Improve omnibox accessibility on Windows.

views/widget/native_widget_win.cc

 // Copyright (c) 2011 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 "views/widget/native_widget_win.h"
 
 #include <dwmapi.h>
 #include <shellapi.h>
 
 #include <algorithm>
@@ skipping 362 matching lines @@
 NativeWidgetWin::NativeWidgetWin(internal::NativeWidgetDelegate* delegate)
     : delegate_(delegate),
       ALLOW_THIS_IN_INITIALIZER_LIST(close_widget_factory_(this)),
       active_mouse_tracking_flags_(0),
       use_layered_buffer_(false),
       layered_alpha_(255),
       ALLOW_THIS_IN_INITIALIZER_LIST(paint_layered_window_factory_(this)),
       ownership_(Widget::InitParams::NATIVE_WIDGET_OWNS_WIDGET),
       can_update_layered_window_(true),
       restore_focus_when_enabled_(false),
-      accessibility_view_events_index_(-1),
-      accessibility_view_events_(kMaxAccessibilityViewEvents),
       previous_cursor_(NULL),
       fullscreen_(false),
       force_hidden_count_(0),
       lock_updates_count_(0),
       saved_window_style_(0),
       ignore_window_pos_changes_(false),
       ALLOW_THIS_IN_INITIALIZER_LIST(ignore_pos_changes_factory_(this)),
       last_monitor_(NULL),
       is_right_mouse_pressed_on_caption_(false),
       restored_enabled_(false),
@@ skipping 45 matching lines @@
   // We need to explicitly activate the window if we've been shown with a state
   // that should activate, because if we're opened from a desktop shortcut while
   // an existing window is already running it doesn't seem to be enough to use
   // one of these flags to activate the window.
   if (show_state == SW_SHOWNORMAL || show_state == SW_SHOWMAXIMIZED)
     Activate();
 
   SetInitialFocus();
 }
 
-View* NativeWidgetWin::GetAccessibilityViewEventAt(int id) {
-  // Convert from MSAA child id.
-  id = -(id + 1);
-  DCHECK(id >= 0 && id < kMaxAccessibilityViewEvents);
-  return accessibility_view_events_[id];
-}
-
-int NativeWidgetWin::AddAccessibilityViewEvent(View* view) {
-  accessibility_view_events_index_ =
-      (accessibility_view_events_index_ + 1) % kMaxAccessibilityViewEvents;
-  accessibility_view_events_[accessibility_view_events_index_] = view;
-
-  // Convert to MSAA child id.
-  return -(accessibility_view_events_index_ + 1);
-}
-
-void NativeWidgetWin::ClearAccessibilityViewEvent(View* view) {
-  for (std::vector<View*>::iterator it = accessibility_view_events_.begin();
-      it != accessibility_view_events_.end();
-      ++it) {
-    if (*it == view)
-      *it = NULL;
-  }
+View* NativeWidgetWin::GetViewByAccessibleId(long child_id) {
+  // The IAccessible2 unique ID is the negation of the child ID;
+  // see the comments in SendNativeAccessibilityEvent for details.
+  return FindViewByIA2UniqueId(-child_id, GetWidget()->GetRootView());
 }
 
 void NativeWidgetWin::PushForceHidden() {
   if (force_hidden_count_++ == 0)
     Hide();
 }
 
 void NativeWidgetWin::PopForceHidden() {
   if (--force_hidden_count_ <= 0) {
     force_hidden_count_ = 0;
@@ skipping 101 matching lines @@
     gfx::Point* offset,
     ui::Layer** layer_parent) {
 }
 
 void NativeWidgetWin::ReorderLayers() {
 }
 
 void NativeWidgetWin::ViewRemoved(View* view) {
   if (drop_target_.get())
     drop_target_->ResetTargetViewIfEquals(view);
-
-  ClearAccessibilityViewEvent(view);
 }
 
 void NativeWidgetWin::SetNativeWindowProperty(const char* name, void* value) {
   // Remove the existing property (if any).
   for (ViewProps::iterator i = props_.begin(); i != props_.end(); ++i) {
     if ((*i)->Key() == name) {
       props_.erase(i);
       break;
     }
   }
@@ skipping 10 matching lines @@
   return tooltip_manager_.get();
 }
 
 bool NativeWidgetWin::IsScreenReaderActive() const {
   return screen_reader_active_;
 }
 
 void NativeWidgetWin::SendNativeAccessibilityEvent(
     View* view,
     ui::AccessibilityTypes::Event event_type) {
-  // Now call the Windows-specific method to notify MSAA clients of this
-  // event.  The widget gives us a temporary unique child ID to associate
-  // with this view so that clients can call get_accChild in
-  // NativeViewAccessibilityWin to retrieve the IAccessible associated
-  // with this view.
-  int child_id = AddAccessibilityViewEvent(view);
-  ::NotifyWinEvent(NativeViewAccessibilityWin::MSAAEvent(event_type),
-                   GetNativeView(), OBJID_CLIENT, child_id);
+  DWORD native_event = NativeViewAccessibilityWin::MSAAEvent(event_type);
+  gfx::NativeView native_view = this->GetNativeView();
+
+  // Get the unique ID from the view's IAccessible2 interface.
+  IAccessible* accessible = view->GetNativeViewAccessible();
+  IAccessible2* accessible2 = NULL;
+  HRESULT hr = accessible->QueryInterface(
+      IID_IAccessible2, reinterpret_cast<void**>(&accessible2));
+  if (hr != S_OK) {
+    // If this is reached, you're probably trying to fire a notification on a
+    // views::NativeViewHost that has only a default IAccessible. You have to
+    // either call ::NotifyWinEvent directly, or override
+    // GetNativeViewAccessible for that view.
+    NOTREACHED();
+    return;
+  }
+  long unique_id;
+  hr = accessible2->get_uniqueID(&unique_id);
+  DCHECK_EQ(hr, S_OK);
+
+  // Send the negation of the unique id as the child id parameter to
+  // NotifyWinEvent. The client will call get_accChild on the top-level
+  // NativeViewAccessibilityWin object, where positive child ids are
+  // interpreted as 1-based child indices, and negative child ids are
+  // interpreted as unique ids.
+  ::NotifyWinEvent(native_event, native_view, OBJID_CLIENT, -unique_id);
 }
 
 void NativeWidgetWin::SetMouseCapture() {
   DCHECK(!HasMouseCapture());
   SetCapture(hwnd());
 }
 
 void NativeWidgetWin::ReleaseMouseCapture() {
   ReleaseCapture();
 }
@@ skipping 1814 matching lines @@
       ::EnableWindow(start, TRUE);
       start = ::GetParent(start);
     }
   }
 }
 
 void NativeWidgetWin::DispatchKeyEventPostIME(const KeyEvent& key) {
   SetMsgHandled(delegate_->OnKeyEvent(key));
 }
 
+View* NativeWidgetWin::FindViewByIA2UniqueId(long id, View* view) {
+  IAccessible* accessible = view->GetNativeViewAccessible();
+  IAccessible2* accessible2 = NULL;
+  if (S_OK == accessible->QueryInterface(
+          IID_IAccessible2, reinterpret_cast<void**>(&accessible2))) {
+    long unique_id;
+    if (S_OK == accessible2->get_uniqueID(&unique_id) && id == unique_id)
+      return view;
+  }
+
+  for (int i = 0; i < view->child_count(); i++) {
+    View* result = FindViewByIA2UniqueId(id, view->child_at(i));
+    if (result)
+      return result;
+  }
+
+  return NULL;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Widget, public:
 
 // static
 void Widget::NotifyLocaleChanged() {
   NOTIMPLEMENTED();
 }
 
 namespace {
 BOOL CALLBACK WindowCallbackProc(HWND hwnd, LPARAM lParam) {
@@ skipping 147 matching lines @@
   return (GetKeyState(VK_LBUTTON) & 0x80) ||
     (GetKeyState(VK_RBUTTON) & 0x80) ||
     (GetKeyState(VK_MBUTTON) & 0x80) ||
     (GetKeyState(VK_XBUTTON1) & 0x80) ||
     (GetKeyState(VK_XBUTTON2) & 0x80);
 }
 
 }  // namespace internal
 
 }  // namespace views