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A generic carousel for displaying multiple similar pieces of content along a horizontal or vertical axis.
Each of the amp-base-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 a single item.
The carousel advances between items if the user swipes or uses the customizable arrow buttons.
Bento AMP allows you to use AMP components in non-AMP pages without needing to commit to fully valid AMP. You can take these components and place them in implementations with frameworks and CMSs that don't support AMP. Read more in our guide Use AMP components in non-AMP pages.
The example below demonstrates amp-base-carousel
component in standalone use.
[example preview="top-frame" playground="false"]
<head>
<script async src="https://cdn.ampproject.org/v0.js"></script>
<link rel="stylesheet" type="text/css" href="https://cdn.ampproject.org/v0/amp-base-carousel-1.0.css">
<script async custom-element="amp-base-carousel" src="https://cdn.ampproject.org/v0/amp-base-carousel-1.0.js"></script>
<style>
amp-base-carousel, amp-base-carousel > div {
aspect-ratio: 4/1;
}
.red-gradient {
background: brown;
background: linear-gradient(90deg, brown 50%, lightsalmon 90%, wheat 100%);
}
.blue-gradient {
background: steelblue;
background: linear-gradient(90deg, steelblue 50%, plum 90%, lavender 100%);
}
.green-gradient {
background: seagreen;
background: linear-gradient(90deg, seagreen 50%, mediumturquoise 90%, turquoise 100%);
}
</style>
</head>
<amp-base-carousel id="my-carousel">
<div class="red-gradient"></div>
<div class="blue-gradient"></div>
<div class="green-gradient"></div>
</amp-base-carousel>
<div class="buttons" style="margin-top: 8px;">
<button id='prev-button'>Go to previous slide</button>
<button id='next-button'>Go to next slide</button>
<button id='go-to-button'>Go to slide with green gradient</button>
</div>
<script>
(async () => {
const carousel = document.querySelector('#my-carousel');
await customElements.whenDefined('amp-base-carousel');
const api = await carousel.getApi();
// programatically advance to next slide
api.next();
// set up button actions
document.querySelector('#prev-button').onclick = () => api.prev();
document.querySelector('#next-button').onclick = () => api.next();
document.querySelector('#go-to-button').onclick = () => api.goToSlide(2);
})();
</script>
[/example]
Bento enabled components in standalone use are highly interactive through their API. In Bento standalone use, the element's API replaces AMP Actions and events and amp-bind
.
The amp-base-carousel
component API is accessible by including the following script tag in your document:
await customElements.whenDefined('amp-base-carousel');
const api = await carousel.getApi();
The amp-base-carousel
API allows you to perform the following actions:
next()
Moves the carousel forwards by advance-count
slides.
api.next();
prev()
Moves the carousel backwards by advance-count
slides.
api.prev();
goToSlide(index: number)
Moves the carousel to the slide specified by the index
argument.
Note: index
will be normalized to a number greater than or equal to 0
and less than the number of slides given.
api.goToSlide(0); // Advance to first slide.
api.goToSlide(length - 1); // Advance to last slide.
The amp-base-carousel
API allows you to register and respond to the following events:
slideChange
This event is triggered when the index displayed by the carousel has changed.
The new index is available via event.data.index
.
carousel.addEventListener('slideChange', (e) => console.log(e.data.index))
Each Bento component has a small CSS library you must include to guarantee proper loading without content shifts. Because of order-based specificity, you must manually ensure that stylesheets are included before any custom styles.
<link rel="stylesheet" type="text/css" href="https://cdn.ampproject.org/v0/amp-base-carousel-1.0.css">
Fully valid AMP pages use the AMP layout system to infer sizing of elements to create a page structure before downloading any remote resources. However, Bento use imports components into less controlled environments and AMP's layout system is inaccessible.
Container type
The amp-base-carousel
component has a defined layout size type. To ensure the component renders correctly, be sure to apply a size to the component and its immediate children (slides) via a desired CSS layout (such as one defined with height
, width
, aspect-ratio
, or other such properties):
amp-base-carousel {
height: 100px;
width: 100%;
}
amp-base-carousel > * {
aspect-ratio: 4/1
}
<amp-base-carousel>
currently requires that you let it know when it is in an
right-to-left (rtl) context (e.g. Arabic, Hebrew pages). While the carousel will
generally work without this, there may be a few bugs. You can let the carousel
know that it should operate as rtl
as follows:
<amp-base-carousel dir="rtl" …>
…
</amp-base-carousel>
If the carousel is in a RTL context, and you want the carousel to operate as
LTR, you can explicitly set the dir="ltr"
on the carousel.
Slides are automatically sized by the carousel when not specifying
mixed-lengths
. You should give the slides layout="flex-item"
:
<amp-base-carousel …>
<amp-img layout="flex-item" src="…"></amp-img>
</amp-base-carousel>
The slides have a default height of 100%
when the carousel is laid out
horizontally. This can easily be changed with CSS or by using
layout="fixed-height"
. When specifying the height, the slide will be
vertically centered within the carousel.
If you want to horizontally center your slide content, you will want to create a wrapping element, and use that to center the content.
When changing the number of visible slides using visible-slides
, in response
to a media query, you will likely want to change the aspect ratio of the
carousel itself to match the new number of visible slides. For example, if you
want to show three slides at a time with a one by one aspect ratio, you would
want an aspect ratio of three by one for the carousel itself. Similiarly, with
four slides at a time you would want an aspect ratio of four by one. In
addition, when changing visible-slides
, you likely want to change
advance-count
.
<!-- Using an aspect ratio of 3:2 for the slides in this example. -->
<amp-base-carousel
layout="responsive"
width="3"
height="1"
heights="(min-width: 600px) calc(100% * 4 * 3 / 2), calc(100% * 3 * 3 / 2)"
visible-count="(min-width: 600px) 4, 3"
advance-count="(min-width: 600px) 4, 3"
>
<amp-img layout="flex-item" src="…"></amp-img>
…
</amp-base-carousel>
The attributes for <amp-base-carousel>
can be configured to use different
options based on a media query. You can also use a value without any media
queries. The format looks like:
<amp-base-carousel
attr-name="(min-width: 1000px) valueOne, (min-width: 600px) valueTwo, defaultValue"
></amp-base-carousel>
The media queries are evaluated from left to right, with the first matching
media query being used. A default value (without a media query) is required. In
this case, if the page has a screen width of 1000px or more, valueOne
is used.
If the width is between 999px and 600px, valueTwo
is used. When it is 599px or
smaller, defaultValue
is used.
Either true
or false
, defaults to false
. When true, uses the existing
width (or height when horizontal) for each of the slides. This allows for a
carousel with slides of different widths to be used.
A number, defaults to 1
. Determines how many slides should be shown at a given
time. Fractional values can be used to make part of a(n) additional slide(s)
visible. This option is ignored when mixed-length
is true
.
A number, defaults to 1
. Determines how many slides the carousel will advance
when advancing using the previous or next arrows. This is useful when specifying
the visible-count
attribute.
Either true
or false
, defaults to false
. Automatically advances the
carousel to the next slide based on a delay. If the user manually changes
slides, then the auto advance is stopped. Note that if loop
is not enabled,
when reaching the last item, the auto advance will move backwards to the first
item.
A number, defaults to 1
. Determines how many slides the carousel will advance
when automatically advancing. This is useful when specifying the visible-count
attribute.
A number, defaults to 1000
. Specifies the amount of time, in milliseconds,
between subsequent automatic advances of the carousel.
A number, defaults to ∞
. The number of times the carousel should advance
through the slides before stopping.
Either true
or false
, defaults to true
. Determines whether or not the
carousel should snap on slides when scrolling.
Either start
or center
. When start aligning, the start of a slide (e.g. the
left edge, when horizontal aligning) is aligned with the start of a carousel.
When center aligning, the center of a slide is aligned with the center of a
carousel.
A number, defaults to 1
. This determines the granularity of snapping and is
useful when using visible-count
.
Either "always"
, "auto"
, or "never"
, defaults to "auto"
. This determines if and when prev/next navigational arrows are displayed. Note: When outset-arrows
is true
, the arrows are shown "always"
.
always
: Arrows are always displayed.auto
: Arrows are displayed when the carousel has most recently received interaction via mouse, and not displayed when the carousel has most recently received interaction via touch. On first load for touch devices, arrows are displayed until first interaction.never
: Arrows are never displayed.
A number, defaults to 0
. This determines the initial slide shown in the
carousel. This may be used with amp-bind
to control which slide is currently
showing.
Either true
or false
, defaults to false
when omitted. When true, the carousel will allow the user to move from the first item back to the last item and visa versa. There must be at least three times the visible-count
of slides present for looping to occur.
Either horizontal
or vertical
, defaults to horizontal
. When horizontal
the carousel will lay out horizontally, with the user being able to swipe left and right. When vertical
, the carousel lays out vertically, with the user being able to swipe up and down.
This element includes common attributes extended to AMP components.
Moves the carousel forwards by advance-count
slides.
Moves the carousel backwards by advance-count
slides.
Moves the carousel to the slide specified by the index
argument.
This event is triggered when the index displayed by the carousel has changed.
The new index is available via event.index
.
You may use the amp-base-carousel
element selector to style the carousel
freely.
Arrow buttons can be customized by passing in your own custom markup. For example, you can recreate the default styling with the following HTML and CSS:
.carousel-prev,
.carousel-next {
filter: drop-shadow(0px 1px 2px #4a4a4a);
width: 40px;
height: 40px;
padding: 20px;
background-color: transparent;
border: none;
outline: none;
}
.carousel-prev {
background-image: url('data:image/svg+xml;charset=utf-8,<svg viewBox="0 0 24 24" xmlns="http://www.w3.org/2000/svg"><path d="M14,7.4 L9.4,12 L14,16.6" fill="none" stroke="#fff" stroke-width="2px" stroke-linejoin="round" stroke-linecap="round" /></svg>');
}
.carousel-next {
background-image: url('data:image/svg+xml;charset=utf-8,<svg viewBox="0 0 24 24" xmlns="http://www.w3.org/2000/svg"><path d="M10,7.4 L14.6,12 L10,16.6" fill="none" stroke="#fff" stroke-width="2px" stroke-linejoin="round" stroke-linecap="round" /></svg>');
}
<amp-base-carousel …>
<div>first slide</div>
…
<button slot="next-arrow" class="carousel-next" aria-label="Next"></button>
<button
slot="prev-arrow"
class="carousel-prev"
aria-label="Previous"
></button>
</amp-base-carousel>
If you want more customization for the arrow buttons, you can use the next
and
prev
actions. For example, if you want to place buttons under the carousel and
use the words "Previous" and "Next" instead of having them in the default
location, you can use the following HTML:
<amp-base-carousel id="carousel-1" …>
…
<div slot="next-arrow"></div>
<div slot="prev-arrow"></div>
</amp-carousel>
<button on="tap:carousel-1.prev()">Previous</button>
<button on="tap:carousel-1.next()">Next</button>
Unlike 0.1
, the experimental 1.0
version of amp-base-carousel
allows configuring the carousel slide orientation via "orientation"="horizontal"|"vertical"
attributes instead of "horizontal"="true"|"false"
attributes.