Revert 46842 - Reimplement accessibility of web content by caching the entire

accessibility tree in the browser process.

Adds new RPCs for a browser tab to request accessibility info from
a renderer; the renderer responds with a complete tree of
accessibility metadata for the entire DOM, which is then cached
in the RenderWidgetHostView. This part is crossplatform and will
help with accessibility on both Windows and Mac OS X.

For Windows, MSAA support for web content has been rewritten to
use this new cache. Tested in JAWS and NVDA screen readers.
Using Chrome with a screen reader is now fast and stable,
unlike the previous implementation. However, note that most
advanced functionality is still not supported, and much work remains
to make Chrome work well with a screen reader. This is a necessary
step to improve stability first.

BUG=25564
BUG=13291
TEST=See http://codereview.chromium.org/1806001

Review URL: http://codereview.chromium.org/1637018

TBR=dmazzoni@chromium.org
Review URL: http://codereview.chromium.org/1989009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@46847 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 208 insertions, 45 deletions

diff --git a/webkit/glue/webaccessibility.cc b/webkit/glue/webaccessibility.cc
index 33232ca..1af91d6 100644
--- a/webkit/glue/webaccessibility.cc
+++ b/webkit/glue/webaccessibility.cc
@@ -1,4 +1,4 @@
-// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
@@ -7,11 +7,16 @@
 #include "third_party/WebKit/WebKit/chromium/public/WebAccessibilityCache.h"
 #include "third_party/WebKit/WebKit/chromium/public/WebAccessibilityObject.h"
 #include "third_party/WebKit/WebKit/chromium/public/WebAccessibilityRole.h"
+#include "third_party/WebKit/WebKit/chromium/public/WebPoint.h"
+#include "third_party/WebKit/WebKit/chromium/public/WebRect.h"
 #include "third_party/WebKit/WebKit/chromium/public/WebString.h"
 
 using WebKit::WebAccessibilityCache;
 using WebKit::WebAccessibilityRole;
 using WebKit::WebAccessibilityObject;
+using WebKit::WebPoint;
+using WebKit::WebRect;
+using WebKit::WebString;
 
 namespace webkit_glue {
 
@@ -96,82 +101,240 @@ WebAccessibility::Role ConvertRole(WebKit::WebAccessibilityRole role) {
   }
 }
 
-uint32 ConvertState(const WebAccessibilityObject& o) {
-  uint32 state = 0;
+long ConvertState(const WebAccessibilityObject& o) {
+  long state = 0;
   if (o.isChecked())
-    state |= (1 << WebAccessibility::STATE_CHECKED);
+    state |= static_cast<long>(1 << WebAccessibility::STATE_CHECKED);
 
   if (o.canSetFocusAttribute())
-    state |= (1 << WebAccessibility::STATE_FOCUSABLE);
+    state |= static_cast<long>(1 << WebAccessibility::STATE_FOCUSABLE);
 
   if (o.isFocused())
-    state |= (1 << WebAccessibility::STATE_FOCUSED);
+    state |= static_cast<long>(1 << WebAccessibility::STATE_FOCUSED);
 
   if (o.isHovered())
-    state |= (1 << WebAccessibility::STATE_HOTTRACKED);
+    state |= static_cast<long>(1 << WebAccessibility::STATE_HOTTRACKED);
 
   if (o.isIndeterminate())
-    state |= (1 << WebAccessibility::STATE_INDETERMINATE);
+    state |= static_cast<long>(1 << WebAccessibility::STATE_INDETERMINATE);
 
   if (o.isAnchor())
-    state |= (1 << WebAccessibility::STATE_LINKED);
+    state |= static_cast<long>(1 << WebAccessibility::STATE_LINKED);
 
   if (o.isMultiSelectable())
-    state |= (1 << WebAccessibility::STATE_MULTISELECTABLE);
+    state |= static_cast<long>(1 << WebAccessibility::STATE_MULTISELECTABLE);
 
   if (o.isOffScreen())
-    state |= (1 << WebAccessibility::STATE_OFFSCREEN);
+    state |= static_cast<long>(1 << WebAccessibility::STATE_OFFSCREEN);
 
   if (o.isPressed())
-    state |= (1 << WebAccessibility::STATE_PRESSED);
+    state |= static_cast<long>(1 << WebAccessibility::STATE_PRESSED);
 
   if (o.isPasswordField())
-    state |= (1 << WebAccessibility::STATE_PROTECTED);
+    state |= static_cast<long>(1 << WebAccessibility::STATE_PROTECTED);
 
   if (o.isReadOnly())
-    state |= (1 << WebAccessibility::STATE_READONLY);
+    state |= static_cast<long>(1 << WebAccessibility::STATE_READONLY);
 
   if (o.isVisited())
-    state |= (1 << WebAccessibility::STATE_TRAVERSED);
+    state |= static_cast<long>(1 << WebAccessibility::STATE_TRAVERSED);
 
   if (!o.isEnabled())
-    state |= (1 << WebAccessibility::STATE_UNAVAILABLE);
+    state |= static_cast<long>(1 << WebAccessibility::STATE_UNAVAILABLE);
 
   return state;
 }
 
-WebAccessibility::WebAccessibility()
-    : id(-1),
-      role(ROLE_NONE),
-      state(-1) {
-}
+int32 WebAccessibility::GetAccObjInfo(WebAccessibilityCache* cache,
+  const WebAccessibility::InParams& in_params,
+  WebAccessibility::OutParams* out_params) {
+  // Find object requested by |object_id|.
+  WebAccessibilityObject active_acc_obj;
 
-WebAccessibility::WebAccessibility(const WebKit::WebAccessibilityObject& src,
-                                   WebKit::WebAccessibilityCache* cache) {
-  Init(src, cache);
-}
+  // Since ids assigned by Chrome starts at 1000, whereas platform-specific ids
+  // used to reference a child will be in a wholly different range, we know
+  // that any id that high should be treated as a non-direct descendant.
+  bool local_child = false;
+  if (cache->isValidId(in_params.child_id)) {
+    // Object is not a direct child, re-map the input parameters accordingly.
+    // The object to be retrieved is referred to by the |in_params.child_id|, as
+    // a result of e.g. a focus event.
+    active_acc_obj = cache->getObjectById(in_params.child_id);
+  } else {
+    local_child = true;
+
+    active_acc_obj = cache->getObjectById(in_params.object_id);
+    if (active_acc_obj.isNull())
+      return RETURNCODE_FAIL;
+
+    // child_id == 0 means self. Otherwise, it's a local child - 1.
+    if (in_params.child_id > 0) {
+      unsigned index = in_params.child_id - 1;
+      if (index >= active_acc_obj.childCount())
+        return RETURNCODE_FAIL;
+
+      active_acc_obj = active_acc_obj.childAt(index);
+    }
+  }
+
+  if (active_acc_obj.isNull())
+    return RETURNCODE_FAIL;
+
+  // Temp paramters for holding output information.
+  WebAccessibilityObject out_acc_obj;
+  string16 out_string;
 
-void WebAccessibility::Init(const WebKit::WebAccessibilityObject& src,
-                            WebKit::WebAccessibilityCache* cache) {
-  name = src.title();
-  value = src.stringValue();
-  action = src.actionVerb();
-  description = src.accessibilityDescription();
-  help = src.helpText();
-  shortcut = src.keyboardShortcut();
-  role = ConvertRole(src.roleValue());
-  state = ConvertState(src);
-  location = src.boundingBoxRect();
-
-  // Add the source object to the cache and store its id.
-  id = cache->addOrGetId(src);
-
-  // Recursively create children.
-  int child_count = src.childCount();
-  children.resize(child_count);
-  for (int i = 0; i < child_count; i++) {
-    children[i].Init(src.childAt(i), cache);
+  switch (in_params.function_id) {
+    case WebAccessibility::FUNCTION_DODEFAULTACTION: {
+      if (!active_acc_obj.performDefaultAction())
+        return RETURNCODE_FALSE;
+      break;
+    }
+    case WebAccessibility::FUNCTION_HITTEST: {
+      WebPoint point(in_params.input_long1, in_params.input_long2);
+      out_acc_obj = active_acc_obj.hitTest(point);
+      if (out_acc_obj.isNull())
+        return RETURNCODE_FALSE;
+      break;
+    }
+    case WebAccessibility::FUNCTION_LOCATION: {
+      WebRect rect = active_acc_obj.boundingBoxRect();
+      out_params->output_long1 = rect.x;
+      out_params->output_long2 = rect.y;
+      out_params->output_long3 = rect.width;
+      out_params->output_long4 = rect.height;
+      break;
+    }
+    case WebAccessibility::FUNCTION_NAVIGATE: {
+      WebAccessibility::Direction dir =
+        static_cast<WebAccessibility::Direction>(in_params.input_long1);
+      switch (dir) {
+        case WebAccessibility::DIRECTION_DOWN:
+        case WebAccessibility::DIRECTION_UP:
+        case WebAccessibility::DIRECTION_LEFT:
+        case WebAccessibility::DIRECTION_RIGHT:
+          // These directions are not implemented, matching Mozilla and IE.
+          return RETURNCODE_FALSE;
+        case WebAccessibility::DIRECTION_LASTCHILD:
+        case WebAccessibility::DIRECTION_FIRSTCHILD:
+          // MSDN states that navigating to first/last child can only be from
+          // self.
+          if (!local_child)
+            return RETURNCODE_FALSE;
+
+          if (dir == WebAccessibility::DIRECTION_FIRSTCHILD) {
+            out_acc_obj = active_acc_obj.firstChild();
+          } else {
+            out_acc_obj = active_acc_obj.lastChild();
+          }
+          break;
+        case WebAccessibility::DIRECTION_NEXT:
+        case WebAccessibility::DIRECTION_PREVIOUS: {
+          if (dir == WebAccessibility::DIRECTION_NEXT) {
+            out_acc_obj = active_acc_obj.nextSibling();
+          } else {
+            out_acc_obj = active_acc_obj.previousSibling();
+          }
+          break;
+        }
+        default:
+          return RETURNCODE_FALSE;
+      }
+
+      if (out_acc_obj.isNull())
+        return RETURNCODE_FALSE;
+
+      break;
+    }
+    case WebAccessibility::FUNCTION_GETCHILD: {
+      out_params->object_id = in_params.object_id;
+      out_acc_obj = active_acc_obj;
+      break;
+    }
+    case WebAccessibility::FUNCTION_CHILDCOUNT: {
+      out_params->output_long1 = active_acc_obj.childCount();
+      break;
+    }
+    case WebAccessibility::FUNCTION_DEFAULTACTION: {
+      out_string = active_acc_obj.actionVerb();
+      if (out_string.empty())
+        return RETURNCODE_FALSE;
+      break;
+    }
+    case WebAccessibility::FUNCTION_DESCRIPTION: {
+      out_string = active_acc_obj.accessibilityDescription();
+      if (out_string.empty())
+        return RETURNCODE_FALSE;
+      // From the Mozilla MSAA implementation:
+      // "Signal to screen readers that this description is speakable and is not
+      // a formatted positional information description. Don't localize the
+      // 'Description: ' part of this string, it will be parsed out by assistive
+      // technologies."
+      out_string = L"Description: " + out_string;
+      break;
+    }
+    case WebAccessibility::FUNCTION_GETFOCUSEDCHILD: {
+      out_acc_obj = active_acc_obj.focusedChild();
+      if (out_acc_obj.isNull())
+        return RETURNCODE_FALSE;
+      break;
+    }
+    case WebAccessibility::FUNCTION_HELPTEXT: {
+      out_string = active_acc_obj.helpText();
+      if (out_string.empty())
+        return RETURNCODE_FALSE;
+      break;
+    }
+    case WebAccessibility::FUNCTION_KEYBOARDSHORTCUT: {
+      out_string = active_acc_obj.keyboardShortcut();
+      if (out_string.empty())
+        return RETURNCODE_FALSE;
+      break;
+    }
+    case WebAccessibility::FUNCTION_NAME: {
+      out_string = active_acc_obj.title();
+      if (out_string.empty())
+        return RETURNCODE_FALSE;
+      break;
+    }
+    case WebAccessibility::FUNCTION_GETPARENT: {
+      out_acc_obj = active_acc_obj.parentObject();
+      if (out_acc_obj.isNull())
+        return RETURNCODE_FALSE;
+      break;
+    }
+    case WebAccessibility::FUNCTION_ROLE: {
+      out_params->output_long1 = ConvertRole(active_acc_obj.roleValue());
+      break;
+    }
+    case WebAccessibility::FUNCTION_STATE: {
+      out_params->output_long1 = ConvertState(active_acc_obj);
+      break;
+    }
+    case WebAccessibility::FUNCTION_VALUE: {
+      out_string = active_acc_obj.stringValue();
+      if (out_string.empty())
+        return RETURNCODE_FALSE;
+      break;
+    }
+    default:
+      // Non-supported function id.
+      return RETURNCODE_FAIL;
   }
+
+  // Output and hashmap assignments, as appropriate.
+  if (!out_string.empty())
+    out_params->output_string = out_string;
+
+  if (out_acc_obj.isNull())
+    return RETURNCODE_TRUE;
+
+  int id = cache->addOrGetId(out_acc_obj);
+  out_params->object_id = id;
+  out_params->output_long1 = -1;
+
+  // TODO(ctguil): Handle simple objects returned.
+  return RETURNCODE_TRUE;
 }
 
 }  // namespace webkit_glue