RenderObject* RenderMultiColumnBlock::layoutSpecialExcludedChild(bool relayoutChildren)
{
if (!m_flowThread)
return 0;
// Update the dimensions of our regions before we lay out the flow thread.
// FIXME: Eventually this is going to get way more complicated, and we will be destroying regions
// instead of trying to keep them around.
bool shouldInvalidateRegions = false;
for (RenderBox* childBox = firstChildBox(); childBox; childBox = childBox->nextSiblingBox()) {
if (childBox == m_flowThread)
continue;
if (relayoutChildren || childBox->needsLayout()) {
if (!m_inBalancingPass && childBox->isRenderMultiColumnSet())
toRenderMultiColumnSet(childBox)->prepareForLayout();
shouldInvalidateRegions = true;
}
}
if (shouldInvalidateRegions)
m_flowThread->invalidateRegions();
if (relayoutChildren)
m_flowThread->setChildNeedsLayout(MarkOnlyThis);
setLogicalTopForChild(*m_flowThread, borderAndPaddingBefore());
m_flowThread->layoutIfNeeded();
determineLogicalLeftPositionForChild(*m_flowThread);
return m_flowThread;
}
void RenderMultiColumnFlowThread::flowThreadDescendantBoxLaidOut(RenderBox* descendant)
{
if (!descendant->isRenderMultiColumnSpannerPlaceholder())
return;
RenderMultiColumnSpannerPlaceholder* placeholder = toRenderMultiColumnSpannerPlaceholder(descendant);
RenderBlock* container = placeholder->containingBlock();
for (RenderBox* prev = previousColumnSetOrSpannerSiblingOf(placeholder->spanner()); prev; prev = previousColumnSetOrSpannerSiblingOf(prev)) {
if (prev->isRenderMultiColumnSet()) {
toRenderMultiColumnSet(prev)->endFlow(container, placeholder->logicalTop());
break;
}
}
for (RenderBox* next = nextColumnSetOrSpannerSiblingOf(placeholder->spanner()); next; next = nextColumnSetOrSpannerSiblingOf(next)) {
if (next->isRenderMultiColumnSet()) {
m_lastSetWorkedOn = toRenderMultiColumnSet(next);
m_lastSetWorkedOn->beginFlow(container);
break;
}
}
}
bool RenderMultiColumnBlock::relayoutForPagination(bool, LayoutUnit, LayoutStateMaintainer& statePusher)
{
if (m_inBalancingPass || !requiresBalancing())
return false;
m_inBalancingPass = true; // Prevent re-entering this method (and recursion into layout).
bool needsRelayout;
bool neededRelayout = false;
bool firstPass = true;
do {
// Column heights may change here because of balancing. We may have to do multiple layout
// passes, depending on how the contents is fitted to the changed column heights. In most
// cases, laying out again twice or even just once will suffice. Sometimes we need more
// passes than that, though, but the number of retries should not exceed the number of
// columns, unless we have a bug.
needsRelayout = false;
for (RenderBox* childBox = firstChildBox(); childBox; childBox = childBox->nextSiblingBox())
if (childBox != m_flowThread && childBox->isRenderMultiColumnSet()) {
RenderMultiColumnSet* multicolSet = toRenderMultiColumnSet(childBox);
if (multicolSet->calculateBalancedHeight(firstPass)) {
multicolSet->setChildNeedsLayout(MarkOnlyThis);
needsRelayout = true;
}
}
if (needsRelayout) {
// Layout again. Column balancing resulted in a new height.
neededRelayout = true;
m_flowThread->setChildNeedsLayout(MarkOnlyThis);
setChildNeedsLayout(MarkOnlyThis);
if (firstPass)
statePusher.pop();
layoutBlock(false);
}
firstPass = false;
} while (needsRelayout);
m_inBalancingPass = false;
return neededRelayout;
}