The arrival of graphical interfaces such as OS/2, Mac OS and Windows meant that key information about what was on the screen could no longer be simply read from a buffer. The information could then be manipulated - for example, magnified or converted into an alternative format such as synthetic speech. Assistive technologies could obtain this information by reading directly from the screen buffer or by intercepting signals being sent to a monitor. With the text-based DOS operating system, the characters on the screen and the cursor position were held in a screen buffer in the computer’s memory. ![]() To understand the role of an accessibility API in making Web applications accessible, it helps to know a bit about how assistive technologies provide access to applications and how that has evolved over time. How do assistive technologies present a web application to make it accessible for their users? Where do they get the information they need? One of the keys is a technology known as the accessibility API (or accessibility application programming interface, to use its full formal title). A firm grasp of the technology is paramount to making informed decisions about accessible design. Successful web accessibility is about anticipating the different needs of all sorts of people, understanding your fellow web users and the different ways they consume information, empathizing with them and their sense of what is convenient and what frustratingly unnecessary barriers you could help them to avoid.Īrmed with this understanding, accessibility becomes a cold, hard technical challenge. A big part of accessibility is, therefore, an easily met responsibility of web developers. ![]() If appropriate content semantics are not available, then assistive technologies will use old and unreliable techniques to make the interface usable. ![]() Technologies work together to extract accessibility information from a web interface and appropriately present it to the user.
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