[New multicol] Eliminate the need for RenderMultiColumnBlock.

Source/core/rendering/RenderBlockFlow.cpp

 /*
  * Copyright (C) 2013 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 21 matching lines @@
 #include "core/rendering/RenderBlockFlow.h"
 
 #include "core/accessibility/AXObjectCache.h"
 #include "core/frame/FrameView.h"
 #include "core/rendering/FastTextAutosizer.h"
 #include "core/rendering/HitTestLocation.h"
 #include "core/rendering/LayoutRectRecorder.h"
 #include "core/rendering/LayoutRepainter.h"
 #include "core/rendering/RenderFlowThread.h"
 #include "core/rendering/RenderLayer.h"
-#include "core/rendering/RenderMultiColumnBlock.h"
+#include "core/rendering/RenderMultiColumnFlowThread.h"
 #include "core/rendering/RenderText.h"
 #include "core/rendering/RenderView.h"
 #include "core/rendering/line/LineWidth.h"
 #include "core/rendering/svg/SVGTextRunRenderingContext.h"
 #include "platform/text/BidiTextRun.h"
 
 using namespace std;
 
 namespace WebCore {
 
@@ skipping 116 matching lines @@
     RenderBlockFlow* renderer = new RenderBlockFlow(0);
     renderer->setDocumentForAnonymous(document);
     return renderer;
 }
 
 RenderBlockFlow* RenderBlockFlow::createAnonymousBlockFlow() const
 {
     return toRenderBlockFlow(createAnonymousWithParentRendererAndDisplay(this, BLOCK));
 }
 
+RenderObject* RenderBlockFlow::layoutSpecialExcludedChild(bool relayoutChildren, SubtreeLayoutScope& layoutScope)
+{
+    if (RenderMultiColumnFlowThread* flowThread = multiColumnFlowThread()) {

[eseidel, 2014/02/25 22:16:05]

nit: I probably would have written this as an early-out instead of a long if
block.

[mstensho (USE GERRIT), 2014/02/25 23:17:53]

Done.

+        setLogicalTopForChild(flowThread, borderBefore() + paddingBefore());
+        flowThread->layoutColumns(relayoutChildren, layoutScope);
+        determineLogicalLeftPositionForChild(flowThread);
+        return flowThread;
+    }
+    return 0;
+}
+
+bool RenderBlockFlow::updateLogicalWidthAndColumnWidth()
+{
+    bool relayoutChildren = RenderBlock::updateLogicalWidthAndColumnWidth();
+    if (RenderMultiColumnFlowThread* flowThread = multiColumnFlowThread()) {
+        if (flowThread->computeColumnCountAndWidth())
+            relayoutChildren = true;

[eseidel, 2014/02/25 22:16:05]

This is just return true.

[mstensho (USE GERRIT), 2014/02/25 23:17:53]

Done.

+    }
+    return relayoutChildren;
+}
+
 void RenderBlockFlow::checkForPaginationLogicalHeightChange(LayoutUnit& pageLogicalHeight, bool& pageLogicalHeightChanged, bool& hasSpecifiedPageLogicalHeight)
 {
-    ColumnInfo* colInfo = columnInfo();
-    if (hasColumns()) {
+    if (RenderMultiColumnFlowThread* flowThread = multiColumnFlowThread()) {
+        // We don't actually update any of the variables. We just subclassed to adjust our column height.
+        updateLogicalHeight();
+        flowThread->setColumnHeightAvailable(std::max<LayoutUnit>(contentLogicalHeight(), 0));
+        setLogicalHeight(0);
+    } else if (hasColumns()) {

[eseidel, 2014/02/25 22:16:05]

So this will go away soon, right?

[mstensho (USE GERRIT), 2014/02/25 23:17:53]

Yes. :)

+        ColumnInfo* colInfo = columnInfo();
+
         if (!pageLogicalHeight) {
             LayoutUnit oldLogicalHeight = logicalHeight();
             setLogicalHeight(0);
             // We need to go ahead and set our explicit page height if one exists, so that we can
             // avoid doing two layout passes.
             updateLogicalHeight();
             LayoutUnit columnHeight = contentLogicalHeight();
             if (columnHeight > 0) {
                 pageLogicalHeight = columnHeight;
                 hasSpecifiedPageLogicalHeight = true;
@@ skipping 142 matching lines @@
 
     if (frameView()->partialLayout().isStopping()) {
         statePusher.pop();
         return true;
     }
 
     // Expand our intrinsic height to encompass floats.
     if (lowestFloatLogicalBottom() > (logicalHeight() - afterEdge) && createsBlockFormattingContext())
         setLogicalHeight(lowestFloatLogicalBottom() + afterEdge);
 
-    if (isRenderMultiColumnBlock()) {
-        if (toRenderMultiColumnBlock(this)->shouldRelayoutMultiColumnBlock()) {
+    if (RenderMultiColumnFlowThread* flowThread = multiColumnFlowThread()) {
+        if (flowThread->recalculateColumnHeights()) {
             setChildNeedsLayout(MarkOnlyThis);
             statePusher.pop();
             return false;
         }
     } else if (hasColumns()) {
         OwnPtr<RenderOverflow> savedOverflow = m_overflow.release();
         if (childrenInline())
             addOverflowFromInlineChildren();
         else
             addOverflowFromBlockChildren();
@@ skipping 1445 matching lines @@
                             break;
                         }
                     }
                 }
             }
         }
 
         parentBlockFlow->markAllDescendantsWithFloatsForLayout();
         parentBlockFlow->markSiblingsWithFloatsForLayout();
     }
+
+    createMultiColumnFlowThreadIfNeeded();
 }
 
 void RenderBlockFlow::updateStaticInlinePositionForChild(RenderBox* child, LayoutUnit logicalTop)
 {
     if (child->style()->isOriginalDisplayInlineType())
         setStaticInlinePositionForChild(child, logicalTop, startAlignedOffsetForLine(logicalTop, false));
     else
         setStaticInlinePositionForChild(child, logicalTop, startOffsetForContent());
 }
 
 void RenderBlockFlow::setStaticInlinePositionForChild(RenderBox* child, LayoutUnit blockOffset, LayoutUnit inlinePosition)
 {
     child->layer()->setStaticInlinePosition(inlinePosition);
 }
 
+void RenderBlockFlow::addChild(RenderObject* newChild, RenderObject* beforeChild)
+{
+    if (RenderMultiColumnFlowThread* flowThread = multiColumnFlowThread())
+        return flowThread->addChild(newChild, beforeChild);
+    RenderBlock::addChild(newChild, beforeChild);
+}
+
 void RenderBlockFlow::moveAllChildrenIncludingFloatsTo(RenderBlock* toBlock, bool fullRemoveInsert)
 {
     RenderBlockFlow* toBlockFlow = toRenderBlockFlow(toBlock);
     moveAllChildrenTo(toBlockFlow, fullRemoveInsert);
 
     // When a portion of the render tree is being detached, anonymous blocks
     // will be combined as their children are deleted. In this process, the
     // anonymous block later in the tree is merged into the one preceeding it.
     // It can happen that the later block (this) contains floats that the
     // previous block (toBlockFlow) did not contain, and thus are not in the
@@ skipping 888 matching lines @@
     return constructTextRun(context, font, string, style,
         determineDirectionality(string, hasStrongDirectionality),
         expansion, flags);
 }
 
 RootInlineBox* RenderBlockFlow::createRootInlineBox()
 {
     return new RootInlineBox(this);
 }
 
+void RenderBlockFlow::createMultiColumnFlowThreadIfNeeded()
+{
+    if ((style()->hasAutoColumnCount() && style()->hasAutoColumnWidth()) || !document().regionBasedColumnsEnabled())
+        return;
+
+    if (multiColumnFlowThread())
+        return;
+
+    setChildrenInline(false);
+    RenderMultiColumnFlowThread* flowThread = RenderMultiColumnFlowThread::createAnonymous(document(), style());
+    RenderBlock::addChild(flowThread);
+    RenderBlockFlowRareData& rareData = ensureRareData();
+    rareData.m_multiColumnFlowThread = flowThread;

[eseidel, 2014/02/25 22:16:05]

Do we need to ASSERT that it doesnt' arleady have one?  I guess
multiColumnFlowThread() above should have already ensured that. :)

[mstensho (USE GERRIT), 2014/02/25 23:17:53]

Done.

You're right about multiColumnFlowThread(), but an assertion is even more
obvious.

+}
+
 RenderBlockFlow::RenderBlockFlowRareData& RenderBlockFlow::ensureRareData()
 {
     if (m_rareData)
         return *m_rareData;
 
     m_rareData = adoptPtr(new RenderBlockFlowRareData(this));
     return *m_rareData;
 }
 
 } // namespace WebCore