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/*
* Copyright (C) 2008 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "modules/accessibility/AXTable.h"
#include "core/dom/ElementTraversal.h"
#include "core/html/HTMLCollection.h"
#include "core/html/HTMLTableCaptionElement.h"
#include "core/html/HTMLTableCellElement.h"
#include "core/html/HTMLTableColElement.h"
#include "core/html/HTMLTableElement.h"
#include "core/html/HTMLTableRowElement.h"
#include "core/html/HTMLTableRowsCollection.h"
#include "core/html/HTMLTableSectionElement.h"
#include "core/layout/LayoutTableCell.h"
#include "modules/accessibility/AXObjectCacheImpl.h"
#include "modules/accessibility/AXTableCell.h"
#include "modules/accessibility/AXTableColumn.h"
#include "modules/accessibility/AXTableRow.h"
namespace blink {
using namespace HTMLNames;
AXTable::AXTable(LayoutObject* layoutObject, AXObjectCacheImpl& axObjectCache)
: AXLayoutObject(layoutObject, axObjectCache)
, m_headerContainer(nullptr)
, m_isAXTable(true)
{
}
AXTable::~AXTable()
{
}
void AXTable::init()
{
AXLayoutObject::init();
m_isAXTable = isTableExposableThroughAccessibility();
}
AXTable* AXTable::create(LayoutObject* layoutObject, AXObjectCacheImpl& axObjectCache)
{
return new AXTable(layoutObject, axObjectCache);
}
bool AXTable::hasARIARole() const
{
if (!m_layoutObject)
return false;
AccessibilityRole ariaRole = ariaRoleAttribute();
if (ariaRole != UnknownRole)
return true;
return false;
}
bool AXTable::isAXTable() const
{
if (!m_layoutObject)
return false;
return m_isAXTable;
}
static bool elementHasAriaRole(const Element* element)
{
if (!element)
return false;
const AtomicString& ariaRole = element->fastGetAttribute(roleAttr);
return (!ariaRole.isNull() && !ariaRole.isEmpty());
}
bool AXTable::isDataTable() const
{
if (!m_layoutObject || !node())
return false;
// Do not consider it a data table if it has an ARIA role.
if (hasARIARole())
return false;
// When a section of the document is contentEditable, all tables should be
// treated as data tables, otherwise users may not be able to work with rich
// text editors that allow creating and editing tables.
if (node() && node()->hasEditableStyle())
return true;
// This employs a heuristic to determine if this table should appear.
// Only "data" tables should be exposed as tables.
// Unfortunately, there is no good way to determine the difference
// between a "layout" table and a "data" table.
LayoutTable* table = toLayoutTable(m_layoutObject);
Node* tableNode = table->node();
if (!isHTMLTableElement(tableNode))
return false;
// Do not consider it a data table if any of its descendants have an ARIA role.
HTMLTableElement* tableElement = toHTMLTableElement(tableNode);
if (elementHasAriaRole(tableElement->tHead()))
return false;
if (elementHasAriaRole(tableElement->tFoot()))
return false;
RefPtrWillBeRawPtr<HTMLCollection> bodies = tableElement->tBodies();
for (unsigned bodyIndex = 0; bodyIndex < bodies->length(); ++bodyIndex) {
Element* bodyElement = bodies->item(bodyIndex);
if (elementHasAriaRole(bodyElement))
return false;
}
RefPtrWillBeRawPtr<HTMLTableRowsCollection> rows = tableElement->rows();
unsigned rowCount = rows->length();
for (unsigned rowIndex = 0; rowIndex < rowCount; ++rowIndex) {
HTMLTableRowElement* rowElement = rows->item(rowIndex);
if (elementHasAriaRole(rowElement))
return false;
RefPtrWillBeRawPtr<HTMLCollection> cells = rowElement->cells();
for (unsigned cellIndex = 0; cellIndex < cells->length(); ++cellIndex) {
if (elementHasAriaRole(cells->item(cellIndex)))
return false;
}
}
// If there is a caption element, summary, THEAD, or TFOOT section, it's most certainly a data table
if (!tableElement->summary().isEmpty() || tableElement->tHead() || tableElement->tFoot() || tableElement->caption())
return true;
// if someone used "rules" attribute than the table should appear
if (!tableElement->rules().isEmpty())
return true;
// if there's a colgroup or col element, it's probably a data table.
if (Traversal<HTMLTableColElement>::firstChild(*tableElement))
return true;
// go through the cell's and check for tell-tale signs of "data" table status
// cells have borders, or use attributes like headers, abbr, scope or axis
table->recalcSectionsIfNeeded();
LayoutTableSection* firstBody = table->firstBody();
if (!firstBody)
return false;
int numCols = firstBody->numColumns();
int numRows = firstBody->numRows();
// If there's only one cell, it's not a good AXTable candidate.
if (numRows == 1 && numCols == 1)
return false;
// If there are at least 20 rows, we'll call it a data table.
if (numRows >= 20)
return true;
// Store the background color of the table to check against cell's background colors.
const ComputedStyle* tableStyle = table->style();
if (!tableStyle)
return false;
Color tableBGColor = tableStyle->visitedDependentColor(CSSPropertyBackgroundColor);
// check enough of the cells to find if the table matches our criteria
// Criteria:
// 1) must have at least one valid cell (and)
// 2) at least half of cells have borders (or)
// 3) at least half of cells have different bg colors than the table, and there is cell spacing
unsigned validCellCount = 0;
unsigned borderedCellCount = 0;
unsigned backgroundDifferenceCellCount = 0;
unsigned cellsWithTopBorder = 0;
unsigned cellsWithBottomBorder = 0;
unsigned cellsWithLeftBorder = 0;
unsigned cellsWithRightBorder = 0;
Color alternatingRowColors[5];
int alternatingRowColorCount = 0;
int headersInFirstColumnCount = 0;
for (int row = 0; row < numRows; ++row) {
int headersInFirstRowCount = 0;
for (int col = 0; col < numCols; ++col) {
LayoutTableCell* cell = firstBody->primaryCellAt(row, col);
if (!cell)
continue;
Node* cellNode = cell->node();
if (!cellNode)
continue;
if (cell->size().width() < 1 || cell->size().height() < 1)
continue;
validCellCount++;
bool isTHCell = cellNode->hasTagName(thTag);
// If the first row is comprised of all <th> tags, assume it is a data table.
if (!row && isTHCell)
headersInFirstRowCount++;
// If the first column is comprised of all <th> tags, assume it is a data table.
if (!col && isTHCell)
headersInFirstColumnCount++;
// in this case, the developer explicitly assigned a "data" table attribute
if (isHTMLTableCellElement(*cellNode)) {
HTMLTableCellElement& cellElement = toHTMLTableCellElement(*cellNode);
if (!cellElement.headers().isEmpty() || !cellElement.abbr().isEmpty()
|| !cellElement.axis().isEmpty() || !cellElement.scope().isEmpty())
return true;
}
const ComputedStyle* computedStyle = cell->style();
if (!computedStyle)
continue;
// If the empty-cells style is set, we'll call it a data table.
if (computedStyle->emptyCells() == HIDE)
return true;
// If a cell has matching bordered sides, call it a (fully) bordered cell.
if ((cell->borderTop() > 0 && cell->borderBottom() > 0)
|| (cell->borderLeft() > 0 && cell->borderRight() > 0))
borderedCellCount++;
// Also keep track of each individual border, so we can catch tables where most
// cells have a bottom border, for example.
if (cell->borderTop() > 0)
cellsWithTopBorder++;
if (cell->borderBottom() > 0)
cellsWithBottomBorder++;
if (cell->borderLeft() > 0)
cellsWithLeftBorder++;
if (cell->borderRight() > 0)
cellsWithRightBorder++;
// If the cell has a different color from the table and there is cell spacing,
// then it is probably a data table cell (spacing and colors take the place of borders).
Color cellColor = computedStyle->visitedDependentColor(CSSPropertyBackgroundColor);
if (table->hBorderSpacing() > 0 && table->vBorderSpacing() > 0
&& tableBGColor != cellColor && cellColor.alpha() != 1)
backgroundDifferenceCellCount++;
// If we've found 10 "good" cells, we don't need to keep searching.
if (borderedCellCount >= 10 || backgroundDifferenceCellCount >= 10)
return true;
// For the first 5 rows, cache the background color so we can check if this table has zebra-striped rows.
if (row < 5 && row == alternatingRowColorCount) {
LayoutObject* layoutRow = cell->parent();
if (!layoutRow || !layoutRow->isBoxModelObject() || !toLayoutBoxModelObject(layoutRow)->isTableRow())
continue;
const ComputedStyle* rowComputedStyle = layoutRow->style();
if (!rowComputedStyle)
continue;
Color rowColor = rowComputedStyle->visitedDependentColor(CSSPropertyBackgroundColor);
alternatingRowColors[alternatingRowColorCount] = rowColor;
alternatingRowColorCount++;
}
}
if (!row && headersInFirstRowCount == numCols && numCols > 1)
return true;
}
if (headersInFirstColumnCount == numRows && numRows > 1)
return true;
// if there is less than two valid cells, it's not a data table
if (validCellCount <= 1)
return false;
// half of the cells had borders, it's a data table
unsigned neededCellCount = validCellCount / 2;
if (borderedCellCount >= neededCellCount
|| cellsWithTopBorder >= neededCellCount
|| cellsWithBottomBorder >= neededCellCount
|| cellsWithLeftBorder >= neededCellCount
|| cellsWithRightBorder >= neededCellCount)
return true;
// half had different background colors, it's a data table
if (backgroundDifferenceCellCount >= neededCellCount)
return true;
// Check if there is an alternating row background color indicating a zebra striped style pattern.
if (alternatingRowColorCount > 2) {
Color firstColor = alternatingRowColors[0];
for (int k = 1; k < alternatingRowColorCount; k++) {
// If an odd row was the same color as the first row, its not alternating.
if (k % 2 == 1 && alternatingRowColors[k] == firstColor)
return false;
// If an even row is not the same as the first row, its not alternating.
if (!(k % 2) && alternatingRowColors[k] != firstColor)
return false;
}
return true;
}
return false;
}
bool AXTable::isTableExposableThroughAccessibility() const
{
// The following is a heuristic used to determine if a
// <table> should be exposed as an AXTable. The goal
// is to only show "data" tables.
if (!m_layoutObject)
return false;
// If the developer assigned an aria role to this, then we
// shouldn't expose it as a table, unless, of course, the aria
// role is a table.
if (hasARIARole())
return false;
return isDataTable();
}
void AXTable::clearChildren()
{
AXLayoutObject::clearChildren();
m_rows.clear();
m_columns.clear();
if (m_headerContainer) {
m_headerContainer->detachFromParent();
m_headerContainer = nullptr;
}
}
void AXTable::addChildren()
{
ASSERT(!isDetached());
if (!isAXTable()) {
AXLayoutObject::addChildren();
return;
}
ASSERT(!m_haveChildren);
m_haveChildren = true;
if (!m_layoutObject || !m_layoutObject->isTable())
return;
LayoutTable* table = toLayoutTable(m_layoutObject);
AXObjectCacheImpl& axCache = axObjectCache();
Node* tableNode = table->node();
if (!isHTMLTableElement(tableNode))
return;
// Add caption
if (HTMLTableCaptionElement* caption = toHTMLTableElement(tableNode)->caption()) {
AXObject* captionObject = axCache.getOrCreate(caption);
if (captionObject && !captionObject->accessibilityIsIgnored())
m_children.append(captionObject);
}
// Go through all the available sections to pull out the rows and add them as children.
table->recalcSectionsIfNeeded();
LayoutTableSection* tableSection = table->topSection();
if (!tableSection)
return;
LayoutTableSection* initialTableSection = tableSection;
while (tableSection) {
HeapHashSet<Member<AXObject>> appendedRows;
unsigned numRows = tableSection->numRows();
for (unsigned rowIndex = 0; rowIndex < numRows; ++rowIndex) {
LayoutTableRow* layoutRow = tableSection->rowLayoutObjectAt(rowIndex);
if (!layoutRow)
continue;
AXObject* rowObject = axCache.getOrCreate(layoutRow);
if (!rowObject || !rowObject->isTableRow())
continue;
AXTableRow* row = toAXTableRow(rowObject);
// We need to check every cell for a new row, because cell spans
// can cause us to miss rows if we just check the first column.
if (appendedRows.contains(row))
continue;
row->setRowIndex(static_cast<int>(m_rows.size()));
m_rows.append(row);
if (!row->accessibilityIsIgnored())
m_children.append(row);
appendedRows.add(row);
}
tableSection = table->sectionBelow(tableSection, SkipEmptySections);
}
// make the columns based on the number of columns in the first body
unsigned length = initialTableSection->numColumns();
for (unsigned i = 0; i < length; ++i) {
AXTableColumn* column = toAXTableColumn(axCache.getOrCreate(ColumnRole));
column->setColumnIndex((int)i);
column->setParent(this);
m_columns.append(column);
if (!column->accessibilityIsIgnored())
m_children.append(column);
}
AXObject* headerContainerObject = headerContainer();
if (headerContainerObject && !headerContainerObject->accessibilityIsIgnored())
m_children.append(headerContainerObject);
}
AXObject* AXTable::headerContainer()
{
if (m_headerContainer)
return m_headerContainer.get();
AXMockObject* tableHeader = toAXMockObject(axObjectCache().getOrCreate(TableHeaderContainerRole));
tableHeader->setParent(this);
m_headerContainer = tableHeader;
return m_headerContainer.get();
}
const AXObject::AXObjectVector& AXTable::columns()
{
updateChildrenIfNecessary();
return m_columns;
}
const AXObject::AXObjectVector& AXTable::rows()
{
updateChildrenIfNecessary();
return m_rows;
}
void AXTable::columnHeaders(AXObjectVector& headers)
{
if (!m_layoutObject)
return;
updateChildrenIfNecessary();
unsigned columnCount = m_columns.size();
for (unsigned c = 0; c < columnCount; c++)
toAXTableColumn(m_columns[c].get())->headerObjectsForColumn(headers);
}
void AXTable::rowHeaders(AXObjectVector& headers)
{
if (!m_layoutObject)
return;
updateChildrenIfNecessary();
unsigned rowCount = m_rows.size();
for (unsigned r = 0; r < rowCount; r++)
toAXTableRow(m_rows[r].get())->headerObjectsForRow(headers);
}
unsigned AXTable::columnCount()
{
updateChildrenIfNecessary();
return m_columns.size();
}
unsigned AXTable::rowCount()
{
updateChildrenIfNecessary();
return m_rows.size();
}
AXTableCell* AXTable::cellForColumnAndRow(unsigned column, unsigned row)
{
updateChildrenIfNecessary();
if (column >= columnCount() || row >= rowCount())
return 0;
// Iterate backwards through the rows in case the desired cell has a rowspan and exists in a previous row.
for (unsigned rowIndexCounter = row + 1; rowIndexCounter > 0; --rowIndexCounter) {
unsigned rowIndex = rowIndexCounter - 1;
const auto& children = m_rows[rowIndex]->children();
// Since some cells may have colspans, we have to check the actual range of each
// cell to determine which is the right one.
for (unsigned colIndexCounter = std::min(static_cast<unsigned>(children.size()), column + 1); colIndexCounter > 0; --colIndexCounter) {
unsigned colIndex = colIndexCounter - 1;
AXObject* child = children[colIndex].get();
if (!child->isTableCell())
continue;
std::pair<unsigned, unsigned> columnRange;
std::pair<unsigned, unsigned> rowRange;
AXTableCell* tableCellChild = toAXTableCell(child);
tableCellChild->columnIndexRange(columnRange);
tableCellChild->rowIndexRange(rowRange);
if ((column >= columnRange.first && column < (columnRange.first + columnRange.second))
&& (row >= rowRange.first && row < (rowRange.first + rowRange.second)))
return tableCellChild;
}
}
return 0;
}
AccessibilityRole AXTable::roleValue() const
{
if (!isAXTable())
return AXLayoutObject::roleValue();
return TableRole;
}
bool AXTable::computeAccessibilityIsIgnored(IgnoredReasons* ignoredReasons) const
{
AXObjectInclusion decision = defaultObjectInclusion(ignoredReasons);
if (decision == IncludeObject)
return false;
if (decision == IgnoreObject)
return true;
if (!isAXTable())
return AXLayoutObject::computeAccessibilityIsIgnored(ignoredReasons);
return false;
}
DEFINE_TRACE(AXTable)
{
visitor->trace(m_rows);
visitor->trace(m_columns);
visitor->trace(m_headerContainer);
AXLayoutObject::trace(visitor);
}
} // namespace blink