IndexedSemanticsModifier class

A widget that annotates the child semantics with an index.

Semantic indexes are used by TalkBack/Voiceover to make announcements about the current scroll state. Certain widgets like the ListView will automatically provide a child index for building semantics. A user may wish to manually provide semantic indexes if not all child of the scrollable contribute semantics.

{@tool snippet}

The example below handles spacers in a scrollable that don't contribute semantics. The automatic indexes would give the spaces a semantic index, causing scroll announcements to erroneously state that there are four items visible.

ListView(
  addSemanticIndexes: false,
  semanticChildCount: 2,
  children: const <Widget>[
    IndexedSemantics(index: 0, child: Text('First')),
    Spacer(),
    IndexedSemantics(index: 1, child: Text('Second')),
    Spacer(),
  ],
)

{@end-tool}

See also:

• CustomScrollView, for an explanation of index semantics.

Inheritance

• Object
• DiagnosticableTree
• Widget
• StatelessWidget
• SingleChildStatelessModifier
• IndexedSemanticsModifier

Available extensions

• ModifierTransformer

Constructors

IndexedSemanticsModifier({Key? key, Key? modifierKey, required int index, Widget? child})

Creates a widget that annotated the first child semantics node with an index.

const

Properties

hashCode → int

The hash code for this object.

no setter, inherited

index → int

The index used to annotate the first child semantics node.

final

key → Key?

Controls how one widget replaces another widget in the tree.

final, inherited

modifierKey → Key?

The actual key of the widget, which Modifier wrapped

final, inherited

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

Methods

build(BuildContext context) → Widget

Describes the part of the user interface represented by this widget.

inherited

buildWithChild(BuildContext context, Widget? child) → Widget

A build method that receives an extra child parameter.

override

createElement() → SingleChildStatelessElement

Create a SingleChildStatelessElement

inherited

debugDescribeChildren() → List<DiagnosticsNode>

Returns a list of DiagnosticsNode objects describing this node's children.

inherited

debugFillProperties(DiagnosticPropertiesBuilder properties) → void

Add additional properties associated with the node.

inherited

modified() → Modifier

Available on Widget, provided by the ModifierTransformer extension

Transform normal widget to Modifier

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent 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

A string representation of this object.

inherited

toStringDeep({String prefixLineOne = '', String? prefixOtherLines, DiagnosticLevel minLevel = DiagnosticLevel.debug, int wrapWidth = 65}) → 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

Operators

operator ==(Object other) → bool

The equality operator.

inherited