[web] better class names for semantics

lib/web_ui/lib/src/engine/semantics/checkable.dart

@@ -49,11 +49,11 @@ _CheckableKind _checkableKindFromSemanticsFlag(
 /// See also [ui.SemanticsFlag.hasCheckedState], [ui.SemanticsFlag.isChecked],
 /// [ui.SemanticsFlag.isInMutuallyExclusiveGroup], [ui.SemanticsFlag.isToggled],
 /// [ui.SemanticsFlag.hasToggledState]
-class Checkable extends PrimaryRoleManager {
+class Checkable extends SemanticRole {
   Checkable(SemanticsObject semanticsObject)
       : _kind = _checkableKindFromSemanticsFlag(semanticsObject),
         super.withBasics(
-          PrimaryRole.checkable,
+          SemanticRoleId.checkable,
           semanticsObject,
           preferredLabelRepresentation: LabelRepresentation.ariaLabel,
         ) {

lib/web_ui/lib/src/engine/semantics/dialog.dart

@@ -6,12 +6,10 @@ import '../dom.dart';
 import '../semantics.dart';
 import '../util.dart';
 
-/// Provides accessibility for dialogs.
-///
-/// See also [Role.dialog].
-class Dialog extends PrimaryRoleManager {
-  Dialog(SemanticsObject semanticsObject) : super.blank(PrimaryRole.dialog, semanticsObject) {
-    // The following secondary roles can coexist with dialog. Generic `RouteName`
+/// Provides accessibility for routes, including dialogs and pop-up menus.
+class Dialog extends SemanticRole {
+  Dialog(SemanticsObject semanticsObject) : super.blank(SemanticRoleId.dialog, semanticsObject) {
+    // The following behaviors can coexist with dialog. Generic `RouteName`
     // and `LabelAndValue` are not used by this role because when the dialog
     // names its own route an `aria-label` is used instead of `aria-describedby`.
     addFocusManagement();
@@ -39,7 +37,7 @@ class Dialog extends PrimaryRoleManager {
 
   void _setDefaultFocus() {
     semanticsObject.visitDepthFirstInTraversalOrder((SemanticsObject node) {
-      final PrimaryRoleManager? roleManager = node.primaryRole;
+      final SemanticRole? roleManager = node.semanticRole;
       if (roleManager == null) {
         return true;
       }
@@ -100,11 +98,15 @@ class Dialog extends PrimaryRoleManager {
 }
 
 /// Supplies a description for the nearest ancestor [Dialog].
-class RouteName extends RoleManager {
-  RouteName(
-    SemanticsObject semanticsObject,
-    PrimaryRoleManager owner,
-  ) : super(Role.routeName, semanticsObject, owner);
+///
+/// This role is assigned to nodes that have `namesRoute` set but not
+/// `scopesRoute`. When both flags are set the node only gets the [Dialog] role.
+///
+/// If the ancestor dialog is missing, this role has no effect. It is up to the
+/// framework, widget, and app authors to make sure a route name is scoped under
+/// a route.
+class RouteName extends SemanticBehavior {
+  RouteName(super.semanticsObject, super.owner);
 
   Dialog? _dialog;
 
@@ -143,11 +145,11 @@ class RouteName extends RoleManager {
 
   void _lookUpNearestAncestorDialog() {
     SemanticsObject? parent = semanticsObject.parent;
-    while (parent != null && parent.primaryRole?.role != PrimaryRole.dialog) {
+    while (parent != null && parent.semanticRole?.role != SemanticRoleId.dialog) {
       parent = parent.parent;
     }
-    if (parent != null && parent.primaryRole?.role == PrimaryRole.dialog) {
-      _dialog = parent.primaryRole! as Dialog;
+    if (parent != null && parent.semanticRole?.role == SemanticRoleId.dialog) {
+      _dialog = parent.semanticRole! as Dialog;
     }
   }
 }

lib/web_ui/lib/src/engine/semantics/focusable.dart

@@ -12,9 +12,9 @@ import 'semantics.dart';
 /// Supplies generic accessibility focus features to semantics nodes that have
 /// [ui.SemanticsFlag.isFocusable] set.
 ///
-/// Assumes that the element being focused on is [SemanticsObject.element]. Role
-/// managers with special needs can implement custom focus management and
-/// exclude this role manager.
+/// Assumes that the element being focused on is [SemanticsObject.element].
+/// Semantic roles with special needs can implement custom focus management and
+/// exclude this behavior.
 ///
 /// `"tab-index=0"` is used because `<flt-semantics>` is not intrinsically
 /// focusable. Examples of intrinsically focusable elements include:
@@ -27,10 +27,9 @@ import 'semantics.dart';
 /// See also:
 ///
 ///   * https://developer.mozilla.org/en-US/docs/Web/Accessibility/Keyboard-navigable_JavaScript_widgets
-class Focusable extends RoleManager {
-  Focusable(SemanticsObject semanticsObject, PrimaryRoleManager owner)
-      : _focusManager = AccessibilityFocusManager(semanticsObject.owner),
-        super(Role.focusable, semanticsObject, owner);
+class Focusable extends SemanticBehavior {
+  Focusable(super.semanticsObject, super.owner)
+      : _focusManager = AccessibilityFocusManager(semanticsObject.owner);
 
   final AccessibilityFocusManager _focusManager;
 
@@ -44,9 +43,9 @@ class Focusable extends RoleManager {
   /// programmatically, simulating the screen reader choosing a default element
   /// to focus on.
   ///
-  /// Returns `true` if the role manager took the focus. Returns `false` if
-  /// this role manager did not take the focus. The return value can be used to
-  /// decide whether to stop searching for a node that should take focus.
+  /// Returns `true` if the node took the focus. Returns `false` if the node did
+  /// not take the focus. The return value can be used to decide whether to stop
+  /// searching for a node that should take focus.
   bool focusAsRouteDefault() {
     _focusManager._lastEvent = AccessibilityFocusManagerEvent.requestedFocus;
     owner.element.focusWithoutScroll();

lib/web_ui/lib/src/engine/semantics/heading.dart

@@ -8,9 +8,9 @@ import 'semantics.dart';
 
 /// Renders semantics objects as headings with the corresponding
 /// level (h1 ... h6).
-class Heading extends PrimaryRoleManager {
+class Heading extends SemanticRole {
   Heading(SemanticsObject semanticsObject)
-      : super.blank(PrimaryRole.heading, semanticsObject) {
+      : super.blank(SemanticRoleId.heading, semanticsObject) {
     addFocusManagement();
     addLiveRegion();
     addRouteName();

lib/web_ui/lib/src/engine/semantics/image.dart

@@ -10,11 +10,11 @@ import 'semantics.dart';
 /// Uses aria img role to convey this semantic information to the element.
 ///
 /// Screen-readers takes advantage of "aria-label" to describe the visual.
-class ImageRoleManager extends PrimaryRoleManager {
-  ImageRoleManager(SemanticsObject semanticsObject)
-      : super.blank(PrimaryRole.image, semanticsObject) {
-    // The following secondary roles can coexist with images. `LabelAndValue` is
-    // not used because this role manager uses special auxiliary elements to
+class ImageSemanticRole extends SemanticRole {
+  ImageSemanticRole(SemanticsObject semanticsObject)
+      : super.blank(SemanticRoleId.image, semanticsObject) {
+    // The following behaviors can coexist with images. `LabelAndValue` is
+    // not used because this behavior uses special auxiliary elements to
     // supply ARIA labels.
     // TODO(yjbanov): reevaluate usage of aux elements, https://github.com/flutter/flutter/issues/129317
     addFocusManagement();

lib/web_ui/lib/src/engine/semantics/incrementable.dart

@@ -19,10 +19,10 @@ import 'semantics.dart';
 /// The input element is disabled whenever the gesture mode switches to pointer
 /// events. This is to prevent the browser from taking over drag gestures. Drag
 /// gestures must be interpreted by the Flutter framework.
-class Incrementable extends PrimaryRoleManager {
+class Incrementable extends SemanticRole {
   Incrementable(SemanticsObject semanticsObject)
       : _focusManager = AccessibilityFocusManager(semanticsObject.owner),
-        super.blank(PrimaryRole.incrementable, semanticsObject) {
+        super.blank(SemanticRoleId.incrementable, semanticsObject) {
     // The following generic roles can coexist with incrementables. Generic focus
     // management is not used by this role because the root DOM element is not
     // the one being focused on, but the internal `<input>` element.

lib/web_ui/lib/src/engine/semantics/label_and_value.dart

@@ -48,7 +48,7 @@ enum LabelRepresentation {
   sizedSpan;
 
   /// Creates the behavior for this label representation.
-  LabelRepresentationBehavior createBehavior(PrimaryRoleManager owner) {
+  LabelRepresentationBehavior createBehavior(SemanticRole owner) {
     return switch (this) {
       ariaLabel => AriaLabelRepresentation._(owner),
       domText => DomTextRepresentation._(owner),
@@ -63,8 +63,8 @@ abstract final class LabelRepresentationBehavior {
 
   final LabelRepresentation kind;
 
-  /// The role manager that this label representation is attached to.
-  final PrimaryRoleManager owner;
+  /// The role that this label representation is attached to.
+  final SemanticRole owner;
 
   /// Convenience getter for the corresponding semantics object.
   SemanticsObject get semanticsObject => owner.semanticsObject;
@@ -109,7 +109,7 @@ abstract final class LabelRepresentationBehavior {
 ///
 ///     <flt-semantics aria-label="Hello, World!"></flt-semantics>
 final class AriaLabelRepresentation extends LabelRepresentationBehavior {
-  AriaLabelRepresentation._(PrimaryRoleManager owner) : super(LabelRepresentation.ariaLabel, owner);
+  AriaLabelRepresentation._(SemanticRole owner) : super(LabelRepresentation.ariaLabel, owner);
 
   String? _previousLabel;
 
@@ -143,7 +143,7 @@ final class AriaLabelRepresentation extends LabelRepresentationBehavior {
 /// no ARIA role set, or the role does not size the element, then the
 /// [SizedSpanRepresentation] representation can be used.
 final class DomTextRepresentation extends LabelRepresentationBehavior {
-  DomTextRepresentation._(PrimaryRoleManager owner) : super(LabelRepresentation.domText, owner);
+  DomTextRepresentation._(SemanticRole owner) : super(LabelRepresentation.domText, owner);
 
   DomText? _domText;
   String? _previousLabel;
@@ -233,7 +233,7 @@ typedef _Measurement = ({
 /// * Use an existing non-text role, e.g. "heading". Sizes correctly, but breaks
 ///   the message (reads "heading").
 final class SizedSpanRepresentation extends LabelRepresentationBehavior {
-  SizedSpanRepresentation._(PrimaryRoleManager owner) : super(LabelRepresentation.sizedSpan, owner) {
+  SizedSpanRepresentation._(SemanticRole owner) : super(LabelRepresentation.sizedSpan, owner) {
     _domText.style
       // `inline-block` is needed for two reasons:
       // - It supports measuring the true size of the text. Pure `block` would
@@ -433,14 +433,13 @@ final class SizedSpanRepresentation extends LabelRepresentationBehavior {
   DomElement get focusTarget => _domText;
 }
 
-/// Renders [SemanticsObject.label] and/or [SemanticsObject.value] to the semantics DOM.
+/// Renders the label for a [SemanticsObject] that can be scanned by screen
+/// readers, web crawlers, and other automated agents.
 ///
-/// The value is not always rendered. Some semantics nodes correspond to
-/// interactive controls. In such case the value is reported via that element's
-/// `value` attribute rather than rendering it separately.
-class LabelAndValue extends RoleManager {
-  LabelAndValue(SemanticsObject semanticsObject, PrimaryRoleManager owner, { required this.preferredRepresentation })
-      : super(Role.labelAndValue, semanticsObject, owner);
+/// See [computeDomSemanticsLabel] for the exact logic that constructs the label
+/// of a semantic node.
+class LabelAndValue extends SemanticBehavior {
+  LabelAndValue(super.semanticsObject, super.owner, { required this.preferredRepresentation });
 
   /// The preferred representation of the label in the DOM.
   ///
@@ -471,7 +470,7 @@ class LabelAndValue extends RoleManager {
   /// If the node has children always use an `aria-label`. Using extra child
   /// nodes to represent the label will cause layout shifts and confuse the
   /// screen reader. If the are no children, use the representation preferred
-  /// by the primary role manager.
+  /// by the role.
   LabelRepresentationBehavior _getEffectiveRepresentation() {
     final LabelRepresentation effectiveRepresentation = semanticsObject.hasChildren
       ? LabelRepresentation.ariaLabel
@@ -491,7 +490,7 @@ class LabelAndValue extends RoleManager {
   /// combination is present.
   String? _computeLabel() {
     // If the node is incrementable the value is reported to the browser via
-    // the respective role manager. We do not need to also render it again here.
+    // the respective role. We do not need to also render it again here.
     final bool shouldDisplayValue = !semanticsObject.isIncrementable && semanticsObject.hasValue;
 
     return computeDomSemanticsLabel(

lib/web_ui/lib/src/engine/semantics/link.dart

@@ -6,9 +6,9 @@ import '../dom.dart';
 import '../semantics.dart';
 
 /// Provides accessibility for links.
-class Link extends PrimaryRoleManager {
+class Link extends SemanticRole {
   Link(SemanticsObject semanticsObject) : super.withBasics(
-    PrimaryRole.link,
+    SemanticRoleId.link,
     semanticsObject,
     preferredLabelRepresentation: LabelRepresentation.domText,
   ) {

lib/web_ui/lib/src/engine/semantics/live_region.dart

@@ -10,15 +10,21 @@ import 'semantics.dart';
 
 /// Manages semantics configurations that represent live regions.
 ///
-/// Assistive technologies treat "aria-live" attribute differently. To keep
-/// the behavior consistent, [AccessibilityAnnouncements.announce] is used.
+/// A live region is a region whose changes will be announced by the screen
+/// reader without the user moving focus onto the node.
+///
+/// Examples of live regions include snackbars and text field errors. Once
+/// identified with this role, they will be able to get the assistive
+/// technology's attention right away.
+///
+/// Different assistive technologies treat "aria-live" attribute differently. To
+/// keep the behavior consistent, [AccessibilityAnnouncements.announce] is used.
 ///
 /// When there is an update to [LiveRegion], assistive technologies read the
 /// label of the element. See [LabelAndValue]. If there is no label provided
 /// no content will be read.
-class LiveRegion extends RoleManager {
-  LiveRegion(SemanticsObject semanticsObject, PrimaryRoleManager owner)
-      : super(Role.liveRegion, semanticsObject, owner);
+class LiveRegion extends SemanticBehavior {
+  LiveRegion(super.semanticsObject, super.owner);
 
   String? _lastAnnouncement;
 

lib/web_ui/lib/src/engine/semantics/platform_view.dart

@@ -20,10 +20,10 @@ import 'semantics.dart';
 /// See also:
 ///   * https://developer.mozilla.org/en-US/docs/Web/Accessibility/ARIA/Attributes/aria-owns
 ///   * https://bugs.webkit.org/show_bug.cgi?id=223798
-class PlatformViewRoleManager extends PrimaryRoleManager {
-  PlatformViewRoleManager(SemanticsObject semanticsObject)
+class PlatformViewSemanticRole extends SemanticRole {
+  PlatformViewSemanticRole(SemanticsObject semanticsObject)
       : super.withBasics(
-          PrimaryRole.platformView,
+          SemanticRoleId.platformView,
           semanticsObject,
           preferredLabelRepresentation: LabelRepresentation.ariaLabel,
         );

lib/web_ui/lib/src/engine/semantics/scrollable.dart

@@ -22,10 +22,10 @@ import 'package:ui/ui.dart' as ui;
 /// contents is less than the size of the viewport the browser snaps
 /// "scrollTop" back to zero. If there is more content than available in the
 /// viewport "scrollTop" may take positive values.
-class Scrollable extends PrimaryRoleManager {
+class Scrollable extends SemanticRole {
   Scrollable(SemanticsObject semanticsObject)
       : super.withBasics(
-          PrimaryRole.scrollable,
+          SemanticRoleId.scrollable,
           semanticsObject,
           preferredLabelRepresentation: LabelRepresentation.ariaLabel,
         ) {