Always anchor to top of the anchor element

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/layout/ScrollAnchor.h"
 
 #include "core/frame/FrameView.h"
 #include "core/frame/UseCounter.h"
 #include "core/layout/LayoutView.h"
 #include "core/layout/line/InlineTextBox.h"
@@ skipping 30 matching lines @@
 
 static LayoutBoxItem scrollerLayoutBoxItem(const ScrollableArea* scroller)
 {
     LayoutBoxItem box = scroller->isFrameView()
         ? toFrameView(scroller)->layoutViewItem()
         : LayoutBoxItem(&toPaintLayerScrollableArea(scroller)->box());
     ASSERT(!box.isNull());
     return box;
 }
 
-static Corner cornerFromCandidateRect(LayoutRect candidateRect, LayoutRect visibleRect)
+static Corner cornerFromCandidateRect(const LayoutObject* layoutObject)
 {
-    if (visibleRect.contains(candidateRect.minXMinYCorner()))
-        return Corner::TopLeft;
-    if (visibleRect.contains(candidateRect.maxXMinYCorner()))
+    ASSERT(layoutObject);
+    if (layoutObject->style()->isFlippedBlocksWritingMode()
+        || !layoutObject->style()->isLeftToRightDirection())
         return Corner::TopRight;
-    if (visibleRect.contains(candidateRect.minXMaxYCorner()))
-        return Corner::BottomLeft;
-    if (visibleRect.contains(candidateRect.maxXMaxYCorner()))
-        return Corner::BottomRight;
     return Corner::TopLeft;
 }
 
 static LayoutPoint cornerPointOfRect(LayoutRect rect, Corner whichCorner)
 {
     switch (whichCorner) {
     case Corner::TopLeft: return rect.minXMinYCorner();
     case Corner::TopRight: return rect.maxXMinYCorner();
-    case Corner::BottomLeft: return rect.minXMaxYCorner();
-    case Corner::BottomRight: return rect.maxXMaxYCorner();
     }
     ASSERT_NOT_REACHED();
     return LayoutPoint();
 }
 
 // Bounds of the LayoutObject relative to the scroller's visible content rect.
 static LayoutRect relativeBounds(const LayoutObject* layoutObject, const ScrollableArea* scroller)
 {
     LayoutRect localBounds;
     if (layoutObject->isBox()) {
@@ skipping 39 matching lines @@
     if (!candidateMovesWithScroller(candidate, m_scroller))
         return ExamineResult(Skip);
 
     LayoutRect candidateRect = relativeBounds(candidate, m_scroller);
     LayoutRect visibleRect = scrollerLayoutBoxItem(m_scroller).overflowClipRect(LayoutPoint());
 
     bool occupiesSpace = candidateRect.width() > 0 && candidateRect.height() > 0;
     if (occupiesSpace && visibleRect.intersects(candidateRect)) {
         return ExamineResult(
             visibleRect.contains(candidateRect) ? Return : Constrain,
-            cornerFromCandidateRect(candidateRect, visibleRect));
+            cornerFromCandidateRect(candidate));
     } else {
         return ExamineResult(Skip);
     }
 }
 
 void ScrollAnchor::findAnchor()
 {
     LayoutObject* stayWithin = scrollerLayoutBox(m_scroller);
     LayoutObject* candidate = stayWithin->nextInPreOrder(stayWithin);
     while (candidate) {
@@ skipping 68 matching lines @@
 void ScrollAnchor::clear()
 {
     LayoutObject* anchorObject = m_anchorObject;
     m_anchorObject = nullptr;
 
     if (anchorObject)
         anchorObject->maybeClearIsScrollAnchorObject();
 }
 
 } // namespace blink