Fix scroll origin, overflow rects, and coordinate flipping for flexbox.

third_party/WebKit/Source/core/layout/LayoutBox.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. 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
@@ skipping 932 matching lines @@
         // FIXME: If we didn't scroll the whole way, do we want to try looking at the frames ownerElement?
         // https://bugs.webkit.org/show_bug.cgi?id=28237
     }
 }
 
 bool LayoutBox::needsPreferredWidthsRecalculation() const
 {
     return style()->paddingStart().hasPercent() || style()->paddingEnd().hasPercent();
 }
 
+IntSize LayoutBox::originAdjustmentForScrollbars() const
+{
+    IntSize size;
+    int adjustmentWidth = verticalScrollbarWidth();
+    if (hasFlippedBlocksWritingMode()
+        || (isHorizontalWritingMode() && shouldPlaceBlockDirectionScrollbarOnLogicalLeft())) {
+        size.expand(adjustmentWidth, 0);
+    }
+    return size;
+}
+
 IntSize LayoutBox::scrolledContentOffset() const
 {
     ASSERT(hasOverflowClip());
     ASSERT(hasLayer());
     // FIXME: Return DoubleSize here. crbug.com/414283.
-    return flooredIntSize(getScrollableArea()->scrollOffset());
+    PaintLayerScrollableArea* scrollableArea = getScrollableArea();
+    IntSize result = flooredIntSize(scrollableArea->scrollOffset()) + originAdjustmentForScrollbars();
+    if (isHorizontalWritingMode() && shouldPlaceBlockDirectionScrollbarOnLogicalLeft())
+        result.expand(-verticalScrollbarWidth(), 0);
+    return result;
 }
 
 bool LayoutBox::mapScrollingContentsRectToBoxSpace(LayoutRect& rect, ApplyOverflowClipFlag applyOverflowClip, VisualRectFlags visualRectFlags) const
 {
     if (!hasOverflowClip())
         return true;
 
     LayoutSize offset = LayoutSize(-scrolledContentOffset());
     if (UNLIKELY(hasFlippedBlocksWritingMode()))
         offset.setWidth(-offset.width());
@@ skipping 3151 matching lines @@
     // Add in visual overflow from the child.  Even if the child clips its overflow, it may still
     // have visual overflow of its own set from box shadows or reflections.  It is unnecessary to propagate this
     // overflow if we are clipping our own overflow.
     if (child->hasSelfPaintingLayer())
         return;
     LayoutRect childVisualOverflowRect = child->visualOverflowRectForPropagation(styleRef());
     childVisualOverflowRect.move(delta);
     addContentsVisualOverflow(childVisualOverflowRect);
 }
 
+bool LayoutBox::hasTopOverflow() const
+{
+    return !style()->isLeftToRightDirection() && !isHorizontalWritingMode();
+}
+
+bool LayoutBox::hasLeftOverflow() const
+{
+    return !style()->isLeftToRightDirection() && isHorizontalWritingMode();
+}
+
 void LayoutBox::addLayoutOverflow(const LayoutRect& rect)
 {
     if (rect.isEmpty())
         return;
 
     LayoutRect clientBox = noOverflowRect();
     if (clientBox.contains(rect))
         return;
 
     // For overflow clip objects, we don't want to propagate overflow into unreachable areas.
     LayoutRect overflowRect(rect);
     if (hasOverflowClip() || isLayoutView()) {
         // Overflow is in the block's coordinate space and thus is flipped for vertical-rl writing
         // mode.  At this stage that is actually a simplification, since we can treat vertical-lr/rl
         // as the same.
-        bool hasTopOverflow = !style()->isLeftToRightDirection() && !isHorizontalWritingMode();
-        bool hasLeftOverflow = !style()->isLeftToRightDirection() && isHorizontalWritingMode();
-        if (isFlexibleBox() && style()->isReverseFlexDirection()) {
-            LayoutFlexibleBox* flexibleBox = toLayoutFlexibleBox(this);
-            if (flexibleBox->isHorizontalFlow())
-                hasLeftOverflow = true;
-            else
-                hasTopOverflow = true;
-        }
-
-        if (!hasTopOverflow)
+        if (hasTopOverflow())
+            overflowRect.shiftMaxYEdgeTo(std::min(overflowRect.maxY(), clientBox.maxY()));
+        else
             overflowRect.shiftYEdgeTo(std::max(overflowRect.y(), clientBox.y()));
+        if (hasLeftOverflow())
+            overflowRect.shiftMaxXEdgeTo(std::min(overflowRect.maxX(), clientBox.maxX()));
         else
-            overflowRect.shiftMaxYEdgeTo(std::min(overflowRect.maxY(), clientBox.maxY()));
-        if (!hasLeftOverflow)
             overflowRect.shiftXEdgeTo(std::max(overflowRect.x(), clientBox.x()));
-        else
-            overflowRect.shiftMaxXEdgeTo(std::min(overflowRect.maxX(), clientBox.maxX()));
 
         // Now re-test with the adjusted rectangle and see if it has become unreachable or fully
         // contained.
         if (clientBox.contains(overflowRect) || overflowRect.isEmpty())
             return;
     }
 
     if (!m_overflow)
         m_overflow = adoptPtr(new BoxOverflowModel(clientBox, borderBoxRect()));
 
@@ skipping 676 matching lines @@
     if (!flowThread) {
         // If there's no flow thread, we're not nested. All pages have the same height. Give up.
         return strutToNextPage;
     }
     // Start searching for a suitable offset at the top of the next page or column.
     LayoutUnit flowThreadOffset = offsetFromLogicalTopOfFirstPage() + nextPageLogicalTop;
     return strutToNextPage + flowThread->nextLogicalTopForUnbreakableContent(flowThreadOffset, contentLogicalHeight) - flowThreadOffset;
 }
 
 } // namespace blink