Refactor how we handle BRs with clearance

Source/core/layout/LayoutBlockFlowLine.cpp

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2003, 2004, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All right reserved.
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
@@ skipping 1517 matching lines @@
         // the replaced elements later. In partial layout mode, line boxes are not
         // deleted and only dirtied. In that case, we can layout the replaced
         // elements at the same time.
         Vector<LayoutBox*> replacedChildren;
         for (InlineWalker walker(this); !walker.atEnd(); walker.advance()) {
             LayoutObject* o = walker.current();
 
             if (!layoutState.hasInlineChild() && o->isInline())
                 layoutState.setHasInlineChild(true);
 
-            if (o->isBR() && o->style()->clear() != CNONE)
-                layoutState.setContainsBRWithClear(true);
-
             if (o->isReplaced() || o->isFloating() || o->isOutOfFlowPositioned()) {
                 LayoutBox* box = toLayoutBox(o);
 
                 updateBlockChildDirtyBitsBeforeLayout(relayoutChildren, *box);
 
                 if (o->isOutOfFlowPositioned()) {
                     o->containingBlock()->insertPositionedObject(box);
                 } else if (o->isFloating()) {
                     layoutState.floats().append(FloatWithRect(box));
                 } else if (isFullLayout || o->needsLayout()) {
@@ skipping 97 matching lines @@
                         layoutState.markForFullLayout();
                         break;
                     }
 
                     layoutState.updatePaintInvalidationRangeFromBox(curr, paginationDelta);
                     curr->adjustBlockDirectionPosition(paginationDelta.toFloat());
                 }
             }
 
             // If the linebox breaks cleanly and with clearance then dirty from at least this point onwards so that we can clear the correct floats without difficulty.
-            if (!firstLineBoxWithBreakAndClearance && curr->endsWithBreak()) {
-                InlineBox* lastBox = style()->isLeftToRightDirection() ? curr->lastLeafChild() : curr->firstLeafChild();
-                if (lastBox && lastBox->layoutObject().isBR() && lastBox->layoutObject().style()->clear() != CNONE)
-                    firstLineBoxWithBreakAndClearance = curr;
-            }
+            if (!firstLineBoxWithBreakAndClearance && lineBoxHasBRWithClearance(curr))
+                firstLineBoxWithBreakAndClearance = curr;
 
             // If a new float has been inserted before this line or before its last known float, just do a full layout.
             bool encounteredNewFloat = false;
             checkFloatsInCleanLine(curr, layoutState.floats(), floatIndex, encounteredNewFloat, dirtiedByFloat);
             if (encounteredNewFloat)
                 layoutState.markForFullLayout();
 
             if (dirtiedByFloat || layoutState.isFullLayout())
                 break;
         }
@@ skipping 71 matching lines @@
         TextDirection direction = style()->direction();
         if (style()->unicodeBidi() == Plaintext)
             direction = determinePlaintextDirectionality(this);
         resolver.setStatus(BidiStatus(direction, isOverride(style()->unicodeBidi())));
         InlineIterator iter = InlineIterator(this, bidiFirstSkippingEmptyInlines(this, resolver.runs(), &resolver), 0);
         resolver.setPosition(iter, numberOfIsolateAncestors(iter));
     }
     return curr;
 }
 
+
+bool LayoutBlockFlow::lineBoxHasBRWithClearance(RootInlineBox* curr)
+{
+    // If the linebox breaks cleanly and with clearance then dirty from at least this point onwards so that we can clear the correct floats without difficulty.
+    if (!curr->endsWithBreak())
+        return false;
+    InlineBox* lastBox = style()->isLeftToRightDirection() ? curr->lastLeafChild() : curr->firstLeafChild();

[leviw_travelin_and_unemployed, 2015/06/22 18:22:42]

I understand you're moving this code around. If we end with a break, won't the
lineBreakObj() on RootInlineBox point to that without having to drill down and
look for the first/last leaf child?

[rhogan, 2015/06/22 20:27:15]

Had to look it up: lineBreakObj() is the object *after* the line break. <br>'s
don't result in lineBreakObj() getting set with the br object, it would only get
one if there was another br object after it. 

Ah, line layout.

+    return lastBox && lastBox->layoutObject().isBR() && lastBox->layoutObject().style()->clear() != CNONE;
+}
+
 void LayoutBlockFlow::determineEndPosition(LineLayoutState& layoutState, RootInlineBox* startLine, InlineIterator& cleanLineStart, BidiStatus& cleanLineBidiStatus)
 {
     ASSERT(!layoutState.endLine());
     size_t floatIndex = layoutState.floatIndex();
     RootInlineBox* last = nullptr;
     for (RootInlineBox* curr = startLine->nextRootBox(); curr; curr = curr->nextRootBox()) {
         if (!curr->isDirty()) {
             bool encounteredNewFloat = false;
             bool dirtiedByFloat = false;
             checkFloatsInCleanLine(curr, layoutState.floats(), floatIndex, encounteredNewFloat, dirtiedByFloat);
             if (encounteredNewFloat)
                 return;
+            if (lineBoxHasBRWithClearance(curr))
+                return;
         }
         if (curr->isDirty())
             last = nullptr;
         else if (!last)
             last = curr;
     }
 
     if (!last)
         return;
 
@@ skipping 54 matching lines @@
 
     return true;
 }
 
 bool LayoutBlockFlow::matchedEndLine(LineLayoutState& layoutState, const InlineBidiResolver& resolver, const InlineIterator& endLineStart, const BidiStatus& endLineStatus)
 {
     if (resolver.position() == endLineStart) {
         if (resolver.status() != endLineStatus)
             return false;
 
-        // A trailing BR can be collapsed as it usually doesn't contribute to the height,
-        // but if it has a clear style we need to force it to layout in the context of floats
-        // to honor that style.
-        if (layoutState.containsBRWithClear() && containsFloats())
-            return false;
         return checkPaginationAndFloatsAtEndLine(layoutState);
     }
 
     // The first clean line doesn't match, but we can check a handful of following lines to try
     // to match back up.
     static int numLines = 8; // The # of lines we're willing to match against.
     RootInlineBox* originalEndLine = layoutState.endLine();
     RootInlineBox* line = originalEndLine;
     for (int i = 0; i < numLines && line; i++, line = line->nextRootBox()) {
         if (line->lineBreakObj() == resolver.position().object() && line->lineBreakPos() == resolver.position().offset()) {
@@ skipping 205 matching lines @@
     LayoutUnit logicalLeft = logicalLeftOffsetForLine(logicalHeight(), false);
     LayoutUnit availableLogicalWidth = logicalRightOffsetForLine(logicalHeight(), false) - logicalLeft;
     updateLogicalWidthForAlignment(textAlign, 0, 0, logicalLeft, totalLogicalWidth, availableLogicalWidth, 0);
 
     if (!style()->isLeftToRightDirection())
         return logicalWidth() - logicalLeft;
     return logicalLeft;
 }
 
 }