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The ARIA Technology Stack: Browsers and Screen Readers

The ARIA Technology Stack: Browsers and Screen Readers. Jonathan Avila Bryan Garaventa. About SSB BART Group. Unmatched Experience Accessibility Focus Implementation-Oriented Solutions Solutions That Reduce Legal Risk Organizational Stability and Continuity

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The ARIA Technology Stack: Browsers and Screen Readers

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  1. The ARIA Technology Stack: Browsers and Screen Readers Jonathan AvilaBryan Garaventa

  2. About SSB BART Group • Unmatched Experience • Accessibility Focus • Implementation-Oriented Solutions • Solutions That Reduce Legal Risk • Organizational Stability and Continuity • Knowledge That Is Up-to-Date, All the Time • Published and Peer Review Auditing Methodology • Fourteen hundred organizations(1445) • Fifteen hundred individual accessibility best practices (1595) • Twenty-two core technology platforms (22) • Fifty-five thousand audits (55,930) • One hundred fifty million accessibility violations (152,351,725) • Three hundred sixty-six thousand human validated accessibility violations (366,096)

  3. Agenda • About SSB BART Group • ARIA • DOM and Accessibility APIs • Screen Reader View • ARIA Examples and Best Practices • References

  4. ARIA • Overview • Accessible Rich Internet Applications Specification (ARIA) • Proposed recommendation of the W3C • ARIA is a set of attributes added to markup such as HTML • <div id="s1" role="progressbar" aria-valuenow="50" aria-valuemin="0" aria-valuemax="100" aria-valuetext="100 percent"/> • HTML5 doctype supports ARIA as valid • Use native semantics whenever possible • Use progressive enhancement • Does not change appearance of the web page • Focuses on access by screen readers • Will change screen reader behavior for better or worse

  5. ARIA • Provide support to users of assistive technology in three main areas that were not previously addressed by (X)HTML: • Indication of main structural areas of a page • Creation of roles and properties of rich user interface elements • e.g. custom controls such as ones that use JavaScript, AJAX, etc. • Method to indicate alerts, page changes, and dynamically updating information • Support by browsers and AT is not consistent • Overview (cont.)

  6. ARIA • Common Assistive Technology with Support for ARIA Screen reader Support • JAWS for Windows 10+ (most common screen reader) • Best support in IE • Non-visual Display Access 2012+ (NVDA) – open source • Best support in Firefox • Window-Eyes 8.0+ • VoiceOver (Mac OS 10.5+ and iOS 4+) Other AT support • Speech recognition – little or no support • Screen magnification – some limited support

  7. ARIA • Browser Support of ARIA Browsers • Internet Explorer 8+ (Windows) • Firefox 3+ (Windows, Linux, Mac, Android) • Chrome (Windows, Mac, Android) • Safari 4+ (Mac OS and iOS) ARIA roles and properties are translated into platform level accessibility APIs by the browser

  8. ARIA • Supported by many JavaScript frameworks • JQuery UI • Dojo/Dijit • GWT • Yahoo UI • Others • Support levels are different and have limitations • AccDC – Accessibility API • Framework Support

  9. DOM and Accessibility APis Two ways AT obtains information and give commands • Document Object Model (DOM) • Applications programming interface (API) Note:Both ways are used simultaneously as neither may be complete enough • Overview

  10. DOM and Accessibility APIs • DOM • HTML structure tree with nodes representing elements and text • Attributes (properties of objects) • Events (actions, e.g. click, keypress, onload, etc.) • Associated styles (CSS) for rendering content

  11. DOM and Accessibility APIs • Accessibility APIs • Applications Programming Interface (API) • Interface for programs to communicate with others • Accessible browsers implement one ore more accessibility API (AAPI) that is built into the browser • May be tied into the operating system or platform • Accessibility API • Translates DOM and ARIA properties and events into API properties and events • Exposes public Properties, Methods, and Events • These can be queried or set by screen readers, to retrieve information

  12. DOM and Accessibility APIs • Browser AT Interaction Process AT View Assistive Technology BrowserView User APIs BrowserControls DOM

  13. DOM and Accessibility APIs • Browser Support of APIs • There are different accessibility APIs • Browsers render ARIA roles and properties to platform level AAPIs including platform level events • MSAA (Firefox and IE) • UI Automation (IE, some FF) • iAccessible2 (Firefox) • ATK/AT-SPI (Linux) • AT requires different techniques for accessing the browser’s API and DOM • Not consistent across browsers

  14. Screen Reader View • Overview • Generates a virtual representation (document) of the page elements • Place links, buttons, form fields, etc. on a line by themselves • Appends or prepends the role in the text of the document • Contains a "forms/focus" mode and a "virtual/browse" view mode • Allows dual use of keystrokes such as arrows and letter to navigate virtual documents • Allows support for interactive controls such as input fields • May automatically go into this interactivity mode

  15. Screen Reader View Example Visited linkNeed Help? Register: Complete all fields in the form. Name Name Edit E-mail Email Edit Register Button

  16. Screen Reader View • Dynamic Content • Virtual view is copy (cache) of page • screen readers have become very good about watching for DOM changes to update view • users shouldn’t end up with stale page content when ARIA and proper DOM techniques are used

  17. Screen Reader View • Keystroke Interaction What happens when a key is pressed

  18. ARIA Examples and Best Practices • Code Example • API name, role, state, or value are updated by ARIA markup • <button> Yes </button> -> MSAA role of PUSHBUTTON • <div> Yes </div> -> MSAA role of DIV • <div role="button“ tabindex=“0” onclick=“...” onkeyup=“...”> Yes </div> -> MSAA role of PUSHBUTTON • Virtual view last items above with screen reader • Yes Button

  19. ARIA Examples and Best Practices • Element Behaviors • ARIA only changes information in the browser’s accessibility API • In browser, e.g. the element is still a div and appears as a div in the DOM • includes all native div event handlers • does not visually change • Developers must implement keyboard and mouse events • onclick, onkeyup • May need to implement focus order, indication of focus • Tabindex=0, CSS outline property

  20. ARIA Examples and Best Practices • Best Practices • Use native HTML elements whenever possible • Implement keyboard accessibility for all users • Ensure it still works however with screen readers • Use of ARIA does not take away the need to design accessible content • e.g. content must still be visually discernible without color • Follow the ARIA specification for each component type • Avoid ARIA hacks to make something work with a particular AT or browser • Placement of ARIA markup on ancestors or descendants may affect support

  21. ARIA Example and Best Practices • Use of certain ARIA roles such as “dialog” or “application” has substantial consequences • Use of aria-labelledby with multiple labels in IE requires tabindex="-1" on each label • Accessible name calculation • If the control has an aria-label or an aria-labelledby attribute the accessible name is to be calculated using the algorithm defined in section 5.2.7. Accessible Name Calculation of the WAI-ARIA 1.0 specification. • role="presentation“ – obscure the meaning of the element • aria-hidden – hide content from AT; keep on screen • Best Practices (cont.)

  22. ARIA Example and Best Practices APIs • Microsoft Inspect – MSAA and UI Automation testing tools • Properties • Tree structure • Microsoft AccEvent – Accessibility event watcher • AccProbe – Multi-platform accessibility API inspection DOM • Firebug Toolbar • AMP Toolbar for Firefox • IE Developer Toolbar • Accessibility Favlets • Testing Tools

  23. References • Object Inspector and other MSAA tools https://www.ssbbartgroup.com/blog/2010/11/08/looking-for-object-inspector-and-other-msaa-tools/ • 2014 WebAIMScreen Reader Usage Surveyhttp://webaim.org/projects/screenreadersurvey5/ • Why keyboard accessibility isn’t the same thing as screen reader accessibility: http://lnkd.in/jYnkZq • Microsoft Active Accessibility (MSAA) http://en.wikipedia.org/wiki/Microsoft_Active_Accessibility • Basic HTML5, ARIA, and Screen Readers http://www.accessibleculture.org/research-files/ozewai2011/basic-html5-aria-screenreaders-presentation.html#(1)

  24. References • ARIA Specification http://www.w3.org/TR/wai-aria/ • ARIA Roles Model http://www.w3.org/TR/wai-aria/roles • ARIA User Agent Implementation http://www.w3.org/TR/wai-aria-implementation/ • HTML to platform level accessibility API http://www.w3.org/TR/2013/WD-html-aapi-20131001/ • Native HTML Semantics (HTML5 content model) http://dev.w3.org/html5/spec-LC/content-models.html

  25. Questions?

  26. Thank You Contact Us Jonathan Avila Chief Accessibility Officer jon.avila@ssbbartgroup.com Bryan Garaventa Senior Accessibility Engineer bryan.garaventa@ssbbartgroup.com SSB Contact Information info@ssbbartgroup.com (800) 889-9659 Follow Us Twitter @SSBBARTGroup LinkedIn www.linkedin.com/company/ssb-bart-group Facebook www.facebook.com/ssbbartgroup Blog www.ssbbartgroup.com/blog

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