I thought I’d give an overview of some of the accessibility features we included in the first demo release of ButtercupReader.

Web Standards and Accessibility

One of the interesting aspects of this project is that, while we have built a highly accessible application, it does not comply with New Zealand Government Web Standards (nor, I suspect, with any other country’s guidelines).

In New Zealand, like other countries, we have a set of accessibility guidelines  we have to follow when building web sites for government departments and agencies. The goal of such guidelines is pretty clear - to make web applications accessible to as wide an audience as possible without disadvantaging those with disabilities.

Of course, no-one’s going to disagree with the intent of these standards – but, as a developer of web applications I am often frustrated by the user experience I’d like to provide to my users but can’t. The web is a restrictive medium at the best of times but not being able to rely on, for example, JavaScript (13.1) makes things even harder (AJAX anyone?). Of course, you can invest time and effort to ensure your site degrades when JavaScript is not enabled but this is often not an option on typically tight budgets and timelines.

Even building an application in HTML is itself a major limitation. We all know that HTML was never intended to be the foundation for delivering complex, interactive web applications. I remember a year or two back when  I thought the end of our obsession with the web was coming - smart clients were the promise of a new future and I could sense the renaissance of the rich client. But no, bloody Web 2.0 arrived on the scene and everyone went gaga for web again.

Microsoft are clearly looking to invest in Rich Internet Applications (RIA) (see .NET RIA Services) but with this comes the challenge of making this relevant in a world where accessibility is increasingly important.

So when the opportunity to work on an accessible Silverlight application came along I thought - great, let’s see what’s possible and where the future of accessible RIA might take us. It would be great if ButtercupReader prompted a rethink in the web standards community about how we can provide accessible applications over the web.

Supporting Screen Readers

One of the reasons that traditional web sites can be made accessible to screen readers is that they know how to interpret well formed HTML and can traverse a document and 'read' its contents. So what happens when you're building an application using XAML? Silverlight makes it possible to mark your XAML up with special attributes to expose accessibility information via a standard known as UIAutomation (UIA). Screen readers, and other accessibility tools, that know about UIA (or its predecessor Microsoft Active Accessibility (MSAA)) can interpret these user interface elements.

<Button    

    x:Name="openBookButton" 

    AutomationProperties.Name="Open Book"  

    AutomationProperties.HelpText="Open a Daisy book from your local computer"

    AutomationProperties.AcceleratorKey="O"

    ...>

</Button>

Using a tool like UISpy you can see the AutomationElement properties that have been exposed.

Mark Rideout has written a more detailed overview of Silverlight accessibility features in his article here, Creating Accessibility-aware Silverlight Content.

Other Accessibility Features

Some of the other accessibility features in ButtercupReader include,

• Shortcut Keys - all functionality is available through the keyboard. One gotcha here is that it is not possible to override the shortcut keys used by the host browser. So, for example, we couldn't trap Ctrl + F to initiate a search. Instead, we chose to implement most shortcuts as single (standard keyboard) keys.

• Self-Voicing - throughout the application, and when you set the focus to an element, you will hear speech to provide contextual information. For example, when a button receives the focus its name (AutomationElement.Name) will be spoken and when you press Numpad * additional help text (AutomationElement.HelpText) is spoken. Note that this feature relies on SAPI and currently only work in IE on Windows.
• Contrast Settings - lots of partially sighted users have a preferred contrast setting. For example, photo-sensitive users will likely choose yellow on black, whereas other users may depend on a high contrast, black on white setting.

• Zoomability - clearly, the ability to be able to zoom into text and images is important and Silverlight makes this possible without losing any quality or definition.

So you can see we've had fun on this project and I really hope it opens up some debate on the future of accessibility on the web.

One of the cool features of ButtercupReader is the ability to open DAISY books that you have published on your own web site. Once you’ve followed the few simple steps below people will be able to link to your books using a link that looks something like,

All you are doing is setting the ref query string parameter to the URL of the package file (*.opf) that describes your book. Easy.

Now, in order for this to work there are a couple of things that you need to do on the web server that is going to be hosting the DAISY book files.

Add MIME Types for DAISY File Extensions

In order for your web server to be able to serve up requests for DAISY files you will need to add some additional MIME types. Currently the only file extensions that ButtercupReader relies on are,

Allow ButtercupReader Access to Your Domain

By default Silverlight is not permitted to access resources (like your DAISY files) on another domain (like your web site). But this is easy to fix. All you need to do is to add a file, naming it clientaccesspolicy.xml, to the root of your web site. This file should look like,

For more information check out the official documentation.

So, give it a try and let me know how you get on.

Hi and welcome to the ButtercupReader blog.

If you nod your head at any of the following, then please click on the Subscribe link – would be great to have you on board.

• You’re interested in Web Accessibility beyond traditional HTML based web sites
• You’re interested in Rich Internet Applications (RIA) and accessibility
• You’re interested to learn about how Silverlight makes it possible to write accessible web applications
• You’re keen to learn more about ButtercupReader – how it works and how to use it
• You want to hear about updates to ButtercupReader

I’d really like to encourage you to comment on posts and send in feedback (the good, bad or indifferent). We’d love to hear what you think and where you’d like to see ButtercupReader go.

We also hope to discuss the wider implications of RIA in the context of existing Government and Industry accessibility guidelines.

Thanks for dropping by.

Andrew Tokeley