void RenderFlowThread::validateRegions()
{
if (m_regionsInvalidated) {
m_regionsInvalidated = false;
m_regionsHaveUniformLogicalHeight = true;
if (hasRegions()) {
LayoutUnit previousRegionLogicalHeight = 0;
bool firstRegionVisited = false;
for (RenderMultiColumnSetList::iterator iter = m_multiColumnSetList.begin(); iter != m_multiColumnSetList.end(); ++iter) {
RenderMultiColumnSet* columnSet = *iter;
LayoutUnit regionLogicalHeight = columnSet->pageLogicalHeight();
if (!firstRegionVisited) {
firstRegionVisited = true;
} else {
if (m_regionsHaveUniformLogicalHeight && previousRegionLogicalHeight != regionLogicalHeight)
m_regionsHaveUniformLogicalHeight = false;
}
previousRegionLogicalHeight = regionLogicalHeight;
}
}
}
updateLogicalWidth(); // Called to get the maximum logical width for the columnSet.
updateRegionsFlowThreadPortionRect();
}
RenderMultiColumnSet* RenderMultiColumnSet::createAnonymous(RenderFlowThread* flowThread)
{
Document& document = flowThread->document();
RenderMultiColumnSet* renderer = new RenderMultiColumnSet(flowThread);
renderer->setDocumentForAnonymous(&document);
return renderer;
}
void RenderMultiColumnBlock::ensureColumnSets()
{
// This function ensures we have the correct column set information before we get into layout.
// For a simple multi-column layout in continuous media, only one column set child is required.
// Once a column is nested inside an enclosing pagination context, the number of column sets
// required becomes 2n-1, where n is the total number of nested pagination contexts. For example:
//
// Column layout with no enclosing pagination model = 2 * 1 - 1 = 1 column set.
// Columns inside pages = 2 * 2 - 1 = 3 column sets (bottom of first page, all the subsequent pages, then the last page).
// Columns inside columns inside pages = 2 * 3 - 1 = 5 column sets.
//
// In addition, column spans will force a column set to "split" into before/after sets around the spanning region.
//
// Finally, we will need to deal with columns inside regions. If regions have variable widths, then there will need
// to be unique column sets created inside any region whose width is different from its surrounding regions. This is
// actually pretty similar to the spanning case, in that we break up the column sets whenever the width varies.
//
// FIXME: For now just make one column set. This matches the old multi-column code.
// Right now our goal is just feature parity with the old multi-column code so that we can switch over to the
// new code as soon as possible.
if (flowThread() && !firstChild()->isRenderMultiColumnSet()) {
RenderMultiColumnSet* columnSet = new (renderArena()) RenderMultiColumnSet(document(), flowThread());
columnSet->setStyle(RenderStyle::createAnonymousStyleWithDisplay(style(), BLOCK));
RenderBlock::addChild(columnSet, firstChild());
flowThread()->addRegionToThread(columnSet);
}
}
LayoutUnit RenderFlowThread::pageLogicalHeightForOffset(LayoutUnit offset)
{
RenderMultiColumnSet* columnSet = columnSetAtBlockOffset(offset);
if (!columnSet)
return 0;
return columnSet->pageLogicalHeight();
}
RenderMultiColumnSet* RenderMultiColumnSet::createAnonymous(RenderFlowThread* flowThread, RenderStyle* parentStyle)
{
Document& document = flowThread->document();
RenderMultiColumnSet* renderer = new RenderMultiColumnSet(flowThread);
renderer->setDocumentForAnonymous(&document);
renderer->setStyle(RenderStyle::createAnonymousStyleWithDisplay(parentStyle, BLOCK));
return renderer;
}
RenderMultiColumnSet* RenderMultiColumnFlowThread::findSetRendering(RenderObject* renderer) const
{
for (RenderMultiColumnSet* multicolSet = firstMultiColumnSet(); multicolSet; multicolSet = multicolSet->nextSiblingMultiColumnSet()) {
if (multicolSet->containsRendererInFlowThread(renderer))
return multicolSet;
}
return nullptr;
}
void RenderFlowThread::collectLayerFragments(LayerFragments& layerFragments, const LayoutRect& layerBoundingBox, const LayoutRect& dirtyRect)
{
ASSERT(!m_regionsInvalidated);
for (RenderMultiColumnSetList::const_iterator iter = m_multiColumnSetList.begin(); iter != m_multiColumnSetList.end(); ++iter) {
RenderMultiColumnSet* columnSet = *iter;
columnSet->collectLayerFragments(layerFragments, layerBoundingBox, dirtyRect);
}
}
void RenderMultiColumnFlowThread::willBeRemovedFromTree()
{
// Detach all column sets from the flow thread. Cannot destroy them at this point, since they
// are siblings of this object, and there may be pointers to this object's sibling somewhere
// further up on the call stack.
for (RenderMultiColumnSet* columnSet = firstMultiColumnSet(); columnSet; columnSet = columnSet->nextSiblingMultiColumnSet())
columnSet->detachRegion();
multiColumnBlockFlow()->setMultiColumnFlowThread(nullptr);
RenderFlowThread::willBeRemovedFromTree();
}
void RenderFlowThread::computeLogicalHeight(LayoutUnit, LayoutUnit logicalTop, LogicalExtentComputedValues& computedValues) const
{
computedValues.m_position = logicalTop;
computedValues.m_extent = 0;
for (RenderMultiColumnSetList::const_iterator iter = m_multiColumnSetList.begin(); iter != m_multiColumnSetList.end(); ++iter) {
RenderMultiColumnSet* columnSet = *iter;
computedValues.m_extent += columnSet->logicalHeightOfAllFlowThreadContent();
}
}
void RenderMultiColumnFlowThread::addRegionToThread(RenderRegion* renderRegion)
{
RenderMultiColumnSet* columnSet = toRenderMultiColumnSet(renderRegion);
if (RenderMultiColumnSet* nextSet = columnSet->nextSiblingMultiColumnSet()) {
RenderRegionList::iterator it = m_regionList.find(nextSet);
ASSERT(it != m_regionList.end());
m_regionList.insertBefore(it, columnSet);
} else
m_regionList.add(columnSet);
renderRegion->setIsValid(true);
}
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;
}
LayoutUnit RenderFlowThread::pageRemainingLogicalHeightForOffset(LayoutUnit offset, PageBoundaryRule pageBoundaryRule)
{
RenderMultiColumnSet* columnSet = columnSetAtBlockOffset(offset);
if (!columnSet)
return 0;
LayoutUnit pageLogicalTop = columnSet->pageLogicalTopForOffset(offset);
LayoutUnit pageLogicalHeight = columnSet->pageLogicalHeight();
LayoutUnit pageLogicalBottom = pageLogicalTop + pageLogicalHeight;
LayoutUnit remainingHeight = pageLogicalBottom - offset;
if (pageBoundaryRule == IncludePageBoundary) {
// If IncludePageBoundary is set, the line exactly on the top edge of a
// columnSet will act as being part of the previous columnSet.
remainingHeight = intMod(remainingHeight, pageLogicalHeight);
}
return remainingHeight;
}
void RenderFlowThread::repaintRectangleInRegions(const LayoutRect& repaintRect) const
{
if (!shouldRepaint(repaintRect) || !hasValidRegionInfo())
return;
ForceHorriblySlowRectMapping slowRectMapping(*this); // We can't use layout state to repaint, since the regions are somewhere else.
// We can't use currentFlowThread as it is possible to have interleaved flow threads and the wrong one could be used.
// Let each columnSet figure out the proper enclosing flow thread.
CurrentRenderFlowThreadDisabler disabler(view());
for (RenderMultiColumnSetList::const_iterator iter = m_multiColumnSetList.begin(); iter != m_multiColumnSetList.end(); ++iter) {
RenderMultiColumnSet* columnSet = *iter;
columnSet->repaintFlowThreadContent(repaintRect);
}
}
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);
}
LayoutRect RenderFlowThread::fragmentsBoundingBox(const LayoutRect& layerBoundingBox)
{
ASSERT(!m_regionsInvalidated);
LayoutRect result;
for (RenderMultiColumnSetList::const_iterator iter = m_multiColumnSetList.begin(); iter != m_multiColumnSetList.end(); ++iter) {
RenderMultiColumnSet* columnSet = *iter;
LayerFragments fragments;
columnSet->collectLayerFragments(fragments, layerBoundingBox, PaintInfo::infiniteRect());
for (size_t i = 0; i < fragments.size(); ++i) {
const LayerFragment& fragment = fragments.at(i);
LayoutRect fragmentRect(layerBoundingBox);
fragmentRect.intersect(fragment.paginationClip);
fragmentRect.moveBy(fragment.paginationOffset);
result.unite(fragmentRect);
}
}
return result;
}
void RenderFlowThread::updateRegionsFlowThreadPortionRect()
{
LayoutUnit logicalHeight = 0;
// FIXME: Optimize not to clear the interval all the time. This implies manually managing the tree nodes lifecycle.
m_multiColumnSetIntervalTree.clear();
m_multiColumnSetIntervalTree.initIfNeeded();
for (RenderMultiColumnSetList::iterator iter = m_multiColumnSetList.begin(); iter != m_multiColumnSetList.end(); ++iter) {
RenderMultiColumnSet* columnSet = *iter;
LayoutUnit columnSetLogicalWidth = columnSet->pageLogicalWidth();
LayoutUnit columnSetLogicalHeight = std::min<LayoutUnit>(RenderFlowThread::maxLogicalHeight() - logicalHeight, columnSet->logicalHeightOfAllFlowThreadContent());
LayoutRect columnSetRect(style()->direction() == LTR ? LayoutUnit() : logicalWidth() - columnSetLogicalWidth, logicalHeight, columnSetLogicalWidth, columnSetLogicalHeight);
columnSet->setFlowThreadPortionRect(isHorizontalWritingMode() ? columnSetRect : columnSetRect.transposedRect());
m_multiColumnSetIntervalTree.add(MultiColumnSetIntervalTree::createInterval(logicalHeight, logicalHeight + columnSetLogicalHeight, columnSet));
logicalHeight += columnSetLogicalHeight;
}
}
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;
}
void RenderMultiColumnFlowThread::autoGenerateRegionsToBlockOffset(LayoutUnit /*offset*/)
{
// This function ensures we have the correct column set information at all times.
// For a simple multi-column layout in continuous media, only one column set child is required.
// Once a column is nested inside an enclosing pagination context, the number of column sets
// required becomes 2n-1, where n is the total number of nested pagination contexts. For example:
//
// Column layout with no enclosing pagination model = 2 * 1 - 1 = 1 column set.
// Columns inside pages = 2 * 2 - 1 = 3 column sets (bottom of first page, all the subsequent pages, then the last page).
// Columns inside columns inside pages = 2 * 3 - 1 = 5 column sets.
//
// In addition, column spans will force a column set to "split" into before/after sets around the spanning element.
//
// Finally, we will need to deal with columns inside regions. If regions have variable widths, then there will need
// to be unique column sets created inside any region whose width is different from its surrounding regions. This is
// actually pretty similar to the spanning case, in that we break up the column sets whenever the width varies.
//
// FIXME: For now just make one column set. This matches the old multi-column code.
// Right now our goal is just feature parity with the old multi-column code so that we can switch over to the
// new code as soon as possible.
RenderMultiColumnSet* firstSet = toRenderMultiColumnSet(firstRegion());
if (firstSet)
return;
invalidateRegions();
RenderBlockFlow* parentBlock = toRenderBlockFlow(parent());
firstSet = new RenderMultiColumnSet(*this, RenderStyle::createAnonymousStyleWithDisplay(&parentBlock->style(), BLOCK));
firstSet->initializeStyle();
parentBlock->RenderBlock::addChild(firstSet);
// Even though we aren't placed yet, we can go ahead and set up our size. At this point we're
// typically in the middle of laying out the thread, attempting to paginate, and we need to do
// some rudimentary "layout" of the set now, so that pagination will work.
firstSet->prepareForLayout();
validateRegions();
}
RenderRegion* RenderMultiColumnFlowThread::mapFromFlowToRegion(TransformState& transformState) const
{
if (!hasValidRegionInfo())
return nullptr;
// Get back into our local flow thread space.
LayoutRect boxRect = transformState.mappedQuad().enclosingBoundingBox();
flipForWritingMode(boxRect);
// FIXME: We need to refactor RenderObject::absoluteQuads to be able to split the quads across regions,
// for now we just take the center of the mapped enclosing box and map it to a column.
LayoutPoint center = boxRect.center();
LayoutUnit centerOffset = isHorizontalWritingMode() ? center.y() : center.x();
RenderRegion* renderRegion = const_cast<RenderMultiColumnFlowThread*>(this)->regionAtBlockOffset(this, centerOffset, true, DisallowRegionAutoGeneration);
if (!renderRegion)
return nullptr;
// Now that we know which multicolumn set we hit, we need to get the appropriate translation offset for the column.
RenderMultiColumnSet* columnSet = toRenderMultiColumnSet(renderRegion);
LayoutPoint translationOffset = columnSet->columnTranslationForOffset(centerOffset);
// Now we know how we want the rect to be translated into the region.
LayoutRect flippedRegionRect(renderRegion->flowThreadPortionRect());
if (isHorizontalWritingMode())
flippedRegionRect.setHeight(columnSet->computedColumnHeight());
else
flippedRegionRect.setWidth(columnSet->computedColumnHeight());
flipForWritingMode(flippedRegionRect);
flippedRegionRect.moveBy(-translationOffset);
// There is an additional offset to apply, which is the offset of the region within the multi-column space.
transformState.move(renderRegion->contentBoxRect().location() - flippedRegionRect.location());
return renderRegion;
}
void RenderMultiColumnFlowThread::flowThreadDescendantInserted(RenderObject* descendant)
{
if (gShiftingSpanner || m_beingEvacuated || descendant->isInFlowRenderFlowThread())
return;
RenderObject* subtreeRoot = descendant;
for (; descendant; descendant = (descendant ? descendant->nextInPreOrder(subtreeRoot) : nullptr)) {
if (descendant->isRenderMultiColumnSpannerPlaceholder()) {
// A spanner's placeholder has been inserted. The actual spanner renderer is moved from
// where it would otherwise occur (if it weren't a spanner) to becoming a sibling of the
// column sets.
RenderMultiColumnSpannerPlaceholder* placeholder = toRenderMultiColumnSpannerPlaceholder(descendant);
if (placeholder->flowThread() != this) {
// This isn't our spanner! It shifted here from an ancestor multicolumn block. It's going to end up
// becoming our spanner instead, but for it to do that we first have to nuke the original spanner,
// and get the spanner content back into this flow thread.
RenderBox* spanner = placeholder->spanner();
// Get info for the move of the original content back into our flow thread.
RenderBoxModelObject* placeholderParent = toRenderBoxModelObject(placeholder->parent());
// We have to nuke the placeholder, since the ancestor already lost the mapping to it when
// we shifted the placeholder down into this flow thread.
RenderObject* placeholderNextSibling = placeholderParent->removeChild(*placeholder);
// Get the ancestor multicolumn flow thread to clean up its mess.
RenderBlockFlow* ancestorBlock = toRenderBlockFlow(spanner->parent());
ancestorBlock->multiColumnFlowThread()->flowThreadRelativeWillBeRemoved(spanner);
// Now move the original content into our flow thread. It will end up calling flowThreadDescendantInserted
// on the new content only, and everything will get set up properly.
ancestorBlock->moveChildTo(placeholderParent, spanner, placeholderNextSibling, true);
// Advance descendant.
descendant = placeholderNextSibling;
// If the spanner was the subtree root, then we're done, since there is nothing else left to insert.
if (!descendant)
return;
// Now that we have done this, we can continue past the spanning content, since we advanced
// descendant already.
if (descendant)
descendant = descendant->previousInPreOrder(subtreeRoot);
continue;
}
ASSERT(!m_spannerMap.get(placeholder->spanner()));
m_spannerMap.add(placeholder->spanner(), placeholder);
ASSERT(!placeholder->firstChild()); // There should be no children here, but if there are, we ought to skip them.
continue;
}
RenderBlockFlow* multicolContainer = multiColumnBlockFlow();
RenderObject* nextRendererInFlowThread = descendant->nextInPreOrderAfterChildren(this);
RenderObject* insertBeforeMulticolChild = nullptr;
if (isValidColumnSpanner(this, descendant)) {
// This is a spanner (column-span:all). Such renderers are moved from where they would
// otherwise occur in the render tree to becoming a direct child of the multicol container,
// so that they live among the column sets. This simplifies the layout implementation, and
// basically just relies on regular block layout done by the RenderBlockFlow that
// establishes the multicol container.
RenderBlockFlow* container = toRenderBlockFlow(descendant->parent());
RenderMultiColumnSet* setToSplit = nullptr;
if (nextRendererInFlowThread) {
setToSplit = findSetRendering(descendant);
if (setToSplit) {
setToSplit->setNeedsLayout();
insertBeforeMulticolChild = setToSplit->nextSibling();
}
}
// Moving a spanner's renderer so that it becomes a sibling of the column sets requires us
// to insert an anonymous placeholder in the tree where the spanner's renderer otherwise
// would have been. This is needed for a two reasons: We need a way of separating inline
// content before and after the spanner, so that it becomes separate line boxes. Secondly,
// this placeholder serves as a break point for column sets, so that, when encountered, we
// end flowing one column set and move to the next one.
RenderMultiColumnSpannerPlaceholder* placeholder = RenderMultiColumnSpannerPlaceholder::createAnonymous(this, toRenderBox(descendant), &container->style());
container->addChild(placeholder, descendant->nextSibling());
container->removeChild(*descendant);
// This is a guard to stop an ancestor flow thread from processing the spanner.
gShiftingSpanner = true;
multicolContainer->RenderBlock::addChild(descendant, insertBeforeMulticolChild);
gShiftingSpanner = false;
// The spanner has now been moved out from the flow thread, but we don't want to
// examine its children anyway. They are all part of the spanner and shouldn't trigger
// creation of column sets or anything like that. Continue at its original position in
// the tree, i.e. where the placeholder was just put.
if (subtreeRoot == descendant)
subtreeRoot = placeholder;
descendant = placeholder;
} else {
// This is regular multicol content, i.e. not part of a spanner.
if (nextRendererInFlowThread && nextRendererInFlowThread->isRenderMultiColumnSpannerPlaceholder()) {
// Inserted right before a spanner. Is there a set for us there?
RenderMultiColumnSpannerPlaceholder* placeholder = toRenderMultiColumnSpannerPlaceholder(nextRendererInFlowThread);
if (RenderObject* previous = placeholder->spanner()->previousSibling()) {
if (previous->isRenderMultiColumnSet())
continue; // There's already a set there. Nothing to do.
}
insertBeforeMulticolChild = placeholder->spanner();
} else if (RenderMultiColumnSet* lastSet = lastMultiColumnSet()) {
// This child is not an immediate predecessor of a spanner, which means that if this
// child precedes a spanner at all, there has to be a column set created for us there
// already. If it doesn't precede any spanner at all, on the other hand, we need a
// column set at the end of the multicol container. We don't really check here if the
// child inserted precedes any spanner or not (as that's an expensive operation). Just
// make sure we have a column set at the end. It's no big deal if it remains unused.
if (!lastSet->nextSibling())
continue;
}
}
// Need to create a new column set when there's no set already created. We also always insert
// another column set after a spanner. Even if it turns out that there are no renderers
// following the spanner, there may be bottom margins there, which take up space.
RenderMultiColumnSet* newSet = new RenderMultiColumnSet(*this, RenderStyle::createAnonymousStyleWithDisplay(&multicolContainer->style(), BLOCK));
newSet->initializeStyle();
multicolContainer->RenderBlock::addChild(newSet, insertBeforeMulticolChild);
invalidateRegions();
// We cannot handle immediate column set siblings at the moment (and there's no need for
// it, either). There has to be at least one spanner separating them.
ASSERT(!previousColumnSetOrSpannerSiblingOf(newSet) || !previousColumnSetOrSpannerSiblingOf(newSet)->isRenderMultiColumnSet());
ASSERT(!nextColumnSetOrSpannerSiblingOf(newSet) || !nextColumnSetOrSpannerSiblingOf(newSet)->isRenderMultiColumnSet());
}
}
LayoutPoint RenderFlowThread::adjustedPositionRelativeToOffsetParent(const RenderBoxModelObject& boxModelObject, const LayoutPoint& startPoint)
{
LayoutPoint referencePoint = startPoint;
// FIXME: This needs to be adapted for different writing modes inside the flow thread.
RenderMultiColumnSet* startColumnSet = columnSetAtBlockOffset(referencePoint.y());
if (startColumnSet) {
// Take into account the offset coordinates of the columnSet.
RenderObject* currObject = startColumnSet;
RenderObject* currOffsetParentRenderer;
Element* currOffsetParentElement;
while ((currOffsetParentElement = currObject->offsetParent()) && (currOffsetParentRenderer = currOffsetParentElement->renderer())) {
if (currObject->isBoxModelObject())
referencePoint.move(toRenderBoxModelObject(currObject)->offsetLeft(), toRenderBoxModelObject(currObject)->offsetTop());
// Since we're looking for the offset relative to the body, we must also
// take into consideration the borders of the columnSet's offsetParent.
if (currOffsetParentRenderer->isBox() && !currOffsetParentRenderer->isBody())
referencePoint.move(toRenderBox(currOffsetParentRenderer)->borderLeft(), toRenderBox(currOffsetParentRenderer)->borderTop());
currObject = currOffsetParentRenderer;
}
// We need to check if any of this box's containing blocks start in a different columnSet
// and if so, drop the object's top position (which was computed relative to its containing block
// and is no longer valid) and recompute it using the columnSet in which it flows as reference.
bool wasComputedRelativeToOtherRegion = false;
const RenderBlock* objContainingBlock = boxModelObject.containingBlock();
while (objContainingBlock) {
// Check if this object is in a different columnSet.
RenderMultiColumnSet* parentStartRegion = 0;
RenderMultiColumnSet* parentEndRegion = 0;
getRegionRangeForBox(objContainingBlock, parentStartRegion, parentEndRegion);
if (parentStartRegion && parentStartRegion != startColumnSet) {
wasComputedRelativeToOtherRegion = true;
break;
}
objContainingBlock = objContainingBlock->containingBlock();
}
if (wasComputedRelativeToOtherRegion) {
// Get the logical top coordinate of the current object.
LayoutUnit top = 0;
if (boxModelObject.isRenderBlock()) {
top = toRenderBlock(&boxModelObject)->offsetFromLogicalTopOfFirstPage();
} else {
if (boxModelObject.containingBlock())
top = boxModelObject.containingBlock()->offsetFromLogicalTopOfFirstPage();
if (boxModelObject.isBox())
top += toRenderBox(&boxModelObject)->topLeftLocation().y();
else if (boxModelObject.isRenderInline())
top -= toRenderInline(&boxModelObject)->borderTop();
}
// Get the logical top of the columnSet this object starts in
// and compute the object's top, relative to the columnSet's top.
LayoutUnit regionLogicalTop = startColumnSet->pageLogicalTopForOffset(top);
LayoutUnit topRelativeToRegion = top - regionLogicalTop;
referencePoint.setY(startColumnSet->offsetTop() + topRelativeToRegion);
// Since the top has been overriden, check if the
// relative positioning must be reconsidered.
if (boxModelObject.isRelPositioned())
referencePoint.move(0, boxModelObject.relativePositionOffset().height());
}
// Since we're looking for the offset relative to the body, we must also
// take into consideration the borders of the columnSet.
referencePoint.move(startColumnSet->borderLeft(), startColumnSet->borderTop());
}
return referencePoint;
}
LayoutUnit RenderFlowThread::pageLogicalTopForOffset(LayoutUnit offset)
{
RenderMultiColumnSet* columnSet = columnSetAtBlockOffset(offset);
return columnSet ? columnSet->pageLogicalTopForOffset(offset) : LayoutUnit();
}
