QAccessible

The QAccessible class provides enums and static functions related to accessibility. More

Inheritance diagram of PySide2.QtGui.QAccessible

Synopsis

Static functions

Detailed Description

This class is part of Accessibility for QWidget Applications.

Accessible applications can be used by people who are not able to use applications by conventional means.

The functions in this class are used for communication between accessible applications (also called AT Servers) and accessibility tools (AT Clients), such as screen readers and braille displays. Clients and servers communicate in the following way:

  • AT Servers notify the clients about events through calls to the updateAccessibility() function.

  • AT Clients request information about the objects in the server. The QAccessibleInterface class is the core interface, and encapsulates this information in a pure virtual API. Implementations of the interface are provided by Qt through the queryAccessibleInterface() API.

The communication between servers and clients is initialized by the setRootObject() function. Function pointers can be installed to replace or extend the default behavior of the static functions in QAccessible .

Qt supports Microsoft Active Accessibility (MSAA), macOS Accessibility, and the Unix/X11 AT-SPI standard. Other backends can be supported using QAccessibleBridge.

In the Unix/X11 AT-SPI implementation, applications become accessible when two conditions are met:

  • org.a11y.Status.IsEnabled DBus property is true

  • org.a11y.Status.ScreenReaderEnabled DBus property is true

An alternative to setting the DBus AT-SPI properties is to set the QT_LINUX_ACCESSIBILITY_ALWAYS_ON environment variable.

In addition to QAccessible ‘s static functions, Qt offers one generic interface, QAccessibleInterface , that can be used to wrap all widgets and objects (e.g., QPushButton ). This single interface provides all the metadata necessary for the assistive technologies. Qt provides implementations of this interface for its built-in widgets as plugins.

When you develop custom widgets, you can create custom subclasses of QAccessibleInterface and distribute them as plugins (using QAccessiblePlugin ) or compile them into the application. Likewise, Qt’s predefined accessibility support can be built as plugin (the default) or directly into the Qt library. The main advantage of using plugins is that the accessibility classes are only loaded into memory if they are actually used; they don’t slow down the common case where no assistive technology is being used.

Qt also includes two convenience classes, QAccessibleObject and QAccessibleWidget , that inherit from QAccessibleInterface and provide the lowest common denominator of metadata (e.g., widget geometry, window title, basic help text). You can use them as base classes when wrapping your custom QObject or QWidget subclasses.

PySide2.QtGui.QAccessible.Event

This enum type defines accessible event types.

Constant

Description

QAccessible.AcceleratorChanged

The keyboard accelerator for an action has been changed.

QAccessible.ActionChanged

An action has been changed.

QAccessible.ActiveDescendantChanged

QAccessible.Alert

A system alert (e.g., a message from a QMessageBox )

QAccessible.AttributeChanged

QAccessible.ContextHelpEnd

Context help ( QWhatsThis ) for an object is finished.

QAccessible.ContextHelpStart

Context help ( QWhatsThis ) for an object is initiated.

QAccessible.DefaultActionChanged

The default QAccessible::Action for the accessible object has changed.

QAccessible.DescriptionChanged

The object’s Description changed.

QAccessible.DialogEnd

A dialog ( QDialog ) has been hidden

QAccessible.DialogStart

A dialog ( QDialog ) has been set visible.

QAccessible.DocumentContentChanged

The contents of a text document have changed.

QAccessible.DocumentLoadComplete

A document has been loaded.

QAccessible.DocumentLoadStopped

A document load has been stopped.

QAccessible.DocumentReload

A document reload has been initiated.

QAccessible.DragDropEnd

A drag and drop operation is about to finished.

QAccessible.DragDropStart

A drag and drop operation is about to be initiated.

QAccessible.Focus

An object has gained keyboard focus.

QAccessible.ForegroundChanged

A window has been activated (i.e., a new window has gained focus on the desktop).

QAccessible.HelpChanged

The Help text property of an object has changed.

QAccessible.HyperlinkEndIndexChanged

The end position of the display text for a hypertext link has changed.

QAccessible.HyperlinkNumberOfAnchorsChanged

The number of anchors in a hypertext link has changed, perhaps because the display text has been split to provide more than one link.

QAccessible.HyperlinkSelectedLinkChanged

The link for the selected hypertext link has changed.

QAccessible.HyperlinkStartIndexChanged

The start position of the display text for a hypertext link has changed.

QAccessible.HypertextChanged

The display text for a hypertext link has changed.

QAccessible.HypertextLinkActivated

A hypertext link has been activated, perhaps by being clicked or via a key press.

QAccessible.HypertextLinkSelected

A hypertext link has been selected.

QAccessible.HypertextNLinksChanged

QAccessible.LocationChanged

An object’s location on the screen has changed.

QAccessible.MenuCommand

A menu item is triggered.

QAccessible.MenuEnd

A menu has been closed (Qt uses for all menus).

QAccessible.MenuStart

A menu has been opened on the menubar (Qt uses for all menus).

QAccessible.NameChanged

The Name property of an object has changed.

QAccessible.ObjectAttributeChanged

QAccessible.ObjectCreated

A new object is created.

QAccessible.ObjectDestroyed

An object is deleted.

QAccessible.ObjectHide

An object is hidden; for example, with hide() . Any children the object that is hidden has do not send this event. It is not sent when an object is hidden as it is being obcured by others.

QAccessible.ObjectReorder

A layout or item view has added, removed, or moved an object (Qt does not use this event).

QAccessible.ObjectShow

An object is displayed; for example, with show() .

QAccessible.PageChanged

QAccessible.ParentChanged

An object’s parent object changed.

QAccessible.PopupMenuEnd

A pop-up menu has closed.

QAccessible.PopupMenuStart

A pop-up menu has opened.

QAccessible.ScrollingEnd

A scrollbar scroll operation has ended (the mouse has released the slider handle).

QAccessible.ScrollingStart

A scrollbar scroll operation is about to start; this may be caused by a mouse press on the slider handle, for example.

QAccessible.SectionChanged

QAccessible.SelectionAdd

An item has been added to the selection in an item view.

QAccessible.SelectionRemove

An item has been removed from an item view selection.

QAccessible.Selection

The selection has changed in a menu or item view.

QAccessible.SelectionWithin

Several changes to a selection has occurred in an item view.

QAccessible.SoundPlayed

A sound has been played by an object

QAccessible.TableCaptionChanged

A table caption has been changed.

QAccessible.TableColumnDescriptionChanged

The description of a table column, typically found in the column’s header, has been changed.

QAccessible.TableColumnHeaderChanged

A table column header has been changed.

QAccessible.TableRowDescriptionChanged

The description of a table row, typically found in the row’s header, has been changed.

QAccessible.TableRowHeaderChanged

A table row header has been changed.

QAccessible.TableSummaryChanged

The summary of a table has been changed.

QAccessible.TextColumnChanged

A text column has been changed.

QAccessible.VisibleDataChanged

The values for this enum are defined to be the same as those defined in the IAccessible2 and MSAA specifications.

PySide2.QtGui.QAccessible.Role

This enum defines the role of an accessible object. The roles are:

Constant

Description

QAccessible.AlertMessage

An object that is used to alert the user.

QAccessible.Animation

An object that displays an animation.

QAccessible.Application

The application’s main window.

QAccessible.Assistant

An object that provids interactive help.

QAccessible.Border

An object that represents a border.

QAccessible.ButtonDropDown

A button that drops down a list of items.

QAccessible.ButtonDropGrid

A button that drops down a grid.

QAccessible.ButtonMenu

A button that drops down a menu.

QAccessible.Canvas

An object that displays graphics that the user can interact with.

QAccessible.Caret

An object that represents the system caret (text cursor).

QAccessible.Cell

A cell in a table.

QAccessible.Chart

An object that displays a graphical representation of data.

QAccessible.CheckBox

An object that represents an option that can be checked or unchecked. Some options provide a “mixed” state, e.g. neither checked nor unchecked.

QAccessible.Client

The client area in a window.

QAccessible.Clock

A clock displaying time.

QAccessible.ColorChooser

A dialog that lets the user choose a color.

QAccessible.Column

A column of cells, usually within a table.

QAccessible.ColumnHeader

A header for a column of data.

QAccessible.ComboBox

A list of choices that the user can select from.

QAccessible.ComplementaryContent

A part of the document or web page that is complementary to the main content, usually a landmark (see WAI-ARIA).

QAccessible.Cursor

An object that represents the mouse cursor.

QAccessible.Desktop

The object represents the desktop or workspace.

QAccessible.Dial

An object that represents a dial or knob.

QAccessible.Dialog

A dialog box.

QAccessible.Document

A document, for example in an office application.

QAccessible.EditableText

Editable text such as a line or text edit.

QAccessible.Equation

An object that represents a mathematical equation.

QAccessible.Footer

A footer in a page (usually in documents).

QAccessible.Form

A web form containing controls.

QAccessible.Graphic

A graphic or picture, e.g. an icon.

QAccessible.Grip

A grip that the user can drag to change the size of widgets.

QAccessible.Grouping

An object that represents a logical grouping of other objects.

QAccessible.Heading

A heading in a document.

QAccessible.HelpBalloon

An object that displays help in a separate, short lived window.

QAccessible.HotkeyField

A hotkey field that allows the user to enter a key sequence.

QAccessible.Indicator

An indicator that represents a current value or item.

QAccessible.LayeredPane

An object that can contain layered children, e.g. in a stack.

QAccessible.Link

A link to something else.

QAccessible.List

A list of items, from which the user can select one or more items.

QAccessible.ListItem

An item in a list of items.

QAccessible.MenuBar

A menu bar from which menus are opened by the user.

QAccessible.MenuItem

An item in a menu or menu bar.

QAccessible.NoRole

The object has no role. This usually indicates an invalid object.

QAccessible.Note

A section whose content is parenthetic or ancillary to the main content of the resource.

QAccessible.PageTab

A page tab that the user can select to switch to a different page in a dialog.

QAccessible.PageTabList

A list of page tabs.

QAccessible.Paragraph

A paragraph of text (usually found in documents).

QAccessible.Pane

A generic container.

QAccessible.PopupMenu

A menu which lists options that the user can select to perform an action.

QAccessible.ProgressBar

The object displays the progress of an operation in progress.

QAccessible.PropertyPage

A property page where the user can change options and settings.

QAccessible.Button

A button.

QAccessible.RadioButton

An object that represents an option that is mutually exclusive with other options.

QAccessible.Row

A row of cells, usually within a table.

QAccessible.RowHeader

A header for a row of data.

QAccessible.ScrollBar

A scroll bar, which allows the user to scroll the visible area.

QAccessible.Section

A section (in a document).

QAccessible.Separator

A separator that divides space into logical areas.

QAccessible.Slider

A slider that allows the user to select a value within a given range.

QAccessible.Sound

An object that represents a sound.

QAccessible.SpinBox

A spin box widget that allows the user to enter a value within a given range.

QAccessible.Splitter

A splitter distributing available space between its child widgets.

QAccessible.StaticText

Static text, such as labels for other widgets.

QAccessible.StatusBar

A status bar.

QAccessible.Table

A table representing data in a grid of rows and columns.

QAccessible.Terminal

A terminal or command line interface.

QAccessible.TitleBar

The title bar caption of a window.

QAccessible.ToolBar

A tool bar, which groups widgets that the user accesses frequently.

QAccessible.ToolTip

A tool tip which provides information about other objects.

QAccessible.Tree

A list of items in a tree structure.

QAccessible.TreeItem

An item in a tree structure.

QAccessible.UserRole

The first value to be used for user defined roles.

QAccessible.WebDocument

HTML document, usually in a browser.

QAccessible.Whitespace

Blank space between other objects.

QAccessible.Window

A top level window.

PySide2.QtGui.QAccessible.Text

This enum specifies string information that an accessible object returns.

Constant

Description

QAccessible.Name

The name of the object. This can be used both as an identifier or a short description by accessible clients.

QAccessible.Description

A short text describing the object.

QAccessible.Value

The value of the object.

QAccessible.Help

A longer text giving information about how to use the object.

QAccessible.Accelerator

The keyboard shortcut that executes the object’s default action.

QAccessible.UserText

The first value to be used for user defined text.

PySide2.QtGui.QAccessible.RelationFlag

This enum type defines bit flags that can be combined to indicate the relationship between two accessible objects.

Constant

Description

QAccessible.Label

The first object is the label of the second object.

QAccessible.Labelled

The first object is labelled by the second object.

QAccessible.Controller

The first object controls the second object.

QAccessible.Controlled

The first object is controlled by the second object.

QAccessible.AllRelations

Used as a mask to specify that we are interesting in information about all relations

Implementations of relations() return a combination of these flags. Some values are mutually exclusive.

PySide2.QtGui.QAccessible.InterfaceType

QAccessibleInterface supports several sub interfaces. In order to provide more information about some objects, their accessible representation should implement one or more of these interfaces.

Note

When subclassing one of these interfaces, interface_cast() needs to be implemented.

Constant

Description

QAccessible.TextInterface

For text that supports selections or is more than one line. Simple labels do not need to implement this interface.

QAccessible.ValueInterface

For objects that are used to manipulate a value, for example slider or scroll bar.

QAccessible.ActionInterface

For interactive objects that allow the user to trigger an action. Basically everything that allows for example mouse interaction.

QAccessible.TableInterface

For lists, tables and trees.

QAccessible.TableCellInterface

For cells in a object.

See also

interface_cast() QAccessibleTextInterface QAccessibleValueInterface QAccessibleActionInterface QAccessibleTableInterface QAccessibleTableCellInterface

PySide2.QtGui.QAccessible.TextBoundaryType

This enum describes different types of text boundaries. It follows the IAccessible2 API and is used in the QAccessibleTextInterface .

Constant

Description

QAccessible.CharBoundary

Use individual characters as boundary.

QAccessible.WordBoundary

Use words as boundaries.

QAccessible.SentenceBoundary

Use sentences as boundary.

QAccessible.ParagraphBoundary

Use paragraphs as boundary.

QAccessible.LineBoundary

Use newlines as boundary.

QAccessible.NoBoundary

No boundary (use the whole text).

static PySide2.QtGui.QAccessible.accessibleInterface(uniqueId)
Parameters

uniqueId – long

Return type

QAccessibleInterface

Returns the QAccessibleInterface belonging to the id .

Returns None if the id is invalid.

static PySide2.QtGui.QAccessible.cleanup()
static PySide2.QtGui.QAccessible.deleteAccessibleInterface(uniqueId)
Parameters

uniqueId – long

Removes the interface belonging to this id from the cache and deletes it. The id becomes invalid an may be re-used by the cache.

static PySide2.QtGui.QAccessible.isActive()
Return type

bool

Returns true if the platform requested accessibility information.

This function will return false until a tool such as a screen reader accessed the accessibility framework. It is still possible to use queryAccessibleInterface() even if accessibility is not active. But there will be no notifications sent to the platform.

It is recommended to use this function to prevent expensive notifications via updateAccessibility() when they are not needed.

static PySide2.QtGui.QAccessible.qAccessibleTextBoundaryHelper(cursor, boundaryType)
Parameters
Return type

getBoundaries is a helper function to find the accessible text boundaries for QTextCursor based documents. documentCursor a valid cursor bound to the document (not null). It needs to ba at the position to look for the boundary boundaryType the type of boundary to find Returns the boundaries as pair

static PySide2.QtGui.QAccessible.queryAccessibleInterface(arg__1)
Parameters

arg__1QObject

Return type

QAccessibleInterface

If a QAccessibleInterface implementation exists for the given object , this function returns a pointer to the implementation; otherwise it returns None .

The function calls all installed factory functions (from most recently installed to least recently installed) until one is found that provides an interface for the class of object . If no factory can provide an accessibility implementation for the class the function loads installed accessibility plugins, and tests if any of the plugins can provide the implementation.

If no implementation for the object’s class is available, the function tries to find an implementation for the object’s parent class, using the above strategy.

All interfaces are managed by an internal cache and should not be deleted.

static PySide2.QtGui.QAccessible.registerAccessibleInterface(iface)
Parameters

ifaceQAccessibleInterface

Return type

long

Call this function to ensure that manually created interfaces are properly memory managed.

Must only be called exactly once per interface iface . This is implicitly called when calling queryAccessibleInterface , calling this function is only required when QAccessibleInterfaces are instantiated with the “new” operator. This is not recommended, whenever possible use the default functions and let queryAccessibleInterface() take care of this.

When it is necessary to reimplement the child() function and returning the child after constructing it, this function needs to be called.

static PySide2.QtGui.QAccessible.setActive(active)
Parameters

activebool

See also

isActive()

static PySide2.QtGui.QAccessible.setRootObject(object)
Parameters

objectQObject

Sets the root object of the accessible objects of this application to object . All other accessible objects are reachable using object navigation from the root object.

Normally, it isn’t necessary to call this function, because Qt sets the QApplication object as the root object immediately before the event loop is entered in exec() .

Use to redirect the function call to a customized handler function.

static PySide2.QtGui.QAccessible.uniqueId(iface)
Parameters

ifaceQAccessibleInterface

Return type

long

Returns the unique ID for the QAccessibleInterface iface .

static PySide2.QtGui.QAccessible.updateAccessibility(event)
Parameters

eventQAccessibleEvent

Notifies about a change that might be relevant for accessibility clients.

event provides details about the change. These include the source of the change and the nature of the change. The event should contain enough information give meaningful notifications.

For example, the type ValueChange indicates that the position of a slider has been changed.

Call this function whenever the state of your accessible object or one of its sub-elements has been changed either programmatically (e.g. by calling setText() ) or by user interaction.

If there are no accessibility tools listening to this event, the performance penalty for calling this function is small, but if determining the parameters of the call is expensive you can test isActive() to avoid unnecessary computation.