TLazAccessibleObject class

In unit Controls

Represents an accessibility object for user or accessibility tool interactions.

Declaration

pascal

TLazAccessibleObject = class

Description

Every TControl has a TLazAccessibleObject instance associated with it, which means that every TControl is potentially accessible. But to actually be usable, the accessible object needs to have its properties set, the most important of which are the role, description and value. Native windowed classes should already receive accessibility properties from the underlying widgetset, while TCustomControl descendants will use the accessibility properties provided by LCL itself.

User applications should add accessibility for their own TCustomControl descendant classes, and possibly customize the descriptions of some elements. It is also possible to make an accessible object invisible to the user, which is done by setting its AccessibleRole property to larIgnored.

Accessibility support in Lazarus is also documented on the Wiki at: https://wiki.lazarus.freepascal.org/LCL_Accessibility.

Properties

`AccessibleName`	public	The name for this accessible object.
`AccessibleDescription`	public	The description of this accessible object.
`AccessibleValue`	public	The value of this accessible object.
`AccessibleRole`	public	The role of this accessible object.
`Position`	public	The position of this accessible object.
`Size`	public	The size of this accessible object.
`Handle`	public	The widgetset handle of this accessible object.

Methods

`WSRegisterClass`	protected	Registers this component class with the current WidgetSet.
`GetAccessibleValue`	protected	Gets the value for the AccessibleValue property.
`GetHandle`	protected	Gets the value for the Handle property.
`Create`	public	Constructor for the class instance.
`Destroy`	public	Destructor for the class instance.
`HandleAllocated`	public	Returns if the handle of this object was already allocated or not.
`InitializeHandle`	public	Utilized to set all properties of this property via widgetset routines when creating the handle.
`SetAccessibleName`	public	Sets the value for AccessibleName.
`SetAccessibleDescription`	public	Setter for the property AccessibleDescription.
`SetAccessibleValue`	public	Setter for the property AccessibleValue.
`SetAccessibleRole`	public	Setter for the property AccessibleRole.
`FindOwnerWinControl`	public	Inspect the tree of accessible objects upwards until it finds a parent which is attached directly to a windowed control, a TWinControl.
`AddChildAccessibleObject`	public	Creates and returns a new child accessibility object.
`InsertChildAccessibleObject`	public	Inserts an already created child accessible object as a child of this one.
`ClearChildAccessibleObjects`	public	Removes all children of this control; freed if they are not attached to a TControl instance.
`RemoveChildAccessibleObject`	public	Removes a child accessible object.
`GetChildAccessibleObjectWithDataObject`	public	Obtains a child accessible object by its DataObject property.
`GetChildAccessibleObjectsCount`	public	Returns the number of direct children that this accessible object has.
`GetChildAccessibleObject`	public	Obtains a child accessible object by its index.
`GetFirstChildAccessibleObject`	public	Searches in sub-controls for the first child accessibility object.
`GetNextChildAccessibleObject`	public	Searches in sub-controls for the next child accessibility object.
`GetSelectedChildAccessibleObject`	public	Returns the currently selected child accessible object or Nil if none are selected; Override this method in your sub class.
`GetChildAccessibleObjectAtPos`	public	Returns the child of this control located at a particular position given as a client position for the control.
`GetEnumerator`	public	Default enumerator for the children.

Fields

`FHandle`	protected	Member with the Handle for the accessibility object.
`FChildrenSortedForDataObject`	protected	Member with the AVL tree for the sorted child objects.
`FAccessibleName`	protected	Member with the value for AccessibleName.
`FAccessibleDescription`	protected	Member with the value for AccessibleDescription.
`FAccessibleValue`	protected	Member with the value for AccessibleValue.
`FAccessibleRole`	protected	Member with the value for AccessibleRole.
`OwnerControl`	public	The control that this accessible object is attached to. It might be the main accessible object of this control or it might represent a sub-part of a control.
`Parent`	public	The parent TLazAccessibleObject of this accessible object.
`DataObject`	public	Available to be used to connect to an object.
`SecondaryHandle`	public	Available for Widgetsets to use.

An experiment, built from development snapshots. Not the official Free Pascal or Lazarus documentation.