static bool isValidColumnSpanner(RenderMultiColumnFlowThread* flowThread, RenderObject* descendant)
{
// We assume that we're inside the flow thread. This function is not to be called otherwise.
ASSERT(descendant->isDescendantOf(flowThread));
// First make sure that the renderer itself has the right properties for becoming a spanner.
RenderStyle& style = descendant->style();
if (style.columnSpan() != ColumnSpanAll || !descendant->isBox() || descendant->isFloatingOrOutOfFlowPositioned())
return false;
RenderBlock* container = descendant->containingBlock();
if (!container->isRenderBlockFlow() || container->childrenInline()) {
// Needs to be block-level.
return false;
}
// This looks like a spanner, but if we're inside something unbreakable, it's not to be treated as one.
for (RenderBox* ancestor = toRenderBox(descendant)->parentBox(); ancestor; ancestor = ancestor->parentBox()) {
if (ancestor->isRenderFlowThread()) {
// Don't allow any intervening non-multicol fragmentation contexts. The spec doesn't say
// anything about disallowing this, but it's just going to be too complicated to
// implement (not to mention specify behavior).
return ancestor == flowThread;
}
ASSERT(ancestor->style().columnSpan() != ColumnSpanAll || !isValidColumnSpanner(flowThread, ancestor));
if (ancestor->isUnsplittableForPagination())
return false;
}
ASSERT_NOT_REACHED();
return false;
}
LayoutState::LayoutState(RenderBox& renderer, const LayoutSize& offset, LayoutUnit pageLogicalHeight, bool pageLogicalHeightChanged, ColumnInfo* columnInfo, bool containingBlockLogicalWidthChanged)
: m_containingBlockLogicalWidthChanged(containingBlockLogicalWidthChanged)
, m_columnInfo(columnInfo)
, m_next(renderer.view()->layoutState())
, m_renderer(renderer)
{
m_flowThread = renderer.isRenderFlowThread() ? toRenderFlowThread(&renderer) : m_next->flowThread();
renderer.view()->pushLayoutState(*this);
bool fixed = renderer.isOutOfFlowPositioned() && renderer.style()->position() == FixedPosition;
if (fixed) {
// FIXME: This doesn't work correctly with transforms.
FloatPoint fixedOffset = renderer.view()->localToAbsolute(FloatPoint(), IsFixed);
m_layoutOffset = LayoutSize(fixedOffset.x(), fixedOffset.y()) + offset;
} else {
m_layoutOffset = m_next->m_layoutOffset + offset;
}
if (renderer.isOutOfFlowPositioned() && !fixed) {
if (RenderObject* container = renderer.container()) {
if (container->style()->hasInFlowPosition() && container->isRenderInline())
m_layoutOffset += toRenderInline(container)->offsetForInFlowPositionedInline(renderer);
}
}
// If we establish a new page height, then cache the offset to the top of the first page.
// We can compare this later on to figure out what part of the page we're actually on,
if (pageLogicalHeight || m_columnInfo || renderer.isRenderFlowThread()) {
m_pageLogicalHeight = pageLogicalHeight;
bool isFlipped = renderer.style()->isFlippedBlocksWritingMode();
m_pageOffset = LayoutSize(m_layoutOffset.width() + (!isFlipped ? renderer.borderLeft() + renderer.paddingLeft() : renderer.borderRight() + renderer.paddingRight()),
m_layoutOffset.height() + (!isFlipped ? renderer.borderTop() + renderer.paddingTop() : renderer.borderBottom() + renderer.paddingBottom()));
m_pageLogicalHeightChanged = pageLogicalHeightChanged;
m_isPaginated = true;
} else {
// If we don't establish a new page height, then propagate the old page height and offset down.
m_pageLogicalHeight = m_next->m_pageLogicalHeight;
m_pageLogicalHeightChanged = m_next->m_pageLogicalHeightChanged;
m_pageOffset = m_next->m_pageOffset;
// Disable pagination for objects we don't support. For now this includes overflow:scroll/auto, inline blocks and
// writing mode roots.
if (renderer.isUnsplittableForPagination()) {
m_pageLogicalHeight = 0;
m_isPaginated = false;
} else {
m_isPaginated = m_pageLogicalHeight || m_next->m_columnInfo || renderer.flowThreadContainingBlock();
}
}
if (!m_columnInfo)
m_columnInfo = m_next->m_columnInfo;
// FIXME: <http://bugs.webkit.org/show_bug.cgi?id=13443> Apply control clip if present.
}