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 class	AnnouncementPriority { low , medium , 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.
virtual	~AccessibilityHandler ()
	Destructor.
const Component &	getComponent () const noexcept
	Returns the Component that this handler represents.
Component &	getComponent () noexcept
	Returns the Component that this handler represents.
AccessibilityRole	getRole () const noexcept
	The type of UI element that this accessibility handler represents.
virtual String	getTitle () const
	The title of the UI element.
virtual String	getDescription () const
	A short description of the UI element.
virtual String	getHelp () const
	Some help text for the UI element (if required).
virtual AccessibleState	getCurrentState () const
	Returns the current state of the UI element.
bool	isIgnored () const
	Returns true if this UI element should be ignored by accessibility clients.
bool	isVisibleWithinParent () const
	Returns true if this UI element is visible within its parent.
const AccessibilityActions &	getActions () const noexcept
	Returns the set of actions that the UI element supports and the associated callbacks.
AccessibilityValueInterface *	getValueInterface () const
	Returns the value interface for this UI element, or nullptr if it is not supported.
AccessibilityTableInterface *	getTableInterface () const
	Returns the table interface for this UI element, or nullptr if it is not supported.
AccessibilityCellInterface *	getCellInterface () const
	Returns the cell interface for this UI element, or nullptr if it is not supported.
AccessibilityTextInterface *	getTextInterface () const
	Returns the text interface for this UI element, or nullptr if it is not supported.
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.
std::vector< AccessibilityHandler * >	getChildren () const
	Returns the unignored children of this UI element in the accessibility hierarchy.
bool	isParentOf (const AccessibilityHandler *possibleChild) const noexcept
	Checks whether a given UI element is a child of this one in the accessibility hierarchy.
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.
AccessibilityHandler *	getChildFocus ()
	Returns the deepest UI element which currently has focus.
bool	hasFocus (bool trueIfChildFocused) const
	Returns true if this UI element has the focus.
void	grabFocus ()
	Tries to give focus to this UI element.
void	giveAwayFocus () const
	If this UI element or any of its children in the accessibility hierarchy currently have focus, this will defocus it.
void	notifyAccessibilityEvent (AccessibilityEvent event) const
	Used to send a notification to any observing accessibility clients that something has changed in the UI element.
AccessibilityNativeHandle *	getNativeImplementation () 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.
static void	postSystemNotification (const String &notificationTitle, const String &notificationBody)
	Posts a local system notification.
static void	clearCurrentlyFocusedHandler ()
static void *	getNativeChildForComponent (Component &component)
static void	setNativeChildForComponent (Component &component, void *nativeChild)
static Component *	getComponentForNativeChild (void *nativeChild)

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

enum class AccessibilityHandler::AnnouncementPriority

strong

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.

References Component.

Referenced by AccessibilityNativeHandle, getChildAt(), getChildFocus(), getChildren(), getParent(), and isParentOf().

~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.

References Component.

getComponent() [2/2]

Component & AccessibilityHandler::getComponent ( )

noexcept

Returns the Component that this handler represents.

References Component.

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

References getValueInterface().

Referenced by getValueInterface().

getTableInterface()

AccessibilityTableInterface * AccessibilityHandler::getTableInterface

(

)

const

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

See also

AccessibilityTableInterface

References getTableInterface().

Referenced by getTableInterface().

getCellInterface()

AccessibilityCellInterface * AccessibilityHandler::getCellInterface

(

)

const

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

See also

AccessibilityCellInterface

References getCellInterface().

Referenced by getCellInterface().

getTextInterface()

AccessibilityTextInterface * AccessibilityHandler::getTextInterface

(

)

const

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

See also

AccessibilityTextInterface

References getTextInterface().

Referenced by getTextInterface().

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.

References AccessibilityHandler(), and getParent().

Referenced by getParent().

getChildren()

std::vector< AccessibilityHandler * > AccessibilityHandler::getChildren

(

)

const

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

References AccessibilityHandler(), and getChildren().

Referenced by getChildren().

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.

References AccessibilityHandler(), and isParentOf().

Referenced by isParentOf().

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.

References AccessibilityHandler(), getChildAt(), and Point.

Referenced by getChildAt().

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

References AccessibilityHandler(), and getChildFocus().

Referenced by getChildFocus().

hasFocus()

bool AccessibilityHandler::hasFocus

(

bool

trueIfChildFocused

)

const

Returns true if this UI element has the focus.

Parameters

trueIfChildFocused

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

References hasFocus().

Referenced by hasFocus().

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

References grabFocus().

Referenced by grabFocus().

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

References giveAwayFocus().

Referenced by giveAwayFocus().

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

References notifyAccessibilityEvent().

Referenced by notifyAccessibilityEvent().

postAnnouncement()

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

static

Posts an announcement to be made to the user.

Parameters

announcementString	a localised string containing the announcement to be read out
priority	the appropriate priority level for the announcement

postSystemNotification()

static void AccessibilityHandler::postSystemNotification ( const String & notificationTitle, const String & notificationBody )

static

Posts a local system notification.

In order for this to do anything, the following conditions must be met.

• At build time:
  • The juce_gui_extra module must be included in the project.
  • Push notifications must be enabled by setting the preprocessor definition JUCE_PUSH_NOTIFICATIONS=1
• At run time:
  • An accessibility client (narrator, voiceover etc.) must be active.

Additionally, on Android, an icon is required for notifications. This must be specified by adding the path to the icon file called "accessibilitynotificationicon" in the "Extra Android Raw Resources" setting in the Projucer.

This will use the push notification client on macOS, iOS and Android. On Windows this will create a system tray icon to post the notification.

Parameters

notificationTitle	the title of the notification
notificationBody	the main body text of the notification

getNativeImplementation()

AccessibilityNativeHandle * AccessibilityHandler::getNativeImplementation

(

)

const

References AccessibilityNativeHandle.

getTypeIndex()

std::type_index AccessibilityHandler::getTypeIndex

(

)

const

clearCurrentlyFocusedHandler()

static void AccessibilityHandler::clearCurrentlyFocusedHandler ( )

static

getNativeChildForComponent()

static void * AccessibilityHandler::getNativeChildForComponent ( Component & component )

static

References Component.

setNativeChildForComponent()

static void AccessibilityHandler::setNativeChildForComponent ( Component & component, void * nativeChild )

static

References Component.

getComponentForNativeChild()

static Component * AccessibilityHandler::getComponentForNativeChild ( void * nativeChild )

static

References Component.