| Package | mx.accessibility |
| Class | public class AccImpl |
| Inheritance | AccImpl flash.accessibility.AccessibilityImplementation |
| Subclasses | AccordionHeaderAccImpl, ButtonAccImpl, ButtonBaseAccImpl, ComboBaseAccImpl, DateChooserAccImpl, DateFieldAccImpl, LabelAccImpl, ListBaseAccImpl, ListBaseAccImpl, MenuBarAccImpl, PanelAccImpl, PanelAccImpl, RichEditableTextAccImpl, SliderAccImpl, SliderBaseAccImpl, SpinnerAccImpl, TabBarAccImpl, TextBaseAccImpl, TreeAccImpl, VideoPlayerAccImpl |
| Language Version : | ActionScript 3.0 |
| Product Version : | Flex 3 |
| Runtime Versions : | Flash Player 9, AIR 1.1 |
It is a subclass of the Flash Player's AccessibilityImplementation class.
When an MX or Spark component is created,
its accessibilityImplementation property
is set to an instance of a subclass of this class.
The Flash Player then uses this object to allow MSAA clients
such as screen readers to see and manipulate the component.
See the flash.accessibility.AccessibilityImplementation class
for additional information about accessibility implementation
classes and MSAA.
Children
The Flash Player does not support
a true hierarchy of accessible objects.
If a DisplayObject has an accessibilityImplementation object,
then the accessibilityImplementation objects
of its children are ignored.
However, the Player does allow a component's accessibility implementation class
to expose MSAA information for its internal parts.
(For example, a List exposes MSAA information about its items.)
The number of children (internal parts)
and the child IDs used to identify them
are determined by the getChildIDArray() method.
In the Player's AccessibilityImplementation base class,
this method simply returns null.
Flex's AccImpl class overrides it to return an empty array.
It also provides a protected utility method,
createChildIDArray() which subclasses with internal parts
can use in their overrides.
Role
The MSAA Role of a component and its internal parts
is determined by the get_accRole() method.
In the Player's AccessibilityImplementation base class,
this method throws a runtime error,
since subclasses are expected to override it.
Flex's AccImpl class has a protected role property
which subclasses generally set in their constructor,
and it overrides get_accRole() to return this property.
Name
The MSAA Name of a component and its internal parts
is determined by the get_accName() method.
In the Player's AccessibilityImplementation base class,
this method simply returns null.
Flex's AccImpl class overrides it to construct a name as follows,
starting with an empty string
and separating added portions with a single space:
accessibilityName of the FormHeading
to a space (" ").accessibilityName of the FormItem
to a space (" ").accessibilityName
(i.e., accessibilityProperties.name) is a space,
no component name is added.getName() method,
defined by AccImpl and implemented by each subclass,
is called to provide a default name.
(For example, ButtonAccImpl implements getName()
to specify that a Button's default name is the label that it displays.)
If not empty, the return value of getName() is added.getName() returned empty),
if the component's toolTip property is set,
that String is added.errorString property is set,
that String is added.Description
The MSAA Description is determined solely by a component's
accessibilityProperties object and not by its
accessibilityImplementation object.
Therefore there is no logic in AccessibilityImplementation or AccImpl
or any subclasses of AccImpl related to the description.
The normal way to set the description in Flex is via the
accessibilityDescription property on UIComponent,
which simply sets accessibilityProperties.description.
State
The MSAA State of a component and its internal parts
is determined by the get_accState() method.
In the Player's AccessibilityImplementation base class,
this method throws a runtime error,
since subclasses are expected to override it.
Flex's AccImpl class does not override it,
but provides a protected utility method, getState(),
for subclasses to use in their overrides.
The getState() method determines the state
as a combination of
Value
The MSAA Value of a component and its internal parts
is determined by the get_accValue() method.
In the Player's AccessibilityImplementation base class,
this method simply returns null.
Flex's AccImpl class does not override it,
but subclasses for components like TextInput do.
Location
The MSAA Location for a component's internal parts,
but not the component itself,
is determined by the get_accLocation() method.
This method is never called with a childID of 0;
instead, the Flash Player determines the MSAA Location of a component
based on its bounding rectangle as determined by getBounds().
Flex's AccImpl class does not override this method,
but subclasses for components with internal parts do.
Default Action
The MSAA DefaultAction for a component and its internal parts
is determined by the get_accDefaultAction() method.
In the Player's AccessibilityImplementation base class,
this method simply returns null.
Flex's AccImpl class does not override it,
but subclasses with default actions do.
These subclasses also override AccessibilityImplementation's
accDoDefaultAction() method
to perform the default action that they advertise.
Other
The MSAA events EVENT_OBJECT_SHOW and EVENT_OBJECT_HIDE are sent when the object is shown or hidden. The corresponding states for these are covered by the Flash Player which does not render any MSAA components that are hidden. When the component is shown the states mentioned for AccImpl are used.
| Property | Defined By | ||
|---|---|---|---|
| eventsToHandle : Array [read-only]
All subclasses must override this function by returning an array
of strings of the events to listen for. | AccImpl | ||
| master : UIComponent
A reference to the UIComponent instance that this AccImpl instance
is making accessible. | AccImpl | ||
| role : uint
Accessibility role of the component being made accessible. | AccImpl | ||
| Method | Defined By | ||
|---|---|---|---|
AccImpl(master:UIComponent)
Constructor. | AccImpl | ||
getFormName(component:UIComponent):String [static]
Method for supporting Form Accessibility. | AccImpl | ||
isAncestorDisabled(component:UIComponent):Boolean [static]
Returns true if an ancestor of the component has enabled set to false. | AccImpl | ||
| Method | Defined By | ||
|---|---|---|---|
eventHandler(event:Event):void
Generic event handler. | AccImpl | ||
getName(childID:uint):String
Returns the name of the accessible component. | AccImpl | ||
getState(childID:uint):uint
Utility method to determine state of the accessible component. | AccImpl | ||
| eventsToHandle | property |
eventsToHandle:Array [read-only] | Language Version : | ActionScript 3.0 |
| Product Version : | Flex 3 |
| Runtime Versions : | Flash Player 9, AIR 1.1 |
All subclasses must override this function by returning an array of strings of the events to listen for.
protected function get eventsToHandle():Array| master | property |
protected var master:UIComponent| Language Version : | ActionScript 3.0 |
| Product Version : | Flex 3 |
| Runtime Versions : | Flash Player 9, AIR 1.1 |
A reference to the UIComponent instance that this AccImpl instance is making accessible.
| role | property |
protected var role:uint| Language Version : | ActionScript 3.0 |
| Product Version : | Flex 3 |
| Runtime Versions : | Flash Player 9, AIR 1.1 |
Accessibility role of the component being made accessible.
| AccImpl | () | Constructor |
public function AccImpl(master:UIComponent)| Language Version : | ActionScript 3.0 |
| Product Version : | Flex 3 |
| Runtime Versions : | Flash Player 9, AIR 1.1 |
Constructor.
Parametersmaster:UIComponent — The UIComponent instance that this AccImpl instance
is making accessible.
|
| eventHandler | () | method |
protected function eventHandler(event:Event):void| Language Version : | ActionScript 3.0 |
| Product Version : | Flex 3 |
| Runtime Versions : | Flash Player 9, AIR 1.1 |
Generic event handler. All AccImpl subclasses must implement this to listen for events from its master component.
Parameters
event:Event |
| getFormName | () | method |
public static function getFormName(component:UIComponent):String| Language Version : | ActionScript 3.0 |
| Product Version : | Flex 3 |
| Runtime Versions : | Flash Player 9, AIR 1.1 |
Method for supporting Form Accessibility. Called from get_accName() in this AccImpl class. Also called from the UIComponentAccProps constructor.
Parameters
component:UIComponent |
String |
| getName | () | method |
protected function getName(childID:uint):String| Language Version : | ActionScript 3.0 |
| Product Version : | Flex 3 |
| Runtime Versions : | Flash Player 9, AIR 1.1 |
Returns the name of the accessible component. All subclasses must implement this instead of implementing get_accName().
Parameters
childID:uint |
String |
| getState | () | method |
protected function getState(childID:uint):uint| Language Version : | ActionScript 3.0 |
| Product Version : | Flex 3 |
| Runtime Versions : | Flash Player 9, AIR 1.1 |
Utility method to determine state of the accessible component.
Parameters
childID:uint |
uint |
| isAncestorDisabled | () | method |
public static function isAncestorDisabled(component:UIComponent):BooleanReturns true if an ancestor of the component has enabled set to false. The given component itself is not checked.
Parameters
component:UIComponent — The UIComponent to check for a disabled ancestor.
|
Boolean — true if the component has a disabled ancestor.
|