Add support for retrieving image thumbnails as part of the accessibility tree.

content/renderer/accessibility/render_accessibility_impl.cc

 // Copyright (c) 2012 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.
 
 #include "content/renderer/accessibility/render_accessibility_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <queue>
@@ skipping 441 matching lines @@
   switch (data.action) {
     case ui::AX_ACTION_BLUR:
       target.setFocused(false);
       break;
     case ui::AX_ACTION_DECREMENT:
       target.decrement();
       break;
     case ui::AX_ACTION_DO_DEFAULT:
       target.performDefaultAction();
       break;
+    case ui::AX_ACTION_GET_IMAGE_DATA:
+      OnGetImageData(target, data.target_rect.size());
+      break;
     case ui::AX_ACTION_HIT_TEST:
       OnHitTest(data.target_point);
       break;
     case ui::AX_ACTION_INCREMENT:
       target.increment();
       break;
     case ui::AX_ACTION_SCROLL_TO_MAKE_VISIBLE:
       target.scrollToMakeVisibleWithSubFocus(
           WebRect(data.target_rect.x(), data.target_rect.y(),
                   data.target_rect.width(), data.target_rect.height()));
@@ skipping 95 matching lines @@
     return;
 
   // This object may not be a leaf node. Force the whole subtree to be
   // re-serialized.
   serializer_.DeleteClientSubtree(obj);
 
   // Explicitly send a tree change update event now.
   HandleAXEvent(obj, ui::AX_EVENT_TREE_CHANGED);
 }
 
+void RenderAccessibilityImpl::OnGetImageData(
+    const blink::WebAXObject& obj, const gfx::Size& max_size) {
+  ScopedFreezeBlinkAXTreeSource freeze(&tree_source_);
+  if (tree_source_.image_data_node_id() == obj.axID())
+    return;
+
+  tree_source_.set_image_data_node_id(obj.axID());
+  tree_source_.set_max_image_data_size(max_size);
+
+  const WebDocument& document = GetMainDocument();
+  if (document.isNull())
+    return;
+
+  serializer_.DeleteClientSubtree(obj);
+  HandleAXEvent(obj, ui::AX_EVENT_IMAGE_FRAME_UPDATED);
+}
+
 void RenderAccessibilityImpl::OnReset(int reset_token) {
   reset_token_ = reset_token;
   serializer_.Reset();
   pending_events_.clear();
 
   const WebDocument& document = GetMainDocument();
   if (!document.isNull()) {
     // Tree-only mode gets used by the automation extension API which requires a
     // load complete event to invoke listener callbacks.
     ui::AXEvent evt = document.accessibilityObject().isLoaded()
@@ skipping 51 matching lines @@
 
   const WebDocument& document = GetMainDocument();
   if (document.isNull())
     return;
 
   document.accessibilityObject().scrollToMakeVisibleWithSubFocus(
       WebRect(bounds.x(), bounds.y(), bounds.width(), bounds.height()));
 }
 
 }  // namespace content