Fix automation API bounding boxes on high-dpi devices

chrome/renderer/extensions/automation_internal_custom_bindings.cc

 // Copyright 2014 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 "chrome/renderer/extensions/automation_internal_custom_bindings.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <memory>
@@ skipping 110 matching lines @@
 // walking up the parent hierarchy to offset by frame offsets and
 // scroll offsets.
 static gfx::Rect ComputeGlobalNodeBounds(TreeCache* cache,
                                          ui::AXNode* node,
                                          gfx::RectF local_bounds) {
   gfx::RectF bounds = local_bounds;
   while (node) {
     if (node->data().transform)
       node->data().transform->TransformRect(&bounds);
 
+    TreeCache* previous_cache = cache;

[aboxhall, 2017/05/26 01:04:59]

Where does cache get mutated?

[dmazzoni, 2017/05/26 06:41:33]

Commented.

     ui::AXNode* container =
         cache->tree.GetFromId(node->data().offset_container_id);
     if (!container) {
       if (node == cache->tree.root()) {
         container = cache->owner->GetParent(node, &cache);
       } else {
         container = cache->tree.root();
       }
     }
 
     if (!container || container == node)
       break;
 
+    // All trees other than the desktop tree are scaled by the device
+    // scale factor. When crossing out of another tree into the desktop
+    // tree, unscale the bounds by the device scale factor.
+    if (previous_cache->tree_id != api::automation::kDesktopTreeID &&
+        cache->tree_id == api::automation::kDesktopTreeID) {
+      float scale_factor = cache->owner->GetDeviceScaleFactor();
+      if (scale_factor > 0)
+        bounds.Scale(1.0 / scale_factor);
+    }
+
     gfx::RectF container_bounds = container->data().location;
     bounds.Offset(container_bounds.x(), container_bounds.y());
 
     int scroll_x = 0;
     int scroll_y = 0;
     if (container->data().GetIntAttribute(ui::AX_ATTR_SCROLL_X, &scroll_x) &&
         container->data().GetIntAttribute(ui::AX_ATTR_SCROLL_Y, &scroll_y)) {
       bounds.Offset(-scroll_x, -scroll_y);
     }
 
     node = container;
   }
 
-  // All trees other than the desktop tree are scaled by the device
-  // scale factor. Unscale them so they're all in consistent units.
-  if (cache->tree_id != api::automation::kDesktopTreeID) {
-    float scale_factor = cache->owner->context()
-                             ->GetRenderFrame()
-                             ->GetRenderView()
-                             ->GetDeviceScaleFactor();
-    if (scale_factor > 0)
-      bounds.Scale(1.0 / scale_factor);
-  }
-
   return gfx::ToEnclosingRect(bounds);
 }
 
 ui::AXNode* FindNodeWithChildTreeId(ui::AXNode* node, int child_tree_id) {
   if (child_tree_id == node->data().GetIntAttribute(ui::AX_ATTR_CHILD_TREE_ID))
     return node;
 
   for (int i = 0; i < node->child_count(); ++i) {
     ui::AXNode* result =
         FindNodeWithChildTreeId(node->ChildAtIndex(i), child_tree_id);
@@ skipping 908 matching lines @@
                                                (*in_out_cache)->tree_id);
   if (parent) {
     (*in_out_cache)->parent_node_id_from_parent_tree = parent->id();
     *in_out_cache = parent_cache;
     return parent;
   }
 
   return nullptr;
 }
 
+float AutomationInternalCustomBindings::GetDeviceScaleFactor() const {
+  return context()->GetRenderFrame()->GetRenderView()->GetDeviceScaleFactor();
+}
+
 void AutomationInternalCustomBindings::RouteTreeIDFunction(
     const std::string& name,
     TreeIDFunction callback) {
   scoped_refptr<TreeIDWrapper> wrapper = new TreeIDWrapper(this, callback);
   RouteFunction(name, base::Bind(&TreeIDWrapper::Run, wrapper));
 }
 
 void AutomationInternalCustomBindings::RouteNodeIDFunction(
     const std::string& name,
     NodeIDFunction callback) {
@@ skipping 323 matching lines @@
     for (auto id : ids)
       nodes->AppendInteger(id);
     args.Append(std::move(nodes));
   }
 
   bindings_system_->DispatchEventInContext("automationInternal.onNodesRemoved",
                                            &args, nullptr, context());
 }
 
 }  // namespace extensions