Keep track of fixed positioning in accessibility tree.

third_party/WebKit/Source/modules/accessibility/AXSpinButton.cpp

 /*
  * Copyright (C) 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 83 matching lines @@
 
 // AXSpinButtonPart
 
 AXSpinButtonPart::AXSpinButtonPart(AXObjectCacheImpl& ax_object_cache)
     : AXMockObject(ax_object_cache), is_incrementor_(false) {}
 
 AXSpinButtonPart* AXSpinButtonPart::Create(AXObjectCacheImpl& ax_object_cache) {
   return new AXSpinButtonPart(ax_object_cache);
 }
 
-void AXSpinButtonPart::GetRelativeBounds(
-    AXObject** out_container,
-    FloatRect& out_bounds_in_container,
-    SkMatrix44& out_container_transform) const {
+void AXSpinButtonPart::GetRelativeBounds(AXObject** out_container,
+                                         FloatRect& out_bounds_in_container,
+                                         SkMatrix44& out_container_transform,
+                                         bool& out_is_fixed_positioned) const {
   *out_container = nullptr;
   out_bounds_in_container = FloatRect();
   out_container_transform.setIdentity();
+  out_is_fixed_positioned = false;

[aboxhall, 2017/06/30 06:07:41]

Is there some reason we couldn't make is_fixed_positioned part of the
WebAXObject API instead of attaching it to this method?

[dmazzoni, 2017/07/06 07:20:22]

I don't want to do that in the WebAXObject API because is_fixed_positioned
is a critical piece of information that's intertwined with the rest of the
bounds info, so I want to force callers to fetch all of them together.

How about this, though - I added a new protected method
GetSimpleRelativeBounds that can be overridden by this
class and two others that have to return their own bounds but
have no use for transforms or fixed positioning. Does that
help readability?

 
   if (!ParentObject())
     return;
 
   // FIXME: This logic should exist in the layout tree or elsewhere, but there
   // is no relationship that exists that can be queried.
   ParentObject()->GetRelativeBounds(out_container, out_bounds_in_container,
-                                    out_container_transform);
+                                    out_container_transform,
+                                    out_is_fixed_positioned);
   out_bounds_in_container = FloatRect(0, 0, out_bounds_in_container.Width(),
                                       out_bounds_in_container.Height());
   if (is_incrementor_) {
     out_bounds_in_container.SetHeight(out_bounds_in_container.Height() / 2);
   } else {
     out_bounds_in_container.SetY(out_bounds_in_container.Y() +
                                  out_bounds_in_container.Height() / 2);
     out_bounds_in_container.SetHeight(out_bounds_in_container.Height() / 2);
   }
   *out_container = ParentObject();
 }
 
 bool AXSpinButtonPart::Press() {
   if (!parent_ || !parent_->IsSpinButton())
     return false;
 
   AXSpinButton* spin_button = ToAXSpinButton(ParentObject());
   if (is_incrementor_)
     spin_button->Step(1);
   else
     spin_button->Step(-1);
 
   return true;
 }
 
 }  // namespace blink