Semantics class
A widget that annotates the widget tree with a description of the meaning of the widgets.
Used by accessibility tools, search engines, and other semantic analysis software to determine the meaning of the application.
See also:
- MergeSemantics, which marks a subtree as being a single node for accessibility purposes.
- ExcludeSemantics, which excludes a subtree from the semantics tree (which might be useful if it is, e.g., totally decorative and not important to the user).
- RenderObject.describeSemanticsConfiguration, the rendering library API through which the Semantics widget is actually implemented.
- SemanticsNode, the object used by the rendering library to represent semantics in the semantics tree.
- SemanticsDebugger, an overlay to help visualize the semantics tree. Can be enabled using WidgetsApp.showSemanticsDebugger or MaterialApp.showSemanticsDebugger.
- Inheritance
- Annotations
- @immutable
Constructors
-
Semantics({Key key,
Widget child, bool container: false, bool explicitChildNodes: false, bool excludeSemantics: false, bool enabled, bool checked, bool selected, bool toggled, bool button, bool link, bool header, bool textField, bool readOnly, bool focusable, bool focused, bool inMutuallyExclusiveGroup, bool obscured, bool multiline, bool scopesRoute, bool namesRoute, bool image, bool liveRegion, int maxValueLength, int currentValueLength, String label, String value, String increasedValue, String decreasedValue, String hint, String onTapHint, String onLongPressHint, TextDirection textDirection, SemanticsSortKey sortKey, VoidCallback onTap, VoidCallback onLongPress, VoidCallback onScrollLeft, VoidCallback onScrollRight, VoidCallback onScrollUp, VoidCallback onScrollDown, VoidCallback onIncrease, VoidCallback onDecrease, VoidCallback onCopy, VoidCallback onCut, VoidCallback onPaste, VoidCallback onDismiss, void onMoveCursorForwardByCharacter(bool extendSelection ), void onMoveCursorBackwardByCharacter(bool extendSelection ), void onSetSelection(TextSelection selection ), VoidCallback onDidGainAccessibilityFocus, VoidCallback onDidLoseAccessibilityFocus, Map< CustomSemanticsAction, VoidCallback> customSemanticsActions}) - Creates a semantic annotation. [...]
-
Semantics.fromProperties({Key key,
Widget child, bool container: false, bool explicitChildNodes: false, bool excludeSemantics: false, @required SemanticsProperties properties} ) -
Creates a semantic annotation using SemanticsProperties. [...]
const
Properties
- child → Widget
-
The widget below this widget in the tree. [...]
final, inherited
- container → bool
-
If container is true, this widget will introduce a new
node in the semantics tree. Otherwise, the semantics will be
merged with the semantics of any ancestors (if the ancestor allows that). [...]
final
- excludeSemantics → bool
-
Whether to replace all child semantics with this node. [...]
final
- explicitChildNodes → bool
-
Whether descendants of this widget are allowed to add semantic information
to the SemanticsNode annotated by this widget. [...]
final
- hashCode → int
-
The hash code for this object. [...]
@nonVirtual, read-only, inherited
- key → Key
-
Controls how one widget replaces another widget in the tree. [...]
final, inherited
- properties → SemanticsProperties
-
Contains properties used by assistive technologies to make the application
more accessible.
final
- runtimeType → Type
-
A representation of the runtime type of the object.
read-only, inherited
Methods
-
createElement(
) → SingleChildRenderObjectElement -
RenderObjectWidgets always inflate to a RenderObjectElement subclass.
inherited
-
createRenderObject(
BuildContext context ) → RenderSemanticsAnnotations -
Creates an instance of the RenderObject class that this
RenderObjectWidget represents, using the configuration described by this
RenderObjectWidget. [...]
override
-
debugDescribeChildren(
) → List< DiagnosticsNode> -
Returns a list of DiagnosticsNode objects describing this node's
children. [...]
@protected, inherited
-
debugFillProperties(
DiagnosticPropertiesBuilder properties ) → void -
Add additional properties associated with the node. [...]
override
-
didUnmountRenderObject(
covariant RenderObject renderObject ) → void -
A render object previously associated with this widget has been removed
from the tree. The given RenderObject will be of the same type as
returned by this object's createRenderObject.
@protected, inherited
-
noSuchMethod(
Invocation invocation ) → dynamic -
Invoked when a non-existent method or property is accessed. [...]
inherited
-
toDiagnosticsNode(
{String name, DiagnosticsTreeStyle style} ) → DiagnosticsNode -
Returns a debug representation of the object that is used by debugging
tools and by DiagnosticsNode.toStringDeep. [...]
inherited
-
toString(
{DiagnosticLevel minLevel: DiagnosticLevel.info} ) → String -
Returns a string representation of this object.
inherited
-
toStringDeep(
{String prefixLineOne: '', String prefixOtherLines, DiagnosticLevel minLevel: DiagnosticLevel.debug} ) → String -
Returns a string representation of this node and its descendants. [...]
inherited
-
toStringShallow(
{String joiner: ', ', DiagnosticLevel minLevel: DiagnosticLevel.debug} ) → String -
Returns a one-line detailed description of the object. [...]
inherited
-
toStringShort(
) → String -
A short, textual description of this widget.
inherited
-
updateRenderObject(
BuildContext context, covariant RenderSemanticsAnnotations renderObject ) → void -
Copies the configuration described by this RenderObjectWidget to the
given RenderObject, which will be of the same type as returned by this
object's createRenderObject. [...]
override
Operators
-
operator ==(
Object other ) → bool -
The equality operator. [...]
@nonVirtual, inherited