Accessibility encompasses more than just providing an alternative to a mouse-driven user interface. At its core, it’s about enabling individuals and supporting their unique viewpoints and working styles.
This chapter presents several compelling reasons why you should access-enable every application you develop. If you’re considering making your application accessible, you should read this chapter. Then, you should read the following chapters to learn how Mac OS X supports accessibility and how easy it is for most applications to incorporate it.
If you’re an assistive application developer, you’re more interested in how Mac OS X supports accessibility. You may choose to skip ahead to “The Mac OS X Accessibility Protocol” to learn about the Mac OS X accessibility protocol.
Millions of people have a disability or special need. These include visual and hearing impairments, physical disabilities, and cognitive and learning challenges. Access to computers is vitally important for this population, because computers can provide a level of independence that is difficult to attain any other way.
As populations around the world age, an increasing number of people will experience age-related disabilities, such as vision or hearing loss. Unlike earlier generations, members of the currently aging population are more accustomed to using computers in their daily lives. They are more likely to store a large portion of their meaningful data in digital form and to embrace digital communication. Current and future generations of the elderly will expect to be able to continue using their computers and accessing their data, regardless of the state of their vision and hearing. Applications that support customizable text displays, access by a screen reader, or the replacement of visual cues by audible ones can serve this population well.
Even people who don’t necessarily identify themselves as disabled can benefit from alternate ways of interacting with applications. Think of a person suffering from carpal tunnel syndrome (a painful condition caused by the compression of a nerve in the wrist) who prefers an application that provides keyboard alternatives to its mouse-driven user interface. By providing alternate ways of using your application, you allow users to choose their own ways to work and express themselves, which ultimately broadens your user base.
Federal regulations like section 508 of the Rehabilitation Act of 1973 in the United States stipulate that computers used in government or educational settings must provide reasonable access for people with disabilities. As this regulation and others like it take effect, entrance into these markets is dependent upon your ability to supply accessible applications.
Like the localization issue a few years ago, accessibility has evolved from a good idea to an essential component of competitive applications. Apple is committed to providing the best platform from which to enter these markets. By access enabling your application and deploying it on Mac OS X, you make your application more attractive to these markets.
Mac OS X is designed to accommodate assistive technologies and has many built-in features to help people with disabilities. Users access most of this functionality through the Universal Access pane of System Preferences. Some of these built-in technologies take advantage of the same accessibility architecture that allows external assistive technologies to access your application.
For example, VoiceOver, the built-in spoken interface introduced in Mac OS X version 10.4, relies on the accessibility architecture to make the navigation and use of the system accessible to users with visual disabilities. If you access-enable your application, VoiceOver helps a visually impaired user use it.
Mac OS X version 10.2 and later builds in support for accessibility. In particular, both Carbon and Cocoa integrate accessibility into their APIs. This means that most of accessibility comes for free when you develop applications with these frameworks. This lets you focus on providing your application-specific information to assistive technologies, which enhances the user’s experience and highlights your application’s unique features.
If you have an established application, you’ll find that the Mac OS X accessibility architecture is designed to allow you to access-enable your application in a selective way. This allows you to enjoy the benefits of accessibility without having to redesign your application. When you’re ready to access-enable your application, be sure to read the document that pertains to your chosen application framework:
Accessibility Programming Guidelines for Carbon
Last updated: 2008-03-11