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@lnikkila /_luma.scss
Last active Aug 29, 2015

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/*
* Calculates the sRGB luma of a colour.
*
* Math nicked from a great Thoughtbot article by Reda Lemeden:
* http://robots.thoughtbot.com/closer-look-color-lightness
*/
@function luma($c) {
$-local-red: red(rgba($c, 1.0));
$-local-green: green(rgba($c, 1.0));
$-local-blue: blue(rgba($c, 1.0));
@return (0.2126 * $-local-red +
0.7152 * $-local-green +
0.0722 * $-local-blue) / 255;
}
/*
* Picks a colour from two options based on which one is more visible
* on the given background colour.
*
* Usage: pick-visible-color($bg-color, $color-1, $color-2)
*/
@import 'luma';
@function pick-visible-color($bg, $c1, $c2) {
$bg-luma: luma($bg);
$c1-luma: luma($c1);
$c2-luma: luma($c2);
$c1-diff: abs($bg-luma - $c1-luma);
$c2-diff: abs($bg-luma - $c2-luma);
@if $c1-diff > $c2-diff {
@return $c1;
} @else {
@return $c2;
}
}
$button-color: crimson;
button {
background-color: $button-color;
@if (lightness($button-color) < 50) {
color: white;
} @else {
color: black;
}
}
/////////////////////////////////////////////////////////////////
// variables/_colors.scss
$button-color: crimson;
// ...
/////////////////////////////////////////////////////////////////
// elements/_buttons.scss
button {
background-color: $button-color;
color: pick-visible-color($button-color, black, white);
// ...
}
/////////////////////////////////////////////////////////////////
// main.scss (Sass's root file)
@import 'variables/colors';
@import 'functions/pick-visible-color';
@import 'elements/buttons';
// ...
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