Accessible Software Design

Taken from several sources

Users With Disabilities

• Sight• Hearing• Mobility• Cognitive • Language impairment• Seizure disorders• Speech impairments

Why Worry About It?

• Profits• Americans With Disabilities Act• Rehabilitation Act• Legislation elsewhere• It is part of ANSI and ISO standards for

usability• Moral High Road

Keys to Accessibility

• Minimize barriers

• Provide compatibility with accessibility utilities– Screen readers

– Voice input

– Others

Accessibility in the Lifecycle• Plan early to accommodate

• Include people with disabilities in feedback process– requirements determination

– usability testing

– Beta testing

• Ensure developers are familiar with accessibility guidelines

• Ensure test team can recognize accessibility problems

• Ensure technical support and customer service have access to accessible environments

How Computers can Become Accessible

• Features in hardware / OS

• Accessibility Aids

• Specialized applications

• Usability features in applications – – Allow Customization

– Follow standard conventions

– Use standard controls

Accessibility Aids

• Require cooperation from application program

• Screen enlargement utilities• Screen readers• Voice input utilities• On screen keyboards• Keyboard filters

Some Basic Principles

• Flexibility

• Choice of input methods

• Choice of output modalities

• Compatibility with accessibility aids

• Consistency

Keyboard Access is Key

• Blind people cannot maneuver a mouse

• Provide keyboard access to all features

• Fully document keyboard interface

• Model keyboard interface on known interfaces

• Allow users to select text using keyboard

• If possible, provide customizable keyboard shortcuts

• Make sure dialog boxes define the correct tab order

Play Nice for Accessibility Aids• If, for example, an accessibility aid is going to verbalize

visual info, they need things to be named and labeled meaningfully– Ensure that every window, object, and graphic is named

appropriately

– Define correct text labels for all controls

– Give every window a user-friendly caption

– Expose names or descriptions for all images

• Expose your elements to the accessibility software

Color• Color is an issue for color blind, and visually

impaired

• Use only colors that user can customize – in control panel

• Use proper foreground / background combinations

• No background images behind text

• Avoid conveying important info via color alone

• Give good contrast of images to background

• Allow MS “High Contrast Option”

Size

• Of importance to visually impaired• Allow the user to select font and font

sizes for displayed info • If feasible, provide draft mode, zoom,

and wrap to window features• Allow the user to adjust size of non-

document elements – such as toolbars• Make sure application is compatible with

changes to system font

Sound

• Good for visually impaired, bad for hearing impaired

• Define Sound Schemes– Allow substitution of visual for sound

– Allow substitution of sound for visual

• Provide a way to turn off sounds

Timings

• Of importance to visually impaired and cognitively impaired

• Allow user to customize any interface timings

• Allow the user to avoid having messages time out

• Flashing can cause seizures – allow slowing down or disabling any rapid screen updates or flashing

Good Layout is Even More Important

• Things that help regular users understand what to do are even more important for visually or cognitively impaired people

• Text labels immediately to left of or above control

• Not ambiguous which of the above

• Text labels end with : (text not requiring input, no : )

• Icons identified with text below, to right, or in tool tip

• Position related objects near each other

Documentation

• Provide documentation on all accessible features

• Provide documentation in accessible format such as ASCII text or HTML (or Braille)

• Include descriptions of any illustrations and tables

• Do not convey important information via color or graphics alone

• Keep high contrast between text and background

• Do not use text smaller than 10 pt

• If possible, bind printed documentation to lie flat

Verifying Accessibility• Test against guidelines discussed here

• Test compatibility with extra large appearance schemes

• Verify that all features can be used without a mouse

• Verify that all keyboard access methods are documented

• If MS, test use with accessibility tools/options

• Test with commercial accessibility aids

• Include people with disabilities and accessibility software vendors in beta tests

• Distribute free evaluation copies to individuals with disabilities, disability organizations, and accessibility software vendors

• Include people with disabilities in your usability tests

• Conduct surveys of your users with disabilities

Anything Special About the Web?

• Resources – Web Accessibility Initiative (WAI) – http://www.w3.org/WAI • "Web Content Accessibility Guidelines 1.0", G. Vanderheiden,

W. Chisholm, and I. Jacobs, eds., May 1999. W3C Recommendation: http://www.w3.org/TR/WAI-WEBCONTENT

• “User Agent Accessibility Guidelines", J. Gunderson and I. Jacobs and E. Hansen, eds., October 2000. W3C Working Draft: http://www.w3.org/TR/2000/WD-UAAG10-20001023

Web Page Accessibility Design• Provide a “skip to main content” link at the top of each

page

• Structure articles with 2 or 3 levels of headings

• For all images, provide associated text

• For all audio content, include at least one of:– Caption or pop-up text window

– Textual transcript

– Textual description

• For all video content, include (audio AND text) at least one of:– transcript

– description

Web Page Accessibility Design• For image maps, provide equivalent text menus

• Provide alternative ways to access items contained within tables

• For online forms that cannot be read by screen utilities, provide alternative methods of communication

• Provide an option to display animation in a non-animated presentation mode

• If accessibility is otherwise impossible, provide a text-only page with equivalent info and functionality

• Follow the standards set by the WWWC for accessibility of Web content

Visual Disabilities Summary• Utilities

– Ensure compatibility with screen-reader utilities

– Ensure compatibility with screen-enlargement utilities

• Screen components– Include meaningful screen and window titles

– Provide associated captions or labels for all controls, objects, icons, and graphics – including graphical menu choices

– Provide a textual summary for each graphic – including graphs

– Allow for screen element scalability

– Support system settings for high contrast

– Avoid displaying or hiding info based on movement of cursor

Visual Disabilities Summary

• Keyboard– Provide a complete keyboard interface

– Provide a logical order of screen navigation

• Color– Use color as a supplemental or enhancing design

characteristic

– Provide a variety of color selections with a range of contrast levels

• Create color combinations based on system colors for the components

• Do not define specific colors

Blindness - WWW Barriers• images that do not have alt text

• complex images (e.g., graphs or charts) that are not adequately described

• video that is not described in text or audio

• tables that do not make sense when read serially (in a cell-by-cell or "linearized" mode)

• frames that do not have "NOFRAME" alternatives, or that do not have meaningful names

• forms that cannot be tabbed through in a logical sequence or that are poorly labeled

• browsers and authoring tools that lack keyboard support for all commands

• browsers and authoring tools that do not use standard applications programmer interfaces for the operating system they are based in

• non-standard document formats that may be difficult for their screen reader to interpret

Low Vision – WWW Barriers

• Web pages with absolute font sizes that do not change (enlarge or reduce) easily

• Web pages that, because of inconsistent layout, are difficult to navigate when enlarged, due to loss of surrounding context

• Web pages, or images on Web pages, that have poor contrast, and whose contrast cannot be easily changed through user override of author style sheets

• imaged text that cannot be re-wrapped

• also many of the barriers listed for blindness, above, depending on the type and extent of visual limitation

Color blindness - WWW

• Color blind online shoppers may not pick up sale prices – the red doesn’t stand out

• Controlling presentation with style sheets

• User override of author style sheets

Color Blindness – WWW Barriers

• color that is used as a unique marker to emphasize text on a Web site

• text that inadequately contrasts with background color or patterns

• browsers that do not support user override of authors' style sheets

Hearing Disabilities Summary

• Provide captions or transcripts of important audio content

• Provide an option to display a visual cue for all audio alerts

• Provide an option to adjust the volume

• Use audio as an enhancing design characteristic

• Provide a spell-check or grammar check utility

Deafness – WWW Barriers

• lack of captions or transcripts of audio on the Web

• lack of content-related images in pages full of text, which can slow comprehension for people whose first language may be a sign language instead of a written/spoken language

• Any requirements for voice input on Web sites

Physical Movement Disabilities Summary

• include weakness, limitations of muscular control , limitations of sensation, joint problems, or missing limbs.

• Provide voice-input systems

• Provide a complete and simple keyboard interface

• Provide a simple mouse interface

• Provide on-screen keyboards

• Provide keyboard filters

Speech or Language Disabilities Summary

• Provide a spell-check or grammar-check utility

• Limit the use of time-based interfaces– Never briefly display critical feedback or

messages and then automatically remove them

– Provide the user an option to adjust the length of a time out

Resources - Corporate

• Microsoft– User Oriented - http://www.microsoft.com/enable/

– Developer Oriented - http://msdn.microsoft.com/library/default.asp?url=/nhp/Default.asp?contentid=28000544

• http://www-3.ibm.com/able/ - links from IBM

Resources - Organizations

• ACM SIGCAPH – Special Interest Group on Computers and the Physically Handicapped - http://www.acm.org/sigcaph/

• www.rit.edu/~easi/access.htm - Equal Access to Software and Information

• trace.wisc.edu/world/computer_access – Designing More Usable Computers and Software

Resources - WWW

• aware.hwg.org/tips - Tips and Techniques for Accessible Web Authoring

• nadc.ucla.edu/dawpi.htm - Web Access resource list

Resources - Government

• www.access-board.gov/sec508/508standards.htm

Resources - Evaluation

• www.cast.org/bobby - www site which will (partially) evaluate a www page for accessibility

End Accessibility