C++ RenderTable::vBorderSpacing方法代码示例

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)
//.........这里部分代码省略.........

//.........这里部分代码省略.........
            // 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;
}

//.........这里部分代码省略.........
        int headersInFirstRowCount = 0;
        for (int col = 0; col < numCols; ++col) {    
            RenderTableCell* cell = firstBody->primaryCellAt(row, col);
            if (!cell)
                continue;
            Node* cellNode = cell->node();
            if (!cellNode)
                continue;
            
            if (cell->width() < 1 || cell->height() < 1)
                continue;
            
            validCellCount++;
            
            HTMLTableCellElement* cellElement = static_cast<HTMLTableCellElement*>(cellNode);
            
            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->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->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;
                RenderStyle* rowRenderStyle = renderRow->style();
                if (!rowRenderStyle)
                    continue;
                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)
        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;
}