diff --git a/scss/_placeholders.scss b/scss/_placeholders.scss new file mode 100644 index 0000000000..2f647cc9ba --- /dev/null +++ b/scss/_placeholders.scss @@ -0,0 +1,51 @@ +.placeholder { + display: inline-block; + min-height: 1em; + vertical-align: middle; + cursor: wait; + background-color: currentColor; + opacity: $placeholder-opacity-max; + + &.btn::before { + display: inline-block; + content: ""; + } +} + +// Sizing +.placeholder-xs { + min-height: .6em; +} + +.placeholder-sm { + min-height: .8em; +} + +.placeholder-lg { + min-height: 1.2em; +} + +// Animation +.placeholder-glow { + .placeholder { + animation: placeholder-glow 2s ease-in-out infinite; + } +} + +@keyframes placeholder-glow { + 50% { + opacity: $placeholder-opacity-min; + } +} + +.placeholder-wave { + mask-image: linear-gradient(130deg, $black 55%, rgba(0, 0, 0, (1 - $placeholder-opacity-min)) 75%, $black 95%); + mask-size: 200% 100%; + animation: placeholder-wave 2s linear infinite; +} + +@keyframes placeholder-wave { + 100% { + mask-position: -200% 0%; + } +} diff --git a/scss/_variables.scss b/scss/_variables.scss index b6aa1b1e95..9e921c07ef 100644 --- a/scss/_variables.scss +++ b/scss/_variables.scss @@ -1203,6 +1203,13 @@ $pagination-border-radius-lg: $border-radius-lg !default; // scss-docs-end pagination-variables +// Placeholders + +// scss-docs-start placeholders +$placeholder-opacity-max: .5 !default; +$placeholder-opacity-min: .2 !default; +// scss-docs-end placeholders + // Cards // scss-docs-start card-variables diff --git a/scss/bootstrap.scss b/scss/bootstrap.scss index eb047a3f29..f051c59a99 100644 --- a/scss/bootstrap.scss +++ b/scss/bootstrap.scss @@ -43,6 +43,7 @@ @import "carousel"; @import "spinners"; @import "offcanvas"; +@import "placeholders"; // Helpers @import "helpers"; diff --git a/site/assets/scss/_component-examples.scss b/site/assets/scss/_component-examples.scss index 8fbfc06c5c..f93f1ee989 100644 --- a/site/assets/scss/_component-examples.scss +++ b/site/assets/scss/_component-examples.scss @@ -292,6 +292,17 @@ } } +// Placeholders +.bd-example-placeholder-cards { + &::after { + display: none; + } + + .card { + width: 18rem; + } +} + // Toasts .bd-example-toasts { min-height: 240px; diff --git a/site/content/docs/5.0/components/placeholders.md b/site/content/docs/5.0/components/placeholders.md new file mode 100644 index 0000000000..f2be6696a1 --- /dev/null +++ b/site/content/docs/5.0/components/placeholders.md @@ -0,0 +1,144 @@ +--- +layout: docs +title: Placeholders +description: Use loading placeholders for your components or pages to indicate something may still be loading. +group: components +toc: true +--- + +## About + +Placeholders can be used to enhance the experience of your application. They're built only with HTML and CSS, meaning you don't need any JavaScript to create them. You will, however, need some custom JavaScript to toggle their visibility. Their appearance, color, and sizing can be easily customized with our utility classes. + +## Example + +In the example below, we take a typical card component and recreate it with placeholders applied to create a "loading card". Size and proportions are the same between the two. + +
+
+ {{< placeholder width="100%" height="180" class="card-img-top" text="false" background="#20c997" >}} +
+
Card title
+

Some quick example text to build on the card title and make up the bulk of the card's content.

+ Go somewhere +
+
+ + +
+ +```html +
+ ... + +
+
Card title
+

Some quick example text to build on the card title and make up the bulk of the card's content.

+ Go somewhere +
+
+ + +``` + +## How it works + +Create placeholders with the `.placeholder` class and a grid column class (e.g., `.col-6`) to set the `width`. They can replace the text inside an element or as be added as a modifier class to an existing component. + +We apply additional styling to `.btn`s via `::before` to ensure the `height` is respected. You may extend this pattern for other situations as needed, or add a ` ` within the element to reflect the height when actual text is rendered in its place. + +{{< example >}} + + + +{{< /example >}} + +{{< callout info >}} +The use of `aria-hidden="true"` only indicates that the element should be hidden to screen readers. The *loading* behaviour of the placeholder depends on how authors will actually use the placeholder styles, how they plan to update things, etc. Some JavasSript code may be needed to *swap* the state of the placeholder and inform AT users of the update. +{{< /callout >}} + +### Width + +You can change the `width` through grid column classes, width utilities, or inline styles. + +{{< example >}} + + + +{{< /example >}} + +### Color + +By default, the `placeholder` uses `currentColor`. This can be overriden with a custom color or utility class. + +{{< example >}} + +{{< placeholders.inline >}} +{{- range (index $.Site.Data "theme-colors") }} + +{{- end -}} +{{< /placeholders.inline >}} +{{< /example >}} + +### Sizing + +The size of `.placeholder`s are based on the typographic style of the parent element. Customize them with sizing modifiers: `.placeholder-lg`, `.placeholder-sm`, or `.placeholder-xs`. + +{{< example >}} + + + + +{{< /example >}} + +### Animation + +Animate placehodlers with `.placeholder-glow` or `.placeholder-wave` to better convey the perception of something being _actively_ loaded. + +{{< example >}} +

+ +

+ +

+ +

+{{< /example >}} + +## Sass + +### Variables + +{{< scss-docs name="placeholders" file="scss/_variables.scss" >}} diff --git a/site/data/sidebar.yml b/site/data/sidebar.yml index 4bfdcc0ab4..df95692afa 100644 --- a/site/data/sidebar.yml +++ b/site/data/sidebar.yml @@ -75,6 +75,7 @@ - title: Navbar - title: Offcanvas - title: Pagination + - title: Placeholders - title: Popovers - title: Progress - title: Scrollspy