HTMLTableElement* AccessibilityTable::tableElement() const
{
if (!m_renderer->isTable())
return nullptr;
RenderTable* table = toRenderTable(m_renderer);
if (table->element() && isHTMLTableElement(table->element()))
return toHTMLTableElement(table->element());
// If the table has a display:table-row-group, then the RenderTable does not have a pointer to it's HTMLTableElement.
// We can instead find it by asking the firstSection for its parent.
RenderTableSection* firstBody = table->firstBody();
if (!firstBody || !firstBody->element())
return nullptr;
Element* actualTable = firstBody->element()->parentElement();
if (!actualTable || !isHTMLTableElement(actualTable))
return nullptr;
return toHTMLTableElement(actualTable);
}
bool AccessibilityTable::isDataTable() const
{
if (!m_renderer)
return false;
// Do not consider it a data table is 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.
RenderTable* table = toRenderTable(m_renderer);
if (!table->element() || !isHTMLTableElement(table->element()))
return false;
// if there is a caption element, summary, THEAD, or TFOOT section, it's most certainly a data table
HTMLTableElement* tableElement = toHTMLTableElement(table->element());
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.
for (const auto& child : childrenOfType<Element>(*tableElement)) {
if (child.hasTagName(colTag) || child.hasTagName(colgroupTag))
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();
RenderTableSection* 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 RenderStyle& tableStyle = table->style();
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) {
RenderTableCell* cell = firstBody->primaryCellAt(row, col);
if (!cell)
continue;
Element* cellElement = cell->element();
if (!cellElement)
continue;
if (cell->width() < 1 || cell->height() < 1)
continue;
validCellCount++;
bool isTHCell = cellElement->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 (cellElement->hasTagName(tdTag) || cellElement->hasTagName(thTag)) {
HTMLTableCellElement* tableCellElement = toHTMLTableCellElement(cellElement);
if (!tableCellElement->headers().isEmpty() || !tableCellElement->abbr().isEmpty()
|| !tableCellElement->axis().isEmpty() || !tableCellElement->scope().isEmpty())
return true;
}
const RenderStyle& renderStyle = cell->style();
// If the empty-cells style is set, we'll call it a data table.
if (renderStyle.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 = renderStyle.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) {
RenderObject* renderRow = cell->parent();
if (!renderRow || !renderRow->isBoxModelObject() || !toRenderBoxModelObject(renderRow)->isTableRow())
continue;
const RenderStyle& rowRenderStyle = renderRow->style();
Color rowColor = rowRenderStyle.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 AccessibilityTable::isTableExposableThroughAccessibility()
{
// 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_renderer || !m_renderer->isTable())
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
AccessibilityRole ariaRole = ariaRoleAttribute();
if (ariaRole == TableRole)
return true;
if (ariaRole != UnknownRole)
return false;
RenderTable* table = static_cast<RenderTable*>(m_renderer);
// 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
Node* tableNode = table->element();
if (!tableNode || !tableNode->hasTagName(tableTag))
return false;
// if there is a caption element, summary, THEAD, or TFOOT section, it's most certainly a data table
HTMLTableElement* tableElement = static_cast<HTMLTableElement*>(tableNode);
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;
// 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
RenderTableSection* 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;
// store the background color of the table to check against cell's background colors
RenderStyle* tableStyle = table->style();
if (!tableStyle)
return false;
Color tableBGColor = tableStyle->backgroundColor();
// 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;
for (int row = 0; row < numRows; ++row) {
for (int col = 0; col < numCols; ++col) {
RenderTableCell* cell = firstBody->cellAt(row, col).cell;
if (!cell)
continue;
Node* cellNode = cell->element();
if (!cellNode)
continue;
if (cell->width() < 1 || cell->height() < 1)
continue;
validCellCount++;
HTMLTableCellElement* cellElement = static_cast<HTMLTableCellElement*>(cellNode);
// in this case, the developer explicitly assigned a "data" table attribute
if (!cellElement->headers().isEmpty() || !cellElement->abbr().isEmpty() ||
!cellElement->axis().isEmpty() || !cellElement->scope().isEmpty())
return true;
RenderStyle* renderStyle = cell->style();
if (!renderStyle)
continue;
// a cell needs to have matching bordered sides, before it can be considered a bordered cell.
if ((cell->borderTop() > 0 && cell->borderBottom() > 0) ||
(cell->borderLeft() > 0 && cell->borderRight() > 0))
borderedCellCount++;
// 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 = renderStyle->backgroundColor();
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;
}
}
// 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)
return true;
// half had different background colors, it's a data table
if (backgroundDifferenceCellCount >= neededCellCount)
return true;
return false;
}