Skip to content

Latest commit

 

History

History
354 lines (271 loc) · 12.2 KB

amp-carousel.md

File metadata and controls

354 lines (271 loc) · 12.2 KB
Raw
$category@ formats teaser
layout
websites
ads
text
Displays multiple similar pieces of content along a horizontal axis.

amp-carousel

Usage

A generic carousel for displaying multiple similar pieces of content along a horizontal axis; meant to be flexible and performant.

Each of the amp-carousel component’s immediate children is considered an item in the carousel. Each of these nodes may also have arbitrary HTML children.

The carousel consists of an arbitrary number of items, as well as optional navigational arrows to go forward or backwards. For type="slides", the arrows moves one item at a time. For type="carousel", the arrows move one carousel's width forwards or backwards at a time.

The carousel advances between items if the user swipes or clicks an optional navigation arrow.

[example preview="inline" playground="true" imports="amp-carousel"]

<amp-carousel
  width="450"
  height="300"
  layout="responsive"
  type="slides"
  role="region"
  aria-label="Basic carousel"
>
  <amp-img
    src="{{server_for_email}}/static/inline-examples/images/image1.jpg"
    width="450"
    height="300"
  ></amp-img>
  <amp-img
    src="{{server_for_email}}/static/inline-examples/images/image2.jpg"
    width="450"
    height="300"
  ></amp-img>
  <amp-img
    src="{{server_for_email}}/static/inline-examples/images/image3.jpg"
    width="450"
    height="300"
  ></amp-img>
</amp-carousel>

[/example]

Differences from <amp-carousel> 0.1

  • autoplay is allowed on type="carousel"
  • loop is allowed on type="carousel"

Migration Notes

  • Update the required script from amp-carousel-0.1 to amp-carousel-0.2.
  • Ensure any CSS for positioning next/previous arrows is still valid. See the styling for more information on arrow positioning.
  • Ensure any CSS used to style the carousel is still valid. The internal DOM structure of <amp-carousel> 0.2 differs from 0.1, effecting CSS selectors targeting internal elements such as amp-carousel > div. Any selectors using the .amp-class-name format should still work.
  • NOTE: Support for amp-carousel-0.1 is limited, with the intent to deprecate in the future.

Advancing to a specific slide

Setting a method for the on attribute on an element to tap:carousel-id.goToSlide(index=N) will, on user tap or click, advance a carousel with the "carousel-id" ID to the slide at index=N (the first slide is at index=0, the second slide is at index=1, and so on).

In the following example, we have a carousel of three images with preview buttons below the carousel. When a user clicks one of the buttons, the corresponding carousel item displays.

[example preview="inline" playground="true" imports="amp-carousel"]

<amp-carousel
  id="carousel-with-preview"
  width="450"
  height="300"
  layout="responsive"
  type="slides"
  role="region"
  aria-label="Carousel with slide previews"
>
  <amp-img
    src="{{server_for_email}}/static/inline-examples/images/image1.jpg"
    width="450"
    height="300"
    layout="responsive"
    alt="apples"
  ></amp-img>
  <amp-img
    src="{{server_for_email}}/static/inline-examples/images/image2.jpg"
    width="450"
    height="300"
    layout="responsive"
    alt="lemons"
  ></amp-img>
  <amp-img
    src="{{server_for_email}}/static/inline-examples/images/image3.jpg"
    width="450"
    height="300"
    layout="responsive"
    alt="blueberries"
  ></amp-img>
</amp-carousel>
<div class="carousel-preview">
  <button on="tap:carousel-with-preview.goToSlide(index=0)">
    <amp-img
      src="{{server_for_email}}/static/inline-examples/images/image1.jpg"
      width="60"
      height="40"
      alt="apples"
    ></amp-img>
  </button>
  <button on="tap:carousel-with-preview.goToSlide(index=1)">
    <amp-img
      src="{{server_for_email}}/static/inline-examples/images/image2.jpg"
      width="60"
      height="40"
      alt="lemons"
    ></amp-img>
  </button>
  <button on="tap:carousel-with-preview.goToSlide(index=2)">
    <amp-img
      src="{{server_for_email}}/static/inline-examples/images/image3.jpg"
      width="60"
      height="40"
      alt="blueberries"
    ></amp-img>
  </button>
</div>

[/example]

Accessibility considerations for amp-carousel

Autoplaying, and particularly infinitely looping, carousels can be very distracting and confusing for users - especially for users with cognitive impairments. In general, we recommend avoiding autoplaying carousels. While autoplaying carousels stop once the user has interacted with the carousel, consider also adding an explicit "Play/Pause" control.

By default, the <amp-carousel> is programmatically identified as a list when rendered (using role="list" on the container element, and role="listitem" on each item). However, for <amp-carousel type="slides">, no specific role is currently provided. As a result, it will not be obvious for assistive technology users reading/navigating through a page when they reach a carousel. We recommend including an explicit role="region" and a descriptive aria-label (either a generic aria-label="Carousel" or a more descriptive label such as aria-label="Latest news items") to <amp-carousel>.

Currently, an <amp-carousel type="slides"> carousel is declared as an ARIA live region (using aria-live="polite"), meaning that every time a new slide is shown, the entire content of the slide is announced by assistive technologies (such as screen readers). Due to the way carousels are initially rendered, this can also result in the carousel's content being announced in its entirety when a page is loaded. This also means that pages that contain an autoplay carousel will continuously announce whenever a slide auto-advances. There is currently no work-around for this issue.

Attributes

type

Specifies the display type for the carousel items, which can be:

  • carousel (default): All slides are shown and are scrollable horizontally. Each slide may specify a different width using CSS.
  • slides: Shows a single slide at a time, with each slide snapping into place as the user swipes.

controls (optional)

Permanently displays left and right arrows for the user to navigate carousel items on mobile devices. By default, navigational arrows disappear after the user swipes to another slide on mobile.

The visibility of arrows can also be controlled via styling, and a media query can be used to only display arrows at certain screen widths. On desktop, arrows are always displayed unless only a single child is present.

data-next-button-aria-label (optional)

Sets the aria-label for the amp-carousel-button-next. If no value is given, the aria-label defaults to 'Next item in carousel'.

data-prev-button-aria-label (optional)

Sets the aria-label for the amp-carousel-button-prev. If no value is given, the aria-label defaults to 'Previous item in carousel'.

data-button-count-format (optional)

A format string that looks like (%s of %s), used as a suffix to the aria-label for amp-carousel-button-next/amp-carousel-button-prev. This provides information to users using a screen reader on their progress through the carousel. If no value is given, this defaults to (%s of %s).

autoplay (optional)

Regularly advances to the next slide without user interaction. If the user manually changes slides, then autoplay is stopped.

If present without a value:

  • By default, advances a slide in 5000 millisecond intervals (5 seconds); this can be overridden by the delay attribute.
  • Requires at least 2 slides for autoplay to occur.

If present with a value:

  • Stops autoplaying after the requisite number of loops are made.

delay (optional)

Specifies the duration (in milliseconds) to delay advancing to the next slide when autoplay is enabled. Note that the minimum allowed value for delay is 1000 milliseconds.

loop (optional)

Allows the user to advance past the first item or the final item. There must be at least 3 slides for looping to occur.

The example below displays a slide carousel with controls, looping, and delayed autoplay.

[example preview="inline" playground="true" imports="amp-carousel"]

<amp-carousel type="slides"
  width="450"
  height="300"
  controls
  loop
  {% if not format=='email'%}  autoplay
  delay="3000"{% endif %}
  data-next-button-aria-label="Go to next slide"
  data-previous-button-aria-label="Go to previous slide"
  role="region"
  aria-label="Looping carousel">
  <amp-img src="{{server_for_email}}/static/inline-examples/images/image1.jpg"
    width="450"
    height="300"></amp-img>
  <amp-img src="{{server_for_email}}/static/inline-examples/images/image2.jpg"
    width="450"
    height="300"></amp-img>
  <amp-img src="{{server_for_email}}/static/inline-examples/images/image3.jpg"
    width="450"
    height="300"></amp-img>
</amp-carousel>

[/example]

slide (optional)

Specifies what index should be shown when the carousel is first rendered. This can be updated with amp-bind to change which index is shown.

common attributes

This element includes common attributes extended to AMP components.

Actions

goToSlide(index=INTEGER)

Advances the carousel to a specified slide index.

toggleAutoplay(toggleOn=true|false)

Toggle the carousel's autoplay status. toggleOn is optional.

Events

slideChange

Fired when the carousel's current slide changes.

// Slide number.
Event.index

Styling

[filter formats="websites, ads"]

  • You may use the amp-carousel element selector to style it freely.
  • You may use the .amp-carousel-slide class selector to target carousel items.
  • The visual state of an amp-carousel button when it's disabled is hidden.
  • By default, .amp-carousel-button uses an inlined SVG as the background-image of the buttons. You may override this with your own SVG or image as in the example below.

Example: Default .amp-carousel-button inlined SVG

.amp-carousel-button-prev {
  background-image: url('data:image/svg+xml;charset=utf-8,%3Csvg xmlns="http://www.w3.org/2000/svg" width="18" height="18" fill="%23fff"%3E%3Cpath d="M15 8.25H5.87l4.19-4.19L9 3 3 9l6 6 1.06-1.06-4.19-4.19H15v-1.5z"/%3E%3C/svg%3E');
}

Example: Overriding the default .amp-carousel-button inlined SVG

.amp-carousel-button-prev {
  background-image: url('data:image/svg+xml;charset=utf-8,%3Csvg xmlns="http://www.w3.org/2000/svg" width="18" height="18" fill="%23fff"%3E%3Cpath d="M11.56 5.56L10.5 4.5 6 9l4.5 4.5 1.06-1.06L8.12 9z"  /%3E%3C/svg%3E');
}

Note that the SVG content needs to have certain characters, including <, > and # encoded. This can be done using a tool like SVGO or using encodeURIComponent.

  • You can position the carousel buttons using align-self and/or relative positioning. Note that the carousel arrows are automatically flipped in RTL, so you should not change their flex order.
.amp-carousel-button-prev {
  position: relative;
  bottom: 20px;
  align-self: flex-end;
}

[/filter]

[filter formats="email"]

  • You may use the amp-carousel element selector to style it freely.
  • You may use the .amp-carousel-slide class selector to target carousel items.
  • The visual state of an amp-carousel button when it's disabled is hidden.
  • By default, .amp-carousel-button uses an inlined SVG as the background-image of the buttons. You may override this with your own image. Some email clients may not support SVG.

Example: Overriding the default .amp-carousel-button inlined SVG

.amp-carousel-button-prev {
  background-image: url('http://example.com/arrow.png');
}

You can position the carousel buttons using align-self and/or relative positioning. Note that the carousel arrows are automatically flipped in RTL, so you should not change their flex order.

.amp-carousel-button-prev {
  position: relative;
  bottom: 20px;
  align-self: flex-end;
}

[/filter]

Validation

See amp-carousel rules in the AMP validator specification.