DropDownListBaseAccImpl  - AS3 Flex

패키지	spark.accessibility
클래스	public class DropDownListBaseAccImpl
상속	DropDownListBaseAccImpl ListBaseAccImpl AccImpl AccessibilityImplementation Object
하위 클래스	ComboBoxAccImpl

언어 버전:

ActionScript 3.0

제품 버전:

Flex 4

런타임 버전:

Flash Player 10, AIR 1.5

DropDownListAccImpl is the accessibility implementation class for spark.components.supportClasses.DropDownListBase.

Although ComboBox has its own accessibility implementation subclass, DropDownList simply uses the one for DropDownListBase. Therefore, the rest of this description refers to the commonly-used DropDownList component rather than the DropDownListBase base class.

When a Spark DropDownList is created, its accessibilityImplementation property is set to an instance of this class. The Flash Player then uses this class to allow MSAA clients such as screen readers to see and manipulate the DropDownList. See the mx.accessibility.AccImpl and flash.accessibility.AccessibilityImplementation classes for background information about accessibility implementation classes and MSAA.

Children

The MSAA children of a DropDownList are its list items. The number of children is the number of items in the dataProvider not just the number of visible renderers.

As described below, the accessibility of the list items is managed by the DropDownList; the accessibilityImplementation and accessibilityProperties of the item renderers are ignored by the Flash Player.

Role

The MSAA Role of a DropDownList is ROLE_SYSTEM_COMBOBOX.

The Role of each list item is ROLE_SYSTEM_LISTITEM.

Name

The MSAA Name of a DropDownList is, by default, an empty string. When wrapped in a FormItem element, the Name is the FormItem's label. To override this behavior, set the DropDownList's accessibilityName property.

The Name of each list item is determined by the DropDownList's itemToLabel() method.

When the Name of the DropDownList or one of its items changes, a DropDownList dispatches the MSAA event EVENT_OBJECT_NAMECHANGE with the proper childID for a list item or 0 for itself.

Description

The MSAA Description of a DropDownList is, by default, an empty string, but you can set the DropDownList's accessibilityDescription property.

The Description of each list item is the empty string.

State

The MSAA State of a DropDownList is a combination of:

• STATE_SYSTEM_UNAVAILABLE (when enabled is false)
• STATE_SYSTEM_FOCUSABLE (when enabled is true)
• STATE_SYSTEM_FOCUSED (when enabled is true and the DropDownList has focus)
• STATE_SYSTEM_EXPANDED (when it is open)
• STATE_SYSTEM_COLLAPSED (when it is closed)

The State of a list item is a combination of:

• STATE_SYSTEM_FOCUSABLE
• STATE_SYSTEM_FOCUSED (when it has focus)
• STATE_SYSTEM_SELECTABLE
• STATE_SYSTEM_SELECTED (when it is selected)

When the State of the DropDownList or one of its list items changes, a DropDownList dispatches the MSAA event EVENT_OBJECT_STATECHANGE with the proper childID for the list item or 0 for itself.

Value

The MSAA Value of a DropDownList is the MSAA Name of the currently selected list item.

The Value of each list item is the empty string.

When the Value of the DropDownList changes, it dispatches the MSAA event EVENT_OBJECT_VALUECHANGE.

Location

The MSAA Location of a DropDownList or a list item is its bounding rectangle.

Default Action

A DropDownList does not have an MSAA DefaultAction

The DefaultAction of a list item is "Double click".

Focus

The DropDownList itself can receive focus, as well as its list items (either while the DropDownList is collapsed or expanded). The EVENT_OBJECT_FOCUS is fired when this happens.

Selection

The DropDownList allows a single item to be selected, in which case an EVENT_OBJECT_SELECTION event is fired.

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