Closed Captions (CC)

With accessibility settings, it’s important that your app follows your user’s device settings. When an app starts up it should grab your user’s current device accessibility settings and adapt to system accessibility changes that your user makes.

As a note, we cannot not render the captions for your app. Your app will need to be in sync with your user’s expectations.

Reading device settings

In order to access your user’s current closed captions settings, your app can call the Accessibility.closedCaptions() method from the Accessibility API:

import { Accessibility } from '@firebolt-js/sdk'

const ccSettings = await Accessibility.closedCaptions()

if (ccSettings.enabled) {
  // the user has captions enabled

Additionally, your app should respect your user’s current closed-captions styles, which they may have set as their personal preference for readability. Continuing from the previous example, you can access the styles property:


See the ClosedCaptionsStyles API for more info on styling properties.

Adapting to real-time changes

While your app is running, or even while your app is playing content, your user may change the closed captions settings on their device. Your app should promptly respond to this change by listening to all closedCaptionsSettingsChanged events:

import { Accessibility } from '@firebolt-js/sdk'

Accessibility.listen(`closedCaptionsSettingsChanged`), ccSettings => {
  // ccSettings is the same structure returned from `closedCaptions()`
  if (ccSettings.enabled) {
    // update your app's CC styles
  else {
    // turn off your app's CC rendering

Example ClosedCaptionsSettings value

    enabled: true,
    styles: {
      fontFamily: 'Monospace sans-serif',
      fontSize: 1,
      fontColor: '#ffffff',
      fontEdge: 'none',
      fontEdgeColor: '#7F7F7F',
      fontOpacity: 100,
      backgroundColor: '#000000',
      backgroundOpacity: 100,
      textAlign: 'center',
      textAlignVertical: 'middle',

For more information about this API, visit the Accessibility API documentation.

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