content/browser/accessibility/browser_accessibility.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.h"
   6
   7 #include <algorithm>
   8
   9 #include "base/logging.h"
  10 #include "base/strings/string_number_conversions.h"
  11 #include "base/strings/string_util.h"
  12 #include "base/strings/utf_string_conversions.h"
  13 #include "content/browser/accessibility/browser_accessibility_manager.h"
  14 #include "content/common/accessibility_messages.h"
  15 #include "ui/accessibility/ax_text_utils.h"
  16
  17 namespace content {
  18
  19 #if !defined(OS_MACOSX) && \
  20     !defined(OS_WIN) && \
  21     !defined(OS_ANDROID)
  22 // We have subclassess of BrowserAccessibility on Mac and Win. For any other
  23 // platform, instantiate the base class.
  24 // static
  25 BrowserAccessibility* BrowserAccessibility::Create() {
  26   return new BrowserAccessibility();
  27 }
  28 #endif
  29
  30 BrowserAccessibility::BrowserAccessibility()
  31     : manager_(NULL),
  32       node_(NULL) {
  33 }
  34
  35 BrowserAccessibility::~BrowserAccessibility() {
  36 }
  37
  38 void BrowserAccessibility::Init(BrowserAccessibilityManager* manager,
  39     ui::AXNode* node) {
  40   manager_ = manager;
  41   node_ = node;
  42 }
  43
  44 bool BrowserAccessibility::PlatformIsLeaf() const {
  45   if (InternalChildCount() == 0)
  46     return true;
  47
  48   // All of these roles may have children that we use as internal
  49   // implementation details, but we want to expose them as leaves
  50   // to platform accessibility APIs.
  51   switch (GetRole()) {
  52     case ui::AX_ROLE_LINE_BREAK:
  53     case ui::AX_ROLE_SLIDER:
  54     case ui::AX_ROLE_STATIC_TEXT:
  55     case ui::AX_ROLE_TEXT_FIELD:
  56       return true;
  57     default:
  58       return false;
  59   }
  60 }
  61
  62 uint32 BrowserAccessibility::PlatformChildCount() const {
  63   return PlatformIsLeaf() ? 0 : InternalChildCount();
  64 }
  65
  66 bool BrowserAccessibility::IsNative() const {
  67   return false;
  68 }
  69
  70 bool BrowserAccessibility::IsDescendantOf(
  71     BrowserAccessibility* ancestor) {
  72   if (this == ancestor) {
  73     return true;
  74   } else if (GetParent()) {
  75     return GetParent()->IsDescendantOf(ancestor);
  76   }
  77
  78   return false;
  79 }
  80
  81 BrowserAccessibility* BrowserAccessibility::PlatformGetChild(
  82     uint32 child_index) const {
  83   DCHECK(child_index < InternalChildCount());
  84   BrowserAccessibility* result = InternalGetChild(child_index);
  85
  86   if (result->HasBoolAttribute(ui::AX_ATTR_IS_AX_TREE_HOST)) {
  87     BrowserAccessibilityManager* child_manager =
  88         manager_->delegate()->AccessibilityGetChildFrame(result->GetId());
  89     if (child_manager)
  90       result = child_manager->GetRoot();
  91   }
  92
  93   return result;
  94 }
  95
  96 bool BrowserAccessibility::PlatformIsChildOfLeaf() const {
  97   BrowserAccessibility* ancestor = GetParent();
  98   while (ancestor) {
  99     if (ancestor->PlatformIsLeaf())
 100       return true;
 101     ancestor = ancestor->GetParent();
 102   }
 103
 104   return false;
 105 }
 106
 107 BrowserAccessibility* BrowserAccessibility::GetPreviousSibling() {
 108   if (GetParent() && GetIndexInParent() > 0)
 109     return GetParent()->InternalGetChild(GetIndexInParent() - 1);
 110
 111   return NULL;
 112 }
 113
 114 BrowserAccessibility* BrowserAccessibility::GetNextSibling() {
 115   if (GetParent() &&
 116       GetIndexInParent() >= 0 &&
 117       GetIndexInParent() < static_cast<int>(
 118           GetParent()->InternalChildCount() - 1)) {
 119     return GetParent()->InternalGetChild(GetIndexInParent() + 1);
 120   }
 121
 122   return NULL;
 123 }
 124
 125 uint32 BrowserAccessibility::InternalChildCount() const {
 126   if (!node_ || !manager_)
 127     return 0;
 128   return static_cast<uint32>(node_->child_count());
 129 }
 130
 131 BrowserAccessibility* BrowserAccessibility::InternalGetChild(
 132     uint32 child_index) const {
 133   if (!node_ || !manager_)
 134     return NULL;
 135   return manager_->GetFromAXNode(node_->ChildAtIndex(child_index));
 136 }
 137
 138 BrowserAccessibility* BrowserAccessibility::GetParent() const {
 139   if (!node_ || !manager_)
 140     return NULL;
 141   ui::AXNode* parent = node_->parent();
 142   if (parent)
 143     return manager_->GetFromAXNode(parent);
 144
 145   if (!manager_->delegate())
 146     return NULL;
 147
 148   BrowserAccessibility* host_node =
 149       manager_->delegate()->AccessibilityGetParentFrame();
 150   if (!host_node)
 151     return NULL;
 152
 153   return host_node->GetParent();
 154 }
 155
 156 int32 BrowserAccessibility::GetIndexInParent() const {
 157   return node_ ? node_->index_in_parent() : -1;
 158 }
 159
 160 int32 BrowserAccessibility::GetId() const {
 161   return node_ ? node_->id() : -1;
 162 }
 163
 164 const ui::AXNodeData& BrowserAccessibility::GetData() const {
 165   CR_DEFINE_STATIC_LOCAL(ui::AXNodeData, empty_data, ());
 166   if (node_)
 167     return node_->data();
 168   else
 169     return empty_data;
 170 }
 171
 172 gfx::Rect BrowserAccessibility::GetLocation() const {
 173   return GetData().location;
 174 }
 175
 176 int32 BrowserAccessibility::GetRole() const {
 177   return GetData().role;
 178 }
 179
 180 int32 BrowserAccessibility::GetState() const {
 181   return GetData().state;
 182 }
 183
 184 const BrowserAccessibility::HtmlAttributes&
 185 BrowserAccessibility::GetHtmlAttributes() const {
 186   return GetData().html_attributes;
 187 }
 188
 189 gfx::Rect BrowserAccessibility::GetLocalBoundsRect() const {
 190   gfx::Rect bounds = GetLocation();
 191   return ElementBoundsToLocalBounds(bounds);
 192 }
 193
 194 gfx::Rect BrowserAccessibility::GetGlobalBoundsRect() const {
 195   gfx::Rect bounds = GetLocalBoundsRect();
 196
 197   // Adjust the bounds by the top left corner of the containing view's bounds
 198   // in screen coordinates.
 199   bounds.Offset(manager_->GetViewBounds().OffsetFromOrigin());
 200
 201   return bounds;
 202 }
 203
 204 gfx::Rect BrowserAccessibility::GetLocalBoundsForRange(int start, int len)
 205     const {
 206   if (GetRole() != ui::AX_ROLE_STATIC_TEXT) {
 207     // Apply recursively to all static text descendants. For example, if
 208     // you call it on a div with two text node children, it just calls
 209     // GetLocalBoundsForRange on each of the two children (adjusting
 210     // |start| for each one) and unions the resulting rects.
 211     gfx::Rect bounds;
 212     for (size_t i = 0; i < InternalChildCount(); ++i) {
 213       BrowserAccessibility* child = InternalGetChild(i);
 214       int child_len = child->GetStaticTextLenRecursive();
 215       if (start < child_len && start + len > 0) {
 216         gfx::Rect child_rect = child->GetLocalBoundsForRange(start, len);
 217         bounds.Union(child_rect);
 218       }
 219       start -= child_len;
 220     }
 221     return ElementBoundsToLocalBounds(bounds);
 222   }
 223
 224   int end = start + len;
 225   int child_start = 0;
 226   int child_end = 0;
 227
 228   gfx::Rect bounds;
 229   for (size_t i = 0; i < InternalChildCount() && child_end < start + len; ++i) {
 230     BrowserAccessibility* child = InternalGetChild(i);
 231     DCHECK_EQ(child->GetRole(), ui::AX_ROLE_INLINE_TEXT_BOX);
 232     std::string child_text;
 233     child->GetStringAttribute(ui::AX_ATTR_VALUE, &child_text);
 234     int child_len = static_cast<int>(child_text.size());
 235     child_start = child_end;
 236     child_end += child_len;
 237
 238     if (child_end < start)
 239       continue;
 240
 241     int overlap_start = std::max(start, child_start);
 242     int overlap_end = std::min(end, child_end);
 243
 244     int local_start = overlap_start - child_start;
 245     int local_end = overlap_end - child_start;
 246
 247     gfx::Rect child_rect = child->GetLocation();
 248     int text_direction = child->GetIntAttribute(
 249         ui::AX_ATTR_TEXT_DIRECTION);
 250     const std::vector<int32>& character_offsets = child->GetIntListAttribute(
 251         ui::AX_ATTR_CHARACTER_OFFSETS);
 252     int start_pixel_offset =
 253         local_start > 0 ? character_offsets[local_start - 1] : 0;
 254     int end_pixel_offset =
 255         local_end > 0 ? character_offsets[local_end - 1] : 0;
 256
 257     gfx::Rect child_overlap_rect;
 258     switch (text_direction) {
 259       case ui::AX_TEXT_DIRECTION_NONE:
 260       case ui::AX_TEXT_DIRECTION_LR: {
 261         int left = child_rect.x() + start_pixel_offset;
 262         int right = child_rect.x() + end_pixel_offset;
 263         child_overlap_rect = gfx::Rect(left, child_rect.y(),
 264                                        right - left, child_rect.height());
 265         break;
 266       }
 267       case ui::AX_TEXT_DIRECTION_RL: {
 268         int right = child_rect.right() - start_pixel_offset;
 269         int left = child_rect.right() - end_pixel_offset;
 270         child_overlap_rect = gfx::Rect(left, child_rect.y(),
 271                                        right - left, child_rect.height());
 272         break;
 273       }
 274       case ui::AX_TEXT_DIRECTION_TB: {
 275         int top = child_rect.y() + start_pixel_offset;
 276         int bottom = child_rect.y() + end_pixel_offset;
 277         child_overlap_rect = gfx::Rect(child_rect.x(), top,
 278                                        child_rect.width(), bottom - top);
 279         break;
 280       }
 281       case ui::AX_TEXT_DIRECTION_BT: {
 282         int bottom = child_rect.bottom() - start_pixel_offset;
 283         int top = child_rect.bottom() - end_pixel_offset;
 284         child_overlap_rect = gfx::Rect(child_rect.x(), top,
 285                                        child_rect.width(), bottom - top);
 286         break;
 287       }
 288       default:
 289         NOTREACHED();
 290     }
 291
 292     if (bounds.width() == 0 && bounds.height() == 0)
 293       bounds = child_overlap_rect;
 294     else
 295       bounds.Union(child_overlap_rect);
 296   }
 297
 298   return ElementBoundsToLocalBounds(bounds);
 299 }
 300
 301 gfx::Rect BrowserAccessibility::GetGlobalBoundsForRange(int start, int len)
 302     const {
 303   gfx::Rect bounds = GetLocalBoundsForRange(start, len);
 304
 305   // Adjust the bounds by the top left corner of the containing view's bounds
 306   // in screen coordinates.
 307   bounds.Offset(manager_->GetViewBounds().OffsetFromOrigin());
 308
 309   return bounds;
 310 }
 311
 312 int BrowserAccessibility::GetWordStartBoundary(
 313     int start, ui::TextBoundaryDirection direction) const {
 314   int word_start = 0;
 315   int prev_word_start = 0;
 316   if (GetRole() != ui::AX_ROLE_STATIC_TEXT) {
 317     for (size_t i = 0; i < InternalChildCount(); ++i) {
 318       BrowserAccessibility* child = InternalGetChild(i);
 319       int child_len = child->GetStaticTextLenRecursive();
 320       int child_word_start = child->GetWordStartBoundary(start, direction);
 321       word_start += child_word_start;
 322       if (child_word_start != child_len)
 323           break;
 324       start -= child_len;
 325     }
 326     return word_start;
 327   }
 328
 329   int child_start = 0;
 330   int child_end = 0;
 331   for (size_t i = 0; i < InternalChildCount(); ++i) {
 332     // The next child starts where the previous one ended.
 333     child_start = child_end;
 334     BrowserAccessibility* child = InternalGetChild(i);
 335     DCHECK_EQ(child->GetRole(), ui::AX_ROLE_INLINE_TEXT_BOX);
 336     const std::string& child_text = child->GetStringAttribute(
 337         ui::AX_ATTR_VALUE);
 338     int child_len = static_cast<int>(child_text.size());
 339     child_end += child_len; // End is one past the last character.
 340
 341     const std::vector<int32>& word_starts = child->GetIntListAttribute(
 342         ui::AX_ATTR_WORD_STARTS);
 343     if (word_starts.empty()) {
 344       word_start = child_end;
 345       continue;
 346     }
 347
 348     int local_start = start - child_start;
 349     std::vector<int32>::const_iterator iter = std::upper_bound(
 350         word_starts.begin(), word_starts.end(), local_start);
 351     if (iter != word_starts.end()) {
 352       if (direction == ui::FORWARDS_DIRECTION) {
 353         word_start = child_start + *iter;
 354       } else if (direction == ui::BACKWARDS_DIRECTION) {
 355         if (iter == word_starts.begin()) {
 356           // Return the position of the last word in the previous child.
 357           word_start = prev_word_start;
 358         } else {
 359           word_start = child_start + *(iter - 1);
 360         }
 361       } else {
 362         NOTREACHED();
 363       }
 364       break;
 365     }
 366
 367     // No word start that is >= to the requested offset has been found.
 368     prev_word_start = child_start + *(iter - 1);
 369     if (direction == ui::FORWARDS_DIRECTION) {
 370       word_start = child_end;
 371     } else if (direction == ui::BACKWARDS_DIRECTION) {
 372       word_start = prev_word_start;
 373     } else {
 374       NOTREACHED();
 375     }
 376   }
 377
 378   return word_start;
 379 }
 380
 381 BrowserAccessibility* BrowserAccessibility::BrowserAccessibilityForPoint(
 382     const gfx::Point& point) {
 383   // The best result found that's a child of this object.
 384   BrowserAccessibility* child_result = NULL;
 385   // The best result that's an indirect descendant like grandchild, etc.
 386   BrowserAccessibility* descendant_result = NULL;
 387
 388   // Walk the children recursively looking for the BrowserAccessibility that
 389   // most tightly encloses the specified point. Walk backwards so that in
 390   // the absence of any other information, we assume the object that occurs
 391   // later in the tree is on top of one that comes before it.
 392   for (int i = static_cast<int>(PlatformChildCount()) - 1; i >= 0; --i) {
 393     BrowserAccessibility* child = PlatformGetChild(i);
 394
 395     // Skip table columns because cells are only contained in rows,
 396     // not columns.
 397     if (child->GetRole() == ui::AX_ROLE_COLUMN)
 398       continue;
 399
 400     if (child->GetGlobalBoundsRect().Contains(point)) {
 401       BrowserAccessibility* result = child->BrowserAccessibilityForPoint(point);
 402       if (result == child && !child_result)
 403         child_result = result;
 404       if (result != child && !descendant_result)
 405         descendant_result = result;
 406     }
 407
 408     if (child_result && descendant_result)
 409       break;
 410   }
 411
 412   // Explanation of logic: it's possible that this point overlaps more than
 413   // one child of this object. If so, as a heuristic we prefer if the point
 414   // overlaps a descendant of one of the two children and not the other.
 415   // As an example, suppose you have two rows of buttons - the buttons don't
 416   // overlap, but the rows do. Without this heuristic, we'd greedily only
 417   // consider one of the containers.
 418   if (descendant_result)
 419     return descendant_result;
 420   if (child_result)
 421     return child_result;
 422
 423   return this;
 424 }
 425
 426 void BrowserAccessibility::Destroy() {
 427   // Allow the object to fire a TextRemoved notification.
 428   manager_->NotifyAccessibilityEvent(ui::AX_EVENT_HIDE, this);
 429   node_ = NULL;
 430   manager_ = NULL;
 431
 432   NativeReleaseReference();
 433 }
 434
 435 void BrowserAccessibility::NativeReleaseReference() {
 436   delete this;
 437 }
 438
 439 bool BrowserAccessibility::HasBoolAttribute(
 440     ui::AXBoolAttribute attribute) const {
 441   const ui::AXNodeData& data = GetData();
 442   for (size_t i = 0; i < data.bool_attributes.size(); ++i) {
 443     if (data.bool_attributes[i].first == attribute)
 444       return true;
 445   }
 446
 447   return false;
 448 }
 449
 450
 451 bool BrowserAccessibility::GetBoolAttribute(
 452     ui::AXBoolAttribute attribute) const {
 453   const ui::AXNodeData& data = GetData();
 454   for (size_t i = 0; i < data.bool_attributes.size(); ++i) {
 455     if (data.bool_attributes[i].first == attribute)
 456       return data.bool_attributes[i].second;
 457   }
 458
 459   return false;
 460 }
 461
 462 bool BrowserAccessibility::GetBoolAttribute(
 463     ui::AXBoolAttribute attribute, bool* value) const {
 464   const ui::AXNodeData& data = GetData();
 465   for (size_t i = 0; i < data.bool_attributes.size(); ++i) {
 466     if (data.bool_attributes[i].first == attribute) {
 467       *value = data.bool_attributes[i].second;
 468       return true;
 469     }
 470   }
 471
 472   return false;
 473 }
 474
 475 bool BrowserAccessibility::HasFloatAttribute(
 476     ui::AXFloatAttribute attribute) const {
 477   const ui::AXNodeData& data = GetData();
 478   for (size_t i = 0; i < data.float_attributes.size(); ++i) {
 479     if (data.float_attributes[i].first == attribute)
 480       return true;
 481   }
 482
 483   return false;
 484 }
 485
 486 float BrowserAccessibility::GetFloatAttribute(
 487     ui::AXFloatAttribute attribute) const {
 488   const ui::AXNodeData& data = GetData();
 489   for (size_t i = 0; i < data.float_attributes.size(); ++i) {
 490     if (data.float_attributes[i].first == attribute)
 491       return data.float_attributes[i].second;
 492   }
 493
 494   return 0.0;
 495 }
 496
 497 bool BrowserAccessibility::GetFloatAttribute(
 498     ui::AXFloatAttribute attribute, float* value) const {
 499   const ui::AXNodeData& data = GetData();
 500   for (size_t i = 0; i < data.float_attributes.size(); ++i) {
 501     if (data.float_attributes[i].first == attribute) {
 502       *value = data.float_attributes[i].second;
 503       return true;
 504     }
 505   }
 506
 507   return false;
 508 }
 509
 510 bool BrowserAccessibility::HasIntAttribute(
 511     ui::AXIntAttribute attribute) const {
 512   const ui::AXNodeData& data = GetData();
 513   for (size_t i = 0; i < data.int_attributes.size(); ++i) {
 514     if (data.int_attributes[i].first == attribute)
 515       return true;
 516   }
 517
 518   return false;
 519 }
 520
 521 int BrowserAccessibility::GetIntAttribute(ui::AXIntAttribute attribute) const {
 522   const ui::AXNodeData& data = GetData();
 523   for (size_t i = 0; i < data.int_attributes.size(); ++i) {
 524     if (data.int_attributes[i].first == attribute)
 525       return data.int_attributes[i].second;
 526   }
 527
 528   return 0;
 529 }
 530
 531 bool BrowserAccessibility::GetIntAttribute(
 532     ui::AXIntAttribute attribute, int* value) const {
 533   const ui::AXNodeData& data = GetData();
 534   for (size_t i = 0; i < data.int_attributes.size(); ++i) {
 535     if (data.int_attributes[i].first == attribute) {
 536       *value = data.int_attributes[i].second;
 537       return true;
 538     }
 539   }
 540
 541   return false;
 542 }
 543
 544 bool BrowserAccessibility::HasStringAttribute(
 545     ui::AXStringAttribute attribute) const {
 546   const ui::AXNodeData& data = GetData();
 547   for (size_t i = 0; i < data.string_attributes.size(); ++i) {
 548     if (data.string_attributes[i].first == attribute)
 549       return true;
 550   }
 551
 552   return false;
 553 }
 554
 555 const std::string& BrowserAccessibility::GetStringAttribute(
 556     ui::AXStringAttribute attribute) const {
 557   const ui::AXNodeData& data = GetData();
 558   CR_DEFINE_STATIC_LOCAL(std::string, empty_string, ());
 559   for (size_t i = 0; i < data.string_attributes.size(); ++i) {
 560     if (data.string_attributes[i].first == attribute)
 561       return data.string_attributes[i].second;
 562   }
 563
 564   return empty_string;
 565 }
 566
 567 bool BrowserAccessibility::GetStringAttribute(
 568     ui::AXStringAttribute attribute, std::string* value) const {
 569   const ui::AXNodeData& data = GetData();
 570   for (size_t i = 0; i < data.string_attributes.size(); ++i) {
 571     if (data.string_attributes[i].first == attribute) {
 572       *value = data.string_attributes[i].second;
 573       return true;
 574     }
 575   }
 576
 577   return false;
 578 }
 579
 580 base::string16 BrowserAccessibility::GetString16Attribute(
 581     ui::AXStringAttribute attribute) const {
 582   std::string value_utf8;
 583   if (!GetStringAttribute(attribute, &value_utf8))
 584     return base::string16();
 585   return base::UTF8ToUTF16(value_utf8);
 586 }
 587
 588 bool BrowserAccessibility::GetString16Attribute(
 589     ui::AXStringAttribute attribute,
 590     base::string16* value) const {
 591   std::string value_utf8;
 592   if (!GetStringAttribute(attribute, &value_utf8))
 593     return false;
 594   *value = base::UTF8ToUTF16(value_utf8);
 595   return true;
 596 }
 597
 598 bool BrowserAccessibility::HasIntListAttribute(
 599     ui::AXIntListAttribute attribute) const {
 600   const ui::AXNodeData& data = GetData();
 601   for (size_t i = 0; i < data.intlist_attributes.size(); ++i) {
 602     if (data.intlist_attributes[i].first == attribute)
 603       return true;
 604   }
 605
 606   return false;
 607 }
 608
 609 const std::vector<int32>& BrowserAccessibility::GetIntListAttribute(
 610     ui::AXIntListAttribute attribute) const {
 611   const ui::AXNodeData& data = GetData();
 612   CR_DEFINE_STATIC_LOCAL(std::vector<int32>, empty_vector, ());
 613   for (size_t i = 0; i < data.intlist_attributes.size(); ++i) {
 614     if (data.intlist_attributes[i].first == attribute)
 615       return data.intlist_attributes[i].second;
 616   }
 617
 618   return empty_vector;
 619 }
 620
 621 bool BrowserAccessibility::GetIntListAttribute(
 622     ui::AXIntListAttribute attribute,
 623     std::vector<int32>* value) const {
 624   const ui::AXNodeData& data = GetData();
 625   for (size_t i = 0; i < data.intlist_attributes.size(); ++i) {
 626     if (data.intlist_attributes[i].first == attribute) {
 627       *value = data.intlist_attributes[i].second;
 628       return true;
 629     }
 630   }
 631
 632   return false;
 633 }
 634
 635 bool BrowserAccessibility::GetHtmlAttribute(
 636     const char* html_attr, std::string* value) const {
 637   for (size_t i = 0; i < GetHtmlAttributes().size(); ++i) {
 638     const std::string& attr = GetHtmlAttributes()[i].first;
 639     if (LowerCaseEqualsASCII(attr, html_attr)) {
 640       *value = GetHtmlAttributes()[i].second;
 641       return true;
 642     }
 643   }
 644
 645   return false;
 646 }
 647
 648 bool BrowserAccessibility::GetHtmlAttribute(
 649     const char* html_attr, base::string16* value) const {
 650   std::string value_utf8;
 651   if (!GetHtmlAttribute(html_attr, &value_utf8))
 652     return false;
 653   *value = base::UTF8ToUTF16(value_utf8);
 654   return true;
 655 }
 656
 657 bool BrowserAccessibility::GetAriaTristate(
 658     const char* html_attr,
 659     bool* is_defined,
 660     bool* is_mixed) const {
 661   *is_defined = false;
 662   *is_mixed = false;
 663
 664   base::string16 value;
 665   if (!GetHtmlAttribute(html_attr, &value) ||
 666       value.empty() ||
 667       EqualsASCII(value, "undefined")) {
 668     return false;  // Not set (and *is_defined is also false)
 669   }
 670
 671   *is_defined = true;
 672
 673   if (EqualsASCII(value, "true"))
 674     return true;
 675
 676   if (EqualsASCII(value, "mixed"))
 677     *is_mixed = true;
 678
 679   return false;  // Not set
 680 }
 681
 682 bool BrowserAccessibility::HasState(ui::AXState state_enum) const {
 683   return (GetState() >> state_enum) & 1;
 684 }
 685
 686 bool BrowserAccessibility::IsCellOrTableHeaderRole() const {
 687   return (GetRole() == ui::AX_ROLE_CELL ||
 688           GetRole() == ui::AX_ROLE_COLUMN_HEADER ||
 689           GetRole() == ui::AX_ROLE_ROW_HEADER);
 690 }
 691
 692 bool BrowserAccessibility::IsEditableText() const {
 693   // These roles don't have readonly set, but they're not editable text.
 694   if (GetRole() == ui::AX_ROLE_SCROLL_AREA ||
 695       GetRole() == ui::AX_ROLE_COLUMN ||
 696       GetRole() == ui::AX_ROLE_TABLE_HEADER_CONTAINER) {
 697     return false;
 698   }
 699
 700   // Note: WebAXStateReadonly being false means it's either a text control,
 701   // or contenteditable. We also check for editable text roles to cover
 702   // another element that has role=textbox set on it.
 703   return (!HasState(ui::AX_STATE_READ_ONLY) ||
 704           GetRole() == ui::AX_ROLE_TEXT_FIELD);
 705 }
 706
 707 bool BrowserAccessibility::IsWebAreaForPresentationalIframe() const {
 708   if (GetRole() != ui::AX_ROLE_WEB_AREA &&
 709       GetRole() != ui::AX_ROLE_ROOT_WEB_AREA) {
 710     return false;
 711   }
 712
 713   BrowserAccessibility* parent = GetParent();
 714   if (!parent)
 715     return false;
 716
 717   BrowserAccessibility* grandparent = parent->GetParent();
 718   if (!grandparent)
 719     return false;
 720
 721   return grandparent->GetRole() == ui::AX_ROLE_IFRAME_PRESENTATIONAL;
 722 }
 723
 724 int BrowserAccessibility::GetStaticTextLenRecursive() const {
 725   if (GetRole() == ui::AX_ROLE_STATIC_TEXT)
 726     return static_cast<int>(GetStringAttribute(ui::AX_ATTR_VALUE).size());
 727
 728   int len = 0;
 729   for (size_t i = 0; i < InternalChildCount(); ++i)
 730     len += InternalGetChild(i)->GetStaticTextLenRecursive();
 731   return len;
 732 }
 733
 734 BrowserAccessibility* BrowserAccessibility::GetParentForBoundsCalculation()
 735     const {
 736   if (!node_ || !manager_)
 737     return NULL;
 738   ui::AXNode* parent = node_->parent();
 739   if (parent)
 740     return manager_->GetFromAXNode(parent);
 741
 742   if (!manager_->delegate())
 743     return NULL;
 744
 745   return manager_->delegate()->AccessibilityGetParentFrame();
 746 }
 747
 748 gfx::Rect BrowserAccessibility::ElementBoundsToLocalBounds(gfx::Rect bounds)
 749     const {
 750   // Walk up the parent chain. Every time we encounter a Web Area, offset
 751   // based on the scroll bars and then offset based on the origin of that
 752   // nested web area.
 753   BrowserAccessibility* parent = GetParentForBoundsCalculation();
 754   bool need_to_offset_web_area =
 755       (GetRole() == ui::AX_ROLE_WEB_AREA ||
 756        GetRole() == ui::AX_ROLE_ROOT_WEB_AREA);
 757   while (parent) {
 758     if (need_to_offset_web_area &&
 759         parent->GetLocation().width() > 0 &&
 760         parent->GetLocation().height() > 0) {
 761       bounds.Offset(parent->GetLocation().x(), parent->GetLocation().y());
 762       need_to_offset_web_area = false;
 763     }
 764
 765     // On some platforms, we don't want to take the root scroll offsets
 766     // into account.
 767     if (parent->GetRole() == ui::AX_ROLE_ROOT_WEB_AREA &&
 768         !manager()->UseRootScrollOffsetsWhenComputingBounds()) {
 769       break;
 770     }
 771
 772     if (parent->GetRole() == ui::AX_ROLE_WEB_AREA ||
 773         parent->GetRole() == ui::AX_ROLE_ROOT_WEB_AREA) {
 774       int sx = 0;
 775       int sy = 0;
 776       if (parent->GetIntAttribute(ui::AX_ATTR_SCROLL_X, &sx) &&
 777           parent->GetIntAttribute(ui::AX_ATTR_SCROLL_Y, &sy)) {
 778         bounds.Offset(-sx, -sy);
 779       }
 780       need_to_offset_web_area = true;
 781     }
 782     parent = parent->GetParentForBoundsCalculation();
 783   }
 784
 785   return bounds;
 786 }
 787
 788 }  // namespace content