content/browser/accessibility/browser

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This source file includes following definitions.
Create
instance_active_
PlatformIsLeaf
PlatformChildCount
DetachTree
InitializeTreeStructure
InitializeData
IsNative
SwapChildren
UpdateParent
SetLocation
IsDescendantOf
PlatformGetChild
GetPreviousSibling
GetNextSibling
GetLocalBoundsRect
GetGlobalBoundsRect
GetLocalBoundsForRange
GetGlobalBoundsForRange
BrowserAccessibilityForPoint
Destroy
NativeReleaseReference
HasBoolAttribute
GetBoolAttribute
GetBoolAttribute
HasFloatAttribute
GetFloatAttribute
GetFloatAttribute
HasIntAttribute
GetIntAttribute
GetIntAttribute
HasStringAttribute
GetStringAttribute
GetStringAttribute
GetString16Attribute
GetString16Attribute
SetStringAttribute
HasIntListAttribute
GetIntListAttribute
GetIntListAttribute
GetHtmlAttribute
GetHtmlAttribute
GetAriaTristate
HasState
IsEditableText
GetTextRecursive
GetStaticTextLenRecursive
// Copyright (c) 2012 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 "content/browser/accessibility/browser_accessibility.h"

#include "base/logging.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_util.h"
#include "base/strings/utf_string_conversions.h"
#include "content/browser/accessibility/browser_accessibility_manager.h"
#include "content/common/accessibility_messages.h"

namespace content {

#if !defined(OS_MACOSX) && \
    !defined(OS_WIN) && \
    !defined(TOOLKIT_GTK) && \
    !defined(OS_ANDROID)
// We have subclassess of BrowserAccessibility on Mac, Linux/GTK,
// and Win. For any other platform, instantiate the base class.
// static
BrowserAccessibility* BrowserAccessibility::Create() {
  return new BrowserAccessibility();
}
#endif

BrowserAccessibility::BrowserAccessibility()
    : manager_(NULL),
      parent_(NULL),
      index_in_parent_(0),
      renderer_id_(0),
      role_(0),
      state_(0),
      instance_active_(false) {
}

BrowserAccessibility::~BrowserAccessibility() {
}

bool BrowserAccessibility::PlatformIsLeaf() const {
  if (child_count() == 0)
    return true;

  // All of these roles may have children that we use as internal
  // implementation details, but we want to expose them as leaves
  // to platform accessibility APIs.
  switch (role_) {
    case ui::AX_ROLE_EDITABLE_TEXT:
    case ui::AX_ROLE_SLIDER:
    case ui::AX_ROLE_STATIC_TEXT:
    case ui::AX_ROLE_TEXT_AREA:
    case ui::AX_ROLE_TEXT_FIELD:
      return true;
    default:
      return false;
  }
}

uint32 BrowserAccessibility::PlatformChildCount() const {
  return PlatformIsLeaf() ? 0 : children_.size();
}

void BrowserAccessibility::DetachTree(
    std::vector<BrowserAccessibility*>* nodes) {
  nodes->push_back(this);
  for (size_t i = 0; i < children_.size(); ++i)
    children_[i]->DetachTree(nodes);
  children_.clear();
  parent_ = NULL;
}

void BrowserAccessibility::InitializeTreeStructure(
    BrowserAccessibilityManager* manager,
    BrowserAccessibility* parent,
    int32 renderer_id,
    int32 index_in_parent) {
  manager_ = manager;
  parent_ = parent;
  renderer_id_ = renderer_id;
  index_in_parent_ = index_in_parent;
}

void BrowserAccessibility::InitializeData(const ui::AXNodeData& src) {
  DCHECK_EQ(renderer_id_, src.id);
  role_ = src.role;
  state_ = src.state;
  string_attributes_ = src.string_attributes;
  int_attributes_ = src.int_attributes;
  float_attributes_ = src.float_attributes;
  bool_attributes_ = src.bool_attributes;
  intlist_attributes_ = src.intlist_attributes;
  html_attributes_ = src.html_attributes;
  location_ = src.location;
  instance_active_ = true;

  GetStringAttribute(ui::AX_ATTR_NAME, &name_);
  GetStringAttribute(ui::AX_ATTR_VALUE, &value_);

  PreInitialize();
}

bool BrowserAccessibility::IsNative() const {
  return false;
}

void BrowserAccessibility::SwapChildren(
    std::vector<BrowserAccessibility*>& children) {
  children.swap(children_);
}

void BrowserAccessibility::UpdateParent(BrowserAccessibility* parent,
                                        int index_in_parent) {
  parent_ = parent;
  index_in_parent_ = index_in_parent;
}

void BrowserAccessibility::SetLocation(const gfx::Rect& new_location) {
  location_ = new_location;
}

bool BrowserAccessibility::IsDescendantOf(
    BrowserAccessibility* ancestor) {
  if (this == ancestor) {
    return true;
  } else if (parent_) {
    return parent_->IsDescendantOf(ancestor);
  }

  return false;
}

BrowserAccessibility* BrowserAccessibility::PlatformGetChild(
    uint32 child_index) const {
  DCHECK(child_index < children_.size());
  return children_[child_index];
}

BrowserAccessibility* BrowserAccessibility::GetPreviousSibling() {
  if (parent_ && index_in_parent_ > 0)
    return parent_->children_[index_in_parent_ - 1];

  return NULL;
}

BrowserAccessibility* BrowserAccessibility::GetNextSibling() {
  if (parent_ &&
      index_in_parent_ >= 0 &&
      index_in_parent_ < static_cast<int>(parent_->children_.size() - 1)) {
    return parent_->children_[index_in_parent_ + 1];
  }

  return NULL;
}

gfx::Rect BrowserAccessibility::GetLocalBoundsRect() const {
  gfx::Rect bounds = location_;

  // Walk up the parent chain. Every time we encounter a Web Area, offset
  // based on the scroll bars and then offset based on the origin of that
  // nested web area.
  BrowserAccessibility* parent = parent_;
  bool need_to_offset_web_area =
      (role_ == ui::AX_ROLE_WEB_AREA ||
       role_ == ui::AX_ROLE_ROOT_WEB_AREA);
  while (parent) {
    if (need_to_offset_web_area &&
        parent->location().width() > 0 &&
        parent->location().height() > 0) {
      bounds.Offset(parent->location().x(), parent->location().y());
      need_to_offset_web_area = false;
    }

    // On some platforms, we don't want to take the root scroll offsets
    // into account.
    if (parent->role() == ui::AX_ROLE_ROOT_WEB_AREA &&
        !manager()->UseRootScrollOffsetsWhenComputingBounds()) {
      break;
    }

    if (parent->role() == ui::AX_ROLE_WEB_AREA ||
        parent->role() == ui::AX_ROLE_ROOT_WEB_AREA) {
      int sx = 0;
      int sy = 0;
      if (parent->GetIntAttribute(ui::AX_ATTR_SCROLL_X, &sx) &&
          parent->GetIntAttribute(ui::AX_ATTR_SCROLL_Y, &sy)) {
        bounds.Offset(-sx, -sy);
      }
      need_to_offset_web_area = true;
    }
    parent = parent->parent();
  }

  return bounds;
}

gfx::Rect BrowserAccessibility::GetGlobalBoundsRect() const {
  gfx::Rect bounds = GetLocalBoundsRect();

  // Adjust the bounds by the top left corner of the containing view's bounds
  // in screen coordinates.
  bounds.Offset(manager_->GetViewBounds().OffsetFromOrigin());

  return bounds;
}

gfx::Rect BrowserAccessibility::GetLocalBoundsForRange(int start, int len)
    const {
  if (role() != ui::AX_ROLE_STATIC_TEXT) {
    // Apply recursively to all static text descendants. For example, if
    // you call it on a div with two text node children, it just calls
    // GetLocalBoundsForRange on each of the two children (adjusting
    // |start| for each one) and unions the resulting rects.
    gfx::Rect bounds;
    for (size_t i = 0; i < children_.size(); ++i) {
      BrowserAccessibility* child = children_[i];
      int child_len = child->GetStaticTextLenRecursive();
      if (start < child_len && start + len > 0) {
        gfx::Rect child_rect = child->GetLocalBoundsForRange(start, len);
        bounds.Union(child_rect);
      }
      start -= child_len;
    }
    return bounds;
  }

  int end = start + len;
  int child_start = 0;
  int child_end = 0;

  gfx::Rect bounds;
  for (size_t i = 0; i < children_.size() && child_end < start + len; ++i) {
    BrowserAccessibility* child = children_[i];
    DCHECK_EQ(child->role(), ui::AX_ROLE_INLINE_TEXT_BOX);
    std::string child_text;
    child->GetStringAttribute(ui::AX_ATTR_VALUE, &child_text);
    int child_len = static_cast<int>(child_text.size());
    child_start = child_end;
    child_end += child_len;

    if (child_end < start)
      continue;

    int overlap_start = std::max(start, child_start);
    int overlap_end = std::min(end, child_end);

    int local_start = overlap_start - child_start;
    int local_end = overlap_end - child_start;

    gfx::Rect child_rect = child->location();
    int text_direction = child->GetIntAttribute(
        ui::AX_ATTR_TEXT_DIRECTION);
    const std::vector<int32>& character_offsets = child->GetIntListAttribute(
        ui::AX_ATTR_CHARACTER_OFFSETS);
    int start_pixel_offset =
        local_start > 0 ? character_offsets[local_start - 1] : 0;
    int end_pixel_offset =
        local_end > 0 ? character_offsets[local_end - 1] : 0;

    gfx::Rect child_overlap_rect;
    switch (text_direction) {
      case ui::AX_TEXT_DIRECTION_NONE:
      case ui::AX_TEXT_DIRECTION_LR: {
        int left = child_rect.x() + start_pixel_offset;
        int right = child_rect.x() + end_pixel_offset;
        child_overlap_rect = gfx::Rect(left, child_rect.y(),
                                       right - left, child_rect.height());
        break;
      }
      case ui::AX_TEXT_DIRECTION_RL: {
        int right = child_rect.right() - start_pixel_offset;
        int left = child_rect.right() - end_pixel_offset;
        child_overlap_rect = gfx::Rect(left, child_rect.y(),
                                       right - left, child_rect.height());
        break;
      }
      case ui::AX_TEXT_DIRECTION_TB: {
        int top = child_rect.y() + start_pixel_offset;
        int bottom = child_rect.y() + end_pixel_offset;
        child_overlap_rect = gfx::Rect(child_rect.x(), top,
                                       child_rect.width(), bottom - top);
        break;
      }
      case ui::AX_TEXT_DIRECTION_BT: {
        int bottom = child_rect.bottom() - start_pixel_offset;
        int top = child_rect.bottom() - end_pixel_offset;
        child_overlap_rect = gfx::Rect(child_rect.x(), top,
                                       child_rect.width(), bottom - top);
        break;
      }
      default:
        NOTREACHED();
    }

    if (bounds.width() == 0 && bounds.height() == 0)
      bounds = child_overlap_rect;
    else
      bounds.Union(child_overlap_rect);
  }

  return bounds;
}

gfx::Rect BrowserAccessibility::GetGlobalBoundsForRange(int start, int len)
    const {
  gfx::Rect bounds = GetLocalBoundsForRange(start, len);

  // Adjust the bounds by the top left corner of the containing view's bounds
  // in screen coordinates.
  bounds.Offset(manager_->GetViewBounds().OffsetFromOrigin());

  return bounds;
}

BrowserAccessibility* BrowserAccessibility::BrowserAccessibilityForPoint(
    const gfx::Point& point) {
  // The best result found that's a child of this object.
  BrowserAccessibility* child_result = NULL;
  // The best result that's an indirect descendant like grandchild, etc.
  BrowserAccessibility* descendant_result = NULL;

  // Walk the children recursively looking for the BrowserAccessibility that
  // most tightly encloses the specified point. Walk backwards so that in
  // the absence of any other information, we assume the object that occurs
  // later in the tree is on top of one that comes before it.
  for (int i = static_cast<int>(PlatformChildCount()) - 1; i >= 0; --i) {
    BrowserAccessibility* child = PlatformGetChild(i);

    // Skip table columns because cells are only contained in rows,
    // not columns.
    if (child->role() == ui::AX_ROLE_COLUMN)
      continue;

    if (child->GetGlobalBoundsRect().Contains(point)) {
      BrowserAccessibility* result = child->BrowserAccessibilityForPoint(point);
      if (result == child && !child_result)
        child_result = result;
      if (result != child && !descendant_result)
        descendant_result = result;
    }

    if (child_result && descendant_result)
      break;
  }

  // Explanation of logic: it's possible that this point overlaps more than
  // one child of this object. If so, as a heuristic we prefer if the point
  // overlaps a descendant of one of the two children and not the other.
  // As an example, suppose you have two rows of buttons - the buttons don't
  // overlap, but the rows do. Without this heuristic, we'd greedily only
  // consider one of the containers.
  if (descendant_result)
    return descendant_result;
  if (child_result)
    return child_result;

  return this;
}

void BrowserAccessibility::Destroy() {
  for (std::vector<BrowserAccessibility*>::iterator iter = children_.begin();
       iter != children_.end();
       ++iter) {
    (*iter)->Destroy();
  }
  children_.clear();

  // Allow the object to fire a TextRemoved notification.
  name_.clear();
  value_.clear();
  PostInitialize();

  manager_->NotifyAccessibilityEvent(ui::AX_EVENT_HIDE, this);

  instance_active_ = false;
  manager_->RemoveNode(this);
  NativeReleaseReference();
}

void BrowserAccessibility::NativeReleaseReference() {
  delete this;
}

bool BrowserAccessibility::HasBoolAttribute(
    ui::AXBoolAttribute attribute) const {
  for (size_t i = 0; i < bool_attributes_.size(); ++i) {
    if (bool_attributes_[i].first == attribute)
      return true;
  }

  return false;
}


bool BrowserAccessibility::GetBoolAttribute(
    ui::AXBoolAttribute attribute) const {
  for (size_t i = 0; i < bool_attributes_.size(); ++i) {
    if (bool_attributes_[i].first == attribute)
      return bool_attributes_[i].second;
  }

  return false;
}

bool BrowserAccessibility::GetBoolAttribute(
    ui::AXBoolAttribute attribute, bool* value) const {
  for (size_t i = 0; i < bool_attributes_.size(); ++i) {
    if (bool_attributes_[i].first == attribute) {
      *value = bool_attributes_[i].second;
      return true;
    }
  }

  return false;
}

bool BrowserAccessibility::HasFloatAttribute(
    ui::AXFloatAttribute attribute) const {
  for (size_t i = 0; i < float_attributes_.size(); ++i) {
    if (float_attributes_[i].first == attribute)
      return true;
  }

  return false;
}

float BrowserAccessibility::GetFloatAttribute(
    ui::AXFloatAttribute attribute) const {
  for (size_t i = 0; i < float_attributes_.size(); ++i) {
    if (float_attributes_[i].first == attribute)
      return float_attributes_[i].second;
  }

  return 0.0;
}

bool BrowserAccessibility::GetFloatAttribute(
    ui::AXFloatAttribute attribute, float* value) const {
  for (size_t i = 0; i < float_attributes_.size(); ++i) {
    if (float_attributes_[i].first == attribute) {
      *value = float_attributes_[i].second;
      return true;
    }
  }

  return false;
}

bool BrowserAccessibility::HasIntAttribute(
    ui::AXIntAttribute attribute) const {
  for (size_t i = 0; i < int_attributes_.size(); ++i) {
    if (int_attributes_[i].first == attribute)
      return true;
  }

  return false;
}

int BrowserAccessibility::GetIntAttribute(ui::AXIntAttribute attribute) const {
  for (size_t i = 0; i < int_attributes_.size(); ++i) {
    if (int_attributes_[i].first == attribute)
      return int_attributes_[i].second;
  }

  return 0;
}

bool BrowserAccessibility::GetIntAttribute(
    ui::AXIntAttribute attribute, int* value) const {
  for (size_t i = 0; i < int_attributes_.size(); ++i) {
    if (int_attributes_[i].first == attribute) {
      *value = int_attributes_[i].second;
      return true;
    }
  }

  return false;
}

bool BrowserAccessibility::HasStringAttribute(
    ui::AXStringAttribute attribute) const {
  for (size_t i = 0; i < string_attributes_.size(); ++i) {
    if (string_attributes_[i].first == attribute)
      return true;
  }

  return false;
}

const std::string& BrowserAccessibility::GetStringAttribute(
    ui::AXStringAttribute attribute) const {
  CR_DEFINE_STATIC_LOCAL(std::string, empty_string, ());
  for (size_t i = 0; i < string_attributes_.size(); ++i) {
    if (string_attributes_[i].first == attribute)
      return string_attributes_[i].second;
  }

  return empty_string;
}

bool BrowserAccessibility::GetStringAttribute(
    ui::AXStringAttribute attribute, std::string* value) const {
  for (size_t i = 0; i < string_attributes_.size(); ++i) {
    if (string_attributes_[i].first == attribute) {
      *value = string_attributes_[i].second;
      return true;
    }
  }

  return false;
}

base::string16 BrowserAccessibility::GetString16Attribute(
    ui::AXStringAttribute attribute) const {
  std::string value_utf8;
  if (!GetStringAttribute(attribute, &value_utf8))
    return base::string16();
  return base::UTF8ToUTF16(value_utf8);
}

bool BrowserAccessibility::GetString16Attribute(
    ui::AXStringAttribute attribute,
    base::string16* value) const {
  std::string value_utf8;
  if (!GetStringAttribute(attribute, &value_utf8))
    return false;
  *value = base::UTF8ToUTF16(value_utf8);
  return true;
}

void BrowserAccessibility::SetStringAttribute(
    ui::AXStringAttribute attribute, const std::string& value) {
  for (size_t i = 0; i < string_attributes_.size(); ++i) {
    if (string_attributes_[i].first == attribute) {
      string_attributes_[i].second = value;
      return;
    }
  }
  if (!value.empty())
    string_attributes_.push_back(std::make_pair(attribute, value));
}

bool BrowserAccessibility::HasIntListAttribute(
    ui::AXIntListAttribute attribute) const {
  for (size_t i = 0; i < intlist_attributes_.size(); ++i) {
    if (intlist_attributes_[i].first == attribute)
      return true;
  }

  return false;
}

const std::vector<int32>& BrowserAccessibility::GetIntListAttribute(
    ui::AXIntListAttribute attribute) const {
  CR_DEFINE_STATIC_LOCAL(std::vector<int32>, empty_vector, ());
  for (size_t i = 0; i < intlist_attributes_.size(); ++i) {
    if (intlist_attributes_[i].first == attribute)
      return intlist_attributes_[i].second;
  }

  return empty_vector;
}

bool BrowserAccessibility::GetIntListAttribute(
    ui::AXIntListAttribute attribute,
    std::vector<int32>* value) const {
  for (size_t i = 0; i < intlist_attributes_.size(); ++i) {
    if (intlist_attributes_[i].first == attribute) {
      *value = intlist_attributes_[i].second;
      return true;
    }
  }

  return false;
}

bool BrowserAccessibility::GetHtmlAttribute(
    const char* html_attr, std::string* value) const {
  for (size_t i = 0; i < html_attributes_.size(); ++i) {
    const std::string& attr = html_attributes_[i].first;
    if (LowerCaseEqualsASCII(attr, html_attr)) {
      *value = html_attributes_[i].second;
      return true;
    }
  }

  return false;
}

bool BrowserAccessibility::GetHtmlAttribute(
    const char* html_attr, base::string16* value) const {
  std::string value_utf8;
  if (!GetHtmlAttribute(html_attr, &value_utf8))
    return false;
  *value = base::UTF8ToUTF16(value_utf8);
  return true;
}

bool BrowserAccessibility::GetAriaTristate(
    const char* html_attr,
    bool* is_defined,
    bool* is_mixed) const {
  *is_defined = false;
  *is_mixed = false;

  base::string16 value;
  if (!GetHtmlAttribute(html_attr, &value) ||
      value.empty() ||
      EqualsASCII(value, "undefined")) {
    return false;  // Not set (and *is_defined is also false)
  }

  *is_defined = true;

  if (EqualsASCII(value, "true"))
    return true;

  if (EqualsASCII(value, "mixed"))
    *is_mixed = true;

  return false;  // Not set
}

bool BrowserAccessibility::HasState(ui::AXState state_enum) const {
  return (state_ >> state_enum) & 1;
}

bool BrowserAccessibility::IsEditableText() const {
  // These roles don't have readonly set, but they're not editable text.
  if (role_ == ui::AX_ROLE_SCROLL_AREA ||
      role_ == ui::AX_ROLE_COLUMN ||
      role_ == ui::AX_ROLE_TABLE_HEADER_CONTAINER) {
    return false;
  }

  // Note: WebAXStateReadonly being false means it's either a text control,
  // or contenteditable. We also check for editable text roles to cover
  // another element that has role=textbox set on it.
  return (!HasState(ui::AX_STATE_READ_ONLY) ||
          role_ == ui::AX_ROLE_TEXT_FIELD ||
          role_ == ui::AX_ROLE_TEXT_AREA);
}

std::string BrowserAccessibility::GetTextRecursive() const {
  if (!name_.empty()) {
    return name_;
  }

  std::string result;
  for (uint32 i = 0; i < PlatformChildCount(); ++i)
    result += PlatformGetChild(i)->GetTextRecursive();
  return result;
}

int BrowserAccessibility::GetStaticTextLenRecursive() const {
  if (role_ == ui::AX_ROLE_STATIC_TEXT)
    return static_cast<int>(GetStringAttribute(ui::AX_ATTR_VALUE).size());

  int len = 0;
  for (size_t i = 0; i < children_.size(); ++i)
    len += children_[i]->GetStaticTextLenRecursive();
  return len;
}

}  // namespace content
/* [<][>][^][v][top][bottom][index][help] */
root/content/browser/accessibility/browser_accessibility.cc

DEFINITIONS
