mdb-ui-kit/scss/includes/_mixins-utilities.scss

// This file is here to emulate the less #contrast function

// TODO: this may be useful for the inverse theme, but if not, remove (it is unused after the removal of fullpalette)

// contrast-color and brightness borrowed from compass
// Copyright (c) 2009-2014 Christopher M. Eppstein
// Complies with license: https://github.com/Compass/compass/blob/stable/LICENSE.markdown
@function contrast-color($color, $dark: $contrasted-dark-default, $light: $contrasted-light-default, $threshold: null) {
  @if $threshold {
    // Deprecated in Compass 0.13
    @warn "The $threshold argment to contrast-color is no longer needed and will be removed in the next release.";
  }
  @if $color == null {
    @return null;
  }
  @else {
    $color-brightness: brightness($color);
    $dark-text-brightness: brightness($dark);
    $light-text-brightness: brightness($light);
    @return if(abs($color-brightness - $light-text-brightness) > abs($color-brightness - $dark-text-brightness), $light, $dark);
  }
}

@function brightness($color) {
  @if type-of($color) == color {
    @return (red($color) * 0.299 + green($color) * 0.587 + blue($color) * 0.114) / 255 * 100%;
  }
  @else {
    @return unquote("brightness(#{$color})");
  }
}