[New Multicolumn] Actual support for layout of column-span:all.

Source/core/rendering/RenderMultiColumnFlowThread.cpp

Index: Source/core/rendering/RenderMultiColumnFlowThread.cpp
diff --git a/Source/core/rendering/RenderMultiColumnFlowThread.cpp b/Source/core/rendering/RenderMultiColumnFlowThread.cpp
index 6eaed6f174181af1b3308840f9bf3bb3b990256a..1a847a502deb6d974b9eb5f0053e3af95dbacf48 100644
--- a/Source/core/rendering/RenderMultiColumnFlowThread.cpp
+++ b/Source/core/rendering/RenderMultiColumnFlowThread.cpp
@@ -32,11 +32,13 @@
 namespace blink {
 
 RenderMultiColumnFlowThread::RenderMultiColumnFlowThread()
-    : m_columnCount(1)
+    : m_lastSetWorkedOn(0)
+    , m_columnCount(1)
     , m_columnHeightAvailable(0)
     , m_inBalancingPass(false)
     , m_needsColumnHeightsRecalculation(false)
     , m_progressionIsInline(true)
+    , m_isBeingEvacuated(false)
 {
     setFlowThreadState(InsideInFlowThread);
 }
@@ -102,6 +104,7 @@ void RenderMultiColumnFlowThread::populate()
 void RenderMultiColumnFlowThread::evacuateAndDestroy()
 {
     RenderBlockFlow* multicolContainer = multiColumnBlockFlow();
+    m_isBeingEvacuated = true;
 
     // Remove all sets.
     while (RenderMultiColumnSet* columnSet = firstMultiColumnSet())
@@ -146,11 +149,33 @@ bool RenderMultiColumnFlowThread::needsNewWidth() const
     return newWidth != logicalWidth();
 }
 
+RenderMultiColumnSet* RenderMultiColumnFlowThread::columnSetAtBlockOffset(LayoutUnit offset) const
+{
+    if (m_lastSetWorkedOn) {
+        // Layout in progress. We are calculating the set heights as we speak, so the column set range
+        // information is not up-to-date.
+        return m_lastSetWorkedOn;
+    }
+
+    ASSERT(!m_regionsInvalidated);
+    if (offset <= 0)
+        return m_multiColumnSetList.isEmpty() ? 0 : m_multiColumnSetList.first();
+
+    MultiColumnSetSearchAdapter adapter(offset);
+    m_multiColumnSetIntervalTree.allOverlapsWithAdapter<MultiColumnSetSearchAdapter>(adapter);
+
+    // If no set was found, the offset is in the flow thread overflow.
+    if (!adapter.result() && !m_multiColumnSetList.isEmpty())
+        return m_multiColumnSetList.last();
+    return adapter.result();
+}
+
 void RenderMultiColumnFlowThread::layoutColumns(bool relayoutChildren, SubtreeLayoutScope& layoutScope)
 {
     if (relayoutChildren)
         layoutScope.setChildNeedsLayout(this);
 
+    m_needsColumnHeightsRecalculation = false;
     if (!needsLayout()) {
         // Just before the multicol container (our parent RenderBlockFlow) finishes laying out, it
         // will call recalculateColumnHeights() on us unconditionally, but we only want that method
@@ -158,7 +183,6 @@ void RenderMultiColumnFlowThread::layoutColumns(bool relayoutChildren, SubtreeLa
         // machinery would kick in needlessly, and trigger additional layout passes. Furthermore, we
         // actually depend on a proper flowthread layout pass in order to do balancing, since it's
         // flowthread layout that sets up content runs.
-        m_needsColumnHeightsRecalculation = false;
         return;
     }
 
@@ -168,10 +192,11 @@ void RenderMultiColumnFlowThread::layoutColumns(bool relayoutChildren, SubtreeLa
             // typically have changed.
             columnSet->resetColumnHeight();
         }
+        if (!m_needsColumnHeightsRecalculation)
+            m_needsColumnHeightsRecalculation = columnSet->isRenderMultiColumnSpannerSet() || columnSet->heightIsAuto();
     }
 
     invalidateRegions();
-    m_needsColumnHeightsRecalculation = heightIsAuto();
     layout();
 }
 
@@ -316,8 +341,71 @@ void RenderMultiColumnFlowThread::willBeRemovedFromTree()
     RenderFlowThread::willBeRemovedFromTree();
 }
 
+bool RenderMultiColumnFlowThread::isColumnSpanner(const RenderObject* descendant) const
+{
+    ASSERT(descendant->isDescendantOf(this));
+    return m_spannerMap.get(descendant);
+}
+
+bool RenderMultiColumnFlowThread::isInsideColumnSpanner(const RenderObject* descendant) const
+{
+    ASSERT(descendant->isDescendantOf(this));
+    return containingColumnSpannerSet(descendant);
+}
+
+LayoutUnit RenderMultiColumnFlowThread::enterColumnSpannerBeforeLayout(RenderBox* renderer, LayoutUnit logicalTop, SubtreeLayoutScope& layoutScope)
+{
+    ASSERT(isColumnSpanner(renderer));
+    RenderMultiColumnSpannerSet* spannerSet = m_spannerMap.get(renderer);
+
+    // FIXME: it's really only necessary to mark the spanner set for layout when the height of
+    // |renderer| changes.
+    spannerSet->setChildNeedsLayout(MarkOnlyThis, &layoutScope);
+
+    RenderMultiColumnSet* previousSet = spannerSet->previousSiblingMultiColumnSet();
+    if (!previousSet) {
+        // The first set is entered at the beginning of flow thread layout. If the first set happens
+        // to be a spanner, we have nothing more to do here.
+        return LayoutUnit();
+    }
+
+    LayoutUnit logicalTopInFlowThread = renderer->parentBlock()->offsetFromLogicalTopOfFirstPage() + logicalTop;
+    LayoutUnit adjustment;
+    if (!previousSet->isRenderMultiColumnSpannerSet() && previousSet->pageLogicalHeight()) {
+        // Pad flow thread offset to a column boundary, so that any content that's supposed to come
+        // after the spanner (or the spanner itself) doesn't bleed into the column preceding the
+        // spanner.
+        LayoutUnit columnLogicalTopInFlowThread = previousSet->pageLogicalTopForOffset(logicalTopInFlowThread);
+        if (columnLogicalTopInFlowThread != logicalTopInFlowThread) {
+            adjustment = columnLogicalTopInFlowThread + previousSet->pageLogicalHeight() - logicalTopInFlowThread;
+            logicalTopInFlowThread += adjustment;
+        }
+    }
+
+    if (!previousSet->isRenderMultiColumnSpannerSet())
+        previousSet->endFlow(logicalTopInFlowThread);
+    spannerSet->beginFlow(logicalTopInFlowThread);
+
+    m_lastSetWorkedOn = spannerSet;
+    return adjustment;
+}
+
+void RenderMultiColumnFlowThread::exitColumnSpannerAfterLayout(RenderBox* renderer, LayoutUnit logicalBottom)
+{
+    ASSERT(m_lastSetWorkedOn == m_spannerMap.get(renderer));
+
+    LayoutUnit logicalBottomInFlowThread = renderer->parentBlock()->offsetFromLogicalTopOfFirstPage() + logicalBottom;
+    m_lastSetWorkedOn->endFlow(logicalBottomInFlowThread);
+    if (RenderMultiColumnSet* nextSet = m_lastSetWorkedOn->nextSiblingMultiColumnSet()) {
+        m_lastSetWorkedOn = nextSet;
+        if (!m_lastSetWorkedOn->isRenderMultiColumnSpannerSet())
+            m_lastSetWorkedOn->beginFlow(logicalBottomInFlowThread);
+    }
+}
+
 void RenderMultiColumnFlowThread::flowThreadDescendantWasInserted(RenderObject* descendant)
 {
+    ASSERT(!m_isBeingEvacuated);
     // Go through the subtree that was just inserted and create column sets (needed by regular
     // column content) and spanner sets (one needed by each spanner).
     for (RenderObject* renderer = descendant; renderer; renderer = renderer->nextInPreOrder(descendant)) {
@@ -335,6 +423,34 @@ void RenderMultiColumnFlowThread::flowThreadDescendantWasInserted(RenderObject*
     }
 }
 
+void RenderMultiColumnFlowThread::flowThreadDescendantWillBeRemoved(RenderObject* descendant)
+{
+    if (m_isBeingEvacuated)
+        return;
+    RenderObject* next;
+    // Remove spanner sets that are no longer needed, and merge column sets around them.
+    for (RenderObject* renderer = descendant; renderer; renderer = next) {
+        RenderMultiColumnSpannerSet* spanner = m_spannerMap.get(renderer);
+        if (!spanner) {
+            next = renderer->nextInPreOrder(descendant);
+            continue;
+        }
+        next = renderer->nextInPreOrderAfterChildren(descendant); // It's a spanner. Its children are of no interest to us.
+        if (RenderMultiColumnSet* nextSet = spanner->nextSiblingMultiColumnSet()) {
+            RenderMultiColumnSet* previousSet = spanner->previousSiblingMultiColumnSet();
+            if (nextSet && !nextSet->isRenderMultiColumnSpannerSet()
+                && previousSet && !previousSet->isRenderMultiColumnSpannerSet()) {
+                // Need to merge two column sets.
+                nextSet->destroy();
+                previousSet->setNeedsLayout();
+                invalidateRegions();
+            }
+        }
+        m_spannerMap.remove(renderer);
+        spanner->destroy();
+    }
+}
+
 void RenderMultiColumnFlowThread::computeLogicalHeight(LayoutUnit logicalHeight, LayoutUnit logicalTop, LogicalExtentComputedValues& computedValues) const
 {
     // We simply remain at our intrinsic height.
@@ -351,9 +467,17 @@ void RenderMultiColumnFlowThread::updateLogicalWidth()
 
 void RenderMultiColumnFlowThread::layout()
 {
+    ASSERT(!m_lastSetWorkedOn);
+    m_lastSetWorkedOn = firstMultiColumnSet();
+    if (m_lastSetWorkedOn)
+        m_lastSetWorkedOn->beginFlow(LayoutUnit());
     RenderFlowThread::layout();
-    if (RenderMultiColumnSet* lastSet = lastMultiColumnSet())
+    if (RenderMultiColumnSet* lastSet = lastMultiColumnSet()) {
+        ASSERT(lastSet == m_lastSetWorkedOn);
+        lastSet->endFlow(logicalHeight());
         lastSet->expandToEncompassFlowThreadContentsIfNeeded();
+    }
+    m_lastSetWorkedOn = 0;
 }
 
 void RenderMultiColumnFlowThread::setPageBreak(LayoutUnit offset, LayoutUnit spaceShortage)
@@ -375,12 +499,6 @@ void RenderMultiColumnFlowThread::updateMinimumPageHeight(LayoutUnit offset, Lay
         multicolSet->updateMinimumColumnHeight(minHeight);
 }
 
-RenderMultiColumnSet* RenderMultiColumnFlowThread::columnSetAtBlockOffset(LayoutUnit /*offset*/) const
-{
-    // For now there's only one column set, so this is easy:
-    return firstMultiColumnSet();
-}
-
 bool RenderMultiColumnFlowThread::addForcedRegionBreak(LayoutUnit offset, RenderObject* /*breakChild*/, bool /*isBefore*/, LayoutUnit* offsetBreakAdjustment)
 {
     if (RenderMultiColumnSet* multicolSet = columnSetAtBlockOffset(offset)) {
@@ -394,8 +512,10 @@ bool RenderMultiColumnFlowThread::addForcedRegionBreak(LayoutUnit offset, Render
 
 bool RenderMultiColumnFlowThread::isPageLogicalHeightKnown() const
 {
-    if (RenderMultiColumnSet* columnSet = lastMultiColumnSet())
-        return columnSet->pageLogicalHeight();
+    for (RenderMultiColumnSet* columnSet = lastMultiColumnSet(); columnSet; columnSet = columnSet->previousSiblingMultiColumnSet()) {
+        if (!columnSet->isRenderMultiColumnSpannerSet())
+            return columnSet->pageLogicalHeight();
+    }
     return false;
 }