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Auto-Rotating Image Carousel with Tabs for Slide Control Example

Auto-Rotating Image Carousel with Tabs for Slide Control Example

Read This First

The code in this example is not intended for production environments. Before using it for any purpose, read this to understand why.

This is an illustrative example of one way of using ARIA that conforms with the ARIA specification.

About This Example

The following example implementation of the Carousel Pattern demonstrates features of the pattern that are essential to accessibility for carousels that automatically start rotating when the page loads. This example also illustrates how to use the tabs pattern to provide users with a way to skip slides in the sequence by directly choosing which one to view. Navigation among slides is provided by a series of circular buttons that function as tabs and are rendered over the rotating slides. Automatic rotation stops when users move focus to any control or link in the carousel or hover the mouse over carousel content. The accessibility features section that follows the example describes these aspects of the design in detail.

Similar examples include:

Example Options

Example

Accessibility Features

Controlling Automatic Slide Rotation

Users can stop and start slide rotation, which is an essential aspect of accessibility of the carousel for a variety of people with disabilities. People with low vision or a cognitive disability that affects visual processing or reading benefit from being able to control slide rotation so they have sufficient time to explore slide content. Similarly, since screen reader users cannot perceive automatic rotation, it can make reading the page confusing and disorienting. For example, when slides are automatically rotating, a screen reader user may read an element on slide one, execute a screen reader command to read the next element, and, instead of hearing the next element on slide one, hear an element from slide 2 without any knowledge that the element just announced is from an entirely new context.

This example includes the following features for giving users control over slide rotation:

  • If operating system preferences have been set for reduced motion or disabling animations, the auto-rotation is initially paused.
  • Hovering the mouse over any carousel content pauses automatic rotation. Automatic rotation resumes when the mouse moves away from the carousel unless another condition that prevents rotation, such as keyboard focus, has been triggered.
  • Moving keyboard focus to any of the carousel content, including the tab elements, pauses automatic rotation. Automatic rotation only resumes if the user explicitly activates the Play button.
  • The carousel also contains a rotation control button that can stop and start automatic rotation.
    • The rotation control button is the first element in the screen reader reading order.
    • The rotation control button is always visible so it is available to all users whether they are interacting via a mouse, keyboard, assistive technology, or touch.
    • If the carousel is rotating, the button's accessible name is Stop Automatic Slide Show, informing screen reader users that the slides are changing in addition to providing a way to stop the changes.
    • If the carousel is not rotating, the accessible name of the button is Start Automatic Slide Show.
    • If a user activates the rotation control button to start rotation it is assumed the user wants auto-rotation to start immediately and focus or hover states within the carousel are ignored.. The rotation will only stop if the button is activated again,
  • The example includes an option to completely disable automatic slide rotation. When this option is selected the start/stop button is not rendered and slides can only be rotated through activation of the tab controls.

Color Contrast of Text and Rotation Controls

In the view of this carousel where the controls and captions are displayed inside the image, background images could cause color contrast for the controls and text to become insufficient. However, this view includes the following features to prevent this potential problem and ensure it meets WCAG 2.1 color contrast requirements:

  • When the tabs controlling the rendering of slides are inside the image, the tabs have foreground and background colors that meet WCAG 2.1 color contrast requirements. In addition, the focus styling uses SVG images that make the focus indicator highly visible when a control receives keyboard focus.
  • The transparency of the caption area is decreased so the caption text meets the WCAG 2.1 color contrast requirements.

One way to avoid the color contrast issues of controls and text inside the image is to move them to outside the image. Moving the controls and text to a solid background makes it easier for the author to control color contrast and for the user to perceive them. An example of this technique is one of the view options.

Focus Styling of the Tablist and Tabs

  • When a tab receives focus, the entire tab list is also highlighted with a border as an affordance that indicates to users that arrow keys are used to navigate among controls in the group.
  • The CSS border width used for focus styling is changed from 0 to 2 pixels when the control receives focus to support visibility of focus when operating system high contrast options are enabled.

Screen Reader Announcement of Slide Changes

When automatic rotation is turned off, the carousel slide content is included in a live region. This makes it easier for screen reader users to scan through the carousel slides. When screen reader users activate a new tab, the new slide content is announced, giving users immediate feedback that helps them determine whether or not to interact with the content. Very importantly, if automatic rotation is turned on, the live region is disabled. If it were not, the page would become unusable as announcements of the continuously changing content constantly interrupt anything else the user is reading.

Note that making a tab panel live is not recommended for typical tabs. In the carousel use case, where the primary intent is quick, light-weight scanning of content, the live region is used to simulate the type of experience that non-screen reader users have with auto-rotation.

Keyboard Support

Rotation Control Button

Key Function
Tab
  • Moves focus through interactive elements in the carousel.
  • Rotation control button and tab list precede the slide content in the Tab sequence.
Enter or Space Toggle automatic rotation of slides in the carousel.

Tabs

Key Function
Tab
  • When focus moves into the tablist, places focus on the active tab element. Each slide in the carousel is controlled by a tab.
  • When the tab list contains the focus, moves focus to the next element in the tab sequence, which is a link in the currently shown slide.
Right Arrow
  • Moves focus to the next tab.
  • If focus is on the last tab, moves focus to the first tab.
  • Shows the slide associated with the newly focused tab.
Left Arrow
  • Moves focus to the previous tab.
  • If focus is on the first tab, moves focus to the last tab.
  • Shows the slide associated with the newly focused tab.
Home Moves focus to the first tab and shows the first slide.
End Moves focus to the last tab and shows the last slide.

Role, Property, State, and Tabindex Attributes

Rotation Control

Role Attribute Element Usage
aria-label button The accessible name changes to reflect the action the button will perform:
  • If automatic rotation is Paused, the label is "Start automatic slide show".
  • If the carousel is rotating automatically, the label is "Stop automatic slide show".

Tabs

Role Attribute Element Usage
Implied role of region section
  • Role region is implied for any section element that has an accessible name.
  • Defines the carousel and its controls as a landmark region.
aria-roledescription="carousel" section
  • Informs assistive technologies to identify the element as a "carousel" rather than as a "region".
  • Affects how assistive technologies render the role but does not affect functionality, such as commands for navigating to landmark regions.
  • NOTE: The aria-roledescription value is defined using the language of the page and should be localized by the author.
aria-label="Highlighted television shows" section Provides a label that describes the content in the carousel region.
aria-live="off" div.carousel-items
  • Applied to a div element that contains all the slides.
  • Identifies the container as a live region that is in the "off" state, meaning assistive technology users are not automatically informed of changes to the region.
  • The live region is off when the carousel is automatically rotating.
aria-live="polite" div.carousel-items
  • Applied to a div element that contains all the slides.
  • Identifies the container element as a live region in the "polite" state, meaning assistive technology users are informed of changes to the region at the next available opportunity.
  • This causes screen readers to automatically announce the content of a slide when its associated tab is activated.
tablist div Indicates that the element serves as a container for a set of tabs.
aria-label="Slides" div Provides an accessible name for the tablist.
tab button
  • Indicates the element serves as a tab control.
  • When focused, it is automatically activated, causing its associated tabpanel (i.e. slide) to be displayed.
aria-label="Slide X" button Provides an accessible name for the tab.
aria-selected="true" button
  • Indicates the tab control is activated and its associated panel is displayed.
  • Set when a tab receives focus.
aria-selected="false" button
  • Indicates the tab control is not active and its associated panel is NOT displayed.
  • Set for all tab elements in the tab set except the for the tab associated with the currently displayed slide.
tabindex="-1" button
  • Removes the element from the page Tab sequence.
  • Set when a tab is not selected so that only the selected tab is in the page Tab sequence.
  • Since the tab element is an HTML button, the tabindex attribute is removed when a tab is selected (activated) rather than setting tabindex="0".
  • This approach to managing focus is described in the section on Managing Focus Within Components Using a Roving tabindex.
aria-controls="IDREF" button Refers to the tabpanel element associated with the tab.
tabpanel div
  • Indicates the element serves as a tabpanel that is controlled by its associated tab element.
  • Is hidden unless its associated tab control is activated.
aria-roledescription="slide" div
  • Informs assistive technologies to identify the element as a "slide" rather than as a "tabpanel".
  • Affects how assistive technologies render the role but does not affect assistive technology functionality.
  • NOTE: The aria-roledescription value is defined using the language of the page and should be localized by the author.
aria-label="X of Y" div
  • Provides an accessible name for the tab panel (slide) that indicates what position the slide is in the set of slides.
  • When combined with the aria-roledescription, a screen reader could announce a tab panel as a slide with its position, e.g., "Slide 1 of 6".

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This is an unpublished draft preview that might include content that is not yet approved. The published website is at w3.org/WAI/.