src/content/browser/accessibility/browser_accessibility_manager_win.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "content/browser/accessibility/browser_accessibility_manager_win.h"
   6
   7 #include "base/command_line.h"
   8 #include "base/win/scoped_comptr.h"
   9 #include "base/win/windows_version.h"
  10 #include "content/browser/accessibility/browser_accessibility_state_impl.h"
  11 #include "content/browser/accessibility/browser_accessibility_win.h"
  12 #include "content/browser/renderer_host/legacy_render_widget_host_win.h"
  13 #include "content/common/accessibility_messages.h"
  14 #include "ui/base/win/atl_module.h"
  15
  16 namespace content {
  17
  18 // static
  19 BrowserAccessibilityManager* BrowserAccessibilityManager::Create(
  20     const ui::AXTreeUpdate& initial_tree,
  21     BrowserAccessibilityDelegate* delegate,
  22     BrowserAccessibilityFactory* factory) {
  23   return new BrowserAccessibilityManagerWin(initial_tree, delegate, factory);
  24 }
  25
  26 BrowserAccessibilityManagerWin*
  27 BrowserAccessibilityManager::ToBrowserAccessibilityManagerWin() {
  28   return static_cast<BrowserAccessibilityManagerWin*>(this);
  29 }
  30
  31 BrowserAccessibilityManagerWin::BrowserAccessibilityManagerWin(
  32     const ui::AXTreeUpdate& initial_tree,
  33     BrowserAccessibilityDelegate* delegate,
  34     BrowserAccessibilityFactory* factory)
  35     : BrowserAccessibilityManager(delegate, factory),
  36       tracked_scroll_object_(NULL),
  37       focus_event_on_root_needed_(false) {
  38   ui::win::CreateATLModuleIfNeeded();
  39   Initialize(initial_tree);
  40 }
  41
  42 BrowserAccessibilityManagerWin::~BrowserAccessibilityManagerWin() {
  43   if (tracked_scroll_object_) {
  44     tracked_scroll_object_->Release();
  45     tracked_scroll_object_ = NULL;
  46   }
  47 }
  48
  49 // static
  50 ui::AXTreeUpdate BrowserAccessibilityManagerWin::GetEmptyDocument() {
  51   ui::AXNodeData empty_document;
  52   empty_document.id = 0;
  53   empty_document.role = ui::AX_ROLE_ROOT_WEB_AREA;
  54   empty_document.state =
  55       (1 << ui::AX_STATE_ENABLED) |
  56       (1 << ui::AX_STATE_READ_ONLY) |
  57       (1 << ui::AX_STATE_BUSY);
  58
  59   ui::AXTreeUpdate update;
  60   update.nodes.push_back(empty_document);
  61   return update;
  62 }
  63
  64 HWND BrowserAccessibilityManagerWin::GetParentHWND() {
  65   if (!delegate_)
  66     return NULL;
  67   return delegate_->AccessibilityGetAcceleratedWidget();
  68 }
  69
  70 IAccessible* BrowserAccessibilityManagerWin::GetParentIAccessible() {
  71   if (!delegate_)
  72     return NULL;
  73   return delegate_->AccessibilityGetNativeViewAccessible();
  74 }
  75
  76 void BrowserAccessibilityManagerWin::MaybeCallNotifyWinEvent(DWORD event,
  77                                                              LONG child_id) {
  78   if (!delegate_)
  79     return;
  80
  81   HWND hwnd = delegate_->AccessibilityGetAcceleratedWidget();
  82   if (!hwnd)
  83     return;
  84
  85   ::NotifyWinEvent(event, hwnd, OBJID_CLIENT, child_id);
  86 }
  87
  88
  89 void BrowserAccessibilityManagerWin::OnNodeCreated(ui::AXNode* node) {
  90   BrowserAccessibilityManager::OnNodeCreated(node);
  91   BrowserAccessibility* obj = GetFromAXNode(node);
  92   LONG unique_id_win = obj->ToBrowserAccessibilityWin()->unique_id_win();
  93   unique_id_to_ax_id_map_[unique_id_win] = obj->GetId();
  94 }
  95
  96 void BrowserAccessibilityManagerWin::OnNodeWillBeDeleted(ui::AXNode* node) {
  97   BrowserAccessibilityManager::OnNodeWillBeDeleted(node);
  98   BrowserAccessibility* obj = GetFromAXNode(node);
  99   if (!obj)
 100     return;
 101   unique_id_to_ax_id_map_.erase(
 102       obj->ToBrowserAccessibilityWin()->unique_id_win());
 103   if (obj == tracked_scroll_object_) {
 104     tracked_scroll_object_->Release();
 105     tracked_scroll_object_ = NULL;
 106   }
 107 }
 108
 109 void BrowserAccessibilityManagerWin::OnWindowFocused() {
 110   // This is called either when this web frame gets focused, or when
 111   // the root of the accessibility tree changes. In both cases, we need
 112   // to fire a focus event on the root and then on the focused element
 113   // within the page, if different.
 114
 115   // Set this flag so that we'll keep trying to fire these focus events
 116   // if they're not successful this time.
 117   focus_event_on_root_needed_ = true;
 118
 119   if (!delegate_ || !delegate_->AccessibilityViewHasFocus())
 120     return;
 121
 122   // Try to fire a focus event on the root first and then the focused node.
 123   // This will clear focus_event_on_root_needed_ if successful.
 124   if (focus_ != tree_->GetRoot())
 125     NotifyAccessibilityEvent(ui::AX_EVENT_FOCUS, GetRoot());
 126   BrowserAccessibilityManager::OnWindowFocused();
 127 }
 128
 129 void BrowserAccessibilityManagerWin::NotifyAccessibilityEvent(
 130     ui::AXEvent event_type,
 131     BrowserAccessibility* node) {
 132   if (!delegate_ || !delegate_->AccessibilityGetAcceleratedWidget())
 133     return;
 134
 135   // Inline text boxes are an internal implementation detail, we don't
 136   // expose them to Windows.
 137   if (node->GetRole() == ui::AX_ROLE_INLINE_TEXT_BOX)
 138     return;
 139
 140   // Don't fire focus, blur, or load complete notifications if the
 141   // window isn't focused, because that can confuse screen readers into
 142   // entering their "browse" mode.
 143   if ((event_type == ui::AX_EVENT_FOCUS ||
 144        event_type == ui::AX_EVENT_BLUR ||
 145        event_type == ui::AX_EVENT_LOAD_COMPLETE) &&
 146       (!delegate_ || !delegate_->AccessibilityViewHasFocus())) {
 147     return;
 148   }
 149
 150   // NVDA gets confused if we focus the main document element when it hasn't
 151   // finished loading and it has no children at all, so suppress that event.
 152   if (event_type == ui::AX_EVENT_FOCUS &&
 153       node == GetRoot() &&
 154       node->PlatformChildCount() == 0 &&
 155       !node->HasState(ui::AX_STATE_BUSY) &&
 156       !node->GetBoolAttribute(ui::AX_ATTR_DOC_LOADED)) {
 157     return;
 158   }
 159
 160   // If a focus event is needed on the root, fire that first before
 161   // this event.
 162   if (event_type == ui::AX_EVENT_FOCUS && node == GetRoot())
 163     focus_event_on_root_needed_ = false;
 164   else if (focus_event_on_root_needed_)
 165     OnWindowFocused();
 166
 167   LONG event_id = EVENT_MIN;
 168   switch (event_type) {
 169     case ui::AX_EVENT_ACTIVEDESCENDANTCHANGED:
 170       event_id = IA2_EVENT_ACTIVE_DESCENDANT_CHANGED;
 171       break;
 172     case ui::AX_EVENT_ALERT:
 173       event_id = EVENT_SYSTEM_ALERT;
 174       break;
 175     case ui::AX_EVENT_ARIA_ATTRIBUTE_CHANGED:
 176       event_id = IA2_EVENT_OBJECT_ATTRIBUTE_CHANGED;
 177       break;
 178     case ui::AX_EVENT_AUTOCORRECTION_OCCURED:
 179       event_id = IA2_EVENT_OBJECT_ATTRIBUTE_CHANGED;
 180       break;
 181     case ui::AX_EVENT_BLUR:
 182       // Equivalent to focus on the root.
 183       event_id = EVENT_OBJECT_FOCUS;
 184       node = GetRoot();
 185       break;
 186     case ui::AX_EVENT_CHECKED_STATE_CHANGED:
 187       event_id = EVENT_OBJECT_STATECHANGE;
 188       break;
 189     case ui::AX_EVENT_CHILDREN_CHANGED:
 190       event_id = EVENT_OBJECT_REORDER;
 191       break;
 192     case ui::AX_EVENT_FOCUS:
 193       event_id = EVENT_OBJECT_FOCUS;
 194       break;
 195     case ui::AX_EVENT_INVALID_STATUS_CHANGED:
 196       event_id = EVENT_OBJECT_STATECHANGE;
 197       break;
 198     case ui::AX_EVENT_LIVE_REGION_CHANGED:
 199       if (node->GetBoolAttribute(ui::AX_ATTR_CONTAINER_LIVE_BUSY))
 200         return;
 201       event_id = EVENT_OBJECT_LIVEREGIONCHANGED;
 202       break;
 203     case ui::AX_EVENT_LOAD_COMPLETE:
 204       event_id = IA2_EVENT_DOCUMENT_LOAD_COMPLETE;
 205       break;
 206     case ui::AX_EVENT_MENU_LIST_ITEM_SELECTED:
 207       event_id = EVENT_OBJECT_FOCUS;
 208       break;
 209     case ui::AX_EVENT_MENU_LIST_VALUE_CHANGED:
 210       event_id = EVENT_OBJECT_VALUECHANGE;
 211       break;
 212     case ui::AX_EVENT_HIDE:
 213       event_id = EVENT_OBJECT_HIDE;
 214       break;
 215     case ui::AX_EVENT_SHOW:
 216       event_id = EVENT_OBJECT_SHOW;
 217       break;
 218     case ui::AX_EVENT_SCROLL_POSITION_CHANGED:
 219       event_id = EVENT_SYSTEM_SCROLLINGEND;
 220       break;
 221     case ui::AX_EVENT_SCROLLED_TO_ANCHOR:
 222       event_id = EVENT_SYSTEM_SCROLLINGSTART;
 223       break;
 224     case ui::AX_EVENT_SELECTED_CHILDREN_CHANGED:
 225       event_id = EVENT_OBJECT_SELECTIONWITHIN;
 226       break;
 227     case ui::AX_EVENT_TEXT_CHANGED:
 228       event_id = EVENT_OBJECT_NAMECHANGE;
 229       break;
 230     case ui::AX_EVENT_TEXT_SELECTION_CHANGED:
 231       event_id = IA2_EVENT_TEXT_CARET_MOVED;
 232       break;
 233     case ui::AX_EVENT_VALUE_CHANGED:
 234       event_id = EVENT_OBJECT_VALUECHANGE;
 235       break;
 236     default:
 237       // Not all WebKit accessibility events result in a Windows
 238       // accessibility notification.
 239       break;
 240   }
 241
 242   if (event_id != EVENT_MIN) {
 243     // Pass the node's unique id in the |child_id| argument to NotifyWinEvent;
 244     // the AT client will then call get_accChild on the HWND's accessibility
 245     // object and pass it that same id, which we can use to retrieve the
 246     // IAccessible for this node.
 247     LONG child_id = node->ToBrowserAccessibilityWin()->unique_id_win();
 248     MaybeCallNotifyWinEvent(event_id, child_id);
 249   }
 250
 251   // If this is a layout complete notification (sent when a container scrolls)
 252   // and there is a descendant tracked object, send a notification on it.
 253   // TODO(dmazzoni): remove once http://crbug.com/113483 is fixed.
 254   if (event_type == ui::AX_EVENT_LAYOUT_COMPLETE &&
 255       tracked_scroll_object_ &&
 256       tracked_scroll_object_->IsDescendantOf(node)) {
 257     MaybeCallNotifyWinEvent(
 258         IA2_EVENT_VISIBLE_DATA_CHANGED,
 259         tracked_scroll_object_->ToBrowserAccessibilityWin()->unique_id_win());
 260     tracked_scroll_object_->Release();
 261     tracked_scroll_object_ = NULL;
 262   }
 263 }
 264
 265 void BrowserAccessibilityManagerWin::OnRootChanged(ui::AXNode* new_root) {
 266   // In order to make screen readers aware of the new accessibility root,
 267   // we need to fire a focus event on it.
 268   OnWindowFocused();
 269 }
 270
 271 void BrowserAccessibilityManagerWin::TrackScrollingObject(
 272     BrowserAccessibilityWin* node) {
 273   if (tracked_scroll_object_)
 274     tracked_scroll_object_->Release();
 275   tracked_scroll_object_ = node;
 276   tracked_scroll_object_->AddRef();
 277 }
 278
 279 BrowserAccessibilityWin* BrowserAccessibilityManagerWin::GetFromUniqueIdWin(
 280     LONG unique_id_win) {
 281   base::hash_map<LONG, int32>::iterator iter =
 282       unique_id_to_ax_id_map_.find(unique_id_win);
 283   if (iter != unique_id_to_ax_id_map_.end()) {
 284     BrowserAccessibility* result = GetFromID(iter->second);
 285     if (result)
 286       return result->ToBrowserAccessibilityWin();
 287   }
 288   return NULL;
 289 }
 290
 291 }  // namespace content