A11yLensOverlay class

Wrap the root of an app in A11yLensOverlay to audit it live:

void main() {
  runApp(A11yLensOverlay(child: const MyApp()));
}

After every frame, it walks the widget tree below child, runs rules and semanticsRules against the snapshot, and draws a colored outline over each violating widget — red for A11ySeverity.error, amber for A11ySeverity.warning, blue for A11ySeverity.info. Tapping an outline opens a popover with the rule, message, and suggested fix.

semanticsRules (on by default) reads the real SemanticsNode tree rather than the Element tree, so it needs an active SemanticsHandle to make the engine compute it — this widget acquires one automatically whenever semanticsRules is non-empty, for as long as it's mounted and enabled. That has a real (debug/profile-only) performance cost; pass semanticsRules: [] to opt out if it matters for a given session. Its own outline/popover widgets are built with excludeFromSemantics: true so they never show up in that tree themselves.

A no-op in release builds: build returns child unchanged, so the walkers, rules, and overlay widgets are all compiled away since kReleaseMode is a compile-time constant. Set enabled to false to also disable it in debug/profile builds (e.g. behind a feature flag).

Inheritance

Constructors

A11yLensOverlay({Key? key, required Widget child, List<A11yRule> rules = const [ContrastRule(), TapTargetSizeRule()], List<A11ySemanticsRule> semanticsRules = const [SemanticLabelRule(), FocusOrderRule()], bool enabled = true})
const

Properties

child → Widget
final
enabled → bool
Set to false to disable auditing without removing the widget (e.g. from a debug settings toggle). Has no effect in release builds, which are always disabled.
final
hashCode → int
The hash code for this object.
no setterinherited
key → Key?
Controls how one widget replaces another widget in the tree.
finalinherited
rules → List<A11yRule>
Element-tree-based checks run against every walked frame. Defaults to the built-in contrast and tap-target-size rules; pass a custom list to add team-specific rules or drop the defaults.
final
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
semanticsRules → List<A11ySemanticsRule>
Semantics-tree-based checks run against every walked frame. Defaults to the built-in semantic-label and focus-order rules. Pass an empty list to disable semantics auditing (and the SemanticsHandle it requires) entirely.
final

Methods

createElement() → StatefulElement
Creates a StatefulElement to manage this widget's location in the tree.
inherited
createState() → State<A11yLensOverlay>
Creates the mutable state for this widget at a given location in the tree.
override
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
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