Bug 1824935 part 3: Add Accessible::ComputedARIARole. r=eeejay

This also exposes this via XPCOM.
This will be used by WebDriver and Dev Tools.

Differential Revision: https://phabricator.services.mozilla.com/D175583

accessible/basetypes/Accessible.cpp

@@ -529,6 +529,47 @@ nsStaticAtom* Accessible::LandmarkRole() const {
              : nullptr;
 }
 
+nsStaticAtom* Accessible::ComputedARIARole() const {
+  const nsRoleMapEntry* roleMap = ARIARoleMap();
+  if (roleMap && roleMap->roleAtom != nsGkAtoms::_empty &&
+      // region has its own Gecko role and it needs to be handled specially.
+      roleMap->roleAtom != nsGkAtoms::region &&
+      (roleMap->roleRule == kUseNativeRole || roleMap->IsOfType(eLandmark) ||
+       roleMap->roleAtom == nsGkAtoms::alertdialog ||
+       roleMap->roleAtom == nsGkAtoms::feed ||
+       roleMap->roleAtom == nsGkAtoms::rowgroup ||
+       roleMap->roleAtom == nsGkAtoms::searchbox)) {
+    // Explicit ARIA role (e.g. specified via the role attribute) which does not
+    // map to a unique Gecko role.
+    return roleMap->roleAtom;
+  }
+  role geckoRole = Role();
+  if (geckoRole == roles::LANDMARK) {
+    // Landmark role from native markup; e.g. <main>, <nav>.
+    return LandmarkRole();
+  }
+  if (geckoRole == roles::GROUPING) {
+    // Gecko doesn't differentiate between group and rowgroup. It uses
+    // roles::GROUPING for both.
+    nsAtom* tag = TagName();
+    if (tag == nsGkAtoms::tbody || tag == nsGkAtoms::tfoot ||
+        tag == nsGkAtoms::thead) {
+      return nsGkAtoms::rowgroup;
+    }
+  }
+  // Role from native markup or layout.
+#define ROLE(_geckoRole, stringRole, ariaRole, atkRole, macRole, macSubrole, \
+             msaaRole, ia2Role, androidClass, nameRule)                      \
+  case roles::_geckoRole:                                                    \
+    return ariaRole;
+  switch (geckoRole) {
+#include "RoleMap.h"
+  }
+#undef ROLE
+  MOZ_ASSERT_UNREACHABLE("Unknown role");
+  return nullptr;
+}
+
 void Accessible::ApplyImplicitState(uint64_t& aState) const {
   // nsAccessibilityService (and thus FocusManager) can be shut down before
   // RemoteAccessibles.

accessible/basetypes/Accessible.h

@@ -352,6 +352,13 @@ class Accessible {
    */
   virtual void Language(nsAString& aLocale) = 0;
 
+  /**
+   * Get the role of this Accessible as an ARIA role token. This might have been
+   * set explicitly (e.g. role="button") or it might be implicit in native
+   * markup (e.g. <button> returns "button").
+   */
+  nsStaticAtom* ComputedARIARole() const;
+
   // Methods that interact with content.
 
   virtual void TakeFocus() const = 0;

accessible/interfaces/nsIAccessible.idl

@@ -345,6 +345,13 @@ interface nsIAccessible : nsISupports
    */
   void announce(in AString announcement, in unsigned short priority);
 
+  /**
+   * Get the role of this Accessible as an ARIA role token. This might have been
+   * set explicitly (e.g. role="button") or it might be implicit in native
+   * markup (e.g. <button> returns "button").
+   */
+  readonly attribute AString computedARIARole;
+
   [notxpcom, nostdcall] InternalLocalAccessible toInternalAccessible();
   [notxpcom, nostdcall] InternalAccessible toInternalGeneric();
 

accessible/moz.build

@@ -40,6 +40,7 @@ BROWSER_CHROME_MANIFESTS += [
     "tests/browser/general/browser.ini",
     "tests/browser/hittest/browser.ini",
     "tests/browser/mac/browser.ini",
+    "tests/browser/role/browser.ini",
     "tests/browser/scroll/browser.ini",
     "tests/browser/selectable/browser.ini",
     "tests/browser/states/browser.ini",

accessible/tests/browser/role/browser.ini

@@ -0,0 +1,11 @@
+[DEFAULT]
+subsuite = a11y
+support-files =
+  head.js
+  !/accessible/tests/browser/shared-head.js
+  !/accessible/tests/mochitest/*.js
+  !/accessible/tests/browser/*.mjs
+prefs =
+  javascript.options.asyncstack_capture_debuggee_only=false
+
+[browser_computedARIARole.js]

accessible/tests/browser/role/browser_computedARIARole.js

@@ -0,0 +1,88 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+addAccessibleTask(
+  `
+<div id="ariaButton" role="button">ARIA button</div>
+<div id="ariaLog" role="log">ARIA log</div>
+<div id="ariaMain" role="main">ARIA main</div>
+<div id="ariaRegion" role="region" aria-label="ARIA region">ARIA region</div>
+<nav id="ariaUnnamedRegion" role="region">ARIA unnamed region</nav>
+<div id="ariaDirectory" role="directory">ARIA directory</div>
+<div id="ariaAlertdialog" role="alertdialog">ARIA alertdialog</div>
+<div id="ariaFeed" role="feed">ARIA feed</div>
+<div id="ariaRowgroup" role="rowgroup">ARIA rowgroup</div>
+<div id="ariaSearchbox" role="searchbox">ARIA searchbox</div>
+<div id="ariaUnknown" role="unknown">unknown ARIA role</div>
+<button id="htmlButton">HTML button</button>
+<button id="toggleButton" aria-pressed="true">toggle button</button>
+<main id="htmlMain">HTML main</main>
+<header id="htmlHeader">HTML header</header>
+<section id="htmlSection">
+  <header id="htmlSectionHeader">HTML header inside section</header>
+</section>
+<section id="htmlRegion" aria-label="HTML region">HTML region</section>
+<fieldset id="htmlFieldset">HTML fieldset</fieldset>
+<table>
+  <tbody id="htmlTbody" tabindex="-1"><tr><th>HTML tbody</th></tr></tbody>
+</table>
+<table role="grid">
+  <tr>
+    <td id="htmlGridcell">HTML implicit gridcell</td>
+  </tr>
+</table>
+<div id="htmlDiv">HTML div</div>
+<span id="htmlSpan" aria-label="HTML span">HTML span</span>
+<iframe id="iframe"></iframe>
+  `,
+  async function(browser, docAcc) {
+    function testComputedARIARole(id, role) {
+      const acc = findAccessibleChildByID(docAcc, id);
+      is(acc.computedARIARole, role, `computedARIARole for ${id} is correct`);
+    }
+
+    testComputedARIARole("ariaButton", "button");
+    testComputedARIARole("ariaLog", "log");
+    // Landmarks map to a single Gecko role.
+    testComputedARIARole("ariaMain", "main");
+    testComputedARIARole("ariaRegion", "region");
+    // Unnamed ARIA regions should ignore the ARIA role.
+    testComputedARIARole("ariaUnnamedRegion", "navigation");
+    // The directory ARIA role is an alias of list.
+    testComputedARIARole("ariaDirectory", "list");
+    // alertdialog, feed, rowgroup and searchbox map to a Gecko role, but it
+    // isn't unique.
+    testComputedARIARole("ariaAlertdialog", "alertdialog");
+    testComputedARIARole("ariaFeed", "feed");
+    testComputedARIARole("ariaRowgroup", "rowgroup");
+    testComputedARIARole("ariaSearchbox", "searchbox");
+    testComputedARIARole("ariaUnknown", "generic");
+    testComputedARIARole("htmlButton", "button");
+    // There is only a single ARIA role for buttons, but Gecko uses different
+    // roles depending on states.
+    testComputedARIARole("toggleButton", "button");
+    testComputedARIARole("htmlMain", "main");
+    testComputedARIARole("htmlHeader", "banner");
+    // <section> only maps to the region ARIA role if it has a label.
+    testComputedARIARole("htmlSection", "generic");
+    // <header> only maps to the banner role if it is not a child of a
+    // sectioning element.
+    testComputedARIARole("htmlSectionHeader", "generic");
+    testComputedARIARole("htmlRegion", "region");
+    // Gecko doesn't have a rowgroup role. Ensure we differentiate for
+    // computedARIARole.
+    testComputedARIARole("htmlFieldset", "group");
+    testComputedARIARole("htmlTbody", "rowgroup");
+    // <td> inside <table role="grid"> implicitly maps to ARIA gridcell.
+    testComputedARIARole("htmlGridcell", "gridcell");
+    // Test generics.
+    testComputedARIARole("htmlDiv", "generic");
+    testComputedARIARole("htmlSpan", "generic");
+    // Some roles can't be mapped to ARIA role tokens.
+    testComputedARIARole("iframe", "");
+  },
+  { chrome: true, topLevel: isCacheEnabled }
+);

accessible/tests/browser/role/head.js

@@ -0,0 +1,18 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+// Load the shared-head file first.
+Services.scriptloader.loadSubScript(
+  "chrome://mochitests/content/browser/accessible/tests/browser/shared-head.js",
+  this
+);
+
+// Loading and common.js from accessible/tests/mochitest/ for all tests, as
+// well as promisified-events.js.
+loadScripts(
+  { name: "common.js", dir: MOCHITESTS_DIR },
+  { name: "promisified-events.js", dir: MOCHITESTS_DIR }
+);

accessible/xpcom/xpcAccessible.cpp

@@ -762,3 +762,17 @@ xpcAccessible::Announce(const nsAString& aAnnouncement, uint16_t aPriority) {
 
   return NS_OK;
 }
+
+NS_IMETHODIMP
+xpcAccessible::GetComputedARIARole(nsAString& aRole) {
+  if (!IntlGeneric()) {
+    return NS_ERROR_FAILURE;
+  }
+
+  nsStaticAtom* ariaRole = IntlGeneric()->ComputedARIARole();
+  if (ariaRole) {
+    ariaRole->ToString(aRole);
+  }
+
+  return NS_OK;
+}

accessible/xpcom/xpcAccessible.h

@@ -93,6 +93,8 @@ class xpcAccessible : public nsIAccessible {
 
   NS_IMETHOD Announce(const nsAString& aAnnouncement, uint16_t aPriority) final;
 
+  NS_IMETHOD GetComputedARIARole(nsAString& aRole) final;
+
  protected:
   xpcAccessible() {}
   virtual ~xpcAccessible() {}