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

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

• New Features in hardware / OS

• Accessibility Aids

• Specialized applications

• Usability features in applications

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 in accessible format such as ASCII text or HTML

• 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., 5 May 1999. W3C Recommendation: http://www.w3.org/TR/1999/WAI-WEBCONTENT-19990505

• “User Agent Accessibility Guidelines", J. Gunderson and I. Jacobs, eds., 28 July 2000. W3C Working Draft:

http://www.w3.org/TR/2000/WD-UAAG10-20001023

Color blindness

• 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

Motor Disabilities• include weakness, limitations of muscular control , limitations of

sensation, joint problems, or missing limbs.

• To use the Web, people with motor disabilities affecting the hands or arms may use

– a specialized mouse;

– a keyboard with a layout of keys that matches their range of hand motion;

– a pointing device such as a head-mouse, head-pointer or mouth-stick; an eye-gaze system;

– voice-recognition software;

• They may activate commands by typing single keystrokes in sequence with a head pointer rather than typing simultaneous keystrokes ("chording") to activate commands.

• may need more time when filling out interactive forms on Web sites

Motor Disabilities – WWW Barriers

• time-limited response options on Web pages

• browsers and authoring tools that do not support keyboard alternatives for mouse commands

• forms that cannot be tabbed through in a logical order (Note: "Tabindex" solution not yet well supported in browsers.)

Repetitive Stress – Carpal Tunnel

• Voice input allows less use of mouse and typing– Problem: WWW sites with streaming audio

conflict with speech recognition

• Alternative keyboard• Using access keys for shortcuts

• Problem: authoring tool accessibility

Hearing Impairment - Deafness

• To use the Web, many people who are deaf rely on captions for audio content.

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

Hearing Impaired

• Some WWW pages have audio that is important part of the content (e.g. university with online audio lessons)

• Making multimedia accessible

Visual Impairment - Blindness• To access the Web, many rely on screen

readers – – outputs this information to a speech synthesizer

and/or

– refreshable braille display.

• Some use text-based browsers such as Lynx, or voice browsers,

• may use rapid navigation strategies such as tabbing through the headings or links on Web pages

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 labelled

• 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

HTML Tables• Problem: Tables can be hard to read for screen readers• you should use the HTML TABLE element and its supporting

elements and attributes (like TR, TD, TH and CAPTION).• A simple data table created with proper data table mark up,

might look like this:

Column 1 Header Column 2 Header

Row 1 Header Column 1 Row 1 Column 2 Row 1

Row 2 Header Column 1 Row 2 Column 2 Row 2

HTML Table

• <TABLE border=1>

• <CAPTION>Example of a simple data table created using HTML markup.</CAPTION>

• <TR><TD></TD><TH>Column 1 header</TH>

• <TH>Column 2 header</TH></TR>

• <TR><TH>Row 1 header</TH>

• <TD>Column 1 Row 1</TD>

• <TD>Column 2 Row 1</TD></TR>

• <TR><TH>Row 2 header</TH>

• <TD>Column 1 Row 2</TD>

• <TD>Column 2 Row 2</TD></TR>

• </TABLE>

HTML for Better Reading • HTML 4.0 also allows you to explicitly link header information to columns and

rows using the "headers" attribute of the <TD> and <TH> elements, e.g.:

• Cups of coffee consumed by each senator

Name Cups Type of Coffee Sugar

T Sexton 10 Expresso No

J. Dinnen 5 Decaf Yes

•If you use the 'headers' attribute, a browser or screen reader might be able to expose or read the contents of the cells (if the user wishes) like this:

•Name: T. Sexton, Cups: 10, Type: Espresso, Sugar: NoName: J. Dinnen, Cups: 5, Type: Decaf, Sugar: Yes

•because each datum is explicitly associated with its appropriate header.

View the markup code that would generate this example

• <TR>

• <TH id="t1">Name</TH>

• <TH id="t2">Cups</TH>

• <TH id="t3" abbr="Type">Type of Coffee</TH>

• <TH id="t4">Sugar?</TH>

• </TR>

• <TR>

• <TD headers="t1">T. Sexton</TD>

• <TD headers="t2">10</TD>

• <TD headers="t3">Espresso</TD>

• <TD headers="t4">No</TD>

• </TR>

• <TR>

• <TD headers="t1">J. Dinnen</TD>

• <TD headers="t2">5</TD>

• <TD headers="t3">Decaf</TD>

• <TD headers="t4">Yes</TD>

• </TR>

More Visual Impairment

• Abbreviations in documents make reading them aloud hard for a mere program– Expanding abbreviations and acronyms

When in Boston, be sure to visit the

<ACRONYM TITLE="Museum of Fine Arts">MFA</ACRONYM>,

<ACRONYM TITLE="Massachusetts Institute of Technology">MIT</ACRONYM> and, of course, the <ACRONYM TITLE="World Wide Web Consortium">W3C</ACRONYM>. These destinations are easily reached via <ABBR TITLE="Massachusetts Avenue">Mass. Ave.</ABBR>

or <ABBR TITLE="Memorial Drive">Mem. Dr.</ABBR>.

More Visual Impairment

• The WWW is full of visual info, graphics, multimedia

Visual Impairment – Low Vision• There are many types of low vision

• To use the Web, some people use extra-large monitors, and

• increase the size of system fonts and images.

• Others use screen magnifiers

• Some use bright contrast

• or choose typefaces is legible given their condition

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

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/swreferences.html- 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