void RenderFlowThread::computeOverflowStateForRegions(LayoutUnit oldClientAfterEdge)
{
LayoutUnit height = oldClientAfterEdge;
LayoutUnit offsetBreakAdjustment = 0;
// Simulate a region break at height. If it points inside an auto logical height region,
// then it may determine the region override logical content height.
addForcedRegionBreak(height, this, false, &offsetBreakAdjustment);
// During the normal layout phase of the flow thread all the auto-height regions have the overrideLogicalContentHeight set to max height.
// We need to clear the overrideLogicalContentHeight for all the regions that didn't receive any content, starting with firstEmptyRegion.
RenderRegion* firstEmptyRegion = 0;
if (view()->normalLayoutPhase())
firstEmptyRegion = regionAtBlockOffset(height + offsetBreakAdjustment);
// FIXME: the visual overflow of middle region (if it is the last one to contain any content in a render flow thread)
// might not be taken into account because the render flow thread height is greater that that regions height + its visual overflow
// because of how computeLogicalHeight is implemented for RenderFlowThread (as a sum of all regions height).
// This means that the middle region will be marked as fit (even if it has visual overflow flowing into the next region)
if (hasRenderOverflow()
&& ( (isHorizontalWritingMode() && visualOverflowRect().maxY() > clientBoxRect().maxY())
|| (!isHorizontalWritingMode() && visualOverflowRect().maxX() > clientBoxRect().maxX())))
height = isHorizontalWritingMode() ? visualOverflowRect().maxY() : visualOverflowRect().maxX();
bool inEmptyRegionsSection = false;
RenderRegion* lastReg = lastRegion();
for (RenderRegionList::iterator iter = m_regionList.begin(); iter != m_regionList.end(); ++iter) {
RenderRegion* region = *iter;
LayoutUnit flowMin = height - (isHorizontalWritingMode() ? region->flowThreadPortionRect().y() : region->flowThreadPortionRect().x());
LayoutUnit flowMax = height - (isHorizontalWritingMode() ? region->flowThreadPortionRect().maxY() : region->flowThreadPortionRect().maxX());
RenderRegion::RegionState previousState = region->regionState();
RenderRegion::RegionState state = RenderRegion::RegionFit;
if (flowMin <= 0)
state = RenderRegion::RegionEmpty;
if (flowMax > 0 && region == lastReg)
state = RenderRegion::RegionOverset;
region->setRegionState(state);
// determine whether the NamedFlow object should dispatch a regionLayoutUpdate event
// FIXME: currently it cannot determine whether a region whose regionOverset state remained either "fit" or "overset" has actually
// changed, so it just assumes that the NamedFlow should dispatch the event
if (previousState != state
|| state == RenderRegion::RegionFit
|| state == RenderRegion::RegionOverset)
setDispatchRegionLayoutUpdateEvent(true);
if (region == firstEmptyRegion)
inEmptyRegionsSection = true;
// Clear the overrideLogicalContentHeight value for autoheight regions that didn't receive any content.
if (inEmptyRegionsSection && region->hasAutoLogicalHeight())
region->clearOverrideLogicalContentHeight();
}
// With the regions overflow state computed we can also set the overset flag for the named flow.
// If there are no valid regions in the chain, overset is true.
m_overset = lastReg ? lastReg->regionState() == RenderRegion::RegionOverset : true;
}
LayoutUnit RenderFlowThread::contentLogicalLeftOfFirstRegion() const
{
if (!hasValidRegionInfo())
return 0;
for (RenderRegionList::const_iterator iter = m_regionList.begin(); iter != m_regionList.end(); ++iter) {
RenderRegion* region = *iter;
if (!region->isValid())
continue;
return isHorizontalWritingMode() ? region->flowThreadPortionRect().x() : region->flowThreadPortionRect().y();
}
ASSERT_NOT_REACHED();
return 0;
}
LayoutUnit RenderFlowThread::contentLogicalLeftOfFirstRegion() const
{
RenderRegion* firstValidRegionInFlow = firstRegion();
if (!firstValidRegionInFlow)
return 0;
return isHorizontalWritingMode() ? firstValidRegionInFlow->flowThreadPortionRect().x() : firstValidRegionInFlow->flowThreadPortionRect().y();
}
RenderRegion* RenderFlowThread::regionAtBlockOffset(LayoutUnit offset, bool extendLastRegion) const
{
ASSERT(!m_regionsInvalidated);
// If no region matches the position and extendLastRegion is true, it will return
// the last valid region. It is similar to auto extending the size of the last region.
RenderRegion* lastValidRegion = 0;
LayoutUnit accumulatedLogicalHeight = 0;
// FIXME: The regions are always in order, optimize this search.
for (RenderRegionList::const_iterator iter = m_regionList.begin(); iter != m_regionList.end(); ++iter) {
RenderRegion* region = *iter;
if (offset <= 0)
return region;
if (extendLastRegion || region->isRenderRegionSet())
lastValidRegion = region;
if (region->hasOverrideHeight() && view()->normalLayoutPhase()) {
accumulatedLogicalHeight += region->overrideLogicalContentHeight();
if (offset < accumulatedLogicalHeight)
return region;
continue;
}
LayoutRect regionRect = region->flowThreadPortionRect();
accumulatedLogicalHeight += isHorizontalWritingMode() ? regionRect.height() : regionRect.width();
if (offset < accumulatedLogicalHeight)
return region;
}
return lastValidRegion;
}
RenderRegion* RenderFlowThread::regionAtBlockOffset(LayoutUnit offset, bool extendLastRegion) const
{
ASSERT(!m_regionsInvalidated);
// If no region matches the position and extendLastRegion is true, it will return
// the last valid region. It is similar to auto extending the size of the last region.
RenderRegion* lastValidRegion = 0;
// FIXME: The regions are always in order, optimize this search.
bool useHorizontalWritingMode = isHorizontalWritingMode();
for (RenderRegionList::const_iterator iter = m_regionList.begin(); iter != m_regionList.end(); ++iter) {
RenderRegion* region = *iter;
if (!region->isValid())
continue;
if (offset <= 0)
return region;
LayoutRect regionRect = region->flowThreadPortionRect();
if ((useHorizontalWritingMode && offset < regionRect.maxY()) || (!useHorizontalWritingMode && offset < regionRect.maxX()))
return region;
if (extendLastRegion || region->isRenderRegionSet())
lastValidRegion = region;
}
return lastValidRegion;
}
void RenderNamedFlowThread::computeOversetStateForRegions(LayoutUnit oldClientAfterEdge)
{
LayoutUnit height = oldClientAfterEdge;
// FIXME: the visual overflow of middle region (if it is the last one to contain any content in a render flow thread)
// might not be taken into account because the render flow thread height is greater that that regions height + its visual overflow
// because of how computeLogicalHeight is implemented for RenderNamedFlowThread (as a sum of all regions height).
// This means that the middle region will be marked as fit (even if it has visual overflow flowing into the next region)
if (hasRenderOverflow()
&& ( (isHorizontalWritingMode() && visualOverflowRect().maxY() > clientBoxRect().maxY())
|| (!isHorizontalWritingMode() && visualOverflowRect().maxX() > clientBoxRect().maxX())))
height = isHorizontalWritingMode() ? visualOverflowRect().maxY() : visualOverflowRect().maxX();
RenderRegion* lastReg = lastRegion();
for (RenderRegionList::iterator iter = m_regionList.begin(); iter != m_regionList.end(); ++iter) {
RenderRegion* region = *iter;
LayoutUnit flowMin = height - (isHorizontalWritingMode() ? region->flowThreadPortionRect().y() : region->flowThreadPortionRect().x());
LayoutUnit flowMax = height - (isHorizontalWritingMode() ? region->flowThreadPortionRect().maxY() : region->flowThreadPortionRect().maxX());
RegionOversetState previousState = region->regionOversetState();
RegionOversetState state = RegionFit;
if (flowMin <= 0)
state = RegionEmpty;
if (flowMax > 0 && region == lastReg)
state = RegionOverset;
region->setRegionOversetState(state);
// determine whether the NamedFlow object should dispatch a regionLayoutUpdate event
// FIXME: currently it cannot determine whether a region whose regionOverset state remained either "fit" or "overset" has actually
// changed, so it just assumes that the NamedFlow should dispatch the event
if (previousState != state
|| state == RegionFit
|| state == RegionOverset)
setDispatchRegionLayoutUpdateEvent(true);
if (previousState != state)
setDispatchRegionOversetChangeEvent(true);
}
// If the number of regions has changed since we last computed the overset property, schedule the regionOversetChange event.
if (previousRegionCountChanged()) {
setDispatchRegionOversetChangeEvent(true);
updatePreviousRegionCount();
}
// With the regions overflow state computed we can also set the overset flag for the named flow.
// If there are no valid regions in the chain, overset is true.
m_overset = lastReg ? lastReg->regionOversetState() == RegionOverset : true;
}
RenderRegion* RenderFlowThread::mapFromFlowToRegion(TransformState& transformState) const
{
if (!hasValidRegionInfo())
return 0;
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 region.
// Note: Using the center in order to avoid rounding errors.
LayoutPoint center = boxRect.center();
RenderRegion* renderRegion = regionAtBlockOffset(isHorizontalWritingMode() ? center.y() : center.x(), true);
if (!renderRegion)
return 0;
LayoutRect flippedRegionRect(renderRegion->flowThreadPortionRect());
flipForWritingMode(flippedRegionRect);
transformState.move(renderRegion->contentBoxRect().location() - flippedRegionRect.location());
return renderRegion;
}
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;
}
// Even if we require the break to occur at offsetBreakInFlowThread, because regions may have min/max-height values,
// it is possible that the break will occur at a different offset than the original one required.
// offsetBreakAdjustment measures the different between the requested break offset and the current break offset.
bool RenderFlowThread::addForcedRegionBreak(LayoutUnit offsetBreakInFlowThread, RenderObject* breakChild, bool isBefore, LayoutUnit* offsetBreakAdjustment)
{
// We take breaks into account for height computation for auto logical height regions
// only in the layout phase in which we lay out the flows threads unconstrained
// and we use the content breaks to determine the overrideContentLogicalHeight for
// auto logical height regions.
if (view()->constrainedFlowThreadsLayoutPhase())
return false;
// Breaks can come before or after some objects. We need to track these objects, so that if we get
// multiple breaks for the same object (for example because of multiple layouts on the same object),
// we need to invalidate every other region after the old one and start computing from fresh.
RenderObjectToRegionMap& mapToUse = isBefore ? m_breakBeforeToRegionMap : m_breakAfterToRegionMap;
RenderObjectToRegionMap::iterator iter = mapToUse.find(breakChild);
if (iter != mapToUse.end()) {
RenderRegionList::iterator regionIter = m_regionList.find(iter->value);
ASSERT(regionIter != m_regionList.end());
ASSERT((*regionIter)->hasAutoLogicalHeight());
initializeRegionsOverrideLogicalContentHeight(*regionIter);
// We need to update the regions flow thread portion rect because we are going to process
// a break on these regions.
updateRegionsFlowThreadPortionRect();
}
// Simulate a region break at offsetBreakInFlowThread. If it points inside an auto logical height region,
// then it determines the region override logical content height.
RenderRegion* region = regionAtBlockOffset(offsetBreakInFlowThread);
if (!region)
return false;
bool overrideLogicalContentHeightComputed = false;
LayoutUnit currentRegionOffsetInFlowThread = isHorizontalWritingMode() ? region->flowThreadPortionRect().y() : region->flowThreadPortionRect().x();
LayoutUnit offsetBreakInCurrentRegion = offsetBreakInFlowThread - currentRegionOffsetInFlowThread;
if (region->hasAutoLogicalHeight()) {
// A forced break can appear only in an auto-height region that didn't have a forced break before.
// This ASSERT is a good-enough heuristic to verify the above condition.
ASSERT(region->maxPageLogicalHeight() == region->overrideLogicalContentHeight());
mapToUse.set(breakChild, region);
overrideLogicalContentHeightComputed = true;
// Compute the region height pretending that the offsetBreakInCurrentRegion is the logicalHeight for the auto-height region.
LayoutUnit regionOverrideLogicalContentHeight = region->computeReplacedLogicalHeightRespectingMinMaxHeight(offsetBreakInCurrentRegion);
// The new height of this region needs to be smaller than the initial value, the max height. A forced break is the only way to change the initial
// height of an auto-height region besides content ending.
ASSERT(regionOverrideLogicalContentHeight <= region->maxPageLogicalHeight());
region->setOverrideLogicalContentHeight(regionOverrideLogicalContentHeight);
currentRegionOffsetInFlowThread += regionOverrideLogicalContentHeight;
} else
currentRegionOffsetInFlowThread += isHorizontalWritingMode() ? region->flowThreadPortionRect().height() : region->flowThreadPortionRect().width();
// If the break was found inside an auto-height region its size changed so we need to recompute the flow thread portion rectangles.
if (overrideLogicalContentHeightComputed)
updateRegionsFlowThreadPortionRect();
if (offsetBreakAdjustment)
*offsetBreakAdjustment = max<LayoutUnit>(0, currentRegionOffsetInFlowThread - offsetBreakInFlowThread);
return overrideLogicalContentHeightComputed;
}
