Support TalkBack commands to move to next/prev element.

BUG=353051

Review URL: https://codereview.chromium.org/200323006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@257542 0039d316-1c4b-4281-b951-d872f2087c98

6 files changed, 209 insertions, 0 deletions

diff --git a/content/browser/accessibility/browser_accessibility_manager.cc b/content/browser/accessibility/browser_accessibility_manager.cc
index c667377..8481b07 100644
--- a/content/browser/accessibility/browser_accessibility_manager.cc
+++ b/content/browser/accessibility/browser_accessibility_manager.cc
@@ -244,6 +244,40 @@ gfx::Rect BrowserAccessibilityManager::GetViewBounds() {
   return gfx::Rect();
 }
 
+BrowserAccessibility* BrowserAccessibilityManager::NextInTreeOrder(
+    BrowserAccessibility* node) {
+  if (!node)
+    return NULL;
+
+  if (node->PlatformChildCount() > 0)
+    return node->PlatformGetChild(0);
+  while (node) {
+    if (node->parent() &&
+        node->index_in_parent() <
+            static_cast<int>(node->parent()->PlatformChildCount()) - 1) {
+      return node->parent()->PlatformGetChild(node->index_in_parent() + 1);
+    }
+    node = node->parent();
+  }
+
+  return NULL;
+}
+
+BrowserAccessibility* BrowserAccessibilityManager::PreviousInTreeOrder(
+    BrowserAccessibility* node) {
+  if (!node)
+    return NULL;
+
+  if (node->parent() && node->index_in_parent() > 0) {
+    node = node->parent()->PlatformGetChild(node->index_in_parent() - 1);
+    while (node->PlatformChildCount() > 0)
+      node = node->PlatformGetChild(node->PlatformChildCount() - 1);
+    return node;
+  }
+
+  return node->parent();
+}
+
 void BrowserAccessibilityManager::UpdateNodesForTesting(
     const ui::AXNodeData& node1,
     const ui::AXNodeData& node2 /* = ui::AXNodeData() */,
diff --git a/content/browser/accessibility/browser_accessibility_manager.h b/content/browser/accessibility/browser_accessibility_manager.h
index bd01f39..ffd754b 100644
--- a/content/browser/accessibility/browser_accessibility_manager.h
+++ b/content/browser/accessibility/browser_accessibility_manager.h
@@ -154,6 +154,10 @@ class CONTENT_EXPORT BrowserAccessibilityManager {
   // scroll offsets separately.
   virtual bool UseRootScrollOffsetsWhenComputingBounds();
 
+  // Walk the tree.
+  BrowserAccessibility* NextInTreeOrder(BrowserAccessibility* node);
+  BrowserAccessibility* PreviousInTreeOrder(BrowserAccessibility* node);
+
   // For testing only: update the given nodes as if they were
   // received from the renderer process in OnAccessibilityEvents.
   // Takes up to 7 nodes at once so tests don't need to create a vector
diff --git a/content/browser/accessibility/browser_accessibility_manager_android.cc b/content/browser/accessibility/browser_accessibility_manager_android.cc
index 9516efe..c079825 100644
--- a/content/browser/accessibility/browser_accessibility_manager_android.cc
+++ b/content/browser/accessibility/browser_accessibility_manager_android.cc
@@ -26,11 +26,31 @@ enum {
   ANDROID_ACCESSIBILITY_EVENT_TYPE_VIEW_TEXT_SELECTION_CHANGED = 8192
 };
 
+enum AndroidHtmlElementType {
+  HTML_ELEMENT_TYPE_SECTION,
+  HTML_ELEMENT_TYPE_LIST,
+  HTML_ELEMENT_TYPE_CONTROL,
+  HTML_ELEMENT_TYPE_ANY
+};
+
 // Restricts |val| to the range [min, max].
 int Clamp(int val, int min, int max) {
   return std::min(std::max(val, min), max);
 }
 
+// These are special unofficial strings sent from TalkBack/BrailleBack
+// to jump to certain categories of web elements.
+AndroidHtmlElementType HtmlElementTypeFromString(base::string16 element_type) {
+  if (element_type == base::ASCIIToUTF16("SECTION"))
+    return HTML_ELEMENT_TYPE_SECTION;
+  else if (element_type == base::ASCIIToUTF16("LIST"))
+    return HTML_ELEMENT_TYPE_LIST;
+  else if (element_type == base::ASCIIToUTF16("CONTROL"))
+    return HTML_ELEMENT_TYPE_CONTROL;
+  else
+    return HTML_ELEMENT_TYPE_ANY;
+}
+
 }  // anonymous namespace
 
 namespace content {
@@ -444,6 +464,63 @@ int BrowserAccessibilityManagerAndroid::CalculateDistanceSquared(
   return dx * dx + dy * dy;
 }
 
+jint BrowserAccessibilityManagerAndroid::FindElementType(
+    JNIEnv* env, jobject obj, jint start_id, jstring element_type_str,
+    jboolean forwards) {
+  BrowserAccessibility* node = GetFromRendererID(start_id);
+  if (!node)
+    return 0;
+
+  AndroidHtmlElementType element_type = HtmlElementTypeFromString(
+      base::android::ConvertJavaStringToUTF16(env, element_type_str));
+
+  node = forwards ? NextInTreeOrder(node) : PreviousInTreeOrder(node);
+  while (node) {
+    switch(element_type) {
+      case HTML_ELEMENT_TYPE_SECTION:
+        if (node->role() == ui::AX_ROLE_ARTICLE ||
+            node->role() == ui::AX_ROLE_APPLICATION ||
+            node->role() == ui::AX_ROLE_BANNER ||
+            node->role() == ui::AX_ROLE_COMPLEMENTARY ||
+            node->role() == ui::AX_ROLE_CONTENT_INFO ||
+            node->role() == ui::AX_ROLE_HEADING ||
+            node->role() == ui::AX_ROLE_MAIN ||
+            node->role() == ui::AX_ROLE_NAVIGATION ||
+            node->role() == ui::AX_ROLE_SEARCH ||
+            node->role() == ui::AX_ROLE_REGION) {
+          return node->renderer_id();
+        }
+        break;
+      case HTML_ELEMENT_TYPE_LIST:
+        if (node->role() == ui::AX_ROLE_LIST ||
+            node->role() == ui::AX_ROLE_GRID ||
+            node->role() == ui::AX_ROLE_TABLE ||
+            node->role() == ui::AX_ROLE_TREE) {
+          return node->renderer_id();
+        }
+        break;
+      case HTML_ELEMENT_TYPE_CONTROL:
+        if (static_cast<BrowserAccessibilityAndroid*>(node)->IsFocusable())
+          return node->renderer_id();
+        break;
+      case HTML_ELEMENT_TYPE_ANY:
+        // In theory, the API says that an accessibility service could
+        // jump to an element by element name, like 'H1' or 'P'. This isn't
+        // currently used by any accessibility service, and we think it's
+        // better to keep them high-level like 'SECTION' or 'CONTROL', so we
+        // just fall back on linear navigation when we don't recognize the
+        // element type.
+        if (static_cast<BrowserAccessibilityAndroid*>(node)->IsClickable())
+          return node->renderer_id();
+        break;
+    }
+
+    node = forwards ? NextInTreeOrder(node) : PreviousInTreeOrder(node);
+  }
+
+  return 0;
+}
+
 void BrowserAccessibilityManagerAndroid::NotifyRootChanged() {
   JNIEnv* env = AttachCurrentThread();
   ScopedJavaLocalRef<jobject> obj = java_ref_.get(env);
diff --git a/content/browser/accessibility/browser_accessibility_manager_android.h b/content/browser/accessibility/browser_accessibility_manager_android.h
index 53cb617..e587eda 100644
--- a/content/browser/accessibility/browser_accessibility_manager_android.h
+++ b/content/browser/accessibility/browser_accessibility_manager_android.h
@@ -57,6 +57,14 @@ class CONTENT_EXPORT BrowserAccessibilityManagerAndroid
   void Blur(JNIEnv* env, jobject obj);
   void ScrollToMakeNodeVisible(JNIEnv* env, jobject obj, int id);
 
+  // Return the id of the next node in tree order in the direction given by
+  // |forwards|, starting with |start_id|, that matches |element_type|,
+  // where |element_type| is a special uppercase string from TalkBack or
+  // BrailleBack indicating general categories of web content like
+  // "SECTION" or "CONTROL".  Return 0 if not found.
+  jint FindElementType(JNIEnv* env, jobject obj, jint start_id,
+                       jstring element_type, jboolean forwards);
+
  protected:
   virtual void NotifyRootChanged() OVERRIDE;
 
diff --git a/content/browser/accessibility/browser_accessibility_manager_unittest.cc b/content/browser/accessibility/browser_accessibility_manager_unittest.cc
index 36e5d23..22d877b 100644
--- a/content/browser/accessibility/browser_accessibility_manager_unittest.cc
+++ b/content/browser/accessibility/browser_accessibility_manager_unittest.cc
@@ -886,4 +886,53 @@ TEST(BrowserAccessibilityManagerTest, MAYBE_BoundsForRangeOnParentElement) {
             root_accessible->GetLocalBoundsForRange(0, 4).ToString());
 }
 
+TEST(BrowserAccessibilityManagerTest, NextPreviousInTreeOrder) {
+  ui::AXNodeData root;
+  root.id = 1;
+  root.role = ui::AX_ROLE_ROOT_WEB_AREA;
+
+  ui::AXNodeData node2;
+  node2.id = 2;
+  root.child_ids.push_back(2);
+
+  ui::AXNodeData node3;
+  node3.id = 3;
+  root.child_ids.push_back(3);
+
+  ui::AXNodeData node4;
+  node4.id = 4;
+  node3.child_ids.push_back(4);
+
+  ui::AXNodeData node5;
+  node5.id = 5;
+  root.child_ids.push_back(5);
+
+  scoped_ptr<BrowserAccessibilityManager> manager(
+      BrowserAccessibilityManager::Create(
+          root,
+          NULL,
+          new CountedBrowserAccessibilityFactory()));
+  manager->UpdateNodesForTesting(node2, node3, node4, node5);
+
+  BrowserAccessibility* root_accessible = manager->GetRoot();
+  BrowserAccessibility* node2_accessible = root_accessible->PlatformGetChild(0);
+  BrowserAccessibility* node3_accessible = root_accessible->PlatformGetChild(1);
+  BrowserAccessibility* node4_accessible =
+      node3_accessible->PlatformGetChild(0);
+  BrowserAccessibility* node5_accessible = root_accessible->PlatformGetChild(2);
+
+  ASSERT_EQ(NULL, manager->NextInTreeOrder(NULL));
+  ASSERT_EQ(node2_accessible, manager->NextInTreeOrder(root_accessible));
+  ASSERT_EQ(node3_accessible, manager->NextInTreeOrder(node2_accessible));
+  ASSERT_EQ(node4_accessible, manager->NextInTreeOrder(node3_accessible));
+  ASSERT_EQ(node5_accessible, manager->NextInTreeOrder(node4_accessible));
+  ASSERT_EQ(NULL, manager->NextInTreeOrder(node5_accessible));
+
+  ASSERT_EQ(NULL, manager->PreviousInTreeOrder(NULL));
+  ASSERT_EQ(node4_accessible, manager->PreviousInTreeOrder(node5_accessible));
+  ASSERT_EQ(node3_accessible, manager->PreviousInTreeOrder(node4_accessible));
+  ASSERT_EQ(node2_accessible, manager->PreviousInTreeOrder(node3_accessible));
+  ASSERT_EQ(root_accessible, manager->PreviousInTreeOrder(node2_accessible));
+}
+
 }  // namespace content
diff --git a/content/public/android/java/src/org/chromium/content/browser/accessibility/BrowserAccessibilityManager.java b/content/public/android/java/src/org/chromium/content/browser/accessibility/BrowserAccessibilityManager.java
index 47209bb..d6a80ea 100644
--- a/content/public/android/java/src/org/chromium/content/browser/accessibility/BrowserAccessibilityManager.java
+++ b/content/public/android/java/src/org/chromium/content/browser/accessibility/BrowserAccessibilityManager.java
@@ -194,6 +194,28 @@ public class BrowserAccessibilityManager {
             case AccessibilityNodeInfo.ACTION_CLEAR_FOCUS:
                 nativeBlur(mNativeObj);
                 return true;
+
+            case AccessibilityNodeInfo.ACTION_NEXT_HTML_ELEMENT: {
+                if (arguments == null)
+                    return false;
+                String elementType = arguments.getString(
+                    AccessibilityNodeInfo.ACTION_ARGUMENT_HTML_ELEMENT_STRING);
+                if (elementType == null)
+                    return false;
+                elementType = elementType.toUpperCase();
+                return jumpToElementType(elementType, true);
+            }
+            case AccessibilityNodeInfo.ACTION_PREVIOUS_HTML_ELEMENT: {
+                if (arguments == null)
+                    return false;
+                String elementType = arguments.getString(
+                    AccessibilityNodeInfo.ACTION_ARGUMENT_HTML_ELEMENT_STRING);
+                if (elementType == null)
+                    return false;
+                elementType = elementType.toUpperCase();
+                return jumpToElementType(elementType, false);
+            }
+
             default:
                 break;
         }
@@ -261,6 +283,16 @@ public class BrowserAccessibilityManager {
         }
     }
 
+    private boolean jumpToElementType(String elementType, boolean forwards) {
+        int id = nativeFindElementType(mNativeObj, mAccessibilityFocusId, elementType, forwards);
+        if (id == 0)
+            return false;
+
+        mAccessibilityFocusId = id;
+        sendAccessibilityEvent(id, AccessibilityEvent.TYPE_VIEW_ACCESSIBILITY_FOCUSED);
+        return true;
+    }
+
     private void sendAccessibilityEvent(int virtualViewId, int eventType) {
         // If mFrameInfoInitialized is false, then the virtual hierarchy
         // doesn't exist in the view of the Android framework, so should
@@ -430,6 +462,9 @@ public class BrowserAccessibilityManager {
         node.setSelected(selected);
         node.setVisibleToUser(visibleToUser);
 
+        node.addAction(AccessibilityNodeInfo.ACTION_NEXT_HTML_ELEMENT);
+        node.addAction(AccessibilityNodeInfo.ACTION_PREVIOUS_HTML_ELEMENT);
+
         if (focusable) {
             if (focused) {
                 node.addAction(AccessibilityNodeInfo.ACTION_CLEAR_FOCUS);
@@ -649,4 +684,6 @@ public class BrowserAccessibilityManager {
     private native void nativeBlur(long nativeBrowserAccessibilityManagerAndroid);
     private native void nativeScrollToMakeNodeVisible(
             long nativeBrowserAccessibilityManagerAndroid, int id);
+    private native int nativeFindElementType(long nativeBrowserAccessibilityManagerAndroid,
+            int startId, String elementType, boolean forwards);
 }