void ColumnBalancer::traverseLines(const LayoutBlockFlow& blockFlow) {
for (const RootInlineBox* line = blockFlow.firstRootBox(); line;
line = line->nextRootBox()) {
LayoutUnit lineTopInFlowThread =
m_flowThreadOffset + line->lineTopWithLeading();
if (lineTopInFlowThread < logicalTopInFlowThread())
continue;
if (lineTopInFlowThread >= logicalBottomInFlowThread())
break;
examineLine(*line);
}
}
void ColumnBalancer::traverseSubtree(const LayoutBox& box)
{
if (box.childrenInline() && box.isLayoutBlockFlow()) {
// Look for breaks between lines.
for (const RootInlineBox* line = toLayoutBlockFlow(box).firstRootBox(); line; line = line->nextRootBox()) {
LayoutUnit lineTopInFlowThread = m_flowThreadOffset + line->lineTopWithLeading();
if (lineTopInFlowThread < group().logicalTopInFlowThread())
continue;
if (lineTopInFlowThread >= group().logicalBottomInFlowThread())
break;
examineLine(*line);
}
}
const LayoutFlowThread* flowThread = group().columnSet().flowThread();
bool isHorizontalWritingMode = flowThread->isHorizontalWritingMode();
// Look for breaks between and inside block-level children. Even if this is a block flow with
// inline children, there may be interesting floats to examine here.
for (const LayoutObject* child = box.slowFirstChild(); child; child = child->nextSibling()) {
if (!child->isBox() || child->isInline())
continue;
const LayoutBox& childBox = toLayoutBox(*child);
LayoutRect overflowRect = childBox.layoutOverflowRect();
LayoutUnit childLogicalBottomWithOverflow = childBox.logicalTop() + (isHorizontalWritingMode ? overflowRect.maxY() : overflowRect.maxX());
if (m_flowThreadOffset + childLogicalBottomWithOverflow <= group().logicalTopInFlowThread()) {
// This child is fully above the fragmentainer group we're examining.
continue;
}
LayoutUnit childLogicalTopWithOverflow = childBox.logicalTop() + (isHorizontalWritingMode ? overflowRect.y() : overflowRect.x());
if (m_flowThreadOffset + childLogicalTopWithOverflow >= group().logicalBottomInFlowThread()) {
// This child is fully below the fragmentainer group we're examining. We cannot just
// stop here, though, thanks to negative margins. So keep looking.
continue;
}
if (childBox.isOutOfFlowPositioned() || childBox.isColumnSpanAll())
continue;
// Tables are wicked. Both table rows and table cells are relative to their table section.
LayoutUnit offsetForThisChild = childBox.isTableRow() ? LayoutUnit() : childBox.logicalTop();
m_flowThreadOffset += offsetForThisChild;
examineBoxAfterEntering(childBox);
// Unless the child is unsplittable, or if the child establishes an inner multicol
// container, we descend into its subtree for further examination.
if (childBox.paginationBreakability() != LayoutBox::ForbidBreaks
&& (!childBox.isLayoutBlockFlow() || !toLayoutBlockFlow(childBox).multiColumnFlowThread()))
traverseSubtree(childBox);
examineBoxBeforeLeaving(childBox);
m_flowThreadOffset -= offsetForThisChild;
}
}
