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 <vector>
   8
   9 #include "base/command_line.h"
  10 #include "base/win/scoped_comptr.h"
  11 #include "base/win/windows_version.h"
  12 #include "content/browser/accessibility/browser_accessibility_state_impl.h"
  13 #include "content/browser/accessibility/browser_accessibility_win.h"
  14 #include "content/browser/renderer_host/legacy_render_widget_host_win.h"
  15 #include "content/common/accessibility_messages.h"
  16 #include "ui/base/win/atl_module.h"
  17
  18 namespace content {
  19
  20 // static
  21 BrowserAccessibilityManager* BrowserAccessibilityManager::Create(
  22     const ui::AXTreeUpdate& initial_tree,
  23     BrowserAccessibilityDelegate* delegate,
  24     BrowserAccessibilityFactory* factory) {
  25   return new BrowserAccessibilityManagerWin(initial_tree, delegate, factory);
  26 }
  27
  28 BrowserAccessibilityManagerWin*
  29 BrowserAccessibilityManager::ToBrowserAccessibilityManagerWin() {
  30   return static_cast<BrowserAccessibilityManagerWin*>(this);
  31 }
  32
  33 BrowserAccessibilityManagerWin::BrowserAccessibilityManagerWin(
  34     const ui::AXTreeUpdate& initial_tree,
  35     BrowserAccessibilityDelegate* delegate,
  36     BrowserAccessibilityFactory* factory)
  37     : BrowserAccessibilityManager(delegate, factory),
  38       tracked_scroll_object_(NULL),
  39       focus_event_on_root_needed_(false) {
  40   ui::win::CreateATLModuleIfNeeded();
  41   Initialize(initial_tree);
  42 }
  43
  44 BrowserAccessibilityManagerWin::~BrowserAccessibilityManagerWin() {
  45   if (tracked_scroll_object_) {
  46     tracked_scroll_object_->Release();
  47     tracked_scroll_object_ = NULL;
  48   }
  49 }
  50
  51 // static
  52 ui::AXTreeUpdate BrowserAccessibilityManagerWin::GetEmptyDocument() {
  53   ui::AXNodeData empty_document;
  54   empty_document.id = 0;
  55   empty_document.role = ui::AX_ROLE_ROOT_WEB_AREA;
  56   empty_document.state =
  57       (1 << ui::AX_STATE_ENABLED) |
  58       (1 << ui::AX_STATE_READ_ONLY) |
  59       (1 << ui::AX_STATE_BUSY);
  60
  61   ui::AXTreeUpdate update;
  62   update.nodes.push_back(empty_document);
  63   return update;
  64 }
  65
  66 HWND BrowserAccessibilityManagerWin::GetParentHWND() {
  67   if (!delegate_)
  68     return NULL;
  69   return delegate_->AccessibilityGetAcceleratedWidget();
  70 }
  71
  72 IAccessible* BrowserAccessibilityManagerWin::GetParentIAccessible() {
  73   if (!delegate_)
  74     return NULL;
  75   return delegate_->AccessibilityGetNativeViewAccessible();
  76 }
  77
  78 void BrowserAccessibilityManagerWin::MaybeCallNotifyWinEvent(
  79     DWORD event, BrowserAccessibility* node) {
  80   BrowserAccessibilityDelegate* delegate = GetDelegateFromRootManager();
  81   if (!delegate) {
  82     // This line and other LOG(WARNING) lines are temporary, to debug
  83     // flaky failures in DumpAccessibilityEvent* tests.
  84     // http://crbug.com/440579
  85     LOG(WARNING) << "Not firing AX event because of no delegate";
  86     return;
  87   }
  88
  89   if (!node->IsNative())
  90     return;
  91
  92   HWND hwnd = delegate->AccessibilityGetAcceleratedWidget();
  93   if (!hwnd) {
  94     LOG(WARNING) << "Not firing AX event because of no hwnd";
  95     return;
  96   }
  97
  98   // Inline text boxes are an internal implementation detail, we don't
  99   // expose them to Windows.
 100   if (node->GetRole() == ui::AX_ROLE_INLINE_TEXT_BOX)
 101     return;
 102
 103   // It doesn't make sense to fire a REORDER event on a leaf node; that
 104   // happens when the node has internal children line inline text boxes.
 105   if (event == EVENT_OBJECT_REORDER && node->PlatformIsLeaf())
 106     return;
 107
 108   // Don't fire focus, or load complete notifications if the
 109   // window isn't focused, because that can confuse screen readers into
 110   // entering their "browse" mode.
 111   if ((event == EVENT_OBJECT_FOCUS ||
 112        event == IA2_EVENT_DOCUMENT_LOAD_COMPLETE) &&
 113       (!delegate_->AccessibilityViewHasFocus())) {
 114     return;
 115   }
 116
 117   // NVDA gets confused if we focus the main document element when it hasn't
 118   // finished loading and it has no children at all, so suppress that event.
 119   if (event == EVENT_OBJECT_FOCUS &&
 120       node == GetRoot() &&
 121       node->PlatformChildCount() == 0 &&
 122       !node->HasState(ui::AX_STATE_BUSY) &&
 123       !node->GetBoolAttribute(ui::AX_ATTR_DOC_LOADED)) {
 124     return;
 125   }
 126
 127   // If a focus event is needed on the root, fire that first before
 128   // this event.
 129   if (event == EVENT_OBJECT_FOCUS && node == GetRoot())
 130     focus_event_on_root_needed_ = false;
 131   else if (focus_event_on_root_needed_)
 132     OnWindowFocused();
 133
 134   LONG child_id = node->ToBrowserAccessibilityWin()->unique_id_win();
 135   ::NotifyWinEvent(event, hwnd, OBJID_CLIENT, child_id);
 136 }
 137
 138 void BrowserAccessibilityManagerWin::OnNodeCreated(ui::AXNode* node) {
 139   BrowserAccessibilityManager::OnNodeCreated(node);
 140   BrowserAccessibility* obj = GetFromAXNode(node);
 141   if (!obj)
 142     return;
 143   if (!obj->IsNative())
 144     return;
 145   LONG unique_id_win = obj->ToBrowserAccessibilityWin()->unique_id_win();
 146   unique_id_to_ax_id_map_[unique_id_win] = obj->GetId();
 147 }
 148
 149 void BrowserAccessibilityManagerWin::OnNodeWillBeDeleted(ui::AXNode* node) {
 150   BrowserAccessibilityManager::OnNodeWillBeDeleted(node);
 151   BrowserAccessibility* obj = GetFromAXNode(node);
 152   if (!obj)
 153     return;
 154   if (!obj->IsNative())
 155     return;
 156   unique_id_to_ax_id_map_.erase(
 157       obj->ToBrowserAccessibilityWin()->unique_id_win());
 158   if (obj == tracked_scroll_object_) {
 159     tracked_scroll_object_->Release();
 160     tracked_scroll_object_ = NULL;
 161   }
 162 }
 163
 164 void BrowserAccessibilityManagerWin::OnWindowFocused() {
 165   // This is called either when this web frame gets focused, or when
 166   // the root of the accessibility tree changes. In both cases, we need
 167   // to fire a focus event on the root and then on the focused element
 168   // within the page, if different.
 169
 170   // Set this flag so that we'll keep trying to fire these focus events
 171   // if they're not successful this time.
 172   focus_event_on_root_needed_ = true;
 173
 174   if (!delegate_ || !delegate_->AccessibilityViewHasFocus())
 175     return;
 176
 177   // Try to fire a focus event on the root first and then the focused node.
 178   // This will clear focus_event_on_root_needed_ if successful.
 179   if (focus_ != tree_->root())
 180     NotifyAccessibilityEvent(ui::AX_EVENT_FOCUS, GetRoot());
 181   BrowserAccessibilityManager::OnWindowFocused();
 182 }
 183
 184 void BrowserAccessibilityManagerWin::UserIsReloading() {
 185   MaybeCallNotifyWinEvent(IA2_EVENT_DOCUMENT_RELOAD, GetRoot());
 186 }
 187
 188 void BrowserAccessibilityManagerWin::NotifyAccessibilityEvent(
 189     ui::AXEvent event_type,
 190     BrowserAccessibility* node) {
 191   BrowserAccessibilityDelegate* root_delegate = GetDelegateFromRootManager();
 192   if (!root_delegate || !root_delegate->AccessibilityGetAcceleratedWidget()) {
 193     LOG(WARNING) << "Not firing AX event because of no root_delegate or hwnd";
 194     return;
 195   }
 196
 197   // Don't fire events when this document might be stale as the user has
 198   // started navigating to a new document.
 199   if (user_is_navigating_away_)
 200     return;
 201
 202   // Inline text boxes are an internal implementation detail, we don't
 203   // expose them to Windows.
 204   if (node->GetRole() == ui::AX_ROLE_INLINE_TEXT_BOX)
 205     return;
 206
 207   // Don't fire focus, blur, or load complete notifications if the
 208   // window isn't focused, because that can confuse screen readers into
 209   // entering their "browse" mode.
 210   if ((event_type == ui::AX_EVENT_FOCUS ||
 211        event_type == ui::AX_EVENT_BLUR ||
 212        event_type == ui::AX_EVENT_LOAD_COMPLETE) &&
 213       !root_delegate->AccessibilityViewHasFocus()) {
 214     return;
 215   }
 216
 217   // NVDA gets confused if we focus the main document element when it hasn't
 218   // finished loading and it has no children at all, so suppress that event.
 219   if (event_type == ui::AX_EVENT_FOCUS &&
 220       node == GetRoot() &&
 221       node->PlatformChildCount() == 0 &&
 222       !node->HasState(ui::AX_STATE_BUSY) &&
 223       !node->GetBoolAttribute(ui::AX_ATTR_DOC_LOADED)) {
 224     return;
 225   }
 226
 227   // If a focus event is needed on the root, fire that first before
 228   // this event.
 229   if (event_type == ui::AX_EVENT_FOCUS && node == GetRoot())
 230     focus_event_on_root_needed_ = false;
 231   else if (focus_event_on_root_needed_)
 232     OnWindowFocused();
 233
 234   LONG event_id = EVENT_MIN;
 235   switch (event_type) {
 236     case ui::AX_EVENT_ACTIVEDESCENDANTCHANGED:
 237       event_id = IA2_EVENT_ACTIVE_DESCENDANT_CHANGED;
 238       break;
 239     case ui::AX_EVENT_ALERT:
 240       event_id = EVENT_SYSTEM_ALERT;
 241       break;
 242     case ui::AX_EVENT_AUTOCORRECTION_OCCURED:
 243       event_id = IA2_EVENT_OBJECT_ATTRIBUTE_CHANGED;
 244       break;
 245     case ui::AX_EVENT_BLUR:
 246       // Equivalent to focus on the root.
 247       event_id = EVENT_OBJECT_FOCUS;
 248       node = GetRoot();
 249       break;
 250     case ui::AX_EVENT_CHILDREN_CHANGED:
 251       event_id = EVENT_OBJECT_REORDER;
 252       break;
 253     case ui::AX_EVENT_FOCUS:
 254       event_id = EVENT_OBJECT_FOCUS;
 255       break;
 256     case ui::AX_EVENT_LIVE_REGION_CHANGED:
 257       if (node->GetBoolAttribute(ui::AX_ATTR_CONTAINER_LIVE_BUSY))
 258         return;
 259       event_id = EVENT_OBJECT_LIVEREGIONCHANGED;
 260       break;
 261     case ui::AX_EVENT_LOAD_COMPLETE:
 262       event_id = IA2_EVENT_DOCUMENT_LOAD_COMPLETE;
 263       break;
 264     case ui::AX_EVENT_SCROLL_POSITION_CHANGED:
 265       event_id = EVENT_SYSTEM_SCROLLINGEND;
 266       break;
 267     case ui::AX_EVENT_SCROLLED_TO_ANCHOR:
 268       event_id = EVENT_SYSTEM_SCROLLINGSTART;
 269       break;
 270     case ui::AX_EVENT_SELECTED_CHILDREN_CHANGED:
 271       event_id = EVENT_OBJECT_SELECTIONWITHIN;
 272       break;
 273     case ui::AX_EVENT_TEXT_SELECTION_CHANGED:
 274       event_id = IA2_EVENT_TEXT_CARET_MOVED;
 275       break;
 276     default:
 277       // Not all WebKit accessibility events result in a Windows
 278       // accessibility notification.
 279       break;
 280   }
 281
 282   if (event_id != EVENT_MIN) {
 283     // Pass the node's unique id in the |child_id| argument to NotifyWinEvent;
 284     // the AT client will then call get_accChild on the HWND's accessibility
 285     // object and pass it that same id, which we can use to retrieve the
 286     // IAccessible for this node.
 287     MaybeCallNotifyWinEvent(event_id, node);
 288   }
 289
 290   // If this is a layout complete notification (sent when a container scrolls)
 291   // and there is a descendant tracked object, send a notification on it.
 292   // TODO(dmazzoni): remove once http://crbug.com/113483 is fixed.
 293   if (event_type == ui::AX_EVENT_LAYOUT_COMPLETE &&
 294       tracked_scroll_object_ &&
 295       tracked_scroll_object_->IsDescendantOf(node)) {
 296     MaybeCallNotifyWinEvent(
 297         IA2_EVENT_VISIBLE_DATA_CHANGED, tracked_scroll_object_);
 298     tracked_scroll_object_->Release();
 299     tracked_scroll_object_ = NULL;
 300   }
 301 }
 302
 303 void BrowserAccessibilityManagerWin::OnAtomicUpdateFinished(
 304     bool root_changed,
 305     const std::vector<ui::AXTreeDelegate::Change>& changes) {
 306   BrowserAccessibilityManager::OnAtomicUpdateFinished(root_changed, changes);
 307
 308   if (root_changed) {
 309     // In order to make screen readers aware of the new accessibility root,
 310     // we need to fire a focus event on it.
 311     OnWindowFocused();
 312   }
 313
 314   // Do a sequence of Windows-specific updates on each node. Each one is
 315   // done in a single pass that must complete before the next step starts.
 316   // The first step moves win_attributes_ to old_win_attributes_ and then
 317   // recomputes all of win_attributes_ other than IAccessibleText.
 318   for (size_t i = 0; i < changes.size(); ++i) {
 319     BrowserAccessibility* obj = GetFromAXNode(changes[i].node);
 320     if (obj && obj->IsNative() && !obj->PlatformIsChildOfLeaf())
 321       obj->ToBrowserAccessibilityWin()->UpdateStep1ComputeWinAttributes();
 322   }
 323
 324   // The next step updates the hypertext of each node, which is a
 325   // concatenation of all of its child text nodes, so it can't run until
 326   // the text of all of the nodes was computed in the previous step.
 327   for (size_t i = 0; i < changes.size(); ++i) {
 328     BrowserAccessibility* obj = GetFromAXNode(changes[i].node);
 329     if (obj && obj->IsNative() && !obj->PlatformIsChildOfLeaf())
 330       obj->ToBrowserAccessibilityWin()->UpdateStep2ComputeHypertext();
 331   }
 332
 333   // The third step fires events on nodes based on what's changed - like
 334   // if the name, value, or description changed, or if the hypertext had
 335   // text inserted or removed. It's able to figure out exactly what changed
 336   // because we still have old_win_attributes_ populated.
 337   // This step has to run after the previous two steps complete because the
 338   // client may walk the tree when it receives any of these events.
 339   // At the end, it deletes old_win_attributes_ since they're not needed
 340   // anymore.
 341   for (size_t i = 0; i < changes.size(); ++i) {
 342     BrowserAccessibility* obj = GetFromAXNode(changes[i].node);
 343     if (obj && obj->IsNative() && !obj->PlatformIsChildOfLeaf()) {
 344       obj->ToBrowserAccessibilityWin()->UpdateStep3FireEvents(
 345           changes[i].type == AXTreeDelegate::SUBTREE_CREATED);
 346     }
 347   }
 348 }
 349
 350 void BrowserAccessibilityManagerWin::TrackScrollingObject(
 351     BrowserAccessibilityWin* node) {
 352   if (tracked_scroll_object_)
 353     tracked_scroll_object_->Release();
 354   tracked_scroll_object_ = node;
 355   tracked_scroll_object_->AddRef();
 356 }
 357
 358 BrowserAccessibilityWin* BrowserAccessibilityManagerWin::GetFromUniqueIdWin(
 359     LONG unique_id_win) {
 360   base::hash_map<LONG, int32>::iterator iter =
 361       unique_id_to_ax_id_map_.find(unique_id_win);
 362   if (iter != unique_id_to_ax_id_map_.end()) {
 363     BrowserAccessibility* result = GetFromID(iter->second);
 364     if (result && result->IsNative())
 365       return result->ToBrowserAccessibilityWin();
 366   }
 367
 368   // Also search all child frames, such as out-of-process iframes or
 369   // guest browser plugins.
 370   if (delegate()) {
 371     std::vector<BrowserAccessibilityManager*> child_frames;
 372     delegate()->AccessibilityGetAllChildFrames(&child_frames);
 373     for (size_t i = 0; i < child_frames.size(); ++i) {
 374       BrowserAccessibilityManagerWin* child_manager =
 375           child_frames[i]->ToBrowserAccessibilityManagerWin();
 376       BrowserAccessibilityWin* result =
 377           child_manager->GetFromUniqueIdWin(unique_id_win);
 378       if (result)
 379         return result;
 380     }
 381   }
 382
 383   return NULL;
 384 }
 385
 386 }  // namespace content