Mac:Accessibility/UniversalAccess: Difference between revisions
(apple seems to have been inspired by me, yay! update to be a intro page to UA instead.) |
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In this way, one could think of UA kind of like a hash table. You ask for an attribute, and get an array, a string, a number, or any other value describing the data you asked for. | In this way, one could think of UA kind of like a hash table. You ask for an attribute, and get an array, a string, a number, or any other value describing the data you asked for. | ||
Users of the UA APIs can easily extend UA just by supporting a new attribute. Whenever someone asks for the value of it. | |||
The first thing an AT typically does, is to ask the [http://developer.apple.com/documentation/Cocoa/Reference/ApplicationKit/Protocols/NSAccessibility_Protocol/Reference/Reference.html#//apple_ref/doc/uid/20000945-BCIIHIGG query widgets about the attributes they support]. It can then go on to see which of those that are "settable", i.e. changable by the user. For example, the value attribute of a textfield is settable. | The first thing an AT typically does, is to ask the [http://developer.apple.com/documentation/Cocoa/Reference/ApplicationKit/Protocols/NSAccessibility_Protocol/Reference/Reference.html#//apple_ref/doc/uid/20000945-BCIIHIGG query widgets about the attributes they support]. It can then go on to see which of those that are "settable", i.e. changable by the user. For example, the value attribute of a textfield is settable. | ||
Revision as of 08:43, 25 May 2006
Introduction to Universal Access
This page previously hosted a quick reference to Apple's accessibility framework. Since then, Apple has updated it to be much more useful. See Apple's definition of the NSAccessibility protocol for a good quick reference.
In the following sections, we will use a few commonly used acronyms for convenience:
- AT, means Assistive Technology, or simply a 3rd party application, e.g., a Screen Reader.
- UA refers to Universal Access - Apple's name for all of their accessibility APIs.
Everything is an Attribute
Developers used to MSAA or ATK will find that UA is very easy to use. Everything is basically done just by querying elements for attributes, and setting them.
In this way, one could think of UA kind of like a hash table. You ask for an attribute, and get an array, a string, a number, or any other value describing the data you asked for.
Users of the UA APIs can easily extend UA just by supporting a new attribute. Whenever someone asks for the value of it.
The first thing an AT typically does, is to ask the query widgets about the attributes they support. It can then go on to see which of those that are "settable", i.e. changable by the user. For example, the value attribute of a textfield is settable.
Roles
An AT can know the "role" of a widget just by asking for the value of the role attribute. The role tells the AT a lot about the widget behaves (button? listbox? etc.)
Actions
An action is a way for the user to interact with the interface, e.g. through a screen reader. For example clicking a button, deleting, or incrementing a value. To know which actions a widget supports, is as easy as asking asking for an array of them.
Notifications
Notifications are sent out to the ATs when something significant in the UI has changed. For example, a new window was opened, or new rows were added to a table.
WebKit additions
Because UA is easily extendable with new attributes, roles and notifications, WebKit has implemented some custom extensions to UA to make it work better in a web context. We've gathered them here as well.
Comments, suggestions, etc
Feel free to add and improve this introduction, or even copy it to another wiki.
--HakanW 05:10, 24 May 2006 (PDT)