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// Copyright 2013 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 <stdint.h>
#include <memory>
#include <ostream>
#include <vector>
#include "build/build_config.h"
#include "ui/accessibility/ax_export.h"
#include "ui/accessibility/ax_node_data.h"
namespace ui {
class AXTableInfo;
class AXLanguageInfo;
// One node in an AXTree.
class AX_EXPORT AXNode final {
// Interface to the tree class that owns an AXNode. We use this instead
// of letting AXNode have a pointer to its AXTree directly so that we're
// forced to think twice before calling an AXTree interface that might not
// be necessary.
class OwnerTree {
// See AXTree.
virtual AXTableInfo* GetTableInfo(const AXNode* table_node) const = 0;
// See AXTree.
virtual AXNode* GetFromId(int32_t id) const = 0;
virtual int32_t GetPosInSet(const AXNode& node,
const AXNode* ordered_set) = 0;
virtual int32_t GetSetSize(const AXNode& node,
const AXNode* ordered_set) = 0;
// The constructor requires a parent, id, and index in parent, but
// the data is not required. After initialization, only index_in_parent
// is allowed to change, the others are guaranteed to never change.
AXNode(OwnerTree* tree, AXNode* parent, int32_t id, int32_t index_in_parent);
virtual ~AXNode();
// Accessors.
OwnerTree* tree() const { return tree_; }
int32_t id() const { return; }
AXNode* parent() const { return parent_; }
int child_count() const { return static_cast<int>(children_.size()); }
const AXNodeData& data() const { return data_; }
const std::vector<AXNode*>& children() const { return children_; }
int index_in_parent() const { return index_in_parent_; }
// Get the child at the given index.
AXNode* ChildAtIndex(int index) const { return children_[index]; }
// Walking the tree skipping ignored nodes.
int GetUnignoredChildCount() const;
AXNode* GetUnignoredChildAtIndex(int index) const;
AXNode* GetUnignoredParent() const;
int GetUnignoredIndexInParent() const;
// Returns true if the node has any of the text related roles.
bool IsTextNode() const;
// Set the node's accessibility data. This may be done during initialization
// or later when the node data changes.
void SetData(const AXNodeData& src);
// Update this node's location. This is separate from |SetData| just because
// changing only the location is common and should be more efficient than
// re-copying all of the data.
// The node's location is stored as a relative bounding box, the ID of
// the element it's relative to, and an optional transformation matrix.
// See ax_node_data.h for details.
void SetLocation(int32_t offset_container_id,
const gfx::RectF& location,
gfx::Transform* transform);
// Set the index in parent, for example if siblings were inserted or deleted.
void SetIndexInParent(int index_in_parent);
// Swap the internal children vector with |children|. This instance
// now owns all of the passed children.
void SwapChildren(std::vector<AXNode*>& children);
// This is called when the AXTree no longer includes this node in the
// tree. Reference counting is used on some platforms because the
// operating system may hold onto a reference to an AXNode
// object even after we're through with it, so this may decrement the
// reference count and clear out the object's data.
void Destroy();
// Return true if this object is equal to or a descendant of |ancestor|.
bool IsDescendantOf(AXNode* ancestor);
// Gets the text offsets where new lines start either from the node's data or
// by computing them and caching the result.
std::vector<int> GetOrComputeLineStartOffsets();
// Accessing accessibility attributes.
// See |AXNodeData| for more information.
bool HasBoolAttribute(ax::mojom::BoolAttribute attribute) const {
return data().HasBoolAttribute(attribute);
bool GetBoolAttribute(ax::mojom::BoolAttribute attribute) const {
return data().GetBoolAttribute(attribute);
bool GetBoolAttribute(ax::mojom::BoolAttribute attribute, bool* value) const {
return data().GetBoolAttribute(attribute, value);
bool HasFloatAttribute(ax::mojom::FloatAttribute attribute) const {
return data().HasFloatAttribute(attribute);
float GetFloatAttribute(ax::mojom::FloatAttribute attribute) const {
return data().GetFloatAttribute(attribute);
bool GetFloatAttribute(ax::mojom::FloatAttribute attribute,
float* value) const {
return data().GetFloatAttribute(attribute, value);
bool HasIntAttribute(ax::mojom::IntAttribute attribute) const {
return data().HasIntAttribute(attribute);
int32_t GetIntAttribute(ax::mojom::IntAttribute attribute) const {
return data().GetIntAttribute(attribute);
bool GetIntAttribute(ax::mojom::IntAttribute attribute, int* value) const {
return data().GetIntAttribute(attribute, value);
bool HasStringAttribute(ax::mojom::StringAttribute attribute) const {
return data().HasStringAttribute(attribute);
const std::string& GetStringAttribute(
ax::mojom::StringAttribute attribute) const {
return data().GetStringAttribute(attribute);
bool GetStringAttribute(ax::mojom::StringAttribute attribute,
std::string* value) const {
return data().GetStringAttribute(attribute, value);
bool GetString16Attribute(ax::mojom::StringAttribute attribute,
base::string16* value) const {
return data().GetString16Attribute(attribute, value);
base::string16 GetString16Attribute(
ax::mojom::StringAttribute attribute) const {
return data().GetString16Attribute(attribute);
bool HasIntListAttribute(ax::mojom::IntListAttribute attribute) const {
return data().HasIntListAttribute(attribute);
const std::vector<int32_t>& GetIntListAttribute(
ax::mojom::IntListAttribute attribute) const {
return data().GetIntListAttribute(attribute);
bool GetIntListAttribute(ax::mojom::IntListAttribute attribute,
std::vector<int32_t>* value) const {
return data().GetIntListAttribute(attribute, value);
bool HasStringListAttribute(ax::mojom::StringListAttribute attribute) const {
return data().HasStringListAttribute(attribute);
const std::vector<std::string>& GetStringListAttribute(
ax::mojom::StringListAttribute attribute) const {
return data().GetStringListAttribute(attribute);
bool GetStringListAttribute(ax::mojom::StringListAttribute attribute,
std::vector<std::string>* value) const {
return data().GetStringListAttribute(attribute, value);
bool GetHtmlAttribute(const char* attribute, base::string16* value) const {
return data().GetHtmlAttribute(attribute, value);
bool GetHtmlAttribute(const char* attribute, std::string* value) const {
return data().GetHtmlAttribute(attribute, value);
// PosInSet and SetSize public methods.
bool IsOrderedSetItem() const;
bool IsOrderedSet() const;
int32_t GetPosInSet();
int32_t GetSetSize();
// Helpers for GetPosInSet and GetSetSize.
// Returns true if the role of ordered set matches the role of item.
// Returns false otherwise.
bool SetRoleMatchesItemRole(const AXNode* ordered_set) const;
const std::string& GetInheritedStringAttribute(
ax::mojom::StringAttribute attribute) const;
base::string16 GetInheritedString16Attribute(
ax::mojom::StringAttribute attribute) const;
// Return a pointer to a string for the language code.
// This will consider the language declared in the DOM, and may eventually
// attempt to automatically detect the language from the text.
// This language code will be BCP 47.
// Returns empty string if no appropriate language was found.
std::string GetLanguage();
// Helper functions for tables, table rows, and table cells.
// Most of these functions construct and cache an AXTableInfo behind
// the scenes to infer many properties of tables.
// These interfaces use attributes provided by the source of the
// AX tree where possible, but fills in missing details and ignores
// specified attributes when they're bad or inconsistent. That way
// you're guaranteed to get a valid, consistent table when using these
// interfaces.
// Table-like nodes (including grids). All indices are 0-based except
// ARIA indices are all 1-based. In other words, the top-left corner
// of the table is row 0, column 0, cell index 0 - but that same cell
// has a minimum ARIA row index of 1 and column index of 1.
bool IsTable() const;
int32_t GetTableColCount() const;
int32_t GetTableRowCount() const;
int32_t GetTableAriaColCount() const;
int32_t GetTableAriaRowCount() const;
int32_t GetTableCellCount() const;
AXNode* GetTableCellFromIndex(int32_t index) const;
AXNode* GetTableCellFromCoords(int32_t row_index, int32_t col_index) const;
void GetTableColHeaderNodeIds(int32_t col_index,
std::vector<int32_t>* col_header_ids) const;
void GetTableRowHeaderNodeIds(int32_t row_index,
std::vector<int32_t>* row_header_ids) const;
void GetTableUniqueCellIds(std::vector<int32_t>* row_header_ids) const;
// Extra computed nodes for the accessibility tree for macOS:
// one column node for each table column, followed by one
// table header container node, or nullptr if not applicable.
std::vector<AXNode*>* GetExtraMacNodes() const;
// Table row-like nodes.
bool IsTableRow() const;
int32_t GetTableRowRowIndex() const;
#if defined(OS_MACOSX)
// Table column-like nodes. These nodes are only present on macOS.
bool IsTableColumn() const;
int32_t GetTableColColIndex() const;
#endif // defined(OS_MACOSX)
// Table cell-like nodes.
bool IsTableCellOrHeader() const;
int32_t GetTableCellIndex() const;
int32_t GetTableCellColIndex() const;
int32_t GetTableCellRowIndex() const;
int32_t GetTableCellColSpan() const;
int32_t GetTableCellRowSpan() const;
int32_t GetTableCellAriaColIndex() const;
int32_t GetTableCellAriaRowIndex() const;
void GetTableCellColHeaderNodeIds(std::vector<int32_t>* col_header_ids) const;
void GetTableCellRowHeaderNodeIds(std::vector<int32_t>* row_header_ids) const;
void GetTableCellColHeaders(std::vector<AXNode*>* col_headers) const;
void GetTableCellRowHeaders(std::vector<AXNode*>* row_headers) const;
// Computes the text offset where each line starts by traversing all child
// leaf nodes.
void ComputeLineStartOffsets(std::vector<int>* line_offsets,
int* start_offset) const;
AXTableInfo* GetAncestorTableInfo() const;
void IdVectorToNodeVector(std::vector<int32_t>& ids,
std::vector<AXNode*>* nodes) const;
// Finds and returns a pointer to ordered set containing node.
AXNode* GetOrderedSet() const;
OwnerTree* tree_; // Owns this.
int index_in_parent_;
AXNode* parent_;
std::vector<AXNode*> children_;
AXNodeData data_;
std::unique_ptr<AXLanguageInfo> language_info_;
// Return an object containing information about the languages used.
// Will walk up tree if needed to determine language.
// Clients should not retain this pointer, instead they should request it
// every time it is needed.
// Returns nullptr if the node has no detectable language.
const AXLanguageInfo* GetLanguageInfo();
AX_EXPORT std::ostream& operator<<(std::ostream& stream, const AXNode& node);
} // namespace ui