Đang tải... (xem toàn văn)
Chapter 14 - Accessibility. The following will be discussed in this chapter: Web accessibility, web accessibility initiative, providing alternatives for multimedia content, accessibility in Microsoft Windows 2000, other accessibility tools.
Chapter 14, Accessibility Outline 14.1 14.2 14.3 14.4 14.5 14.6 Introduction Web Accessibility Web Accessibility Initiative Providing Alternatives for Multimedia Content 14.4.1 Readability 14.4.2 Using Voice Synthesis and Recognition with Voice XML Accessibility in Microsoft Windows 2000 14.5.1 Tools for VisuallyImpaired People 14.5.2 Tools for HearingImpaired People 14.5.3 Tools for Users Who Have Difficulty Using the Keyboard 14.5.4 Microsoft Narrator 14.5.5 Microsoft OnScreen Keyboard 14.5.6 Accessibility Features in Microsoft Internet Explorer 5.0 Other Accessibility Tools 2001 Prentice Hall, Inc. All rights reserved 14.1 Introduction • Persons with disabilities make up a significant portion of the population, and legal ramifications exist for Web sites that discriminate by not providing adequate and universal access to the site’s resources • In this chapter, we explore: – The Web Accessibility Initiative and its requirements – Various laws regarding businesses and their availability to people with disabilities – How some companies have developed their systems, products and services to meet the needs of this demographic 2001 Prentice Hall, Inc. All rights reserved 14.2 Web Accessibility • In 1999, a lawsuit was filed by the National Federation for the Blind (NFB) against AOL for not supplying access to its services to people with visual disabilities, a mandate of the Americans with Disabilities Act of 1990 • WeMedia.com is dedicated to providing disabled individuals with the same opportunities as the general population – Provides online educational opportunities for people with disabilities 2001 Prentice Hall, Inc. All rights reserved 14.2 Web Accessibility Ac t Purp o se Americans with Disabilities Act The ADA prohibits discrimination on the basis of disability in employment, state and local government, public accommodations, commercial facilities, transportation, and telecommunications. Telecommunications Act of 1996 The Telecommunications Act of 1996 contains two amendments to Section 255 and Section 251(a)(2) of the Communications Act of 1934. These amendments require that communication devices, such as cell phones, telephones and pagers, be accessible to individuals with disabilities. Individuals with Disabilities Educational materials in the school setting must be made accessible to children with Education Act of 1997 disabilities. Acts designed to protect access to the Internet for people with disabilities. 2001 Prentice Hall, Inc. All rights reserved 14.2 Web Accessibility We Media home page. (Courtesy of We Media Inc.) 2001 Prentice Hall, Inc. All rights reserved 14.2 Web Accessibility • The Internet has also enabled disabled individuals to work in a vast array of new fields – Prior to its advent, 25 percent of the 15 million Americans with disabilities found employment as a result of the Americans with Disabilities Act (ADA) – Technologies such as voice activation, visual enhancers and auditory aids afford disabled individuals with more work opportunities – Information provided through technology will have to be equally accessible to individuals with disabilities – Sites heavily laden with graphic images might have to simplify their appearance 2001 Prentice Hall, Inc. All rights reserved 14.3 Web Accessibility Initiative • On April 7, 1997, the World Wide Web Consortium (W3C) launched the Web Accessibility Initiative (WAI ) – An attempt to make the Web more accessible • Accessibility – Refers to the level of usability of an application or Web site for people with disabilities – The vast majority of Web sites are considered inaccessible to people with visual, learning or mobility impairments – A high level of accessibility is difficult to achieve 2001 Prentice Hall, Inc. All rights reserved 14.3 Web Accessibility Initiative • The Web Content Accessibility Guidelines 1.0 are divided into a threetier structure of checkpoints according to their priority – Priorityone checkpoints are those that must be met to ensure accessibility – Prioritytwo checkpoints, though not essential, are highly recommended – Prioritythree checkpoints improve accessibility slightly – The WAI also presents a supplemental list of quick tips— this list contains checkpoints aimed at solving priority one problems 2001 Prentice Hall, Inc. All rights reserved 14.4 Providing Alternatives for Multimedia Content • WAI requirement – Ensure that every image, movie and sound used on a Web page is accompanied by a description called an ALT tag that clearly defines its purpose • Intended to provide a short description of an HTML object which may not load properly on all user agents • Specialized user agents – An application that interprets Webpage source code and translates it into formatted text and images – Screen readers are programs that allow users to hear what is being displayed on their screen – Braille displays are devices that receive data from screen reading software and output the data as braille 2001 Prentice Hall, Inc. All rights reserved 14.4 Providing Alternatives for Multimedia Content – Web pages with large amounts of multimedia content are difficult for user agents to interpret, unless designed properly • Images, movies and other nonHTML objects cannot be read by screen readers – Provide multimediabased information in a variety of ways – Useragent technology is unable to make image maps accessible to blind people or others who cannot use a mouse • Include a link at the top of each Web page that provides easy access to the page’s content so users can use the link to bypass inaccessible elements 2001 Prentice Hall, Inc. All rights reserved 14.5.3 Tools for Users Who Have Difficulty Using the Keyboard Set Automatic Timeouts 2001 Prentice Hall, Inc. All rights reserved 14.5.4 Microsoft Narrator • Microsoft Narrator – A texttospeech program for visually impaired people – Reads text, describes the current desktop environment and alerts the user when certain Windows events occur – A screen reader that works with Internet Explorer, Wordpad, Notepad and most programs in the Control Panel • The Voice button enables the user to change the pitch, volume and speed of the narrator voice 2001 Prentice Hall, Inc. All rights reserved 14.5.4 Microsoft Narrator Narrator Window 2001 Prentice Hall, Inc. All rights reserved 14.5.4 Microsoft Narrator Narrator reading Notepad text 2001 Prentice Hall, Inc. All rights reserved 14.5.5 Microsoft OnScreen Keyboard • OnScreen Keyboard • Clicker 4 by Inclusive Technology – Developed as an aid for people who cannot effectively use a keyboard – Keys can have letters, numbers, entire words or even pictures on them 2001 Prentice Hall, Inc. All rights reserved 14.5.5 Microsoft OnScreen Keyboard Microsoft On-Screen Keyboard 2001 Prentice Hall, Inc. All rights reserved 14.5.6 Accessibility Features in Microsoft Internet Explorer 5.0 • The accessibility options in Microsoft Internet Explorer 5.0 augment the user’s Web browsing – Users are able to ignore Web colors, Web fonts and fontsize tags – Users can specify a style sheet that formats every Web site the user visits, according to that user’s personal preferences 2001 Prentice Hall, Inc. All rights reserved 14.5.6 Accessibility Features in Microsoft Internet Explorer 5.0 Microsoft Internet Explorer 5.0’s Accessibility options 2001 Prentice Hall, Inc. All rights reserved 14.5.6 Accessibility Features in Microsoft Internet Explorer 5.0 • Always expand ALT text for images – By default, Internet Explorer 5.0 hides some of the text, if it exceeds the size of the image it describes – Forces all of the text to be shown • Move system caret with focus/selection changes – Intended to make screen reading more effective – Some screen readers use the system caret (the blinking vertical bar associated with editing text) to decide what is read and if this option is not activated, screen readers may not read Web pages correctly • Allows the user to select text size 2001 Prentice Hall, Inc. All rights reserved 14.5.6 Accessibility Features in Microsoft Internet Explorer 5.0 Advanced accessibility settings in Microsoft Internet Explorer 5.0 2001 Prentice Hall, Inc. All rights reserved 14.5.6 Accessibility Features in Microsoft Internet Explorer 5.0 Accessing the Text Size menu in Microsoft Internet Explorer 5.0 2001 Prentice Hall, Inc. All rights reserved 14.6 Other Accessibility Tools • Software exists to help those with different types of disabilities • Braille keyboard – Similar to a standard keyboard except that in addition to letters on every key, it has the equivalent braille symbol – Most often, braille keyboards are combined with a speech synthesizer or a braille display, so users are able to interact with the computers and verify that their typing is correct – The development of speech synthesizers is also enabling other technologies, such as VoiceXML and AuralCSS to improve • Allow visually impaired people and those who cannot read to access Web sites 2001 Prentice Hall, Inc. All rights reserved 14.6 Other Accessibility Tools • Markup languages – Languages such as HTML and XML, designed to layout and link text files • Hearingimpaired Web users benefit from Synchronized Multimedia Integration Language (SMIL ) – Designed to add extra tracks—layers of content found within a single audio or video file • Products are also being designed to help severely handicapped persons – EagleEyes, developed by researchers at Boston College, is a system that recognizes a user’s eye movements and translates them to move the cursor 2001 Prentice Hall, Inc. All rights reserved 14.6 Other Accessibility Tools • CitXCorp – Developing technology that translates information over the Web through the telephone • Information on regulations governing the design of Web sites to accommodate people with disabilities can be found at www.accessboard gov • Adobe Acrobat and Adobe’s PDF – Will be manufactured to comply with Microsoft’s application programming interface (API), allowing businesses to reach a disabled audience • JetForm Corp. serverbased XML software – Allows users to download a format modified to best meet their needs 2001 Prentice Hall, Inc. All rights reserved 14.6 JAWS Feature • JAWS (Job Access With Sound) is a screen reader – Created by HenterJoyce, a division of Freedom Scientific and a company that tries to help visually impaired people use technology • The JAWS demo is fully functional and includes an extensive help menu that is highly customized – User can select which voice to utilize, the rate at which text is spoken and create keyboard shortcuts – JAWS also includes special key commands for popular programs, such as Microsoft Internet Explorer and Microsoft Word 2001 Prentice Hall, Inc. All rights reserved ... portion of the population, and legal ramifications exist for Web sites that discriminate by not providing adequate and universal access to the site’s resources • In this chapter, we explore: – The Web Accessibility Initiative and its requirements... 14.2 Web Accessibility • In 1999, a lawsuit was filed by the National Federation for the Blind (NFB) against AOL for not supplying access to its services to people with visual disabilities, a mandate of the Americans ... 2001 Prentice Hall, Inc. All rights reserved 14.5 Accessibility in Microsoft Windows 2000 • Since Microsoft Windows 95, Microsoft has included accessibility features in its operating systems and many of its applications • Accessibility