Media features use cases for personalization
From Accessible Platform Architectures Working Group
This page collects use cases for media features used for personalization of web pages. These are supposed to justify a new set of media features as proposed by CSS media queries level 5. References:
- Media Features Privacy Model proposal from the now-defunct IndieUI User Context draft
- Action item 2239
- Media Queries Level 5
- Issue #3488. mediaqueries-5: Privacy considerations
- Christophe Strobbe's inventory of GPII common terms
- Niklas Schildhauer's presentation on MQ5 and personalization
Proposed media features
Feel free to extend the following table with use cases. For more detailed use cases, you may create new subpages.
| Media feature | Values | Use case | Operating systems setting |
|---|---|---|---|
| captionsEnabled | true, false | A video player in a webpage would automatically play captions. | Most operating systems have a setting for this |
| audioDescriptionEnabled | true, false | A video player in a webpage would automatically enable audio descriptions. If the player does not support this, an alternative video (with Audio description) would be loaded. | - |
| signLanguageEnabled | true, false | An alternative video (in sign language) would be loaded. | - |
| signLanguage | language tag conforming to IETF BCP 47 | A sign language video in the user's preferred language is chosen, if available. | - |
| pictogramsEnabled | true, false | A web page would would automatically add pictograms to support people with a reading disability or a general cognitive disability. | - |
| displaySkiplinks | always, onfocus, never | A skip-link would be automatically shown or suppressed. | - |
| tableOfContents | true, false | At the beginning of a page, a table of contents is shown as an additional means of navigation. | - |
| sessionTimeout | integer (seconds) | Determines how many seconds a user can remain inactive before a session times out. People with certain specific disabilities need longer session timeouts. This would serve a need in WCAG 2, SC 2.2.1 Timing Adjustable (A). | - |
| selfVoicingEnabled | true, false | Determines whether a Web application's self-voicing feature should be enabled. | - |
| (new media feature) | (values) | (use case) | (OS setting) |
| (new media feature) | (values) | (use case) | (OS setting) |
| (new media feature) | (values) | (use case) | (OS setting) |
Other use cases that would replace the need for a user style sheet
The following proposed "parameters" would require that a web author can reference their values in their code (e.g. CSS) rather than just switching based on their values.
- foregroundColor, backgroundColor (CSS color value). For many people, high contrast is not an optimal font change. Some people use color to minimize the impact of permanent floaters or scotomas (scars). Most users do not know how to create and enable a user style sheet in their browser.
- fontSize (integer). Not uniform, different sizes for different usage. SC 1.4.10 is a partial fix, but it is very useful to enlarge different elements by different factors. 1.4.10 only enables one zoom. Word wrapping is always essential.
- fontFamily. This is useful because different fonts have different critical print sizes. Sometimes if you cannot enlarge enough a font family shift will give you the edge you need.
- viewportWidth. Many people have a limited visual field. Rather than zooming to 320px width, they required reducing the viewport width to 320px. So, reduced width with normal font size is used.
- Layout. Users often need a new layout that does not look like the author's layout, but still keeps the reading order. This is a readjustment of visual layout similar to but not the same as the readjustment required for screen reader reading. Turning of positioning is very important. This has gotten a log harder with grids etc.
