Accessible EPUB 3 Page 11
by Matt Garrish
Your current BMI is:
Writing the reader’s body mass index value to the embedded span will cause the whole text to be read. If you set the attribute to false (or omit it), only the prose in the element containing the text change gets announced. Using our last example, only the body mass index value in isolation would be announced.
You can further control this behavior by also attaching the aria-relevant attribute. This attribute allows you to specify, for example, that all node changes in the region should be announced, only new node additions, or only deletions (e.g., for including data feeds). It can also be set to only identify text changes. You can even combine values (the default is additions text).
We could use these attributes to set up a fictional author update box using an ordered list as follows:
What's the Author Saying…
- …
Only the new list items added for each incoming message will be read now. The old messages we pull out will disappear silently. (And I’ve also added a traditional link out for anyone who doesn’t have scripting enabled!)
There are also special roles that automatically identify a region as live. Instead of using the aria-live attribute to indicate our results field, we could have instead set up an alert region as follows:
The following roles are also treated as indicating live regions: marquee, log, status, and timer.
And that’s a quick run-through of how to ensure that all readers get alerted of changes you make to the content. It’s not a complicated process, but you need to remember to ensure that you set these regions otherwise a segment of your readers will not get your updates.
Note
My hope is these sections have given you an easy introduction to ARIA and the features it provides to make EPUB content accessible
For additional information, some good starting points include: the coverage given in Universal Design for Web Applications by Wendy Chisholm and Matt May (also an excellent guide to accessible Web content development); Gez Lemon’s introduction to creating rich applications; and, of course, the authoring practices guide that accompanies the ARIA specification.
A Blank Slate: Canvas
Another anticipated use for scripting is to automate the new HTML5 canvas element. This element provides an automatable surface for drawing on, whether it’s done by the content creator (games, animations, etc.) or the reader (drawing or writing surface), which is why I omitted tackling it with the rest of the semantics and structure elements.
Although a potentially interesting element to use in ebooks, at this time the canvas element remains largely a black hole to assistive technologies. A summary of the discussions that have been taking place to fix the accessibility problems as of writing is available on the Paciello Group website. Fixes for these accessibility issues will undoubtedly come in time, perhaps directly for the element or perhaps through WAI-ARIA, but it’s too soon to say.
So is the answer to avoid the element completely until the problems are solved? It would be nice if you could, but wouldn’t be realistic to expect of everyone. Using it judiciously would be a better course to steer.
For now including accessible alternatives is about all you can do. If you’re using the element to draw graphs and charts, you could add a description with the data using the aria-describedby attribute and the techniques we outlined while dealing with images. If you’re using the element for games and the like, consider the issues we detailed at the outset of the section in determining how much information to give.
With canvas, we really have to wait and see, unfortunately.
Chapter 4. Conclusion
EPUB 3 holds out much promise, but only if you care about the quality of your content and actively work to make it better. If I’ve done my job, though, accessibility is hopefully no longer a foreign concept or impossible-sounding ideal anymore. It’s fundamentally about high-quality data, with hooks in for people who can’t consume the content in its native format, whether auditory or visual.
The people you need to produce accessible EPUBs are not hard to find, either. Web content developers abound as the internet generation comes of age. And unlike in the early dark days of web accessibility, more and more people are learning WCAG and WAI-ARIA guidelines for accessible production. They’re not skills you can ignore as a developer, as so much basic accessibility legislation is premised on them now.
My point, however, is only that creating accessible EPUB 3 publications is not a costly proposition. It doesn’t require seeking out highly-specialized skills that won’t provide you a return on your investment. Reflowable web content is the direction publishing is heading in, and well down the road to.
But to wrap up, no guide can ever make you take action, only impart some measure of knowledge. Assuming I’ve met that threshold, the onus is now on you to take what you’ve learned and put it to good use.
EPUB 3 Best Practices Teaser
Accessible EPUB 3 is an excerpt of the book EPUB 3 Best Practices, currently in development for publication in 2012.
For more details and updates on its anticipated release date, keep an eye on the web page for the book:
http://shop.oreilly.com/product/0636920024897.do
Figure 4-1. EPUB 3 Best Practices, coming in 2012
About the Book
The new EPUB 3 specification from the IDPF incorporates a wide range of technologies and functionality that are set to revolutionize electronic publishing. The format is poised to make the static two-dimensional page a thing of the past, introducing the world to new rich multimedia reading experiences and scripted interactivity. But a specification that offers so much can be a daunting thing to learn.
EPUB 3 Best Practices steps in to help fill the knowledge void. Authored by people involved in the development of the specification, and with extensive experience in electronic publishing, this guide will provide you with a solid foundation on which to begin developing your own EPUBs. Topics covered include:
A comprehensive survey of accessible production features and best practices
A walkthrough of the new global language support features
An introduction to the new multimedia elements and how to use them to embed content
A guide to best practices for authoring of interactive elements and scripting
A review of publication and distribution metadata
Techniques for fixed and adaptive layouts
EPUB 3 Best Practices is a must-read for anyone looking to unleash the potential of the new format.
About the Author
Matt Garrish lives and works in Toronto where he does what he can to help bridge the print divide that sadly still keeps much of the world's literature and information from being available to everyone. He's worked closely with CNIB and the DAISY Consortium in their efforts to make the world a more accessible place — including editing the Z39.86 Authoring and Interchange specification — and drew on his years of experience ripping the guts out of EPUBs to make braille when invited to work as the editor of the EPUB3 revision. He is the author of "What is EPUB3?."