rendertablecell.cpp

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    if (border1.style() == BHIDDEN || border2.style() == BHIDDEN)
        return CollapsedBorderValue(); // No border should exist at this location.
    
    // Rule #2 above.  A style of 'none' has lowest priority and always loses to any other border.
    if (border2.style() == BNONE)
        return border1;
    if (border1.style() == BNONE)
        return border2;

    // The first part of rule #3 above. Wider borders win.
    if (border1.width() != border2.width())
        return border1.width() > border2.width() ? border1 : border2;
    
    // The borders have equal width.  Sort by border style.
    if (border1.style() != border2.style())
        return border1.style() > border2.style() ? border1 : border2;
    
    // The border have the same width and style.  Rely on precedence (cell over row over row group, etc.)
    return border1.precedence >= border2.precedence ? border1 : border2;
}

CollapsedBorderValue RenderTableCell::collapsedLeftBorder(bool rtl) const
{
    RenderTable* tableElt = table();
    bool leftmostColumn;
    if (!rtl)
        leftmostColumn = col() == 0;
    else {
        int effCol = tableElt->colToEffCol(col() + colSpan() - 1);
        leftmostColumn = effCol == tableElt->numEffCols() - 1;
    }
    
    // For border left, we need to check, in order of precedence:
    // (1) Our left border.
    CollapsedBorderValue result(&style()->borderLeft(), BCELL);
    
    // (2) The right border of the cell to the left.
    RenderTableCell* prevCell = rtl ? tableElt->cellAfter(this) : tableElt->cellBefore(this);
    if (prevCell) {
        result = rtl ? compareBorders(result, CollapsedBorderValue(&prevCell->style()->borderRight(), BCELL)) : compareBorders(CollapsedBorderValue(&prevCell->style()->borderRight(), BCELL), result);
        if (!result.exists())
            return result;
    } else if (leftmostColumn) {
        // (3) Our row's left border.
        result = compareBorders(result, CollapsedBorderValue(&parent()->style()->borderLeft(), BROW));
        if (!result.exists())
            return result;
        
        // (4) Our row group's left border.
        result = compareBorders(result, CollapsedBorderValue(&section()->style()->borderLeft(), BROWGROUP));
        if (!result.exists())
            return result;
    }
    
    // (5) Our column and column group's left borders.
    bool startColEdge;
    bool endColEdge;
    RenderTableCol* colElt = tableElt->colElement(col() + (rtl ? colSpan() - 1 : 0), &startColEdge, &endColEdge);
    if (colElt && (!rtl ? startColEdge : endColEdge)) {
        result = compareBorders(result, CollapsedBorderValue(&colElt->style()->borderLeft(), BCOL));
        if (!result.exists())
            return result;
        if (colElt->parent()->isTableCol() && (!rtl ? !colElt->previousSibling() : !colElt->nextSibling())) {
            result = compareBorders(result, CollapsedBorderValue(&colElt->parent()->style()->borderLeft(), BCOLGROUP));
            if (!result.exists())
                return result;
        }
    }
    
    // (6) The right border of the column to the left.
    if (!leftmostColumn) {
        colElt = tableElt->colElement(col() + (rtl ? colSpan() : -1), &startColEdge, &endColEdge);
        if (colElt && (!rtl ? endColEdge : startColEdge)) {
            result = rtl ? compareBorders(result, CollapsedBorderValue(&colElt->style()->borderRight(), BCOL)) : compareBorders(CollapsedBorderValue(&colElt->style()->borderRight(), BCOL), result);
            if (!result.exists())
                return result;
        }
    } else {
        // (7) The table's left border.
        result = compareBorders(result, CollapsedBorderValue(&tableElt->style()->borderLeft(), BTABLE));
        if (!result.exists())
            return result;
    }
    
    return result;
}

CollapsedBorderValue RenderTableCell::collapsedRightBorder(bool rtl) const
{
    RenderTable* tableElt = table();
    bool rightmostColumn;
    if (rtl)
        rightmostColumn = col() == 0;
    else {
        int effCol = tableElt->colToEffCol(col() + colSpan() - 1);
        rightmostColumn = effCol == tableElt->numEffCols() - 1;
    }
    
    // For border right, we need to check, in order of precedence:
    // (1) Our right border.
    CollapsedBorderValue result = CollapsedBorderValue(&style()->borderRight(), BCELL);
    
    // (2) The left border of the cell to the right.
    if (!rightmostColumn) {
        RenderTableCell* nextCell = rtl ? tableElt->cellBefore(this) : tableElt->cellAfter(this);
        if (nextCell && nextCell->style()) {
            result = rtl ? compareBorders(CollapsedBorderValue(&nextCell->style()->borderLeft(), BCELL), result) : compareBorders(result, CollapsedBorderValue(&nextCell->style()->borderLeft(), BCELL));
            if (!result.exists())
                return result;
        }
    } else {
        // (3) Our row's right border.
        result = compareBorders(result, CollapsedBorderValue(&parent()->style()->borderRight(), BROW));
        if (!result.exists())
            return result;
        
        // (4) Our row group's right border.
        result = compareBorders(result, CollapsedBorderValue(&section()->style()->borderRight(), BROWGROUP));
        if (!result.exists())
            return result;
    }
    
    // (5) Our column and column group's right borders.
    bool startColEdge;
    bool endColEdge;
    RenderTableCol* colElt = tableElt->colElement(col() + (rtl ? 0 : colSpan() - 1), &startColEdge, &endColEdge);
    if (colElt && (!rtl ? endColEdge : startColEdge)) {
        result = compareBorders(result, CollapsedBorderValue(&colElt->style()->borderRight(), BCOL));
        if (!result.exists())
            return result;
        if (colElt->parent()->isTableCol() && (!rtl ? !colElt->nextSibling() : !colElt->previousSibling())) {
            result = compareBorders(result, CollapsedBorderValue(&colElt->parent()->style()->borderRight(), BCOLGROUP));
            if (!result.exists())
                return result;
        }
    }
    
    // (6) The left border of the column to the right.
    if (!rightmostColumn) {
        colElt = tableElt->colElement(col() + (rtl ? -1 : colSpan()), &startColEdge, &endColEdge);
        if (colElt && (!rtl ? startColEdge : endColEdge)) {
            result = rtl ? compareBorders(CollapsedBorderValue(&colElt->style()->borderLeft(), BCOL), result) : compareBorders(result, CollapsedBorderValue(&colElt->style()->borderLeft(), BCOL));
            if (!result.exists())
                return result;
        }
    } else {
        // (7) The table's right border.
        result = compareBorders(result, CollapsedBorderValue(&tableElt->style()->borderRight(), BTABLE));
        if (!result.exists())
            return result;
    }
    
    return result;
}

CollapsedBorderValue RenderTableCell::collapsedTopBorder() const
{
    // For border top, we need to check, in order of precedence:
    // (1) Our top border.
    CollapsedBorderValue result = CollapsedBorderValue(&style()->borderTop(), BCELL);
    
    RenderTableCell* prevCell = table()->cellAbove(this);
    if (prevCell) {
        // (2) A previous cell's bottom border.
        result = compareBorders(CollapsedBorderValue(&prevCell->style()->borderBottom(), BCELL), result);
        if (!result.exists()) 
            return result;
    }
    
    // (3) Our row's top border.
    result = compareBorders(result, CollapsedBorderValue(&parent()->style()->borderTop(), BROW));
    if (!result.exists())
        return result;
    
    // (4) The previous row's bottom border.
    if (prevCell) {
        RenderObject* prevRow = 0;
        if (prevCell->section() == section())
            prevRow = parent()->previousSibling();
        else
            prevRow = prevCell->section()->lastChild();
    
        if (prevRow) {
            result = compareBorders(CollapsedBorderValue(&prevRow->style()->borderBottom(), BROW), result);
            if (!result.exists())
                return result;
        }
    }
    
    // Now check row groups.
    RenderTableSection* currSection = section();
    if (!row()) {
        // (5) Our row group's top border.
        result = compareBorders(result, CollapsedBorderValue(&currSection->style()->borderTop(), BROWGROUP));
        if (!result.exists())
            return result;
        
        // (6) Previous row group's bottom border.
        currSection = table()->sectionAbove(currSection);
        if (currSection) {
            result = compareBorders(CollapsedBorderValue(&currSection->style()->borderBottom(), BROWGROUP), result);
            if (!result.exists())
                return result;
        }
    }
    
    if (!currSection) {
        // (8) Our column and column group's top borders.
        RenderTableCol* colElt = table()->colElement(col());
        if (colElt) {
            result = compareBorders(result, CollapsedBorderValue(&colElt->style()->borderTop(), BCOL));
            if (!result.exists())
                return result;
            if (colElt->parent()->isTableCol()) {
                result = compareBorders(result, CollapsedBorderValue(&colElt->parent()->style()->borderTop(), BCOLGROUP));
                if (!result.exists())
                    return result;
            }
        }
        
        // (9) The table's top border.
        result = compareBorders(result, CollapsedBorderValue(&table()->style()->borderTop(), BTABLE));
        if (!result.exists())
            return result;
    }
    
    return result;
}

CollapsedBorderValue RenderTableCell::collapsedBottomBorder() const
{
    // For border top, we need to check, in order of precedence:
    // (1) Our bottom border.
    CollapsedBorderValue result = CollapsedBorderValue(&style()->borderBottom(), BCELL);
    
    RenderTableCell* nextCell = table()->cellBelow(this);
    if (nextCell) {
        // (2) A following cell's top border.
        result = compareBorders(result, CollapsedBorderValue(&nextCell->style()->borderTop(), BCELL));
        if (!result.exists())
            return result;
    }
    
    // (3) Our row's bottom border. (FIXME: Deal with rowspan!)
    result = compareBorders(result, CollapsedBorderValue(&parent()->style()->borderBottom(), BROW));
    if (!result.exists())
        return result;
    
    // (4) The next row's top border.
    if (nextCell) {
        result = compareBorders(result, CollapsedBorderValue(&nextCell->parent()->style()->borderTop(), BROW));
        if (!result.exists())
            return result;
    }
    
    // Now check row groups.
    RenderTableSection* currSection = section();
    if (row() + rowSpan() >= static_cast<RenderTableSection*>(currSection)->numRows()) {
        // (5) Our row group's bottom border.
        result = compareBorders(result, CollapsedBorderValue(&currSection->style()->borderBottom(), BROWGROUP));
        if (!result.exists())
            return result;
        
        // (6) Following row group's top border.
        currSection = table()->sectionBelow(currSection);
        if (currSection) {
            result = compareBorders(result, CollapsedBorderValue(&currSection->style()->borderTop(), BROWGROUP));
            if (!result.exists())
                return result;
        }
    }
    
    if (!currSection) {
        // (8) Our column and column group's bottom borders.
        RenderTableCol* colElt = table()->colElement(col());
        if (colElt) {
            result = compareBorders(result, CollapsedBorderValue(&colElt->style()->borderBottom(), BCOL));
            if (!result.exists()) return result;
            if (colElt->parent()->isTableCol()) {
                result = compareBorders(result, CollapsedBorderValue(&colElt->parent()->style()->borderBottom(), BCOLGROUP));
                if (!result.exists())
                    return result;
            }
        }
        
        // (9) The table's bottom border.
        result = compareBorders(result, CollapsedBorderValue(&table()->style()->borderBottom(), BTABLE));
        if (!result.exists())
            return result;
    }
    
    return result;    
}

int RenderTableCell::borderLeft() const