Accessibility: Difference between revisions
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: Users of non-visual browsers cannot see images. They can read the <code>alt</code> tags of normal images, but background images are not presented like normal images. | : Users of non-visual browsers cannot see images. They can read the <code>alt</code> tags of normal images, but background images are not presented like normal images. | ||
; Image <code>alt</code> and <code>title</code> attributes should differ | ; Image <code>alt</code> and <code>title</code> attributes should differ | ||
: An image <code>alt</code> tag provides a text equivalent to an image, whereas a <code>title</code> attribute adds supplementary information about the purpose or action associated with an image. Simply repeating the same text in <code>alt</code> and <code>title</code> attributes adds little and can be annoying for screen reader users. | : An image <code>alt</code> tag provides a text equivalent to an image, whereas a <code>title</code> attribute adds supplementary information about the purpose or action associated with an image link. Simply repeating the same text in <code>alt</code> and <code>title</code> attributes adds little and can be annoying for screen reader users. | ||
; Support dynamic interaction with [[ARIA]] attributes | ; Support dynamic interaction with [[ARIA]] attributes | ||
: Events triggered by AJAX and JavaScript can be less obvious to users of non-visual browsers. [[ARIA]] attributes can assist users of such browsers to follow a dynamic change. | : Events triggered by AJAX and JavaScript can be less obvious to users of non-visual browsers. [[ARIA]] attributes can assist users of such browsers to follow a dynamic change. |
Revision as of 02:03, 19 October 2012
Websites built with accessibility in mind are flexible in meeting different user needs, preferences and situations. Though these methods can increase usability for everyone who uses the Web they are often legally required to be implemented in a specific effort to prevent discrimination against people with disabilities.
Starting points
These are some readable introductions to accessibility that cover; what accessibility is, why it is important, as well as practical advice.
- Web Accessibility Initiative's Introduction to Web Accessibility
- Mark Pilgrim's Dive into Accessibility
- Joe Clark's Building Accessible Websites book
- Use CSS, but still use headings, strong and emphasis
- It is generally a good idea to separate a document's content HTML from how it is presented using CSS. There are some tags that affect a document's presentation but also contribute to the structure and meaning of the content. These tags should remain in HTML. This includes heading tags
<h1>, <h2>, <h3>...
, which are used to form the document's hierarchical structure, and<strong>
and<em>
tags, which are used to add meaning to sections of text. - Avoid using background images for important information
- Users of non-visual browsers cannot see images. They can read the
alt
tags of normal images, but background images are not presented like normal images. - Image
alt
andtitle
attributes should differ - An image
alt
tag provides a text equivalent to an image, whereas atitle
attribute adds supplementary information about the purpose or action associated with an image link. Simply repeating the same text inalt
andtitle
attributes adds little and can be annoying for screen reader users. - Support dynamic interaction with ARIA attributes
- Events triggered by AJAX and JavaScript can be less obvious to users of non-visual browsers. ARIA attributes can assist users of such browsers to follow a dynamic change.
- Use labels with inputs
- Context can easily be lost without a visual presentation. Labels are needed on all input input elements (except button) to describe their purpose in a form. Labels should be unique on a page. Repeated elements should have a unique label that identifies the element within its context.
- Use appropriate page titles
- A page title is a starting point for a screen reader. Page titles should be unique and should make sense for the page. Avoid generic page titles.
- All pages should be navigable using just a keyboard
- It should be possible navigate to all points on a page just using a keyboard. Important events triggered by a mouse event should be able to be triggered when the item receives focus through keyboard navigation.
Web standards, guidelines and legislation
International
- Web Accessibility Initiative
- Web Content Accessibility Guidelines (WCAG)
- Web Content Accessibility Guidelines 2.0 (draft)
- An article on the problems with WCAG2 from A List Apart
USA
UK
Germany
Tools
Firefox extensions
- Firefox Accessibility Extension by the Illinois Center for Information Technology and Web Accessibility (iCITA)
- Web developer extension for Firefox
- Blank Your Monitor and Easy Reading Extension for Firefox
- plugin for Firebug
- contrast plugin for Firefox
Accessibility validation tools
- W3C validation (for HTML in Moodle, CSS and RSS)
- Web accessibility evaluation tool
- Cynthia Says accessibility checker
Screen readers
- Fangs – the screen reader emulator for Firefox
- NVDA NonVisual Desktop Access - open source screen reader for Windows
See also this long list of accessibility tools.
Resources
- Web Standards.org's Accessibility Task Force Manifesto
- Accessibility articles from A List Apart
- Mark Pilgrim's Won’t somebody please think of the gerbils?
- Dive Into Accessibility by Mark Pilgrim
- Building Accessible Websites by Joe Clark (online version)
- Wikipedia article on Web Accessibility
- Validity and Accessibility
- Videos showing as student accessing another Learning Management System via Screen Reader software
See also
- Semantic HTML
- Accessibility forum on Moodle.org
- Using Moodle New Accessibility Themes forum discussion
- See en:Usability FAQ for the related concept of usability.
- en:Moodle Accessibility Specification
- http://moodle.org/mod/forum/discuss.php?d=127807#p559951
- The Introduction to Moodle Programming provides some extensive information and discussion on accessibility.
- EASY: Interface Between The Virtual Environment Moodle Learning and People with Visual Impairments
- BBC blog post on how their Web 2.0 homepage was made accessible
- BBC Accessibility Help
- Accessibility Compliance in Moodle 1.8
- Compliance with Italian Legislation on Accessibility