[New Multicolumn] Layout support for column-span:all.

Source/core/rendering/RenderMultiColumnSet.cpp

 /*
  * Copyright (C) 2012 Apple Inc.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 49 matching lines @@
 
 RenderMultiColumnSet* RenderMultiColumnSet::previousSiblingMultiColumnSet() const
 {
     for (RenderObject* sibling = previousSibling(); sibling; sibling = sibling->previousSibling()) {
         if (sibling->isRenderMultiColumnSet())
             return toRenderMultiColumnSet(sibling);
     }
     return 0;
 }
 
+void RenderMultiColumnSet::setLogicalTopInFlowThread(LayoutUnit logicalTop)
+{
+    LayoutRect rect = flowThreadPortionRect();
+    if (isHorizontalWritingMode())
+        rect.setY(logicalTop);
+    else
+        rect.setX(logicalTop);
+    setFlowThreadPortionRect(rect);
+}
+
+void RenderMultiColumnSet::setLogicalBottomInFlowThread(LayoutUnit logicalBottom)
+{
+    LayoutRect rect = flowThreadPortionRect();
+    if (isHorizontalWritingMode())
+        rect.shiftMaxYEdgeTo(logicalBottom);
+    else
+        rect.shiftMaxXEdgeTo(logicalBottom);
+    setFlowThreadPortionRect(rect);
+}
+
+bool RenderMultiColumnSet::heightIsAuto() const
+{
+    RenderMultiColumnFlowThread* flowThread = multiColumnFlowThread();
+    if (!flowThread->isRenderPagedFlowThread()) {
+        if (multiColumnBlockFlow()->style()->columnFill() == ColumnFillBalance)
+            return true;
+        if (RenderBox* next = nextSiblingBox()) {
+            if (next->isRenderMultiColumnSpannerPlaceholder()) {
+                // If we're followed by a spanner, we need to balance.
+                return true;
+            }
+        }
+    }
+    return !flowThread->columnHeightAvailable();
+}
+
 LayoutSize RenderMultiColumnSet::flowThreadTranslationAtOffset(LayoutUnit blockOffset) const
 {
     unsigned columnIndex = columnIndexAtOffset(blockOffset);
     LayoutRect portionRect(flowThreadPortionRectAt(columnIndex));
     flipForWritingMode(portionRect);
     LayoutRect columnRect(columnRectAt(columnIndex));
     flipForWritingMode(columnRect);
     return contentBoxRect().location() + columnRect.location() - portionRect.location();
 }
 
@@ skipping 103 matching lines @@
     ASSERT(m_minSpaceShortage > 0); // We should never _shrink_ the height!
     ASSERT(m_minSpaceShortage != RenderFlowThread::maxLogicalHeight()); // If this happens, we probably have a bug.
     if (m_minSpaceShortage == RenderFlowThread::maxLogicalHeight())
         return m_columnHeight; // So bail out rather than looping infinitely.
 
     return m_columnHeight + m_minSpaceShortage;
 }
 
 void RenderMultiColumnSet::addContentRun(LayoutUnit endOffsetFromFirstPage)
 {
-    if (!multiColumnFlowThread()->heightIsAuto())
+    if (!heightIsAuto())
         return;
     if (!m_contentRuns.isEmpty() && endOffsetFromFirstPage <= m_contentRuns.last().breakOffset())
         return;
     // Append another item as long as we haven't exceeded used column count. What ends up in the
     // overflow area shouldn't affect column balancing.
     if (m_contentRuns.size() < usedColumnCount())
         m_contentRuns.append(ContentRun(endOffsetFromFirstPage));
 }
 
 bool RenderMultiColumnSet::recalculateColumnHeight(BalancedHeightCalculation calculationMode)
 {
-    if (previousSiblingMultiColumnSet()) {
-        // FIXME: column spanner layout is not yet implemented. Until it's in place, we only operate
-        // on the first set during layout. We need to ignore the others here, or assertions will
-        // fail.
-        return false;
+    LayoutUnit oldColumnHeight = m_columnHeight;
+
+    m_maxColumnHeight = calculateMaxColumnHeight();
+
+    if (heightIsAuto()) {
+        if (calculationMode == GuessFromFlowThreadPortion) {
+            // Post-process the content runs and find out where the implicit breaks will occur.
+            distributeImplicitBreaks();
+        }
+        LayoutUnit newColumnHeight = calculateColumnHeight(calculationMode);
+        setAndConstrainColumnHeight(newColumnHeight);
+        // After having calculated an initial column height, the multicol container typically needs at
+        // least one more layout pass with a new column height, but if a height was specified, we only
+        // need to do this if we think that we need less space than specified. Conversely, if we
+        // determined that the columns need to be as tall as the specified height of the container, we
+        // have already laid it out correctly, and there's no need for another pass.
+    } else {
+        // The position of the column set may have changed, in which case height available for
+        // columns may have changed as well.
+        setAndConstrainColumnHeight(m_columnHeight);
     }
-    ASSERT(multiColumnFlowThread()->heightIsAuto());
-
-    LayoutUnit oldColumnHeight = m_columnHeight;
-    if (calculationMode == GuessFromFlowThreadPortion) {
-        // Post-process the content runs and find out where the implicit breaks will occur.
-        distributeImplicitBreaks();
-    }
-    LayoutUnit newColumnHeight = calculateColumnHeight(calculationMode);
-    setAndConstrainColumnHeight(newColumnHeight);
-
-    // After having calculated an initial column height, the multicol container typically needs at
-    // least one more layout pass with a new column height, but if a height was specified, we only
-    // need to do this if we think that we need less space than specified. Conversely, if we
-    // determined that the columns need to be as tall as the specified height of the container, we
-    // have already laid it out correctly, and there's no need for another pass.
 
     // We can get rid of the content runs now, if we haven't already done so. They are only needed
     // to calculate the initial balanced column height. In fact, we have to get rid of them before
     // the next layout pass, since each pass will rebuild this.
     m_contentRuns.clear();
 
     if (m_columnHeight == oldColumnHeight)
         return false; // No change. We're done.
 
     m_minSpaceShortage = RenderFlowThread::maxLogicalHeight();
@@ skipping 14 matching lines @@
 
 void RenderMultiColumnSet::resetColumnHeight()
 {
     // Nuke previously stored minimum column height. Contents may have changed for all we know.
     m_minimumColumnHeight = 0;
 
     m_maxColumnHeight = calculateMaxColumnHeight();
 
     LayoutUnit oldColumnHeight = pageLogicalHeight();
 
-    if (multiColumnFlowThread()->heightIsAuto())
+    if (heightIsAuto())
         m_columnHeight = 0;
     else
         setAndConstrainColumnHeight(heightAdjustedForSetOffset(multiColumnFlowThread()->columnHeightAvailable()));
 
     if (pageLogicalHeight() != oldColumnHeight)
         setChildNeedsLayout(MarkOnlyThis);
 
     // Content runs are only needed in the initial layout pass, in order to find an initial column
     // height, and should have been deleted afterwards. We're about to rebuild the content runs, so
     // the list needs to be empty.
@@ skipping 317 matching lines @@
 
 void RenderMultiColumnSet::detachRegion()
 {
     if (m_flowThread) {
         m_flowThread->removeRegionFromThread(this);
         m_flowThread = 0;
     }
 }
 
 }