Role class
Allows ARIA Accessibility attributes to be added to widgets so that they can be identified by assistive technology.
ARIA roles define widgets and page structure that can be interpreted by a reader application/device. There is a set of abstract roles which are used as building blocks of the roles hierarchy structural and define the common properties and states for the concrete roles. Abstract roles cannot be set to HTML elements.
This class defines some of the supported operations for a role -- set/get/remove role to/from a DOM element.
For more details about ARIA roles check The Roles Model .
class Role {
static final String ATTR_NAME_ROLE = "role";
String _roleName;
Role(String roleName) {
assert (roleName != null); // : "Role name cannot be null";
this._roleName = roleName;
}
/**
* Gets the role for the element {@code element}. If none is set, "" is returned.
*
* @param element HTML element
* @return The role attribute value
*/
String get(dart_html.Element element) {
assert (element != null); // : "Element cannot be null.";
return element.attributes[ATTR_NAME_ROLE];
}
/**
* Gets the role name
*
* @return The role name
*/
String getName() {
return _roleName;
}
/**
* Removes the role for element {@code element}
*
* @param element HTML element
*/
void remove(dart_html.Element element) {
assert (element != null); // : "Element cannot be null.";
element.attributes.remove(ATTR_NAME_ROLE);
}
/**
* Sets the role to element {@code element}
*
* @param element HTML element
*/
void set(dart_html.Element element) {
assert (element != null); // : "Element cannot be null.";
element.attributes[ATTR_NAME_ROLE] = _roleName;
}
}
Subclasses
Static Properties
final String ATTR_NAME_ROLE #
static final String ATTR_NAME_ROLE = "role"
Constructors
new Role(String roleName) #
Creates a new Object instance.
Object instances have no meaningful state, and are only useful through their identity. An Object instance is equal to itself only.
Role(String roleName) {
assert (roleName != null); // : "Role name cannot be null";
this._roleName = roleName;
}
Methods
String get(Element element) #
Gets the role for the element {@code element}. If none is set, "" is returned.
@param element HTML element @return The role attribute value
String get(dart_html.Element element) {
assert (element != null); // : "Element cannot be null.";
return element.attributes[ATTR_NAME_ROLE];
}
String getName() #
Gets the role name
@return The role name
String getName() {
return _roleName;
}
void remove(Element element) #
Removes the role for element {@code element}
@param element HTML element
void remove(dart_html.Element element) {
assert (element != null); // : "Element cannot be null.";
element.attributes.remove(ATTR_NAME_ROLE);
}
void set(Element element) #
Sets the role to element {@code element}
@param element HTML element
void set(dart_html.Element element) {
assert (element != null); // : "Element cannot be null.";
element.attributes[ATTR_NAME_ROLE] = _roleName;
}