[New Multicolumn] Add support for column-span:all

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 534 matching lines @@
         child->setY(logicalTop);
     } else {
         child->setX(logicalTop);
     }
 }
 
 void RenderBlockFlow::layoutBlockChild(RenderBox* child, MarginInfo& marginInfo, LayoutUnit& previousFloatLogicalBottom)
 {
     LayoutUnit oldPosMarginBefore = maxPositiveMarginBefore();
     LayoutUnit oldNegMarginBefore = maxNegativeMarginBefore();
+    bool childIsColumnSpanner = child->isColumnSpanAll();
+
+    if (childIsColumnSpanner) {

[Julien - ping for review, 2014/09/30 00:39:32]

Nit: This looks like it should be a RAII so that we enter / leave are always
paired.

+        // Margins of a column spanner cannot collapse with anything. Block direction margins on
+        // spanners will be ignored here, inside flow thread layout. Instead they'll be added around
+        // the RenderMultiColumnSpannerSet. Now skip past the pending margin that belongs to the
+        // columns.
+        setLogicalHeight(logicalHeight() + marginInfo.margin());
+        marginInfo.clearMargin();
+        LayoutUnit adjustment = flowThreadContainingBlock()->enterColumnSpanner(child, logicalHeight());
+        // A spanner needs to start at an exact column boundary inside the flow thread, so that it
+        // doesn't bleed into a preceding column. That's what the adjustment is about.
+        setLogicalHeight(logicalHeight() + adjustment);
+    }
 
     // The child is a normal flow object. Compute the margins we will use for collapsing now.
     child->computeAndSetBlockDirectionMargins(this);
 
     // Try to guess our correct logical top position. In most cases this guess will
     // be correct. Only if we're wrong (when we compute the real logical top position)
     // will we have to potentially relayout.
     LayoutUnit estimateWithoutPagination;
     LayoutUnit logicalTopEstimate = estimateLogicalTopPosition(child, marginInfo, estimateWithoutPagination);
 
@@ skipping 115 matching lines @@
     bool didNotLayoutAndNeedsPaintInvalidation = !childHadLayout && child->checkForPaintInvalidation();
 
     if (didNotDoFullLayoutAndMoved || didNotLayoutAndNeedsPaintInvalidation)
         child->invalidatePaintForOverhangingFloats(true);
 
     if (paginated) {
         // Check for an after page/column break.
         LayoutUnit newHeight = applyAfterBreak(child, logicalHeight(), marginInfo);
         if (newHeight != height())
             setLogicalHeight(newHeight);
+
+        if (childIsColumnSpanner) {
+            flowThreadContainingBlock()->leaveColumnSpanner(child, logicalHeight());
+            ASSERT(!marginInfo.margin());
+        }
     }
 }
 
 LayoutUnit RenderBlockFlow::adjustBlockChildForPagination(LayoutUnit logicalTopAfterClear, LayoutUnit estimateWithoutPagination, RenderBox* child, bool atBeforeSideOfBlock)
 {
     RenderBlockFlow* childBlockFlow = child->isRenderBlockFlow() ? toRenderBlockFlow(child) : 0;
 
     if (estimateWithoutPagination != logicalTopAfterClear) {
         // Our guess prior to pagination movement was wrong. Before we attempt to paginate, let's try again at the new
         // position.
@@ skipping 578 matching lines @@
             marginInfo.clearMargin();
         }
 
         if (marginInfo.margin())
             marginInfo.setHasMarginAfterQuirk(hasMarginAfterQuirk(child));
     }
 
     // If margins would pull us past the top of the next page, then we need to pull back and pretend like the margins
     // collapsed into the page edge.
     LayoutState* layoutState = view()->layoutState();
-    if (layoutState->isPaginated() && layoutState->pageLogicalHeight() && logicalTop > beforeCollapseLogicalTop) {
+    if (layoutState->isPaginated() && layoutState->pageLogicalHeight() && logicalTop > beforeCollapseLogicalTop && !child->isColumnSpanAll()) {
         LayoutUnit oldLogicalTop = logicalTop;
         logicalTop = std::min(logicalTop, nextPageLogicalTop(beforeCollapseLogicalTop));
         setLogicalHeight(logicalHeight() + (logicalTop - oldLogicalTop));
     }
 
     if (previousBlockFlow) {
         // If |child| is a self-collapsing block it may have collapsed into a previous sibling and although it hasn't reduced the height of the parent yet
         // any floats from the parent will now overhang.
         LayoutUnit oldLogicalHeight = logicalHeight();
         setLogicalHeight(logicalTop);
@@ skipping 195 matching lines @@
         }
 
         // Collapse the result with our current margins.
         if (!discardMarginBefore)
             logicalTopEstimate += std::max(marginInfo.positiveMargin(), positiveMarginBefore) - std::max(marginInfo.negativeMargin(), negativeMarginBefore);
     }
 
     // Adjust logicalTopEstimate down to the next page if the margins are so large that we don't fit on the current
     // page.
     LayoutState* layoutState = view()->layoutState();
-    if (layoutState->isPaginated() && layoutState->pageLogicalHeight() && logicalTopEstimate > logicalHeight())
+    if (layoutState->isPaginated() && layoutState->pageLogicalHeight() && logicalTopEstimate > logicalHeight() && !child->isColumnSpanAll())
         logicalTopEstimate = std::min(logicalTopEstimate, nextPageLogicalTop(logicalHeight()));
 
     logicalTopEstimate += getClearDelta(child, logicalTopEstimate);
 
     estimateWithoutPagination = logicalTopEstimate;
 
     if (layoutState->isPaginated()) {
         // If the object has a page or column break value of "before", then we should shift to the top of the next page.
         logicalTopEstimate = applyBeforeBreak(child, logicalTopEstimate);
 
@@ skipping 1424 matching lines @@
     FrameView* frameView = document().view();
     LayoutUnit top = (style()->position() == FixedPosition) ? 0 : frameView->scrollOffset().height();
     int visibleHeight = frameView->visibleContentRect(IncludeScrollbars).height();
     if (height() < visibleHeight)
         top += (visibleHeight - height()) / 2;
     setY(top);
     dialog->setCentered(top);
 }
 
 } // namespace blink