Merge pull request #21298 from twbs/carousel

Refactor carousel

1 files changed, 86 insertions, 38 deletions

diff --git a/docs/components/carousel.md b/docs/components/carousel.md
index 3942309f0..8dd819fba 100644
--- a/docs/components/carousel.md
+++ b/docs/components/carousel.md
@@ -5,7 +5,11 @@ description: A slideshow component for cycling through elements—images or slid
 group: components
 ---
 
-A slideshow component for cycling through elements—images or slides of text—like a carousel. In browsers where the [Page Visibility API](https://www.w3.org/TR/page-visibility/) is supported, the carousel will avoid sliding when the webpage is not visible to the user (such as when the browser tab is inactive, the browser window is minimized, etc.). **Nested carousels are not supported.**
+The carousel is a slideshow for cycling through a series of content, built with CSS 3D transforms and a bit of JavaScript. It works with a series of images, text, or custom markup. It also includes support for previous/next controls and indicators.
+
+In browsers where the [Page Visibility API](https://www.w3.org/TR/page-visibility/) is supported, the carousel will avoid sliding when the webpage is not visible to the user (such as when the browser tab is inactive, the browser window is minimized, etc.).
+
+Please be aware that nested carousels are not supported, and carousels are generally not compliant with accessibility standards.
 
 ## Contents
 
@@ -14,32 +18,86 @@ A slideshow component for cycling through elements—images or slides of text—
 
 ## Example
 
-When building carousels, be sure your slides are the same size as one another. The carousel doesn't automatically crop images to the same dimensions for you across slides.
+Carousels don't automatically normalize slide dimensions. As such, you may need to use additional utilities or custom styles to appropriately size content. While carousels support previous/next controls and indicators, they're not explicitly required. Add and customize as you see fit.
+
+Be sure to set a unique id on the `.carousel` for optional controls, especially if you're using multiple carousels on a single page.
+
+### Slides only
+
+Here's a carousel with slides only. Note the presence of the `.d-block` and `.img-fluid` on carousel images to prevent browser default image alignment.
+
+{% example html %}
+<div id="carouselExampleSlidesOnly" class="carousel slide" data-ride="carousel">
+  <div class="carousel-inner" role="listbox">
+    <div class="carousel-item active">
+      <img class="d-block img-fluid" data-src="holder.js/800x400?auto=yes&bg=777&fg=555&text=First slide" alt="First slide">
+    </div>
+    <div class="carousel-item">
+      <img class="d-block img-fluid" data-src="holder.js/800x400?auto=yes&bg=666&fg=444&text=Second slide" alt="Second slide">
+    </div>
+    <div class="carousel-item">
+      <img class="d-block img-fluid" data-src="holder.js/800x400?auto=yes&bg=555&fg=333&text=Third slide" alt="Third slide">
+    </div>
+  </div>
+</div>
+{% endexample %}
+
+### With controls
+
+Adding in the previous and next controls:
+
+{% example html %}
+<div id="carouselExampleControls" class="carousel slide" data-ride="carousel">
+  <div class="carousel-inner" role="listbox">
+    <div class="carousel-item active">
+      <img class="d-block img-fluid" data-src="holder.js/800x400?auto=yes&bg=777&fg=555&text=First slide" alt="First slide">
+    </div>
+    <div class="carousel-item">
+      <img class="d-block img-fluid" data-src="holder.js/800x400?auto=yes&bg=666&fg=444&text=Second slide" alt="Second slide">
+    </div>
+    <div class="carousel-item">
+      <img class="d-block img-fluid" data-src="holder.js/800x400?auto=yes&bg=555&fg=333&text=Third slide" alt="Third slide">
+    </div>
+  </div>
+  <a class="carousel-control-prev" href="#carouselExampleControls" role="button" data-slide="prev">
+    <span class="carousel-control-prev-icon" aria-hidden="true"></span>
+    <span class="sr-only">Previous</span>
+  </a>
+  <a class="carousel-control-next" href="#carouselExampleControls" role="button" data-slide="next">
+    <span class="carousel-control-next-icon" aria-hidden="true"></span>
+    <span class="sr-only">Next</span>
+  </a>
+</div>
+{% endexample %}
+
+### With indicators
+
+You can also add the indicators to the carousel, alongside the controls, too.
 
 {% example html %}
-<div id="carousel-example-generic" class="carousel slide" data-ride="carousel">
+<div id="carouselExampleIndicators" class="carousel slide" data-ride="carousel">
   <ol class="carousel-indicators">
-    <li data-target="#carousel-example-generic" data-slide-to="0" class="active"></li>
-    <li data-target="#carousel-example-generic" data-slide-to="1"></li>
-    <li data-target="#carousel-example-generic" data-slide-to="2"></li>
+    <li data-target="#carouselExampleIndicators" data-slide-to="0" class="active"></li>
+    <li data-target="#carouselExampleIndicators" data-slide-to="1"></li>
+    <li data-target="#carouselExampleIndicators" data-slide-to="2"></li>
   </ol>
   <div class="carousel-inner" role="listbox">
     <div class="carousel-item active">
-      <img data-src="holder.js/900x500/auto/#777:#555/text:First slide" alt="First slide">
+      <img class="d-block img-fluid" data-src="holder.js/800x400?auto=yes&bg=777&fg=555&text=First slide" alt="First slide">
     </div>
     <div class="carousel-item">
-      <img data-src="holder.js/900x500/auto/#666:#444/text:Second slide" alt="Second slide">
+      <img class="d-block img-fluid" data-src="holder.js/800x400?auto=yes&bg=666&fg=444&text=Second slide" alt="Second slide">
     </div>
     <div class="carousel-item">
-      <img data-src="holder.js/900x500/auto/#555:#333/text:Third slide" alt="Third slide">
+      <img class="d-block img-fluid" data-src="holder.js/800x400?auto=yes&bg=555&fg=333&text=Third slide" alt="Third slide">
     </div>
   </div>
-  <a class="left carousel-control" href="#carousel-example-generic" role="button" data-slide="prev">
-    <span class="icon-prev" aria-hidden="true"></span>
+  <a class="carousel-control-prev" href="#carouselExampleIndicators" role="button" data-slide="prev">
+    <span class="carousel-control-prev-icon" aria-hidden="true"></span>
     <span class="sr-only">Previous</span>
   </a>
-  <a class="right carousel-control" href="#carousel-example-generic" role="button" data-slide="next">
-    <span class="icon-next" aria-hidden="true"></span>
+  <a class="carousel-control-next" href="#carouselExampleIndicators" role="button" data-slide="next">
+    <span class="carousel-control-next-icon" aria-hidden="true"></span>
     <span class="sr-only">Next</span>
   </a>
 </div>
@@ -57,45 +115,45 @@ Bootstrap exclusively uses CSS3 for its animations, but Internet Explorer 9 does
 The `.active` class needs to be added to one of the slides. Otherwise, the carousel will not be visible.
 {% endcallout %}
 
-### Optional captions
+### With captions
 
-Add captions to your slides easily with the `.carousel-caption` element within any `.carousel-item`. Place just about any optional HTML within there and it will be automatically aligned and formatted.
+Add captions to your slides easily with the `.carousel-caption` element within any `.carousel-item`. They can be easily hidden on smaller viewports, as shown below, with optional [display utilities]({{ site.baseurl }}/utilities/display-property/). We hide them initially with `.d-none` and bring them back on medium-sized devices with `.d-md-block`.
 
 <div class="bd-example">
-  <div id="carousel-example-captions" class="carousel slide" data-ride="carousel">
+  <div id="carouselExampleCaptions" class="carousel slide" data-ride="carousel">
     <ol class="carousel-indicators">
-      <li data-target="#carousel-example-captions" data-slide-to="0" class="active"></li>
-      <li data-target="#carousel-example-captions" data-slide-to="1"></li>
-      <li data-target="#carousel-example-captions" data-slide-to="2"></li>
+      <li data-target="#carouselExampleCaptions" data-slide-to="0" class="active"></li>
+      <li data-target="#carouselExampleCaptions" data-slide-to="1"></li>
+      <li data-target="#carouselExampleCaptions" data-slide-to="2"></li>
     </ol>
     <div class="carousel-inner" role="listbox">
       <div class="carousel-item active">
-        <img data-src="holder.js/900x500/auto/#777:#777" alt="First slide image">
-        <div class="carousel-caption">
+        <img class="d-block img-fluid" data-src="holder.js/800x400?auto=yes&bg=777&fg=555&text=First slide" alt="First slide">
+        <div class="carousel-caption d-none d-md-block">
           <h3>First slide label</h3>
           <p>Nulla vitae elit libero, a pharetra augue mollis interdum.</p>
         </div>
       </div>
       <div class="carousel-item">
-        <img data-src="holder.js/900x500/auto/#666:#666" alt="Second slide image">
-        <div class="carousel-caption">
+        <img class="d-block img-fluid" data-src="holder.js/800x400?auto=yes&bg=666&fg=444&text=Second slide" alt="Second slide">
+        <div class="carousel-caption d-none d-md-block">
           <h3>Second slide label</h3>
           <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit.</p>
         </div>
       </div>
       <div class="carousel-item">
-        <img data-src="holder.js/900x500/auto/#555:#555" alt="Third slide image">
-        <div class="carousel-caption">
+        <img class="d-block img-fluid" data-src="holder.js/800x400?auto=yes&bg=555&fg=333&text=Third slide" alt="Third slide">
+        <div class="carousel-caption d-none d-md-block">
           <h3>Third slide label</h3>
           <p>Praesent commodo cursus magna, vel scelerisque nisl consectetur.</p>
         </div>
       </div>
     </div>
-    <a class="left carousel-control" href="#carousel-example-captions" role="button" data-slide="prev">
+    <a class="carousel-control carousel-control-left" href="#carouselExampleCaptions" role="button" data-slide="prev">
       <span class="icon-prev" aria-hidden="true"></span>
       <span class="sr-only">Previous</span>
     </a>
-    <a class="right carousel-control" href="#carousel-example-captions" role="button" data-slide="next">
+    <a class="carousel-control carousel-control-right" href="#carouselExampleCaptions" role="button" data-slide="next">
       <span class="icon-next" aria-hidden="true"></span>
       <span class="sr-only">Next</span>
     </a>
@@ -105,25 +163,15 @@ Add captions to your slides easily with the `.carousel-caption` element within a
 {% highlight html %}
 <div class="carousel-item">
   <img src="..." alt="...">
-  <div class="carousel-caption">
+  <div class="carousel-caption d-none d-md-block">
     <h3>...</h3>
     <p>...</p>
   </div>
 </div>
 {% endhighlight %}
 
-{% callout danger %}
-#### Accessibility issue
-
-The carousel component is generally not compliant with accessibility standards. If you need to be compliant, please consider other options for presenting your content.
-{% endcallout %}
-
 ## Usage
 
-### Multiple carousels
-
-Carousels require the use of an `id` on the outermost container (the `.carousel`) for carousel controls to function properly. When adding multiple carousels, or when changing a carousel's `id`, be sure to update the relevant controls.
-
 ### Via data attributes
 
 Use data attributes to easily control the position of the carousel. `data-slide` accepts the keywords `prev` or `next`, which alters the slide position relative to its current position. Alternatively, use `data-slide-to` to pass a raw slide index to the carousel `data-slide-to="2"`, which shifts the slide position to a particular index beginning with `0`.