Complete live region support in ChromeVox Next.

chrome/browser/resources/chromeos/chromevox/cvox2/background/background.js

Index: chrome/browser/resources/chromeos/chromevox/cvox2/background/background.js
diff --git a/chrome/browser/resources/chromeos/chromevox/cvox2/background/background.js b/chrome/browser/resources/chromeos/chromevox/cvox2/background/background.js
index f38f7071b783b22e7fb106e627359b517d0ec1ec..8d9bf04ccbf8871f375aeb163d0f3ebbf3d6a1ca 100644
--- a/chrome/browser/resources/chromeos/chromevox/cvox2/background/background.js
+++ b/chrome/browser/resources/chromeos/chromevox/cvox2/background/background.js
@@ -75,6 +75,21 @@ Background = function() {
    */
   this.mode_ = ChromeVoxMode.COMPAT;
 
+  /**
+   * The time the last live region event was output.
+   * @type {Date}
+   * @private
+   */
+  this.lastLiveRegionTime_ = new Date(0);
+
+  /**
+   * Ids of nodes that have been announced as part of a live region since

[Peter Lundblad, 2015/11/20 13:42:58]

nit: there are no ids stored in the set.

[dmazzoni, 2015/11/23 20:16:50]

Done.

+   *     |this.lastLiveRegionTime_|, to prevent duplicate announcements.
+   * @type {WeakSet}

[Peter Lundblad, 2015/11/20 13:42:58]

{!WeakSet}
Does the compiler support
{!WeakSet<AutomationNode>}
? It worked when I used for a Map.

[dmazzoni, 2015/11/23 20:16:50]

It worked! Thanks.

+   * @private
+   */
+  this.liveRegionNodeSet_ = new WeakSet();
+
   // Manually bind all functions to |this|.
   for (var func in this) {
     if (typeof(this[func]) == 'function')
@@ -125,9 +140,18 @@ Background = function() {
   // Classic keymap.
   cvox.ChromeVoxKbHandler.handlerKeyMap = cvox.KeyMap.fromDefaults();
 
+  chrome.automation.setTreeChangeObserverMask('liveRegionTreeChanges');
   chrome.automation.addTreeChangeObserver(this.onTreeChange);
 };
 
+/**
+ * Live region events received in fewer than this many milliseconds will
+ * queue, otherwise they'll be output with a category flush.
+ * @type {number}
+ * @const
+ */
+Background.LIVE_REGION_QUEUE_TIME_MS = 500;
+
 Background.prototype = {
   /** Forces ChromeVox Next to be active for all tabs. */
   forceChromeVoxNextActive: function() {
@@ -424,6 +448,8 @@ Background.prototype = {
       evt.preventDefault();
       evt.stopPropagation();
     }
+
+    Output.flushNextSpeechUtterance();
   },
 
   /**
@@ -498,22 +524,33 @@ Background.prototype = {
    * @param {chrome.automation.TreeChange} treeChange
    */
   onTreeChange: function(treeChange) {
-    if (this.mode_ === ChromeVoxMode.CLASSIC || !cvox.ChromeVox.isActive)
-      return;
-
     var node = treeChange.target;
     if (!node.containerLiveStatus)
       return;
 
-    if (node.containerLiveRelevant.indexOf('additions') >= 0 &&
-        treeChange.type == 'nodeCreated')
-      this.outputLiveRegionChange_(node, null);
-    if (node.containerLiveRelevant.indexOf('text') >= 0 &&
-        treeChange.type == 'nodeChanged')
-      this.outputLiveRegionChange_(node, null);
-    if (node.containerLiveRelevant.indexOf('removals') >= 0 &&
-        treeChange.type == 'nodeRemoved')
-      this.outputLiveRegionChange_(node, '@live_regions_removed');
+    var skip = false;

[Peter Lundblad, 2015/11/20 13:42:58]

Get rid of this and return early instead?

[dmazzoni, 2015/11/23 20:16:50]

Done.

+
+    if (this.mode_ === ChromeVoxMode.CLASSIC || !cvox.ChromeVox.isActive) {
+      skip = true;
+    } else if (!this.currentRange_) {
+      skip = true;
+    } else if (!AutomationUtil.isInSameWebpage(
+        node, this.currentRange_.start.node)) {
+      skip = true;
+    }
+
+    if (!skip) {
+      var type = treeChange.type;
+      var relevant = node.containerLiveRelevant;
+      if (relevant.indexOf('additions') >= 0 &&

[David Tseng, 2015/11/24 18:46:30]

Where do relevant strings come from? This looks pretty error prone.

[dmazzoni, 2015/11/30 22:02:47]

This is from the ARIA spec, I'm not sure we should define them ourselves.

FWIW, we don't try to parse the string because this is the format some native
APIs want anyway (they just want the validated string value of the ARIA
attribute).

+          (type == 'nodeCreated' || type == 'subtreeCreated')) {
+        this.outputLiveRegionChange_(node, null);
+      }
+      if (relevant.indexOf('text') >= 0 && type == 'nodeChanged')
+        this.outputLiveRegionChange_(node, null);
+      if (relevant.indexOf('removals') >= 0 && type == 'nodeRemoved')
+        this.outputLiveRegionChange_(node, '@live_regions_removed');
+    }
   },
 
   /**
@@ -526,13 +563,51 @@ Background.prototype = {
    * @private
    */
   outputLiveRegionChange_: function(node, opt_prependFormatStr) {
+    if (node.containerLiveBusy)
+      return;
+
+    if (node.containerLiveAtomic && !node.liveAtomic) {
+      if (node.parent)
+        this.outputLiveRegionChange_(node.parent, opt_prependFormatStr);
+      return;
+    }
+
     var range = cursors.Range.fromNode(node);
     var output = new Output();
     if (opt_prependFormatStr) {
       output.format(opt_prependFormatStr);
     }
-    output.withSpeech(range, null, Output.EventType.NAVIGATE);
+    output.withSpeech(range, range, Output.EventType.NAVIGATE);
+
+    if (output.empty && node.liveAtomic) {
+      output.format('$descendants', node);
+    }
+
     output.withSpeechCategory(cvox.TtsCategory.LIVE);
+
+    if (output.empty)
+      return;
+
+    // Enqueue live region updates that were received at approximately
+    // the same time, otherwise flush previous live region updates.
+    var currentTime = new Date();
+    var queueTime = Background.LIVE_REGION_QUEUE_TIME_MS;
+    if (currentTime - this.lastLiveRegionTime_ > queueTime) {
+      this.liveRegionNodeSet_ = new WeakSet();
+      output.withQueueMode(cvox.QueueMode.CATEGORY_FLUSH);
+      this.lastLiveRegionTime_ = currentTime;
+    } else {
+      output.withQueueMode(cvox.QueueMode.QUEUE);
+    }
+
+    var parent = node;
+    while (parent) {
+      if (this.liveRegionNodeSet_.has(parent))
+        return;
+      parent = parent.parent;
+    }
+
+    this.liveRegionNodeSet_.add(node);
     output.go();
   },