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Defines a contract between user-interface components and an assistive technology
that provides access to those components. If a Java application fully supports
the Java Accessibility API, then it should be compatible with, and friendly
toward, assistive technologies such as screen readers, screen magnifiers,
etc. With a Java application that fully supports the Java Accessibility
API, no screen reader off screen model would be necessary because the API
provides all of the information normally contained in an off screen model.
The Java Accessibility API package consists of 8 Java programming language
interfaces, and 6 Java programming language classes. These are described
below.
Interface Accessible is the main interface
of the Java Accessibility API. All components that support the Java Accessibility
API must implement this interface. It contains a single method, getAccessibleContext,
that returns an instance of the class AccessibleContext.
Sun thinks that implementing this interface is the absolute minimum requirement
of every object that is part of the user interface of a Java application,
if that program is to be compatible with assistive technologies.
AccessibleContext represents the minimum
information all accessible objects return and is obtained by calling the
getAccessibleContext method on an object that implements the Accessible
interface. This information includes the accessible name, description,
role, and state
of the object, as well as information about the parent and children of
the object. In addition, JavaBeans TM
property change support is also included to allow assisitive technologies
learn when the values of the accessible properties change. AccessibleContext
also contains methods for obtaining more specific accessibility information
about a component. If the component supports it, these methods will return
an object that implements one or more of the following interfaces:
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AccessibleAction - the object can
perform one or more actions. This interface provides the standard mechanism
for an assistive technology to determine what those actions are and tell
the object to perform those actions. Any object that can be manipulated
should return an object that implements this interface when the getAccessibleAction
method is called on an AccessibleContext.
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AccessibleComponent - the object
has a graphical representation. This interface provides the standard mechanism
for an assistive technology to determine and set the graphical representation
of the object. Any object that is rendered on the screen should return
an object that implements this interface when the getAccessibleComponent
method is called on an AccessibleContext.
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AccessibleSelection - the object
allows its children to be selected. This interface provides the standard
mechanism for an assistive technology to determine the currently selected
children as well as modify the selection set. Any object that has children
that can be selected should return an object that implements this interface
when the getAccessibleSelection method is called on an AccessibleContext.
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AccessibleText - the object presents
editable textual information on the display. This interface provides the
standard mechanism for an assistive technology to access that text via
its content, attributes, and spatial location. Any object that contains
editable text should return an object that implements this interface when
the getAccessibleText method is called on an AccessibleContext.
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AccessibleHypertext - the object
presents hypertext information on the display. This interface provides
the standard mechanism for an assistive technology to access that hypertext
via its content, attributes, and spatial location. Any object that contains
hypertext should return an object that implements this interface when the
getAccessibleText method is called on an AccessibleContext.
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AccessibleValue - the object supports
a numerical value. This interface provides the standard mechanism for an
assistive technology to determine and set the current value of the object,
as well as the minimum and maximum values. Any object that supports a numerical
value should return an object that implements this interface when the getAccessibleValue
method is called on an AccessibleContext.
This class encapsulates the Accessible object's role in the user interface
and is obtained by calling the getAccessibleRole method on an
AccessibleContext. Accessible roles include
"Check box", "Menu Item", "Panel", etc. These roles are identified by the
constants in this class such as AccessibleRole.CHECK_BOX, AccessibleRole.MENU_ITEM,
and AccessibleRole.PANEL. The constants in this class present
a strongly typed enumeration of common object roles. A public constructor
for this class has been purposely omitted and applications should use one
of the constants from this class. Although this class pre-defines a large
list of standard roles, it is extensible so additional programmer-defined
roles can be added in the future without needing to modify the base class.
This class encapsulates a particular state of the Accessible object. Accessible
states include things like "Armed", "Busy", "Checked", "Focused", etc.
These roles are identified by the constants in this class such as AccessibleState.ARMED,
AccessibleState.BUSY, AccessibleState.CHECKED, and AccessibleState.FOCUSED.
The sum of all the states of an Accessible object is called the AccessibleStateSet,
and can be obtained by calling the getAccessibleStateSet method
on an AccessibleContext.
The constants in this class present a strongly typed enumeration of
common object roles. A public constructor for this class has been purposely
omitted and applications should use one of the constants from this class.
Although this class pre-defines a large list of standard roles, it is extensible
so additional, programmer-defined roles can be added in the future without
needing to modify the base class.
This class encapsulates a collection of states of the Accessible object
and is obtained by calling the getAccessibleStateSet method on
an AccessibleContext. Since an object
might have multiple states (e.g. it might be both "Checked" and "Focused"),
this class is needed to encapsulate a collection of these states. Methods
in the class provide for retrieving the individual AccessibleStates
on the state set.
This class is used to maintain a strongly typed enumeration. It is the
super class of both the AccessibleRole and
AccessibleState classes. Programmers normally
do not interact with this class directly, but will instead use the AccessibleRole
and AccessibleState classes.
The AccessibleAction interface should
be supported by any object that can perform one or more actions. This interface
provides the standard mechanism for an assistive technology to determine
what those actions are as well as tell the object to perform those actions.
Any object that can be manipulated should support this interface.
Applications can determine if an object supports the AccessibleAction
interface by first obtaining its AccessibleContext
(see Accessible) and then calling the getAccessibleAction
method of AccessibleContext. If the return
value is not null, the object supports this interface.
The AccessibleComponent interface
should be supported by any object that is rendered on the screen. This
interface provides the standard mechanism for an assistive technology to
determine and set the graphical representation of an object.
Applications can determine if an object supports the AccessibleComponent
interface by first obtaining its AccessibleContext
(see Accessible) and then calling the getAccessibleComponent
method of AccessibleContext. If the return
value is not null, the object supports this interface.
The AccessibleSelection interface
provides the standard mechanism for an assistive technology to determine
what the current selected children are, as well as modify the selection
set. Any object that has children that can be selected should support this
the AccessibleSelection interface.
Applications can determine if an object supports the AccessibleSelection
interface by first obtaining its AccessibleContext
(see Accessible) and then calling the getAccessibleSelection
method of AccessibleContext. If the return
value is not null, the object supports this interface.
Interface AccessibleText is the contract
for making rich, editable text Accessible. Not all text displayed on the
screen is rich and editable (e.g. text contained in buttons, labels, menus,
etc., which users aren't expected to manipulate). However, objects containing
editable text must implement interface AccessibleText if they are to interoperate
with assistive technologies.
This interface provides support for going between pixel coordinates
and the text at a given pixel coordinate, for retrieving the letter, word,
and sentence at, before, or after a given position in the text. This interface
provides support for retrieving the attributes of the character at a given
position in the text (font, font size, style, etc.), as well as getting
the selected text (if any), the length of the text, and the location of
the text caret.
Applications can determine if an object supports the AccessibleText
interface by first obtaining its AccessibleContext
(see Accessible) and then calling the getAccessibleText
method of AccessibleContext. If the return
value is not null, the object supports this interface.
The AccessibleHypertext interface
should be supported by any object that presents hypertext information on
the display. This interface provides the standard mechanism for an assistive
technology to access that text via its content, attributes, and spatial
location. It also provides standard mechanisms for manipulating hyperlinks.
Applications can determine if an object supports the AccessibleHypertext
interface by first obtaining its AccessibleContext
(see Accessible) and then calling the AccessibleContext.getAccessibleText()
method of AccessibleContext. If the return
value is a class which extends AccessibleHypertext, then that object supports
AccessibleHypertext.
An object that is a hyperlink should support the AccessibleHyperlink
interface. An object that implements this interface will be returned
by calling the getLink method on an AccessibleHypertext
object.
The AccessibleValue interface should
be supported by any object that supports a numerical value (e.g., a scroll
bar). This interface provides the standard mechanism for an assistive technology
to determine and set the numerical value as well as get the minimum and
maximum values.
Applications can determine if an object supports the AccessibleValue
interface by first obtaining its AccessibleContext
(see Accessible) and then calling the getAccessibleValue
method of AccessibleContext. If the return
value is not null, the object supports this interface.
@since 1.2
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