if themes in this repo would also set vim.o.background, which is used by some plugins.

For example, https://github.com/nvim-tree/nvim-web-devicons, use this variable to select different colors for icons

Aug 28 '23 14:08 simonmandlik

I'm open to suggestions, but there's no good way to automate vim.o.background for the themes which are sourced from the base-16 repo. A heuristic could work, but it'd be brittle. If you want to open a PR added a heuristic to .setup I'd consider merging it.

Sep 12 '23 01:09 RRethy

I like the idea of setting vim.o.background.

How about the following method of determining whether a color scheme has a light or dark background?

Get the background color (base00) of a color scheme.
Calculate the relative luminance of base00. Call it l1.
Calculate the relative luminance of the middle gray (i.e. rgb(50% 50% 50%) in the CSS syntax). Call it l2.
If l1 < l2, the color scheme is dark because it is darker than the middle gray, otherwise, it is light.

Edit: I wrote an example in Lua, but it's awkward since I'm new to Lua.

Lua Script

#!/usr/bin/env lua
--- A demonstration to determine whether a color scheme is light or dark.
-- @module demo

--- Parses a hexadecimal sRGB color and returns a table containing three
-- components: red, green, and blue, each in the range [0.0, 1.0].
-- @tparam string hex An sRGB color represented in the hexadecimal format #RRGGBB.
-- @treturn {float,float,float} A table containing the red, green, and blue
-- components of the given color, normalized to the range [0.0, 1.0].
-- @usage
-- local result = srgb("#FFFFFF")
-- local r = result[1]
-- local g = result[2]
-- local b = result[3]
local function srgb(hex)
    local stripped = string.sub(hex, 2)  -- Removes the prefix "#"
    local srgb = tonumber(stripped, 16)
    return {
        (srgb >> 16 & 0XFF) / 255.0,  -- red
        (srgb >> 8  & 0XFF) / 255.0,  -- green
        (srgb       & 0XFF) / 255.0,  -- blue
    }
end

--- Converts sRGB to linear RGB.
-- @tparam {float,float,float} srgb An sRGB color with each component normalized
-- to the range [0.0, 1.0].
-- @treturn {float,float,float} A table containing the red, green, and blue
-- components of the given linear RGB color.
-- @usage
-- local normalized_srgb = { 1.0, 1.0, 1.0 }
-- local result = linear_rgb(normalized_srgb)
-- local r = result[1]
-- local g = result[2]
-- local b = result[3]
local function linear_rgb(srgb)
    local linear = {}
    for i, component in pairs(srgb) do
        if component <= 0.04045 then
            linear[i] = component / 12.92
        else
            linear[i] = ((component + 0.055) / 1.055) ^ 2.4
        end
    end
    return linear
end

--- Calculates the relative luminance of a linear RGB color.
-- @tparam {float,float,float} linear_rgb A linear RGB color.
-- @treturn float The relative luminance of the given color.
-- @usage
-- local linear_rgb = {1.0, 1.0, 1.0}
-- local relative_luminance = luminance(linear_rgb)
local function luminance(linear_rgb)
    local r, g, b = table.unpack(linear_rgb)
    return 0.2126 * r + 0.7152 * g + 0.0722 * b
end

--- Calculates the relative luminance of a hexedecimal sRGB color.
-- @tparam string hex An sRGB color in the hexadecimal format #RRGGBB.
-- @treturn float The relative luminance of the given color.
-- @usage local relative_luminance = luminance_from_hex_srgb("#FFFFFF")
local function luminance_from_hex_srgb(hex)
    local srgb = srgb(hex)
    local linear_rgb = linear_rgb(srgb)
    return luminance(linear_rgb)
end

--- Calculates the relative luminance of the middle gray (#808080).
-- @treturn float The relative luminance of the middle gray (#808080).
local function middle_gray()
    local srgb = {0.5, 0.5, 0.5}
    local linear_rgb = linear_rgb(srgb)
    return luminance(linear_rgb)
end

--- Runs the demonstration.
local function demo()
    local color_schemes = require("colors")
    local l2 = middle_gray()

    for name, colors in pairs(color_schemes) do
        local l1 = luminance_from_hex_srgb(colors.base00)
        if l1 < l2 then
            print(string.format("%s is dark", name))
        else
            print(string.format("%s is light", name))
        end
    end
end

demo()

Here is a manually summarized table of the results. It looks pretty good to me.

Table

colorscheme	background color	Calculated `vim.o.background`
3024	`#090300`	`dark`
apathy	`#031a16`	`dark`
apprentice	`#262626`	`dark`
ashes	`#1c2023`	`dark`
atelier-cave	`#19171c`	`dark`
atelier-dune	`#20201d`	`dark`
atelier-estuary	`#22221b`	`dark`
atelier-forest	`#1b1918`	`dark`
atelier-heath	`#1b181b`	`dark`
atelier-lakeside	`#161b1d`	`dark`
atelier-plateau	`#1b1818`	`dark`
atelier-savanna	`#171c19`	`dark`
atelier-seaside	`#131513`	`dark`
atelier-sulphurpool	`#202746`	`dark`
atlas	`#002635`	`dark`
ayu-dark	`#0f1419`	`dark`
ayu-mirage	`#171b24`	`dark`
bespin	`#28211c`	`dark`
black-metal	`#000000`	`dark`
black-metal-bathory	`#000000`	`dark`
black-metal-burzum	`#000000`	`dark`
black-metal-dark-funeral	`#000000`	`dark`
black-metal-gorgoroth	`#000000`	`dark`
black-metal-immortal	`#000000`	`dark`
black-metal-khold	`#000000`	`dark`
black-metal-marduk	`#000000`	`dark`
black-metal-mayhem	`#000000`	`dark`
black-metal-nile	`#000000`	`dark`
black-metal-venom	`#000000`	`dark`
blueforest	`#141f2e`	`dark`
blueish	`#182430`	`dark`
brewer	`#0c0d0e`	`dark`
bright	`#000000`	`dark`
brogrammer	`#1f1f1f`	`dark`
brushtrees-dark	`#485867`	`dark`
catppuccin	`#1e1e28`	`dark`
catppuccin-frappe	`#303446`	`dark`
catppuccin-macchiato	`#24273a`	`dark`
catppuccin-mocha	`#1e1e2e`	`dark`
chalk	`#151515`	`dark`
circus	`#191919`	`dark`
classic-dark	`#151515`	`dark`
codeschool	`#232c31`	`dark`
colors	`#111111`	`dark`
da-one-black	`#000000`	`dark`
da-one-gray	`#181818`	`dark`
da-one-ocean	`#171726`	`dark`
da-one-sea	`#22273d`	`dark`
danqing	`#2d302f`	`dark`
darcula	`#2b2b2b`	`dark`
darkmoss	`#171e1f`	`dark`
darktooth	`#1d2021`	`dark`
darkviolet	`#000000`	`dark`
decaf	`#2d2d2d`	`dark`
default-dark	`#181818`	`dark`
dracula	`#282936`	`dark`
edge-dark	`#262729`	`dark`
eighties	`#2d2d2d`	`dark`
embers	`#16130f`	`dark`
equilibrium-dark	`#0c1118`	`dark`
equilibrium-gray-dark	`#111111`	`dark`
espresso	`#2d2d2d`	`dark`
eva	`#2a3b4d`	`dark`
eva-dim	`#2a3b4d`	`dark`
evenok-dark	`#000000`	`dark`
everforest	`#2f383e`	`dark`
flat	`#2c3e50`	`dark`
framer	`#181818`	`dark`
gigavolt	`#202126`	`dark`
google-dark	`#1d1f21`	`dark`
gotham	`#0c1014`	`dark`
grayscale-dark	`#101010`	`dark`
greenscreen	`#001100`	`dark`
gruber	`#181818`	`dark`
gruvbox-dark-hard	`#1d2021`	`dark`
gruvbox-dark-medium	`#282828`	`dark`
gruvbox-dark-pale	`#262626`	`dark`
gruvbox-dark-soft	`#32302f`	`dark`
gruvbox-material-dark-hard	`#202020`	`dark`
gruvbox-material-dark-medium	`#292828`	`dark`
gruvbox-material-dark-soft	`#32302f`	`dark`
hardcore	`#212121`	`dark`
harmonic16-dark	`#0b1c2c`	`dark`
heetch	`#190134`	`dark`
helios	`#1d2021`	`dark`
hopscotch	`#322931`	`dark`
horizon-dark	`#1c1e26`	`dark`
horizon-terminal-dark	`#1c1e26`	`dark`
humanoid-dark	`#232629`	`dark`
ia-dark	`#1a1a1a`	`dark`
icy	`#021012`	`dark`
irblack	`#000000`	`dark`
isotope	`#000000`	`dark`
kanagawa	`#1f1f28`	`dark`
katy	`#292d3e`	`dark`
kimber	`#222222`	`dark`
lime	`#1a1a2f`	`dark`
macintosh	`#000000`	`dark`
marrakesh	`#201602`	`dark`
materia	`#263238`	`dark`
material	`#263238`	`dark`
material-darker	`#212121`	`dark`
material-palenight	`#292d3e`	`dark`
material-vivid	`#202124`	`dark`
mellow-purple	`#1e0528`	`dark`
mocha	`#3b3228`	`dark`
monokai	`#272822`	`dark`
mountain	`#0f0f0f`	`dark`
nebula	`#22273b`	`dark`
nord	`#2e3440`	`dark`
nova	`#3c4c55`	`dark`
ocean	`#2b303b`	`dark`
oceanicnext	`#1b2b34`	`dark`
onedark	`#282c34`	`dark`
outrun-dark	`#00002a`	`dark`
pandora	`#131213`	`dark`
papercolor-dark	`#1c1c1c`	`dark`
paraiso	`#2f1e2e`	`dark`
pasque	`#271c3a`	`dark`
phd	`#061229`	`dark`
pico	`#000000`	`dark`
pinky	`#171517`	`dark`
pop	`#000000`	`dark`
porple	`#292c36`	`dark`
primer-dark	`#010409`	`dark`
primer-dark-dimmed	`#1c2128`	`dark`
purpledream	`#100510`	`dark`
qualia	`#101010`	`dark`
railscasts	`#2b2b2b`	`dark`
rebecca	`#292a44`	`dark`
rose-pine	`#191724`	`dark`
rose-pine-moon	`#232136`	`dark`
sandcastle	`#282c34`	`dark`
selenized-black	`#181818`	`dark`
selenized-dark	`#103c48`	`dark`
seti	`#151718`	`dark`
shades-of-purple	`#1e1e3f`	`dark`
shadesmear-dark	`#232323`	`dark`
silk-dark	`#0e3c46`	`dark`
snazzy	`#282a36`	`dark`
solarflare	`#18262f`	`dark`
solarized-dark	`#002b36`	`dark`
spaceduck	`#16172d`	`dark`
spacemacs	`#1f2022`	`dark`
standardized-dark	`#222222`	`dark`
stella	`#2b213c`	`dark`
summercamp	`#1c1810`	`dark`
summerfruit-dark	`#151515`	`dark`
synth-midnight-dark	`#050608`	`dark`
tango	`#2e3436`	`dark`
tender	`#282828`	`dark`
tokyo-city-dark	`#171d23`	`dark`
tokyo-city-terminal-dark	`#171d23`	`dark`
tokyo-night-dark	`#1a1b26`	`dark`
tokyo-night-storm	`#24283b`	`dark`
tokyo-night-terminal-dark	`#16161e`	`dark`
tokyo-night-terminal-storm	`#24283b`	`dark`
tokyodark	`#11121d`	`dark`
tokyodark-terminal	`#11121d`	`dark`
tomorrow-night	`#1d1f21`	`dark`
tomorrow-night-eighties	`#2d2d2d`	`dark`
tube	`#231f20`	`dark`
twilight	`#1e1e1e`	`dark`
unikitty-dark	`#2e2a31`	`dark`
unikitty-reversible	`#2e2a31`	`dark`
uwunicorn	`#241b26`	`dark`
vice	`#17191e`	`dark`
vulcan	`#041523`	`dark`
windows-10	`#0c0c0c`	`dark`
windows-95	`#000000`	`dark`
windows-highcontrast	`#000000`	`dark`
windows-nt	`#000000`	`dark`
woodland	`#231e18`	`dark`
xcode-dusk	`#282b35`	`dark`
zenbones	`#191919`	`dark`
zenburn	`#383838`	`dark`
atelier-cave-light	`#efecf4`	`light`
atelier-dune-light	`#fefbec`	`light`
atelier-estuary-light	`#f4f3ec`	`light`
atelier-forest-light	`#f1efee`	`light`
atelier-heath-light	`#f7f3f7`	`light`
atelier-lakeside-light	`#ebf8ff`	`light`
atelier-plateau-light	`#f4ecec`	`light`
atelier-savanna-light	`#ecf4ee`	`light`
atelier-seaside-light	`#f4fbf4`	`light`
atelier-sulphurpool-light	`#f5f7ff`	`light`
ayu-light	`#fafafa`	`light`
brushtrees	`#e3efef`	`light`
catppuccin-latte	`#eff1f5`	`light`
classic-light	`#f5f5f5`	`light`
cupcake	`#fbf1f2`	`light`
cupertino	`#ffffff`	`light`
da-one-paper	`#faf0dc`	`light`
da-one-white	`#ffffff`	`light`
danqing-light	`#fcfefd`	`light`
default-light	`#f8f8f8`	`light`
dirtysea	`#e0e0e0`	`light`
edge-light	`#fafafa`	`light`
emil	`#efefef`	`light`
equilibrium-gray-light	`#f1f1f1`	`light`
equilibrium-light	`#f5f0e7`	`light`
fruit-soda	`#f1ecf1`	`light`
github	`#ffffff`	`light`
google-light	`#ffffff`	`light`
grayscale-light	`#f7f7f7`	`light`
gruvbox-light-hard	`#f9f5d7`	`light`
gruvbox-light-medium	`#fbf1c7`	`light`
gruvbox-light-soft	`#f2e5bc`	`light`
gruvbox-material-light-hard	`#f9f5d7`	`light`
gruvbox-material-light-medium	`#fbf1c7`	`light`
gruvbox-material-light-soft	`#f2e5bc`	`light`
harmonic16-light	`#f7f9fb`	`light`
heetch-light	`#feffff`	`light`
horizon-light	`#fdf0ed`	`light`
horizon-terminal-light	`#fdf0ed`	`light`
humanoid-light	`#f8f8f2`	`light`
ia-light	`#f6f6f6`	`light`
material-lighter	`#fafafa`	`light`
mexico-light	`#f8f8f8`	`light`
one-light	`#fafafa`	`light`
papercolor-light	`#eeeeee`	`light`
primer-light	`#fafbfc`	`light`
rose-pine-dawn	`#faf4ed`	`light`
sagelight	`#f8f8f8`	`light`
sakura	`#feedf3`	`light`
selenized-light	`#fbf3db`	`light`
selenized-white	`#ffffff`	`light`
shadesmear-light	`#dbdbdb`	`light`
shapeshifter	`#f9f9f9`	`light`
silk-light	`#e9f1ef`	`light`
solarflare-light	`#f5f7fa`	`light`
solarized-light	`#fdf6e3`	`light`
standardized-light	`#ffffff`	`light`
still-alive	`#f0f0f0`	`light`
summerfruit-light	`#ffffff`	`light`
synth-midnight-light	`#dddfe0`	`light`
tokyo-city-light	`#fbfbfd`	`light`
tokyo-city-terminal-light	`#fbfbfd`	`light`
tokyo-night-light	`#d5d6db`	`light`
tokyo-night-terminal-light	`#d5d6db`	`light`
tomorrow	`#ffffff`	`light`
unikitty-light	`#ffffff`	`light`
windows-10-light	`#f2f2f2`	`light`
windows-95-light	`#fcfcfc`	`light`
windows-highcontrast-light	`#fcfcfc`	`light`
windows-nt-light	`#ffffff`	`light`

Apr 07 '24 11:04 mamekoro

@mamekoro I'm open to PRs.

May 17 '24 15:05 RRethy