[New Multicolumn] Intrinsic/preferred logical width calculation for spanners.

Source/core/rendering/RenderBlock.cpp

Index: Source/core/rendering/RenderBlock.cpp
diff --git a/Source/core/rendering/RenderBlock.cpp b/Source/core/rendering/RenderBlock.cpp
index cef0c517f6daa44f7db1c7f8a2e2b92dd65fbb52..aef2895bd5757cd85e4ccb23a5548e8bad8f0f2f 100644
--- a/Source/core/rendering/RenderBlock.cpp
+++ b/Source/core/rendering/RenderBlock.cpp
@@ -2956,7 +2956,11 @@ void RenderBlock::computeIntrinsicLogicalWidths(LayoutUnit& minLogicalWidth, Lay
 
     maxLogicalWidth = std::max(minLogicalWidth, maxLogicalWidth);
 
-    adjustIntrinsicLogicalWidthsForColumns(minLogicalWidth, maxLogicalWidth);
+    // The new ("region based") multicol implementation will do this adjustment on the flow thread,

[Julien - ping for review, 2015/01/27 09:31:37]

Let's remove the use of 'new' as we will want to switch soonish.

[mstensho (USE GERRIT), 2015/01/27 10:20:23]

Done.

+    // and not here on the multicol container, so that spanners won't incorrectly be treated as
+    // column content (and have spanners' preferred widths multiplied by the number of columns, etc.).
+    if (style()->specifiesColumns() && !document().regionBasedColumnsEnabled())
+        adjustIntrinsicLogicalWidthsForColumns(minLogicalWidth, maxLogicalWidth);
 
     if (isTableCell()) {
         Length tableCellWidth = toLayoutTableCell(this)->styleOrColLogicalWidth();
@@ -3041,8 +3045,9 @@ void RenderBlock::computeBlockPreferredLogicalWidths(LayoutUnit& minLogicalWidth
     RenderBlock* containingBlock = this->containingBlock();
     LayoutUnit floatLeftWidth = 0, floatRightWidth = 0;
     while (child) {
-        // Positioned children don't affect the min/max width
-        if (child->isOutOfFlowPositioned()) {
+        // Positioned children don't affect the min/max width. Spanners only affect the min/max
+        // width of the multicol container, not the flow thread.
+        if (child->isOutOfFlowPositioned() || child->isColumnSpanAll()) {
             child = child->nextSibling();
             continue;
         }
@@ -3083,6 +3088,12 @@ void RenderBlock::computeBlockPreferredLogicalWidths(LayoutUnit& minLogicalWidth
         } else {
             childMinPreferredLogicalWidth = child->minPreferredLogicalWidth();
             childMaxPreferredLogicalWidth = child->maxPreferredLogicalWidth();
+            if (child->isRenderFlowThread()) {
+                // The preferred intrinsic widths that a flow thread reports pertains to the column
+                // width, but here we want the preferred multicol container width, so we need to
+                // adjust with that in mind.
+                adjustIntrinsicLogicalWidthsForColumns(childMinPreferredLogicalWidth, childMaxPreferredLogicalWidth);
+            }
         }
 
         LayoutUnit w = childMinPreferredLogicalWidth + margin;