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AccessibilityHandler Class Reference

Base class for accessible Components. More...

Classes

struct  Interfaces
 Utility struct which holds one or more accessibility interfaces. More...
 

Public Types

enum  AnnouncementPriority { AnnouncementPriority::low, AnnouncementPriority::medium, AnnouncementPriority::high }
 A priority level that can help an accessibility client determine how to handle an announcement request. More...
 

Public Member Functions

 AccessibilityHandler (Component &componentToWrap, AccessibilityRole accessibilityRole, AccessibilityActions actions={}, Interfaces interfaces={})
 Constructor. More...
 
virtual ~AccessibilityHandler ()
 Destructor. More...
 
const ComponentgetComponent () const noexcept
 Returns the Component that this handler represents. More...
 
ComponentgetComponent () noexcept
 Returns the Component that this handler represents. More...
 
AccessibilityRole getRole () const noexcept
 The type of UI element that this accessibility handler represents. More...
 
virtual String getTitle () const
 The title of the UI element. More...
 
virtual String getDescription () const
 A short description of the UI element. More...
 
virtual String getHelp () const
 Some help text for the UI element (if required). More...
 
virtual AccessibleState getCurrentState () const
 Returns the current state of the UI element. More...
 
bool isIgnored () const
 Returns true if this UI element should be ignored by accessibility clients. More...
 
bool isVisibleWithinParent () const
 Returns true if this UI element is visible within its parent. More...
 
const AccessibilityActionsgetActions () const noexcept
 Returns the set of actions that the UI element supports and the associated callbacks. More...
 
AccessibilityValueInterfacegetValueInterface () const
 Returns the value interface for this UI element, or nullptr if it is not supported. More...
 
AccessibilityTableInterfacegetTableInterface () const
 Returns the table interface for this UI element, or nullptr if it is not supported. More...
 
AccessibilityCellInterfacegetCellInterface () const
 Returns the cell interface for this UI element, or nullptr if it is not supported. More...
 
AccessibilityTextInterfacegetTextInterface () const
 Returns the text interface for this UI element, or nullptr if it is not supported. More...
 
AccessibilityHandlergetParent () const
 Returns the first unignored parent of this UI element in the accessibility hierarchy, or nullptr if this is a root element without a parent. More...
 
std::vector< AccessibilityHandler * > getChildren () const
 Returns the unignored children of this UI element in the accessibility hierarchy. More...
 
bool isParentOf (const AccessibilityHandler *possibleChild) const noexcept
 Checks whether a given UI element is a child of this one in the accessibility hierarchy. More...
 
AccessibilityHandlergetChildAt (Point< int > screenPoint)
 Returns the deepest child of this UI element in the accessibility hierarchy that contains the given screen point, or nullptr if there is no child at this point. More...
 
AccessibilityHandlergetChildFocus ()
 Returns the deepest UI element which currently has focus. More...
 
bool hasFocus (bool trueIfChildFocused) const
 Returns true if this UI element has the focus. More...
 
void grabFocus ()
 Tries to give focus to this UI element. More...
 
void giveAwayFocus () const
 If this UI element or any of its children in the accessibility hierarchy currently have focus, this will defocus it. More...
 
void notifyAccessibilityEvent (AccessibilityEvent event) const
 Used to send a notification to any observing accessibility clients that something has changed in the UI element. More...
 
AccessibilityNativeHandlegetNativeImplementation () const
 
std::type_index getTypeIndex () const
 

Static Public Member Functions

static void postAnnouncement (const String &announcementString, AnnouncementPriority priority)
 Posts an announcement to be made to the user. More...
 

Detailed Description

Base class for accessible Components.

This class wraps a Component and provides methods that allow an accessibility client, such as VoiceOver on macOS, or Narrator on Windows, to control it.

It handles hierarchical navigation, properties, state, and various interfaces.

Member Enumeration Documentation

◆ AnnouncementPriority

A priority level that can help an accessibility client determine how to handle an announcement request.

Exactly what this controls is platform-specific, but generally a low priority announcement will be read when the screen reader is free, whereas a high priority announcement will interrupt the current speech.

Enumerator
low 
medium 
high 

Constructor & Destructor Documentation

◆ AccessibilityHandler()

AccessibilityHandler::AccessibilityHandler ( Component componentToWrap,
AccessibilityRole  accessibilityRole,
AccessibilityActions  actions = {},
Interfaces  interfaces = {} 
)

Constructor.

This will create a AccessibilityHandler which wraps the provided Component and makes it visible to accessibility clients. You must also specify a role for the UI element from the AccessibilityRole list which best describes it.

To enable users to interact with the UI element you should provide the set of supported actions and their associated callbacks via the accessibilityActions parameter.

For UI elements that support more complex interaction the value, text, table, and cell interfaces should be implemented as required and passed as the final argument of this constructor. See the documentation of these classes for more information about the types of control they represent and which methods need to be implemented.

◆ ~AccessibilityHandler()

virtual AccessibilityHandler::~AccessibilityHandler ( )
virtual

Destructor.

Member Function Documentation

◆ getComponent() [1/2]

const Component& AccessibilityHandler::getComponent ( ) const
noexcept

Returns the Component that this handler represents.

◆ getComponent() [2/2]

Component& AccessibilityHandler::getComponent ( )
noexcept

Returns the Component that this handler represents.

◆ getRole()

AccessibilityRole AccessibilityHandler::getRole ( ) const
noexcept

The type of UI element that this accessibility handler represents.

See also
AccessibilityRole

◆ getTitle()

virtual String AccessibilityHandler::getTitle ( ) const
virtual

The title of the UI element.

This will be read out by the system and should be concise, preferably matching the visible title of the UI element (if any). For example, this might be the text of a button or a simple label.

The default implementation will call Component::getTitle(), but you can override this to return a different string if required.

If neither a name nor a description is provided then the UI element may be ignored by accessibility clients.

This must be a localised string.

◆ getDescription()

virtual String AccessibilityHandler::getDescription ( ) const
virtual

A short description of the UI element.

This may be read out by the system. It should not include the type of the UI element and should ideally be a single word, for example "Open" for a button that opens a window.

The default implementation will call Component::getDescription(), but you can override this to return a different string if required.

If neither a name nor a description is provided then the UI element may be ignored by accessibility clients.

This must be a localised string.

◆ getHelp()

virtual String AccessibilityHandler::getHelp ( ) const
virtual

Some help text for the UI element (if required).

This may be read out by the system. This string functions in a similar way to a tooltip, for example "Click to open window." for a button which opens a window.

The default implementation will call Component::getHelpText(), but you can override this to return a different string if required.

This must be a localised string.

◆ getCurrentState()

virtual AccessibleState AccessibilityHandler::getCurrentState ( ) const
virtual

Returns the current state of the UI element.

The default implementation of this method will set the focusable flag and, if this UI element is currently focused, will also set the focused flag.

◆ isIgnored()

bool AccessibilityHandler::isIgnored ( ) const

Returns true if this UI element should be ignored by accessibility clients.

◆ isVisibleWithinParent()

bool AccessibilityHandler::isVisibleWithinParent ( ) const

Returns true if this UI element is visible within its parent.

This will always return true for UI elements with the AccessibleState::accessibleOffscreen flag set.

◆ getActions()

const AccessibilityActions& AccessibilityHandler::getActions ( ) const
noexcept

Returns the set of actions that the UI element supports and the associated callbacks.

◆ getValueInterface()

AccessibilityValueInterface* AccessibilityHandler::getValueInterface ( ) const

Returns the value interface for this UI element, or nullptr if it is not supported.

See also
AccessibilityValueInterface

◆ getTableInterface()

AccessibilityTableInterface* AccessibilityHandler::getTableInterface ( ) const

Returns the table interface for this UI element, or nullptr if it is not supported.

See also
AccessibilityTableInterface

◆ getCellInterface()

AccessibilityCellInterface* AccessibilityHandler::getCellInterface ( ) const

Returns the cell interface for this UI element, or nullptr if it is not supported.

See also
AccessibilityCellInterface

◆ getTextInterface()

AccessibilityTextInterface* AccessibilityHandler::getTextInterface ( ) const

Returns the text interface for this UI element, or nullptr if it is not supported.

See also
AccessibilityTextInterface

◆ getParent()

AccessibilityHandler* AccessibilityHandler::getParent ( ) const

Returns the first unignored parent of this UI element in the accessibility hierarchy, or nullptr if this is a root element without a parent.

◆ getChildren()

std::vector<AccessibilityHandler*> AccessibilityHandler::getChildren ( ) const

Returns the unignored children of this UI element in the accessibility hierarchy.

◆ isParentOf()

bool AccessibilityHandler::isParentOf ( const AccessibilityHandler possibleChild) const
noexcept

Checks whether a given UI element is a child of this one in the accessibility hierarchy.

◆ getChildAt()

AccessibilityHandler* AccessibilityHandler::getChildAt ( Point< int screenPoint)

Returns the deepest child of this UI element in the accessibility hierarchy that contains the given screen point, or nullptr if there is no child at this point.

◆ getChildFocus()

AccessibilityHandler* AccessibilityHandler::getChildFocus ( )

Returns the deepest UI element which currently has focus.

This can be a child of this UI element or, if no child is focused, this element itself.

Note that this can be different to the value of the Component with keyboard focus returned by Component::getCurrentlyFocusedComponent().

See also
hasFocus

◆ hasFocus()

bool AccessibilityHandler::hasFocus ( bool  trueIfChildFocused) const

Returns true if this UI element has the focus.

Parameters
trueIfChildFocusedif this is true, this method will also return true if any child of this UI element in the accessibility hierarchy has focus

◆ grabFocus()

void AccessibilityHandler::grabFocus ( )

Tries to give focus to this UI element.

If the UI element is focusable and not ignored this will update the currently focused element, try to give keyboard focus to the Component it represents, and notify any listening accessibility clients that the current focus has changed.

See also
hasFocus, giveAwayFocus

◆ giveAwayFocus()

void AccessibilityHandler::giveAwayFocus ( ) const

If this UI element or any of its children in the accessibility hierarchy currently have focus, this will defocus it.

This will also give away the keyboard focus from the Component it represents, and notify any listening accessibility clients that the current focus has changed.

See also
hasFocus, grabFocus

◆ notifyAccessibilityEvent()

void AccessibilityHandler::notifyAccessibilityEvent ( AccessibilityEvent  event) const

Used to send a notification to any observing accessibility clients that something has changed in the UI element.

See also
AccessibilityEvent

◆ postAnnouncement()

static void AccessibilityHandler::postAnnouncement ( const String announcementString,
AnnouncementPriority  priority 
)
static

Posts an announcement to be made to the user.

Parameters
announcementStringa localised string containing the announcement to be read out
prioritythe appropriate priority level for the announcement

◆ getNativeImplementation()

AccessibilityNativeHandle* AccessibilityHandler::getNativeImplementation ( ) const

◆ getTypeIndex()

std::type_index AccessibilityHandler::getTypeIndex ( ) const

The documentation for this class was generated from the following file: