Transcript WCAG 2.0

OZeWAI – December 2007
WCAG 2.0
* based on Editor’s draft
May – November 2007
Dr Sofia Celic
then and now…
In 1999…
In 2007…
• HTML,
PDF (image),
Javascript (image swap)
• XHTML, CSS, Flash,
PDF (text, text alt),
Javascript (AJAX)
• Static, information
pages
• Dynamic, interactive, social
networking
• Desktop, laptop
• + phones, car, tv, fridge…
• IE, Netscape
• + Opera, Safari, Firefox…
• For accessibility…
stable and referenceable
document was… WCAG 1
• For accessibility…
stable and referenceable document
is…
WCAG 1 !
OZeWAI - Dec 2007
WCAG 1 & 2
WCAG 1
WCAG 2
• Principles
• Guidelines
• Guidelines
• Checkpoints
• Success Criteria
– Priority 1, 2, 3
• Conformance Level
A, AA, AAA
– Level A, AA, AAA
• Conformance Level
A, AA, AAA
OZeWAI - Dec 2007
WCAG 2.0 documents
• WCAG 2.0
–
–
–
–
principles (POUR)
technology neutral guidelines
testable success criteria
when in Recommendation status, can not be updated
• Understanding WCAG 2.0
– explanations
– can be updated
• Techniques for WCAG 2.0
– technology specific examples
– sufficient, advisory, failures
– can be updated
OZeWAI - Dec 2007
WCAG 2.0 Quick Ref
OZeWAI - Dec 2007
Layers of guidance
Principles  Guidelines  Success Criteria  Techniques
Principle 1: Perceivable - Information and user interface
components must be perceivable by users
Guideline 1.4 Distinguishable: Make it easier for users to
see and hear content including separating foreground
from background
Success Criteria: Use of colour; Minimum colour contrast;
Enhanced colour contrast; User audio control; Low or no
background audio; Text resize; Visual presentation
& Images of text.
Techniques
OZeWAI - Dec 2007
The Principles
1. Perceivable
Information and user interface components must be
perceivable by users.
2. Operable
User interface components must be operable by users.
3. Understandable
Information and operation of user interface must be
understandable by users.
4. Robust
Content must be robust enough that it can be interpreted
reliably by a wide variety of user agents, including assistive
technologies.
OZeWAI - Dec 2007
Technology neutral
WCAG 1 – Checkpoint 3.4
Use relative rather than absolute units in markup language
attribute values and style sheet property values.
WCAG 2 – Success Criterion 1.4.4
Resize text: Text (but not images of text) can be resized
without assistive technology up to 200 percent without loss of
content or functionality.
OZeWAI - Dec 2007
WCAG 2 – Success Criterion 1.4.4 [Resize text]
Sufficient Technique example
•
Ensuring that text containers resize when the text
resizes AND using measurements that are relative
to other measurements in the content by using one
or more of the following techniques:
– Techniques for relative measurements
•
•
•
C12: Using percent for font sizes (CSS)
C13: Using named font sizes (CSS)
C14: Using em units for font sizes (CSS)
– Techniques for text container resizing
•
•
Calculating size and position in a way that scales with text size
(Scripting)
G146: Using liquid layout
OZeWAI - Dec 2007
Testable
WCAG 1 - Checkpoint 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.
WCAG 2 – Success Criterion 1.4.3
Contrast (Minimum): Text and images of text have a contrast
ratio of at least 5:1, except for the following:
• Larger-scale with contrast ratio ≥ 3:1
• inactive component, pure decoration, incidental or not visible
to anyone.
(rephrased)
OZeWAI - Dec 2007
SC Levels
All levels
– important access issues for people with disabilities
– testable
A or AA or AAA
–
–
–
–
–
essential (even assistive technology can't make it accessible)
applicable to all Web sites and types of content
skills that could reasonably be achieved by authors
limitations on the "look & feel" and/or function
workarounds
OZeWAI - Dec 2007
Will it be enough?
Usability
“There are many general usability guidelines that
make content more usable by all people, including
those with disabilities. However, in WCAG 2.0, we
only include those guidelines that address problems
particular to people with disabilities.”
For example: form controls
Advisory techniques
“Changing the background color or border of the element
with focus.”
“Starting section headings with unique information”
OZeWAI - Dec 2007
Will it be enough?
Testable
“otherwise it would not be possible to determine
whether a page met or failed to meet the success
criteria”
Example Advisory technique that is testable:
“Avoiding fully justified text”
Example Success Criteria that are less testable:
“Web pages have descriptive titles.”
“Labels and headings are descriptive. ”
OZeWAI - Dec 2007
VA’s major user group
Low vision users – font size; colour combinations
Images of *important* text are allowed in WCAG 2.0
at Level A… and sometimes AA & AAA.
Images must be “not loaded” in graphical browsers to
access the text alternatives
(to be able to apply the required visual aspects).
Are there problems with this?
OZeWAI - Dec 2007
Images off
OZeWAI - Dec 2007
Images off
OZeWAI - Dec 2007
Images off
OZeWAI - Dec 2007
Image maps
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VA’s major user group
Low vision users – font size; colour combinations
 May need to use a screen reader for Level A sites
because image text alternatives may overlap with
other text in the web page or be cropped.
To include users who do not use a third-party assistive
technology…
 Level AA is a minimum conformance target.
OZeWAI - Dec 2007
Will it be enough?
WCAG 2.0 sufficient techniques
plus
• advisory techniques
• usability guidelines
• guidelines for cognitive & learning disabilities
• multi-modal
• validity
• others?
OZeWAI - Dec 2007
Terminology
Baseline is now:
Accessibility-supported technologies
– must be supported by users' assistive technology
(tested for interoperability)
– must have accessibility-supported user agents that are
available to users
(widely distributed; closed environment; equally avail to all)
Web units is now:
Web pages
OZeWAI - Dec 2007
Conformance
• Conformance Level
– A, AA or AAA in full
– or conforming alternate version is provided
• Applies to full Web pages
– Parts of web pages can not be excluded
• Rely only on accessibility supported technologies
– Does not prohibit non-accessibility supported technologies
• All web pages within a process must conform
– Or none can claim conformance
• Non-interference to access
– By non-accessibility supported technologies or accessibility
supported technologies used in a non-conforming way
OZeWAI - Dec 2007
steps
• Last Call
• Candidate Recommendation
– Implementations
• Proposed Recommendation
– Endorsements
• W3C Recommendation
OZeWAI - Dec 2007
Closure…
WCAG 2.0
•
More generic
•
More testable
•
Doesn’t claim to meet everyone’s need
•
May need to be supplemented with other
guidelines/standards/advisory techniques
•
User testing is still important
Understand your users, the technologies, and where
these guidelines fit into the toolbox.
OZeWAI - Dec 2007
WCAG 2 draft
Thank you!
Questions?
[email protected]
OZeWAI - Dec 2007