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Update color and background-color utilities
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- Adds new functions to generate additional Sass maps
- Adds new root variables for rgb() versions of our theme colors, plus a few extras
- Adds ability to change the alpha transparency of text color and background color utilities with new utilities, inline styles, or local CSS var
- Updates documentation for color and background-color utilities pages
- Deprecates .text-black-50 and .text-white-50 since those (and additional transparency levels) can be generated on the fly

Change approach slightly to prevent cascade
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@mdo
mdo committed Aug 4, 2021
1 parent a2f92d1 commit e72916e
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35 changes: 35 additions & 0 deletions scss/_functions.scss
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Expand Up @@ -32,6 +32,41 @@
}
}

// Colors
@function to-rgb($value) {
@return red($value), green($value), blue($value);
}

@function rgba-css-var($identifier, $target) {
@return rgba(var(--#{$variable-prefix}#{$identifier}-rgb), var(--#{$variable-prefix}#{$target}-opacity));
}

// stylelint-disable scss/dollar-variable-pattern
@function map-loop($map, $func, $args...) {
$_map: ();

@each $key, $value in $map {
// allow to pass the $key and $value of the map as an function argument
$_args: ();
@each $arg in $args {
$_args: append($_args, if($arg == "$key", $key, if($arg == "$value", $value, $arg)));
}

$_map: map-merge($_map, ($key: call(get-function($func), $_args...)));
}

@return $_map;
}
// stylelint-enable scss/dollar-variable-pattern

@function varify($list) {
$result: null;
@each $entry in $list {
$result: append($result, var(--#{$variable-prefix}#{$entry}), space);
}
@return $result;
}

// Internal Bootstrap function to turn maps into its negative variant.
// It prefixes the keys with `n` and makes the value negative.
@function negativify-map($map) {
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8 changes: 8 additions & 0 deletions scss/_root.scss
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Expand Up @@ -8,6 +8,14 @@
--#{$variable-prefix}#{$color}: #{$value};
}

@each $color, $value in $theme-colors-rgb {
--#{$variable-prefix}#{$color}-rgb: #{$value};
}

--#{$variable-prefix}white-rgb: #{to-rgb($white)};
--#{$variable-prefix}black-rgb: #{to-rgb($black)};
--#{$variable-prefix}body-rgb: #{to-rgb($body-color)};

// Use `inspect` for lists so that quoted items keep the quotes.
// See https://github.com/sass/sass/issues/2383#issuecomment-336349172
--#{$variable-prefix}font-sans-serif: #{inspect($font-family-sans-serif)};
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39 changes: 31 additions & 8 deletions scss/_utilities.scss
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Expand Up @@ -514,32 +514,55 @@ $utilities: map-merge(
"color": (
property: color,
class: text,
local-vars: (
"text-opacity": 1
),
values: map-merge(
$theme-colors,
$utilities-text-colors,
(
"white": $white,
"body": $body-color,
"muted": $text-muted,
"black-50": rgba($black, .5),
"white-50": rgba($white, .5),
"black-50": rgba($black, .5), // deprecated
"white-50": rgba($white, .5), // deprecated
"reset": inherit,
)
)
),
"text-opacity": (
css-var: true,
class: text-opacity,
values: (
25: .25,
50: .5,
75: .75,
100: 1
)
),
// scss-docs-end utils-color
// scss-docs-start utils-bg-color
"background-color": (
property: background-color,
class: bg,
local-vars: (
"bg-opacity": 1
),
values: map-merge(
$theme-colors,
$utilities-bg-colors,
(
"body": $body-bg,
"white": $white,
"transparent": transparent
)
)
),
"bg-opacity": (
css-var: true,
class: bg-opacity,
values: (
10: .1,
25: .25,
50: .5,
75: .75,
100: 1
)
),
// scss-docs-end utils-bg-color
"gradient": (
property: background-image,
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26 changes: 26 additions & 0 deletions scss/_variables.scss
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Expand Up @@ -90,6 +90,10 @@ $theme-colors: (
) !default;
// scss-docs-end theme-colors-map

// scss-docs-start theme-colors-rgb
$theme-colors-rgb: map-loop($theme-colors, to-rgb, "$value") !default;
// scss-docs-end theme-colors-rgb

// The contrast ratio to reach against white, to determine if color changes from "light" to "dark". Acceptable values for WCAG 2.0 are 3, 4.5 and 7.
// See https://www.w3.org/TR/WCAG20/#visual-audio-contrast-contrast
$min-contrast-ratio: 4.5 !default;
Expand Down Expand Up @@ -401,6 +405,28 @@ $body-bg: $white !default;
$body-color: $gray-900 !default;
$body-text-align: null !default;

// Utilities maps
//
// Extends the default `$theme-colors` maps to help create our utilities.

// scss-docs-start utilities-colors
$utilities-colors: map-merge(
$theme-colors-rgb,
(
"black": to-rgb($black),
"white": to-rgb($white),
"body": to-rgb($body-color)
)
) !default;
// scss-docs-end utilities-colors

// scss-docs-start utilities-text-colors
$utilities-text-colors: map-loop($utilities-colors, rgba-css-var, "$key", "text") !default;
// scss-docs-end utilities-text-colors

// scss-docs-start utilities-bg-colors
$utilities-bg-colors: map-loop($utilities-colors, rgba-css-var, "$key", "bg") !default;
// scss-docs-end utilities-bg-colors

// Links
//
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33 changes: 27 additions & 6 deletions scss/mixins/_utilities.scss
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Expand Up @@ -41,25 +41,46 @@
}
}

$is-css-var: map-get($utility, css-var);
$is-local-vars: map-get($utility, local-vars);
$is-rtl: map-get($utility, rtl);

@if $value != null {
@if $is-rtl == false {
/* rtl:begin:remove */
}
.#{$property-class + $infix + $property-class-modifier} {
@each $property in $properties {
#{$property}: $value if($enable-important-utilities, !important, null);

@if $is-css-var {
.#{$property-class + $infix + $property-class-modifier} {
--#{$variable-prefix}#{$property-class}: #{$value};
}
}

@each $pseudo in $state {
.#{$property-class + $infix + $property-class-modifier}-#{$pseudo}:#{$pseudo} {
@each $pseudo in $state {
.#{$property-class + $infix + $property-class-modifier}-#{$pseudo}:#{$pseudo} {
--#{$variable-prefix}#{$property-class}: #{$value};
}
}
} @else {
.#{$property-class + $infix + $property-class-modifier} {
@each $property in $properties {
@if $is-local-vars {
@each $local-var, $value in $is-local-vars {
--#{$variable-prefix}#{$local-var}: #{$value};
}
}
#{$property}: $value if($enable-important-utilities, !important, null);
}
}

@each $pseudo in $state {
.#{$property-class + $infix + $property-class-modifier}-#{$pseudo}:#{$pseudo} {
@each $property in $properties {
#{$property}: $value if($enable-important-utilities, !important, null);
}
}
}
}

@if $is-rtl == false {
/* rtl:end:remove */
}
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46 changes: 46 additions & 0 deletions site/content/docs/5.0/utilities/background.md
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Expand Up @@ -35,6 +35,44 @@ Do you need a gradient in your custom CSS? Just add `background-image: var(--bs-
{{< /colors.inline >}}
{{< /markdown >}}

## Opacity

<small class="d-inline-flex px-2 py-1 font-monospace text-muted border rounded-3">Added in v5.1.0</small>

As of v5.1.0, `background-color` utilities are generated with Sass using CSS variables. This allows for real-time color changes without compilation and dynamic alpha transparency changes.

### How it works

Consider our default `.bg-success` utility.

```css
.bg-success {
--bs-bg-opacity: 1;
background-color: rgba(var(--bs-success-rgb), var(--bs-bg-opacity)) !important;
}
```

We use an RGB version of our `--bs-succes` (with the value of `25, 135, 84`) CSS variable and attached a second CSS variable, `--bs-bg-opacity`, for the alpha transparency (with no default value, but a fallback of `1`). That means anytime you use `.bg-success` now, your computed `color` value is `rgba(25, 135, 84, 1)`.

### Example

To change that opacity, override `--bs-bg-opacity` via custom styles or inline styles.

{{< example >}}
<div class="bg-success p-2 text-white">This is default success background</div>
<div class="bg-success p-2" style="--bs-bg-opacity: .5;">This is 50% opacity success background</div>
{{< /example >}}

Or, choose from any of the `.bg-opacity` utilities:

{{< example >}}
<div class="bg-success p-2 text-white">This is default success background</div>
<div class="bg-success p-2 text-white bg-opacity-75">This is 75% opacity success background</div>
<div class="bg-success p-2 text-dark bg-opacity-50">This is 50% opacity success background</div>
<div class="bg-success p-2 text-dark bg-opacity-25">This is 25% opacity success background</div>
<div class="bg-success p-2 text-dark bg-opacity-10">This is 10% opacity success background</div>
{{< /example >}}

## Sass

In addition to the following Sass functionality, consider reading about our included [CSS custom properties]({{< docsref "/customize/css-variables" >}}) (aka CSS variables) for colors and more.
Expand Down Expand Up @@ -63,6 +101,14 @@ Grayscale colors are also available as a Sass map. **This map is not used to gen

{{< scss-docs name="gray-colors-map" file="scss/_variables.scss" >}}

RGB colors are generated from a separate Sass map:

{{< scss-docs name="theme-colors-rgb" file="scss/_variables.scss" >}}

And background color opacities build on that with their own map that's consumed by the utilities API:

{{< scss-docs name="utilities-bg-colors" file="scss/_variables.scss" >}}

### Mixins

**No mixins are used to generate our background utilities**, but we do have some additional mixins for other situations where you'd like to create your own gradients.
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49 changes: 49 additions & 0 deletions site/content/docs/5.0/utilities/colors.md
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Expand Up @@ -23,10 +23,51 @@ Colorize text with color utilities. If you want to colorize links, you can use t
<p class="text-white-50 bg-dark">.text-white-50</p>
{{< /example >}}

{{< callout warning >}}
**Deprecation:** With the addition of `.text-opacity-*` utilities and CSS variables for text utilities, `.text-black-50` and `.text-white-50` are deprecated as of v5.1.0. They'll be removed in v6.0.0.
{{< /callout >}}

{{< callout info >}}
{{< partial "callout-warning-color-assistive-technologies.md" >}}
{{< /callout >}}

## Opacity

<small class="d-inline-flex px-2 py-1 font-monospace text-muted border rounded-3">Added in v5.1.0</small>

As of v5.1.0, text color utilities are generated with Sass using CSS variables. This allows for real-time color changes without compilation and dynamic alpha transparency changes.

### How it works

Consider our default `.text-primary` utility.

```css
.text-primary {
--bs-text-opacity: 1;
color: rgba(var(--bs-primary-rgb), var(--bs-text-opacity)) !important;
}
```

We use an RGB version of our `--bs-primary` (with the value of `13, 110, 253`) CSS variable and attached a second CSS variable, `--bs-text-opacity`, for the alpha transparency (with no default value, but a fallback of `1`). That means anytime you use `.text-primary` now, your computed `color` value is `rgba(13, 110, 253, 1)`.

### Example

To change that opacity, override `--bs-text-opacity` via custom styles or inline styles.

{{< example >}}
<div class="text-primary">This is default primary text</div>
<div class="text-primary" style="--bs-text-opacity: .5;">This is 50% opacity primary text</div>
{{< /example >}}

Or, choose from any of the `.text-opacity` utilities:

{{< example >}}
<div class="text-primary">This is default primary text</div>
<div class="text-primary text-opacity-75">This is 75% opacity primary text</div>
<div class="text-primary text-opacity-50">This is 50% opacity primary text</div>
<div class="text-primary text-opacity-25">This is 25% opacity primary text</div>
{{< /example >}}

## Specificity

Sometimes contextual classes cannot be applied due to the specificity of another selector. In some cases, a sufficient workaround is to wrap your element's content in a `<div>` or more semantic element with the desired class.
Expand Down Expand Up @@ -57,6 +98,14 @@ Grayscale colors are also available as a Sass map. **This map is not used to gen

{{< scss-docs name="gray-colors-map" file="scss/_variables.scss" >}}

RGB colors are generated from a separate Sass map:

{{< scss-docs name="theme-colors-rgb" file="scss/_variables.scss" >}}

And color opacities build on that with their own map that's consumed by the utilities API:

{{< scss-docs name="utilities-text-colors" file="scss/_variables.scss" >}}

### Utilities API

Color utilities are declared in our utilities API in `scss/_utilities.scss`. [Learn how to use the utilities API.]({{< docsref "/utilities/api#using-the-api" >}})
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