Bug 1479042 - Handle text insertion and name change events as live regions and announce. r=yzen

Differential Revision: https://phabricator.services.mozilla.com/D21612

--HG--
extra : moz-landing-system : lando

accessible/android/AccessibleWrap.cpp

@@ -13,8 +13,10 @@
 #include "SessionAccessibility.h"
 #include "nsAccessibilityService.h"
 #include "nsPersistentProperties.h"
+#include "nsIAccessibleAnnouncementEvent.h"
 #include "nsIStringBundle.h"
 #include "nsAccUtils.h"
+#include "nsTextEquivUtils.h"
 
 #include "mozilla/a11y/PDocAccessibleChild.h"
 
@@ -84,6 +86,8 @@ nsresult AccessibleWrap::HandleAccEvent(AccEvent* aEvent) {
   nsresult rv = Accessible::HandleAccEvent(aEvent);
   NS_ENSURE_SUCCESS(rv, rv);
 
+  accessible->HandleLiveRegionEvent(aEvent);
+
   if (IPCAccessibilityActive()) {
     return NS_OK;
   }
@@ -619,3 +623,77 @@ mozilla::java::GeckoBundle::LocalRef AccessibleWrap::ToBundle(
 
   return nodeInfo;
 }
+
+void AccessibleWrap::GetTextEquiv(nsString& aText) {
+  if (nsTextEquivUtils::HasNameRule(this, eNameFromSubtreeIfReqRule)) {
+    // This is an accessible that normally doesn't get its name from its
+    // subtree, so we collect the text equivalent explicitly.
+    nsTextEquivUtils::GetTextEquivFromSubtree(this, aText);
+  } else {
+    Name(aText);
+  }
+}
+
+bool AccessibleWrap::HandleLiveRegionEvent(AccEvent* aEvent) {
+  auto eventType = aEvent->GetEventType();
+  if (eventType != nsIAccessibleEvent::EVENT_TEXT_INSERTED &&
+      eventType != nsIAccessibleEvent::EVENT_NAME_CHANGE) {
+    // XXX: Right now only announce text inserted events. aria-relevant=removals
+    // is potentially on the chopping block[1]. We also don't support editable
+    // text because we currently can't descern the source of the change[2].
+    // 1. https://github.com/w3c/aria/issues/712
+    // 2. https://bugzilla.mozilla.org/show_bug.cgi?id=1531189
+    return false;
+  }
+
+  if (aEvent->IsFromUserInput()) {
+    return false;
+  }
+
+  nsCOMPtr<nsIPersistentProperties> attributes = Attributes();
+  nsString live;
+  nsresult rv =
+      attributes->GetStringProperty(NS_LITERAL_CSTRING("container-live"), live);
+  if (!NS_SUCCEEDED(rv)) {
+    return false;
+  }
+
+  uint16_t priority = live.EqualsIgnoreCase("assertive")
+                          ? nsIAccessibleAnnouncementEvent::ASSERTIVE
+                          : nsIAccessibleAnnouncementEvent::POLITE;
+
+  nsString atomic;
+  rv = attributes->GetStringProperty(NS_LITERAL_CSTRING("container-atomic"),
+                                     atomic);
+
+  Accessible* announcementTarget = this;
+  nsAutoString announcement;
+  if (atomic.EqualsIgnoreCase("true")) {
+    Accessible* atomicAncestor = nullptr;
+    for (Accessible* parent = announcementTarget; parent;
+         parent = parent->Parent()) {
+      Element* element = parent->Elm();
+      if (element &&
+          element->AttrValueIs(kNameSpaceID_None, nsGkAtoms::aria_atomic,
+                               nsGkAtoms::_true, eCaseMatters)) {
+        atomicAncestor = parent;
+        break;
+      }
+    }
+
+    if (atomicAncestor) {
+      announcementTarget = atomicAncestor;
+      static_cast<AccessibleWrap*>(atomicAncestor)->GetTextEquiv(announcement);
+    }
+  } else {
+    GetTextEquiv(announcement);
+  }
+
+  announcement.CompressWhitespace();
+  if (announcement.IsEmpty()) {
+    return false;
+  }
+
+  announcementTarget->Announce(announcement, priority);
+  return true;
+}

accessible/android/AccessibleWrap.h

@@ -79,6 +79,10 @@ class AccessibleWrap : public Accessible {
 
   virtual role WrapperRole() { return Role(); }
 
+  void GetTextEquiv(nsString& aText);
+
+  bool HandleLiveRegionEvent(AccEvent* aEvent);
+
   static void GetRoleDescription(role aRole,
                                  nsIPersistentProperties* aAttributes,
                                  nsAString& aGeckoRole,

mobile/android/geckoview/src/androidTest/java/org/mozilla/geckoview/test/AccessibilityTest.kt

@@ -103,6 +103,7 @@ class AccessibilityTest : BaseSessionTest() {
         fun onTextTraversal(event: AccessibilityEvent) { }
         fun onWinContentChanged(event: AccessibilityEvent) { }
         fun onWinStateChanged(event: AccessibilityEvent) { }
+        fun onAnnouncement(event: AccessibilityEvent) { }
     }
 
     @Before fun setup() {
@@ -134,6 +135,7 @@ class AccessibilityTest : BaseSessionTest() {
                     AccessibilityEvent.TYPE_VIEW_TEXT_TRAVERSED_AT_MOVEMENT_GRANULARITY -> newDelegate.onTextTraversal(event)
                     AccessibilityEvent.TYPE_WINDOW_CONTENT_CHANGED -> newDelegate.onWinContentChanged(event)
                     AccessibilityEvent.TYPE_WINDOW_STATE_CHANGED -> newDelegate.onWinStateChanged(event)
+                    AccessibilityEvent.TYPE_ANNOUNCEMENT -> newDelegate.onAnnouncement(event)
                     else -> {}
                 }
                 return false
@@ -591,6 +593,9 @@ class AccessibilityTest : BaseSessionTest() {
                 createNodeInfo(rootNode.getChildId(0)).childCount, equalTo(1))
         mainSession.evaluateJS("$('#to_show').style.display = 'none';")
         sessionRule.waitUntilCalled(object : EventDelegate {
+            @AssertCalled(count = 0)
+            override fun onAnnouncement(event: AccessibilityEvent) { }
+
             @AssertCalled(count = 1)
             override fun onWinContentChanged(event: AccessibilityEvent) { }
         })
@@ -599,6 +604,105 @@ class AccessibilityTest : BaseSessionTest() {
                 createNodeInfo(rootNode.getChildId(0)).childCount, equalTo(0))
     }
 
+    @Test fun testLiveRegion() {
+        sessionRule.session.loadString(
+                "<div id=\"to_change\"aria-live=\"polite\"></div>","text/html")
+        waitForInitialFocus()
+
+        mainSession.evaluateJS("$('#to_change').textContent = 'Hello';")
+        sessionRule.waitUntilCalled(object : EventDelegate {
+            @AssertCalled(count = 1)
+            override fun onAnnouncement(event: AccessibilityEvent) {
+                assertThat("Announcement is correct", event.text[0].toString(), equalTo("Hello"))
+            }
+
+            @AssertCalled(count = 1)
+            override fun onWinContentChanged(event: AccessibilityEvent) { }
+        })
+    }
+
+    @Test fun testLiveRegionDescendant() {
+        sessionRule.session.loadString(
+                "<div aria-live='polite'><p id='to_show'>I will be shown</p></div>","text/html")
+        waitForInitialFocus()
+
+        mainSession.evaluateJS("$('#to_show').style.display = 'none';")
+        sessionRule.waitUntilCalled(object : EventDelegate {
+            @AssertCalled(count = 0)
+            override fun onAnnouncement(event: AccessibilityEvent) { }
+
+            @AssertCalled(count = 1)
+            override fun onWinContentChanged(event: AccessibilityEvent) { }
+        })
+
+        mainSession.evaluateJS("$('#to_show').style.display = 'block';")
+        sessionRule.waitUntilCalled(object : EventDelegate {
+            @AssertCalled(count = 1)
+            override fun onAnnouncement(event: AccessibilityEvent) {
+                assertThat("Announcement is correct", event.text[0].toString(), equalTo("I will be shown"))
+            }
+
+            @AssertCalled(count = 1)
+            override fun onWinContentChanged(event: AccessibilityEvent) { }
+        })
+    }
+
+    @Test fun testLiveRegionAtomic() {
+        sessionRule.session.loadString(
+                "<div aria-live='polite' aria-atomic='true' id='container'>The time is <p>3pm</p></div>","text/html")
+        waitForInitialFocus()
+
+        mainSession.evaluateJS("$('p').textContent = '4pm';")
+        sessionRule.waitUntilCalled(object : EventDelegate {
+            @AssertCalled(count = 1)
+            override fun onAnnouncement(event: AccessibilityEvent) {
+                assertThat("Announcement is correct", event.text[0].toString(), equalTo("The time is 4pm"))
+            }
+
+            @AssertCalled(count = 1)
+            override fun onWinContentChanged(event: AccessibilityEvent) { }
+        })
+
+        mainSession.evaluateJS("$('#container').removeAttribute('aria-atomic'); $('p').textContent = '5pm';")
+        sessionRule.waitUntilCalled(object : EventDelegate {
+            @AssertCalled(count = 1)
+            override fun onAnnouncement(event: AccessibilityEvent) {
+                assertThat("Announcement is correct", event.text[0].toString(), equalTo("5pm"))
+            }
+
+            @AssertCalled(count = 1)
+            override fun onWinContentChanged(event: AccessibilityEvent) { }
+        })
+    }
+
+    @Test fun testLiveRegionImage() {
+        sessionRule.session.loadString(
+                "<div aria-live='polite' aria-atomic='true'>This picture is <img src='data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw==' alt='happy'></div>","text/html")
+        waitForInitialFocus()
+
+        mainSession.evaluateJS("console.log('eeejay', $('img').naturalWidth); $('img').alt = 'sad';")
+        sessionRule.waitUntilCalled(object : EventDelegate {
+            @AssertCalled(count = 1)
+            override fun onAnnouncement(event: AccessibilityEvent) {
+                assertThat("Announcement is correct", event.text[0].toString(), equalTo("This picture is sad"))
+            }
+        })
+    }
+
+    @Test fun testLiveRegionImageLabeledBy() {
+        sessionRule.session.loadString(
+                "<img src='data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw==' aria-live='polite' aria-labelledby='l1'><span id='l1'>Hello</span><span id='l2'>Goodbye</span>","text/html")
+        waitForInitialFocus()
+
+        mainSession.evaluateJS("$('img').setAttribute('aria-labelledby', 'l2');")
+        sessionRule.waitUntilCalled(object : EventDelegate {
+            @AssertCalled(count = 1)
+            override fun onAnnouncement(event: AccessibilityEvent) {
+                assertThat("Announcement is correct", event.text[0].toString(), equalTo("Goodbye"))
+            }
+        })
+    }
+
     private fun screenContainsNode(nodeId: Int): Boolean {
         var node = createNodeInfo(nodeId)
         var nodeBounds = Rect()