José Luis Fuertes / Loïc Martínez Normand Computer Science School. Technical University of Madrid.

Transcription

1 José Luis Fuertes / Loïc Martínez Normand Computer Science School. Technical University of Madrid. Specific facts of web design Web Accessibility The World Wide Web Consortium (W3C) and The Web Accessibility Initiative (WAI) Web Content Accessibility Guidelines 2.0 1

2 Web design is very different from paper design!! We cannot control the context of use: Device types User preferences Functional diversity of people Assistive technologies Limiting tasks Content and structure are essential!! 2

3 Screen Format Web Browser Internet explorer Firefox Size Resolution 800x x x 1600 Text size a a... Opera Safari Chrome Konkeror Lynx 3

4 News, information, commerce, entertainment, classroom education, distance learning, job searching, workplace interaction, civic participation, government services. Schools, libraries, print materials, discourse of the workplace, Some of the traditional resources were accessible; some not an unprecedented access to information for people with disabilities 4

5 Physic or sensorial impairments Cognitive or language impairments Disabling environments (noise, bad lights,...) Old or slow devices Modern devices Web accessibility is good for everyone!!! The power of the Web is in its universality. Access by everyone regardless of disability is an essential aspect Tim Berners-Lee 5

6 Created by Tim Berners-Lee in Europe (CERN) 1989: project Information Management: a proposal 1990: first browser + editor: WorldWideWeb 1993: CERN declares WWW to be free. Mosaic browser. 1994: First WWW conference Created in 1994 by Tim Berners-Lee (MIT) Hosts: MIT (USA), ERCIM (Europe), Keio University (Japan), Beihang University (China) Currently 389 members In addition: regional offices (19) 6

7 Goal: web accessibility Launched in 1997 Includes industry, disability organizations, research centres, government Protocols and Formats Developing Guidelines for Accessibility Evaluation and Repair Tools Education and Outreach Research and Development 7

8 How to make Web content accessible to people with disabilities WCAG 1.0: May 1999 WCAG 2.0: December 2008! Goals: (1) The tool should be accessible (2) It should produce accessible content by default (3) It should support and encourage the author in creating accessible content ATAG 1.0: February 2000 ATAG 2.0: latest draft (candidate recommendation) November 2013 Issues: (1) Accessibility of the user interface (2) Rendering of accessibility information (3) User control of the software UAAG 1.0: December 2002 UAAG 2.0: latest draft November

9 Web pages, web sites, web applications Web developers and designers, Authoring tool and evaluation tool developers, and Others who need a technical standard (not novices) 9

10 Guidelines (14) Checkpoints (65) Principles (4) Guidelines (12) Success criteria (61) Techniques & Failures (many) Information and user interface components must be presentable to users in ways they can perceive. They can't be invisible to all of their senses. User interface components and navigation must be operable by users. The interface can t require interaction that the user cannot perform. Information and the operation of the user interface must be understandable by users. The content or operation cannot be beyond their understanding. Content must be robust enough that it can be interpreted reliably by a wide variety of user agents, including assistive technologies. As technologies and user agents evolve, the content should remain accessible. 10

11 They can be automatically tested, or human evaluators should reach the same conclusions (80%) Current, future, non-w3c Adaptable, flexible for different situations, and developing technologies and techniques 2.2 Ensure that foreground and background color combinations provide sufficient contrast when viewed by someone having color deficits or when viewed on a black and white screen [P2 images P3 text] The visual presentation of text and images of text has a contrast ratio of at least 4.5:1 [Level AA]. Exceptions: Large text (3:1), Incidental, Logotypes. 11

12 WCAG 2.0 allows more movement, within defined parameters Scripting allowed! There are techniques for scripting (client and server) Ajax, DHTML WAI-ARIA The recommendation normative Principles, guidelines, success criteria informative Techniques Sufficient techniques, advisory techniques, failures General, HTML, CSS, Client-side Scripting, Server-side Scripting, SMIL, Plain text, ARIA, Flash (new), Silverlight (new), PDF (new) Understanding Provides rationale Quick Reference ( how to meet ) 12

13 José Luis Fuertes / Loïc Martínez Normand Computer Science School. Technical University of Madrid. 13