RenderRegion* RenderMultiColumnFlowThread::regionAtBlockOffset(const RenderBox* box, LayoutUnit offset, bool extendLastRegion, RegionAutoGenerationPolicy autoGenerationPolicy)
{
if (!m_inLayout)
return RenderFlowThread::regionAtBlockOffset(box, offset, extendLastRegion, autoGenerationPolicy);
// Layout in progress. We are calculating the set heights as we speak, so the region range
// information is not up-to-date.
RenderMultiColumnSet* columnSet = m_lastSetWorkedOn ? m_lastSetWorkedOn : firstMultiColumnSet();
if (!columnSet) {
// If there's no set, bail. This multicol is empty or only consists of spanners. There
// are no regions.
return nullptr;
}
// The last set worked on is a good guess. But if we're not within the bounds, search for the
// right one.
if (offset < columnSet->logicalTopInFlowThread()) {
do {
if (RenderMultiColumnSet* prev = columnSet->previousSiblingMultiColumnSet())
columnSet = prev;
else
break;
} while (offset < columnSet->logicalTopInFlowThread());
} else {
while (offset >= columnSet->logicalBottomInFlowThread()) {
RenderMultiColumnSet* next = columnSet->nextSiblingMultiColumnSet();
if (!next || !next->hasBeenFlowed())
break;
columnSet = next;
}
}
return columnSet;
}
void RenderMultiColumnFlowThread::setRegionRangeForBox(const RenderBox* box, RenderRegion* startRegion, RenderRegion* endRegion)
{
// Some column sets may have zero height, which means that two or more sets may start at the
// exact same flow thread position, which means that some parts of the code may believe that a
// given box lives in sets that it doesn't really live in. Make some adjustments here and
// include such sets if they are adjacent to the start and/or end regions.
for (RenderMultiColumnSet* columnSet = toRenderMultiColumnSet(startRegion)->previousSiblingMultiColumnSet(); columnSet; columnSet = columnSet->previousSiblingMultiColumnSet()) {
if (columnSet->logicalHeightInFlowThread())
break;
startRegion = columnSet;
}
for (RenderMultiColumnSet* columnSet = toRenderMultiColumnSet(startRegion)->nextSiblingMultiColumnSet(); columnSet; columnSet = columnSet->nextSiblingMultiColumnSet()) {
if (columnSet->logicalHeightInFlowThread())
break;
endRegion = columnSet;
}
RenderFlowThread::setRegionRangeForBox(box, startRegion, endRegion);
}