Views a11y: Implement AXPlatformNode::FromNativeViewAccessible on all platforms.

ui/views/accessibility/native_view_accessibility.cc

 // Copyright (c) 2013 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 "ui/views/accessibility/native_view_accessibility.h"
 
 #include "base/memory/ptr_util.h"
 #include "base/strings/utf_string_conversions.h"
+#include "ui/accessibility/platform/ax_platform_node.h"
 #include "ui/events/event_utils.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/views/controls/native/native_view_host.h"
 #include "ui/views/view.h"
 #include "ui/views/widget/widget.h"
 
 namespace views {
 
-#if !defined(PLATFORM_HAS_NATIVE_VIEW_ACCESSIBILITY_IMPL)
 // static
-std::unique_ptr<NativeViewAccessibility> NativeViewAccessibility::Create(
+std::unique_ptr<NativeViewAccessibility> NativeViewAccessibility::CreateForView(
     View* view) {
-  // Use WrapUnique over MakeUnique to invoke the protected constructor.
-  return base::WrapUnique<NativeViewAccessibility>(
-      new NativeViewAccessibility(view));
+  return base::WrapUnique(Create(view));
 }
-#endif  // !defined(PLATFORM_HAS_NATIVE_VIEW_ACCESSIBILITY_IMPL)
 
 NativeViewAccessibility::NativeViewAccessibility(View* view)
     : view_(view),
       parent_widget_(nullptr),
       ax_node_(nullptr) {
   ax_node_ = ui::AXPlatformNode::Create(this);
 }
 
 NativeViewAccessibility::~NativeViewAccessibility() {
   if (ax_node_)
@@ skipping 82 matching lines @@
 }
 
 gfx::NativeWindow NativeViewAccessibility::GetTopLevelWidget() {
   if (view_->GetWidget())
     return view_->GetWidget()->GetTopLevelWidget()->GetNativeWindow();
   return nullptr;
 }
 
 gfx::NativeViewAccessible NativeViewAccessibility::GetParent() {
   if (view_->parent())
     return view_->parent()->GetNativeViewAccessible();

[tapted, 2017/03/06 01:43:09]

I think this is where we need GetForView? Except GetParent() here will always
return nullptr on ChromeOS. (so what happens if we don't define GetForView on
ChromeOS at all?)

[Patti Lor, 2017/03/13 03:03:25]

Unfortunately I think we need this for GetChildCount() in the next CL
(https://crrev.com/2119413004/). The issue is that we need a NVA instance to
check if the View is ignored. Alternatively, I think we could check this
manually by inlining IsAccessibilityFocusableWhenEnabled() (see next CL again)
and also checking view_->GetAccessibleNodeData(), and then I think it would be
possible.

Or we could leave GetChildCount(), ChildAtIndex(), HitTestSync, and GetParent()
unimplemented for CrOS?

[tapted, 2017/03/13 04:07:02]

It's possible we need GetChildCount on CrOS.. (but also maybe not: only
AXPlatformBase calls it, and none exists on CrOS).

But ChildAtIndex(), HitTestSync() and GetParent() must all just return nullptr
on CrOS.



Essentially... it seems NativeViewAccessibility doesn't need to (and shouldn't)
implement ui::AXPlatformNodeDelegate on ChromeOS.

Perhaps we want NativeViewAccessibility and PlatformNativeViewAccessibility that
inherits form NVA.

[Patti Lor, 2017/03/19 23:10:26]

Thanks for your giant refactor Trent! It took a bit of time to rebase but
everything seems to work and seems a lot nicer too :))

 
   if (parent_widget_)
     return parent_widget_->GetRootView()->GetNativeViewAccessible();
 
   return nullptr;
 }
 
 gfx::Vector2d NativeViewAccessibility::GetGlobalCoordinateOffset() {
   return gfx::Vector2d(0, 0);  // location is already in screen coordinates.
 }
@@ skipping 95 matching lines @@
   }
 }
 
 void NativeViewAccessibility::SetParentWidget(Widget* parent_widget) {
   if (parent_widget_)
     parent_widget_->RemoveObserver(this);
   parent_widget_ = parent_widget;
   parent_widget_->AddObserver(this);
 }
 
+// static
+NativeViewAccessibility* NativeViewAccessibility::GetForView(View* view) {
+#if defined(PLATFORM_HAS_NATIVE_VIEW_ACCESSIBILITY_IMPL)
+  // Retrieving the gfx::NativeViewAccessible also ensures that a
+  // NativeViewAccessibility exists for the given View.
+  gfx::NativeViewAccessible native_object = view->GetNativeViewAccessible();
+  ui::AXPlatformNode* node =
+      ui::AXPlatformNode::FromNativeViewAccessible(native_object);
+  DCHECK(node);
+  return static_cast<NativeViewAccessibility*>(node->GetDelegate());
+#else
+  // Platforms (currently ChromeOS) without a native implementation also have no
+  // gfx::NativeViewAccessible, so make sure a NativeViewAccessibility exists
+  // and return the instance belonging to |view|.
+  view->GetNativeViewAccessible();
+  return view->native_view_accessibility_.get();

[tapted, 2017/03/06 01:43:09]

The CL description needs to be clear why this is needed too (I think it's
related to skipping over parents?)

[Patti Lor, 2017/03/13 03:03:25]

Updated the description with why we need a fallback with friend
NativeViewAccessibility for CrOS - let me know if that's not what you meant?

+#endif
+}
+
+#if !defined(PLATFORM_HAS_NATIVE_VIEW_ACCESSIBILITY_IMPL)
+// static
+NativeViewAccessibility* NativeViewAccessibility::Create(View* view) {
+  return new NativeViewAccessibility(view);
+}
+#endif  // !defined(PLATFORM_HAS_NATIVE_VIEW_ACCESSIBILITY_IMPL)
+
 void NativeViewAccessibility::PopulateChildWidgetVector(
     std::vector<Widget*>* result_child_widgets) {
   // Only attach child widgets to the root view.
   Widget* widget = view_->GetWidget();
   if (!widget || widget->GetRootView() != view_)
     return;
 
   std::set<Widget*> child_widgets;
   Widget::GetAllOwnedWidgets(widget->GetNativeView(), &child_widgets);
   for (auto iter = child_widgets.begin(); iter != child_widgets.end(); ++iter) {
@@ skipping 16 matching lines @@
               child_widget_platform_node->GetDelegate());
       if (child_widget_view_accessibility->parent_widget() != widget)
         child_widget_view_accessibility->SetParentWidget(widget);
     }
 
     result_child_widgets->push_back(child_widget);
   }
 }
 
 }  // namespace views