void LayoutMultiColumnFlowThread::appendNewFragmentainerGroupIfNeeded(LayoutUnit offsetInFlowThread)
{
if (!isPageLogicalHeightKnown()) {
// If we have no clue about the height of the multicol container, bail. This situation
// occurs initially when an auto-height multicol container is nested inside another
// auto-height multicol container. We need at least an estimated height of the outer
// multicol container before we can check what an inner fragmentainer group has room for.
// Its height is indefinite for now.
return;
}
LayoutMultiColumnSet* columnSet = columnSetAtBlockOffset(offsetInFlowThread);
if (columnSet->isInitialHeightCalculated()) {
// We only insert additional fragmentainer groups in the initial layout pass. We only want
// to balance columns in the last fragmentainer group (if we need to balance at all), so we
// want that last fragmentainer group to be the same one in all layout passes that follow.
return;
}
if (!columnSet->hasFragmentainerGroupForColumnAt(offsetInFlowThread)) {
FragmentationContext* enclosingFragmentationContext = this->enclosingFragmentationContext();
if (!enclosingFragmentationContext)
return; // Not nested. We'll never need more rows than the one we already have then.
ASSERT(!isLayoutPagedFlowThread());
// We have run out of columns here, so we add another row to hold more columns. When we add
// a new row, it implicitly means that we're inserting another column in our enclosing
// multicol container. That in turn may mean that we've run out of columns there too.
const MultiColumnFragmentainerGroup& newRow = columnSet->appendNewFragmentainerGroup();
if (LayoutMultiColumnFlowThread* enclosingFlowThread = enclosingFragmentationContext->associatedFlowThread())
enclosingFlowThread->appendNewFragmentainerGroupIfNeeded(newRow.blockOffsetInEnclosingFragmentationContext());
}
}
void LayoutMultiColumnFlowThread::appendNewFragmentainerGroupIfNeeded(LayoutUnit bottomOffsetInFlowThread)
{
if (!isPageLogicalHeightKnown()) {
// If we have no clue about the height of the multicol container, bail. This situation
// occurs initially when an auto-height multicol container is nested inside another
// auto-height multicol container. We need at least an estimated height of the outer
// multicol container before we can check what an inner fragmentainer group has room for.
// Its height is indefinite for now.
return;
}
// TODO(mstensho): bottomOffsetInFlowThread is an endpoint-exclusive offset, i.e. the offset
// just after the bottom of some object. So, ideally, columnSetAtBlockOffset() should be
// informed about this (i.e. take a PageBoundaryRule argument). This is not the only place with
// this issue; see also pageRemainingLogicalHeightForOffset().
LayoutMultiColumnSet* columnSet = columnSetAtBlockOffset(bottomOffsetInFlowThread);
if (columnSet->isInitialHeightCalculated()) {
// We only insert additional fragmentainer groups in the initial layout pass. We only want
// to balance columns in the last fragmentainer group (if we need to balance at all), so we
// want that last fragmentainer group to be the same one in all layout passes that follow.
return;
}
if (!columnSet->hasFragmentainerGroupForColumnAt(bottomOffsetInFlowThread)) {
FragmentationContext* enclosingFragmentationContext = this->enclosingFragmentationContext();
if (!enclosingFragmentationContext)
return; // Not nested. We'll never need more rows than the one we already have then.
ASSERT(!isLayoutPagedFlowThread());
// We have run out of columns here, so we add another row to hold more columns. When we add
// a new row, it implicitly means that we're inserting another column in our enclosing
// multicol container. That in turn may mean that we've run out of columns there too.
const MultiColumnFragmentainerGroup& newRow = columnSet->appendNewFragmentainerGroup();
if (LayoutMultiColumnFlowThread* enclosingFlowThread = enclosingFragmentationContext->associatedFlowThread())
enclosingFlowThread->appendNewFragmentainerGroupIfNeeded(newRow.blockOffsetInEnclosingFragmentationContext() + newRow.logicalHeight());
}
}
LayoutMultiColumnFlowThread* LayoutMultiColumnFlowThread::enclosingFlowThread() const
{
if (isLayoutPagedFlowThread()) {
// Paged overflow containers should never be fragmented by enclosing fragmentation
// contexts. They are to be treated as unbreakable content.
return nullptr;
}
if (multiColumnBlockFlow()->isInsideFlowThread())
return toLayoutMultiColumnFlowThread(locateFlowThreadContainingBlockOf(*multiColumnBlockFlow()));
return nullptr;
}
