1 files changed, 84 insertions, 23 deletions
diff --git a/vendor/twbs/bootstrap/scss/_functions.scss b/vendor/twbs/bootstrap/scss/_functions.scss
index 9c0660315..29114fc81 100644
--- a/vendor/twbs/bootstrap/scss/_functions.scss
+++ b/vendor/twbs/bootstrap/scss/_functions.scss
@@ -32,6 +32,29 @@
   }
 }
 
+// Internal Bootstrap function to turn maps into its negative variant.
+// It prefixes the keys with `n` and makes the value negative.
+@function negativify-map($map) {
+  $result: ();
+  @each $key, $value in $map {
+    @if $key != 0 {
+      $result: map-merge($result, ("n" + $key: (-$value)));
+    }
+  }
+  @return $result;
+}
+
+// Get multiple keys from a sass map
+@function map-get-multiple($map, $values) {
+  $result: ();
+  @each $key, $value in $map {
+    @if (index($values, $key) != null) {
+      $result: map-merge($result, ($key: $value));
+    }
+  }
+  @return $result;
+}
+
 // Replace `$search` with `$replace` in `$string`
 // Used on our SVG icon backgrounds for custom forms.
 //
@@ -70,41 +93,79 @@
 }
 
 // Color contrast
-@function color-yiq($color, $dark: $yiq-text-dark, $light: $yiq-text-light) {
-  $r: red($color);
-  $g: green($color);
-  $b: blue($color);
+// See https://github.com/twbs/bootstrap/pull/30168
+
+// A list of pre-calculated numbers of pow(($value / 255 + .055) / 1.055, 2.4). (from 0 to 255)
+// stylelint-disable-next-line scss/dollar-variable-default, scss/dollar-variable-pattern
+$_luminance-list: .0008 .001 .0011 .0013 .0015 .0017 .002 .0022 .0025 .0027 .003 .0033 .0037 .004 .0044 .0048 .0052 .0056 .006 .0065 .007 .0075 .008 .0086 .0091 .0097 .0103 .011 .0116 .0123 .013 .0137 .0144 .0152 .016 .0168 .0176 .0185 .0194 .0203 .0212 .0222 .0232 .0242 .0252 .0262 .0273 .0284 .0296 .0307 .0319 .0331 .0343 .0356 .0369 .0382 .0395 .0409 .0423 .0437 .0452 .0467 .0482 .0497 .0513 .0529 .0545 .0561 .0578 .0595 .0612 .063 .0648 .0666 .0685 .0704 .0723 .0742 .0762 .0782 .0802 .0823 .0844 .0865 .0887 .0908 .0931 .0953 .0976 .0999 .1022 .1046 .107 .1095 .1119 .1144 .117 .1195 .1221 .1248 .1274 .1301 .1329 .1356 .1384 .1413 .1441 .147 .15 .1529 .1559 .159 .162 .1651 .1683 .1714 .1746 .1779 .1812 .1845 .1878 .1912 .1946 .1981 .2016 .2051 .2086 .2122 .2159 .2195 .2232 .227 .2307 .2346 .2384 .2423 .2462 .2502 .2542 .2582 .2623 .2664 .2705 .2747 .2789 .2831 .2874 .2918 .2961 .3005 .305 .3095 .314 .3185 .3231 .3278 .3325 .3372 .3419 .3467 .3515 .3564 .3613 .3663 .3712 .3763 .3813 .3864 .3916 .3968 .402 .4072 .4125 .4179 .4233 .4287 .4342 .4397 .4452 .4508 .4564 .4621 .4678 .4735 .4793 .4851 .491 .4969 .5029 .5089 .5149 .521 .5271 .5333 .5395 .5457 .552 .5583 .5647 .5711 .5776 .5841 .5906 .5972 .6038 .6105 .6172 .624 .6308 .6376 .6445 .6514 .6584 .6654 .6724 .6795 .6867 .6939 .7011 .7084 .7157 .7231 .7305 .7379 .7454 .7529 .7605 .7682 .7758 .7835 .7913 .7991 .807 .8148 .8228 .8308 .8388 .8469 .855 .8632 .8714 .8796 .8879 .8963 .9047 .9131 .9216 .9301 .9387 .9473 .956 .9647 .9734 .9823 .9911 1;
+
+@function color-contrast($background, $color-contrast-dark: $color-contrast-dark, $color-contrast-light: $color-contrast-light, $min-contrast-ratio: $min-contrast-ratio) {
+  $foregrounds: $color-contrast-light, $color-contrast-dark, $white, $black;
+  $max-ratio: 0;
+  $max-ratio-color: null;
+
+  @each $color in $foregrounds {
+    $contrast-ratio: contrast-ratio($background, $color);
+    @if $contrast-ratio > $min-contrast-ratio {
+      @return $color;
+    } @else if $contrast-ratio > $max-ratio {
+      $max-ratio: $contrast-ratio;
+      $max-ratio-color: $color;
+    }
+  }
 
-  $yiq: (($r * 299) + ($g * 587) + ($b * 114)) / 1000;
+  @warn "Found no color leading to #{$min-contrast-ratio}:1 contrast ratio against #{$background}...";
 
-  @if ($yiq >= $yiq-contrasted-threshold) {
-    @return $dark;
-  } @else {
-    @return $light;
-  }
+  @return $max-ratio-color;
+}
+
+@function contrast-ratio($background, $foreground: $color-contrast-light) {
+  $l1: luminance($background);
+  $l2: luminance(opaque($background, $foreground));
+
+  @return if($l1 > $l2, ($l1 + .05) / ($l2 + .05), ($l2 + .05) / ($l1 + .05));
 }
 
-// Retrieve color Sass maps
-@function color($key: "blue") {
-  @return map-get($colors, $key);
+// Return WCAG2.0 relative luminance
+// See https://www.w3.org/WAI/GL/wiki/Relative_luminance
+// See https://www.w3.org/TR/WCAG20-TECHS/G17.html#G17-tests
+@function luminance($color) {
+  $rgb: (
+    "r": red($color),
+    "g": green($color),
+    "b": blue($color)
+  );
+
+  @each $name, $value in $rgb {
+    $value: if($value / 255 < .03928, $value / 255 / 12.92, nth($_luminance-list, $value + 1));
+    $rgb: map-merge($rgb, ($name: $value));
+  }
+
+  @return (map-get($rgb, "r") * .2126) + (map-get($rgb, "g") * .7152) + (map-get($rgb, "b") * .0722);
 }
 
-@function theme-color($key: "primary") {
-  @return map-get($theme-colors, $key);
+// Return opaque color
+// opaque(#fff, rgba(0, 0, 0, .5)) => #808080
+@function opaque($background, $foreground) {
+  @return mix(rgba($foreground, 1), $background, opacity($foreground) * 100);
 }
 
-@function gray($key: "100") {
-  @return map-get($grays, $key);
+// scss-docs-start color-functions
+// Tint a color: mix a color with white
+@function tint-color($color, $weight) {
+  @return mix(white, $color, $weight);
 }
 
-// Request a theme color level
-@function theme-color-level($color-name: "primary", $level: 0) {
-  $color: theme-color($color-name);
-  $color-base: if($level > 0, $black, $white);
-  $level: abs($level);
+// Shade a color: mix a color with black
+@function shade-color($color, $weight) {
+  @return mix(black, $color, $weight);
+}
 
-  @return mix($color-base, $color, $level * $theme-color-interval);
+// Shade the color if the weight is positive, else tint it
+@function shift-color($color, $weight) {
+  @return if($weight > 0, shade-color($color, $weight), tint-color($color, -$weight));
 }
+// scss-docs-end color-functions
 
 // Return valid calc
 @function add($value1, $value2, $return-calc: true) {