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Carousel Specification

Radoslav Mirchev edited this page Feb 17, 2021 · 20 revisions
  1. Revision History
  2. Objectives
  3. User Stories
  4. Acceptance criteria
  5. Functionality
  6. API
  7. Accessibility
  8. Internationalization
  9. Test plan
  • Konstantin Dinev | Date:
  • Radoslav Mirchev | Date: Feb 17, 2021
  • Simeon Simeonov | Date:
Version User Date Notes
0.1 Stanka Bozalieva Oct 5, 2018 Initial draft
0.2 Stefan Ivanov Oct 9, 2019 Update - in progress
1.0 Zdravko Kolev Nov 7, 2019 Add Test plan
2.0 Zdravko Kolev Feb 1, 2021 Update Accessibility section

A carousel component is used to browse a collection of slides like galleries of images, cards, on-boarding tutorials or page-based interfaces. It can be used as a separate full – screen element or inside another component

igx-carousel can be used as standalone component in order to show a set of slides. It should be highly customizable, providing capabilities like slide transitions and animations, hide\show navigation buttons, dynamically load images, i18n and accessibility support.

End user

As end user I would like to:

  • Be able to navigate through a set of slides.
  • Be able to navigate the slides via Next and Previous soft buttons.
  • Be able to navigate the slides via the keyboard arrows.
  • Be able to select and show a particular slide from the collection through pager/thumbs.
  • Be able to interact with the slide so that it would open other relevant content.
  • Have an indication about the current slide in the context of the collection.


As a developer I want to:

  • Be able to provide the slides to be displayed using ngFor directive.
<igx-carousel [interval]="interval" [pause]="pause" [loop]="loop">
     <igx-slide *ngFor="let slide of slides;" [active]="">
         <img [src]="slide.image">
  • Be able to provide the slides to be displayed through pure markup
<igx-carousel [interval]="interval" [pause]="pause" [loop]="loop">
    <igx-slide [active]="">
        <img [src]="...">
        <img [src]="...">
  • I expect to have buttons for moving to the Next/Previous slide.
  • I expect to have templatable indicators that support precise navigation, show the current status/active slide and progress. Such a template can be created for gots (Page indicators - iOS), a small thumb for every slide, or another custom layout.
  • I want to create slide templates that can trigger an action that would take the user to a news article for example
  • I want to be able a threshold for the number of slides (5 by default) within which navigation indicators are shown e.g. dots
  • The indication area is to be replaced with informative text, e.g. “3 of 6”, when there would be more than the max number of navigable slides.
  • I want to utilize touch gestures on the carousel such as:
    • Flick left or right to change the active slide
    • Pan left/right to peek to the next/previous slide without changing the active slide unless panning beyond a certain threshold and lifting your finger
  • I want to show more than one slide at a time (similar to coverflow on MacOS)
  • I want to be disable navigation of the carousel which would hide dots/thumbnail indicators and navigation buttons but also disables all gestures and interactions for the carousel
  • Height ( % ) vertical direction
  • Width ( % ) horizontal direction
  • I want to be able to make the carousel slides loop (false by default allowing the first slide can only go forward/ last slide can only go backwards)
  • I want to configure the carousel to auto-play on every 3 seconds or another arbitrary amount of time (auto-play is disabled by default)
    • On touch devices auto-play pauses when a long press is performed on the current slide
    • On desktop devices auto-play pauses on mouse enter on the carousel and un-pauses on mouse leave after a 2 second timeout or another arbitrary amount of time
  • I want to be able to set active slide shown by default when the page loads
  • I want to set the active slide programmatically
  • I expect to have default slide in and slide out animations for a slide that are applied when transition occurs. I also need to be able to tweak or override them.
  1. Have carousel that shows image/set of images.
  2. Have carousel that should navigation button and image indicators.
  3. Have the ability to stop, pause or play the image transition.
  4. Have the ability to change current active slide.

End User Experience

igx-carousel should always display initial image and navigation buttons or image indicators.

Developer Experience

igx-carousel should provide properties, events and methods what will manage carousel configuration and behaviors.

User Interface

The end user interface consists of:

  1. Navigation buttons

  2. Slide indicators

  3. Slides container


  • loop - Should the carousel wrap back to the first slide after it reaches the last. Defaults to true.
  • pause - Should the carousel stop playing on user interaction. Defaults to true.
  • interval - The amount of time in milliseconds between slides transition.
  • navigation - Controls should the carousel render the left/right navigation buttons. Defaults to true.
  • total - The number of slides the carousel currently has.
  • current - The index of the slide currently showing.
  • isPlaying - Returns whether the carousel is paused/playing.
  • isDestroyed - If the carousel is destroyed (ngOnDestroy was called).


  • onSlideChanged - Emitted on slide change.
  • onSlideAdded - Emitted when a slide is being added to the carousel.
  • onSlideRemoved - Emitted whe a slide is being removed from the carousel.
  • onCarouselPaused - Emitted when the carousel is pausing.
  • onCarouselPlaying - Emitted when the carousel starts/resumes playing.


  • play() - Emits onCarouselPlaying event and starts the transition between slides.
  • stop() - Emits onCarouselPaused event and stops the transition between slides.
  • prev() - Switches to the previous slide. Emits onSlideChanged event.
  • next() - Switches to the next slide. Emits onSlideChanged event.
  • add(slide: IgxSlide) - Adds a slide to the carousel. Emits onSlideAdded event.
  • remove(slide: IgxSlide) - Removes an existing slide from the carousel. Emits onSlideRemoved event.
  • get(index: Number) - Returns the slide with the given index or null.
  • select(slide: IgxSlide, direction: Direction) - Selects the slide and the direction to transition to. Emits onSlideChanged event.

WAI-ARIA Roles, States, and Properties

  • The Carousel base element role is region - section containing content that is relevant to specific purpose and users will likely want to be able to navigate easily.
  • Carousel indicators are with role tab - grouping label providing a mechanism for selecting the tab content that is to be rendered to the user
  • The element that serves as the container for the set of tabs (carousel indicators) role is set to tablist.
  • Each slide element is set with role tabpanel.
  • The element that serves as the container for the set of igx-slides is set with aria-live="polite". Both options are
    • off: if the carousel is automatically rotating.
    • polite: if the carousel is NOT automatically rotating.

Carousel component

  • aria-roledescription='carousel'
  • aria-selected=""
  • aria-controls="'panel-' + slide.index"
  • aria-live="!interval || stoppedByInteraction ? 'polite' : 'off'"
  • aria-label="carousel"
  • aria-label="setAriaLabel(slide)" - slide based
  • aria-label (buttons)
    • aria-label="resourceStrings.igx_carousel_previous_slide" (keydown.enter)="prev()"
    • aria-label="resourceStrings.igx_carousel_next_slide" (keydown.enter)="next()"

Slide component

  • attr.role="tabpanel" - container for the resources associated with a tab, where each tab is contained in a tablist.
  • id="panel-${this.index}"
  • aria-labelledby="tab-${this.index}-${}"
  • aria-selected="active" active slide - class.igx-slide--current
Key Result
Arrow right Next slide
Arrow left Previous slide
Home First slide
End Last slide
Key Result
Arrow right Previous slide
Arrow left Next slide

The informative text for the indication area that reads e.g. "3 of 6" should have a localizable string for the "of" text.


Base tests

  1. Test first slide active state on initial loading. The slide should be focused on the initial load of the carousel.
  2. If a slide element is set as [active]=”true”, it should be with the active state on initial load of the carousel
  3. Test input [navigation]. When it set to false the arrow buttons should be hidden. When [navigation] is set to “true” the arrow buttons should be visible.
  4. Test input [keyboardSupport]. When it’s set to “false” you cannot change slides with arrow keys.
  5. Test slides changing with keyboard actions arrowLeft, arrowRight, home and end keys. Event onSlideChanged should be fired.
  6. Test slides changing with indicators. Event onSlideChanged should be fired.
  7. Test slides changing with navigation keys (ui buttons). Event onSlideChanged should be fired.
  8. Test input [loop]. Test navigation from the first and last slide.
  9. Test input [maximumIndicatorsCount]. The indicators should be visible only when the slides count is less than the [maximumIndicatorsCount]. Test showing of indicators labels.
  10. Test input [indicatorsOrientation]. When it is set to top/bottom the indicators should be previewed on top/bottom location of the slide.
  11. Test setting of [indicatorTemplate].
  12. Test that when slides collection is change and a slide is added/removed the Carousel slides collection should be changed and events onSlideAdded and onSlideRemoved should be fired.
  13. Test that when all slides are removed the navigation buttons and indicators won’t be shown.
  14. Test inputs [interval] and [pause].
  15. Test setting of [animationType] (no visual testing)
  16. Test that when [interval] is set and hover carousel the playing should be paused and then started on mouse unhover. Events onCarouselPaused and onCarouselPlaying should be fired.


  1. Test methods select(), next() and prev()
  2. Test methods total(), get() and current()
  3. Test methods add() and remove(). The slides should be added/removed in the carousel.
  4. Test methods play(), stop() and isPlaying()


  1. Visually verify that fadeIn animation is applied as enterAnimation for fade CarouselAnimationType
  2. Visually verify that slide animation is applied as enterAnimation for slide CarouselAnimationType, and slide for leaveAnimation
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