foundation-sites/scss/util/_mixins.scss

// Foundation for Sites by ZURB
// foundation.zurb.com
// Licensed under MIT Open Source

////
/// @group functions
////

/// Creates an inner box-shadow for only one side
/// 
/// @param {Keyword} $side - Side the shadow is supposed to appear. Can be `top`, `left`, `right` or `bottom`.
/// @param {Number} $size - Width for the target side.
/// @param {Color} $color - Color of the shadow.
@mixin inner-side-shadow(
  $side: bottom,
  $size: 20px,
  $color: rgba($black, 0.25)
) {

  $helper: round($size * 0.65);

  @if ($side == top) {
    box-shadow: inset 0 $helper $size (-1)*$helper $color;
  } @else if ($side == left) {
    box-shadow: inset $helper 0 $size (-1)*$helper $color;
  } @else if ($side == right) {
    box-shadow: inset (-1)*$helper 0 $size (-1)*$helper $color;
  } @else if ($side == bottom) {
    box-shadow: inset 0 (-1)*$helper $size (-1)*$helper $color;
  }
}

/// Creates a CSS triangle, which can be used for dropdown arrows, dropdown pips, and more. Use this mixin inside a `&::before` or `&::after` selector, to attach the triangle to an existing element.
///
/// @param {Number} $triangle-size - Width of the triangle.
/// @param {Color} $triangle-color - Color of the triangle.
/// @param {Keyword} $triangle-direction - Direction the triangle points. Can be `up`, `right`, `down`, or `left`.
@mixin css-triangle(
  $triangle-size,
  $triangle-color,
  $triangle-direction
) {
  display: block;
  width: 0;
  height: 0;

  border: inset $triangle-size;

  content: '';

  @if ($triangle-direction == down) {
    border-bottom-width: 0;
    border-top-style: solid;
    border-color: $triangle-color transparent transparent;
  }
  @if ($triangle-direction == up) {
    border-top-width: 0;
    border-bottom-style: solid;
    border-color: transparent transparent $triangle-color;
  }
  @if ($triangle-direction == right) {
    border-right-width: 0;
    border-left-style: solid;
    border-color: transparent transparent transparent $triangle-color;
  }
  @if ($triangle-direction == left) {
    border-left-width: 0;
    border-right-style: solid;
    border-color: transparent $triangle-color transparent transparent;
  }
}

/// Creates a menu icon with a set width, height, number of bars, and colors. The mixin uses the height of the icon and the weight of the bars to determine spacing. <div class="docs-example-burger"></div>
///
/// @param {Color} $color [$black] - Color to use for the icon.
/// @param {Color} $color-hover [$dark-gray] - Color to use when the icon is hovered over.
/// @param {Number} $width [20px] - Width of the icon.
/// @param {Number} $height [16px] - Height of the icon.
/// @param {Number} $weight [2px] - Height of individual bars in the icon.
/// @param {Number} $bars [3] - Number of bars in the icon.
@mixin hamburger(
  $color: $black,
  $color-hover: $dark-gray,
  $width: 20px,
  $height: 16px,
  $weight: 2px,
  $bars: 3
) {
  // box-shadow CSS output
  $shadow: ();
  $hover-shadow: ();

  // Spacing between bars is calculated based on the total height of the icon and the weight of each bar
  $spacing: ($height - ($weight * $bars)) / ($bars - 1);

  @if unit($spacing) == 'px' {
    $spacing: floor($spacing);
  }

  @for $i from 2 through $bars {
    $offset: ($weight + $spacing) * ($i - 1);
    $shadow: append($shadow, 0 $offset 0 $color, comma);
  }

  // Icon container
  position: relative;
  display: inline-block;
  vertical-align: middle;
  width: $width;
  height: $height;
  cursor: pointer;

  // Icon bars
  &::after {
    position: absolute;
    top: 0;
    left: 0;

    display: block;
    width: 100%;
    height: $weight;

    background: $color;
    box-shadow: $shadow;

    content: '';
  }

  // Hover state
  @if $color-hover {
    // Generate CSS
    @for $i from 2 through $bars {
      $offset: ($weight + $spacing) * ($i - 1);
      $hover-shadow: append($hover-shadow, 0 $offset 0 $color-hover, comma);
    }

    &:hover::after {
      background: $color-hover;
      box-shadow: $hover-shadow;
    }
  }
}

/// Adds a downward-facing triangle as a background image to an element. The image is formatted as an SVG, making it easy to change the color. Because Internet Explorer doesn't support encoded SVGs as background images, a PNG fallback is also included.
/// There are two PNG fallbacks: a black triangle and a white triangle. The one used depends on the lightness of the input color.
///
/// @param {Color} $color [$black] - Color to use for the triangle.
@mixin background-triangle($color: $black) {
  $rgb: 'rgb%28#{round(red($color))}, #{round(green($color))}, #{round(blue($color))}%29';

  background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' version='1.1' width='32' height='24' viewBox='0 0 32 24'><polygon points='0,0 32,0 16,24' style='fill: #{$rgb}'></polygon></svg>");

  @media screen and (min-width:0\0) {
    @if lightness($color) < 60% {
      // White triangle
      background-image: url('data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACAAAAAYCAYAAACbU/80AAAAGXRFWHRTb2Z0d2FyZQBBZG9iZSBJbWFnZVJlYWR5ccllPAAAAIpJREFUeNrEkckNgDAMBBfRkEt0ObRBBdsGXUDgmQfK4XhH2m8czQAAy27R3tsw4Qfe2x8uOO6oYLb6GlOor3GF+swURAOmUJ+RwtEJs9WvTGEYxBXqI1MQAZhCfUQKRzDMVj+TwrAIV6jvSUEkYAr1LSkcyTBb/V+KYfX7xAeusq3sLDtGH3kEGACPWIflNZfhRQAAAABJRU5ErkJggg==');
    }
    @else {
      // Black triangle
      background-image: url('data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACAAAAAYCAYAAACbU/80AAAAGXRFWHRTb2Z0d2FyZQBBZG9iZSBJbWFnZVJlYWR5ccllPAAAAMBJREFUeNrEllsOhCAMRVszC9IlzU7KCmVHTJsoMWYMUtpyv9BgbuXQB5ZSdgBYYY4ycgBivk8KYFsQMfMiTTBP4o3nUzCKzOabLJbLy2/g31evGkAginR4/ZegKH5qX3bJCscA3t0x3kgO5tQFyhhFf50xRqFLbyMUNJQzgyjGS/wgCpvKqkRBpuWrE4V9d+1E4dPUXqIg107SQOE/2DRQxMwTDygIInVDET9T3lCoj/6j/VCmGjZOl2lKpZ8AAwDQP7zIimDGFQAAAABJRU5ErkJggg==');
    }
  }
}

/// Applies the micro clearfix hack popularized by Nicolas Gallagher. Include this mixin on a container if its children are all floated, to give the container a proper height.
/// The clearfix is augmented with specific styles to prevent borders in flexbox environments
/// @link http://nicolasgallagher.com/micro-clearfix-hack/ Micro Clearfix Hack
/// @link http://danisadesigner.com/blog/flexbox-clear-fix-pseudo-elements/ Flexbox fix
@mixin clearfix {
  &::before,
  &::after {
    display: table;
    content: ' ';

    @if $global-flexbox {
      flex-basis: 0;
      order: 1;
    }
  }

  &::after {
    clear: both;
  }
}

/// Adds CSS for a "quantity query" selector that automatically sizes elements based on how many there are inside a container.
/// @link http://alistapart.com/article/quantity-queries-for-css Quantity Queries for CSS
///
/// @param {Number} $max - Maximum number of items to detect. The higher this number is, the more CSS that's required to cover each number of items.
/// @param {Keyword} $elem [li] - Tag to use for sibling selectors.
@mixin auto-width($max, $elem: li) {
  @for $i from 2 through $max {
    &:nth-last-child(#{$i}):first-child,
    &:nth-last-child(#{$i}):first-child ~ #{$elem} {
      width: percentage(1 / $i);
    }
  }
}

/// Removes the focus ring around an element when a mouse input is detected.
@mixin disable-mouse-outline {
  [data-whatinput='mouse'] & {
    outline: 0;
  }
}

/// Makes an element visually hidden, but still accessible to keyboards and assistive devices.
/// @link http://snook.ca/archives/html_and_css/hiding-content-for-accessibility Hiding Content for Accessibility
/// @link http://hugogiraudel.com/2016/10/13/css-hide-and-seek/
@mixin element-invisible {
  position: absolute !important;
  width: 1px;
  height: 1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
  clip-path: inset(50%);
  border: 0;
}

/// Reverses the CSS output created by the `element-invisible()` mixin.
@mixin element-invisible-off {
  position: static !important;
  width: auto;
  height: auto;
  overflow: visible;
  clip: auto;
  white-space: normal;
  clip-path: none;
}

/// Vertically centers the element inside of its first non-static parent,
/// @link http://www.sitepoint.com/centering-with-sass/ Centering With Sass
@mixin vertical-center {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
}

/// Horizontally centers the element inside of its first non-static parent,
/// @link http://www.sitepoint.com/centering-with-sass/ Centering With Sass
@mixin horizontal-center {
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
}

/// Absolutely centers the element inside of its first non-static parent,
/// @link http://www.sitepoint.com/centering-with-sass/ Centering With Sass
@mixin absolute-center {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}

/// Iterates through breakpoints defined in `$breakpoint-classes` and prints the CSS inside the mixin at each breakpoint's media query. Use this with the grid, or any other component that has responsive classes.
///
/// @param {Boolean} $small [true] - If `false`, the mixin will skip the `small` breakpoint. Use this with components that don't prefix classes with `small-`, only `medium-` and up.
/// @param {Boolean} $auto-insert-breakpoints [true] - If `false`, the mixin will iterate over breakpoints without doing the media query itself. Useful for more complex media query generation as in the margin grid.
@mixin -zf-each-breakpoint($small: true, $auto-insert-breakpoints: true) {
  $list: $breakpoint-classes;

  @if not $small {
    $list: sl-remove($list, $-zf-zero-breakpoint);
  }

  @each $name in $list {
    $-zf-size: $name !global;

    @if $auto-insert-breakpoints {
      @include breakpoint($name) {
        @content;
      }
    }
    @else {
      @content;
    }
  }
}

/// Generate the `@content` passed to the mixin with a value `$-zf-bp-value` related to a breakpoint, depending on the `$name` parameter:
/// - For a single value, `$-zf-bp-value` is this value.
/// - For a breakpoint name, `$-zf-bp-value` is the corresponding breakpoint value in `$map`.
/// - For "auto", `$-zf-bp-value` is the corresponding breakpoint value in `$map` and is passed to `@content`, which is made responsive for each breakpoint of `$map`.
/// @param {Number|Array|Keyword} $name [auto] - Single value, breakpoint name, or list of breakpoint names to use. "auto" by default.
/// @param {Number|Map} $map - Map of breakpoints and values or single value to use.
@mixin -zf-breakpoint-value(
  $name: auto,
  $map: null
) {
  @if $name == auto and type-of($map) == 'map' {
    // "auto"
    @each $k, $v in $map {
      @include breakpoint($k) {
        @include -zf-breakpoint-value($v, $map) {
          @content;
        }
      }
    }
  }
  @else {
    // breakpoint name
    @if type-of($name) == 'string' {
      $name: -zf-get-bp-val($map, $name);
    }

    // breakpoint value
    $-zf-bp-value: $name !global;
    @content;
  }
}