Fix preferred logical widths of orthogonal writing modes

third_party/WebKit/Source/core/frame/FrameView.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ skipping 816 matching lines @@
     lifecycle().advanceTo(DocumentLifecycle::InPerformLayout);
 
     TemporaryChange<bool> changeInPerformLayout(m_inPerformLayout, true);
 
     // performLayout is the actual guts of layout().
     // FIXME: The 300 other lines in layout() probably belong in other helper functions
     // so that a single human could understand what layout() is actually doing.
 
     forceLayoutParentViewIfNeeded();
 
+    if (hasOrthogonalWritingModeRoots())
+        layoutOrthogonalWritingModeRoots();
+
     if (inSubtreeLayout) {
         if (m_analyzer)
             m_analyzer->increment(LayoutAnalyzer::PerformLayoutRootLayoutObjects, m_layoutSubtreeRootList.size());
         while (LayoutObject* root = m_layoutSubtreeRootList.takeDeepestRoot()) {
             if (!root->needsLayout())
                 continue;
             layoutFromRootObject(*root);
 
             // We need to ensure that we mark up all layoutObjects up to the LayoutView
             // for paint invalidation. This simplifies our code as we just always
@@ skipping 842 matching lines @@
 void FrameView::clearLayoutSubtreeRoot(const LayoutObject& root)
 {
     m_layoutSubtreeRootList.removeRoot(const_cast<LayoutObject&>(root));
 }
 
 void FrameView::clearLayoutSubtreeRootsAndMarkContainingBlocks()
 {
     m_layoutSubtreeRootList.clearAndMarkContainingBlocksForLayout();
 }
 
+void FrameView::addOrthogonalWritingModeRoot(LayoutBox& root)
+{
+    m_orthogonalWritingModeRootList.addRoot(root);
+}
+
+void FrameView::removeOrthogonalWritingModeRoot(LayoutBox& root)
+{
+    m_orthogonalWritingModeRootList.removeRoot(root);
+}
+
+bool FrameView::hasOrthogonalWritingModeRoots() const
+{
+    return !m_orthogonalWritingModeRootList.isEmpty();
+}
+
+void FrameView::layoutOrthogonalWritingModeRoots()
+{
+    while (LayoutObject* root = m_orthogonalWritingModeRootList.takeDeepestRoot()) {
+        ASSERT(root->isBox() && toLayoutBox(*root).isOrthogonalWritingModeRoot());
+        if (!root->needsLayout()
+            || root->isOutOfFlowPositioned()
+            || root->isColumnSpanAll()
+            || !root->styleRef().logicalHeight().isIntrinsicOrAuto()) {

[ojan, 2016/01/22 02:22:35]

If it's any of these last three, maybe we just shouldn't put it in
m_orthogonalWritingModeRootList in the first place? 

[kojii, 2016/01/22 02:33:51]

Yeah, thought about it. But then we'll need to check if these properties are
changed and add to/remove from the list. To do so, we'll need to check
writing-mode whenever 'position' or 'height' property were changed.

Given orthogonal is much rarer than changing 'position' or 'height', having
longer list than really necessary looks better to doing such checks. Does this
look reasonable trade-off?

+            continue;
+        }
+        LayoutState layoutState(*root);

[ojan, 2016/01/22 02:22:35]

I'm not 100% sure creating a LayoutState without dealing with any of the
ancestors is correct. I guess that's the fundamental assumption of this approach
though. :) Taking a quick look at the LayoutState code, I don't see a problem,
but Levi and Morten should probably take a close look here.

[kojii, 2016/01/22 02:33:51]

Yeah, wasn't sure either, but reading around and testing some cases seems to
work better than I expected. Thank you for giving your thoughts. I'll ask Levi
more on this point.

+        root->layout();
+    }
+}
+
 void FrameView::scheduleRelayout()
 {
     ASSERT(m_frame->view() == this);
 
     if (!m_layoutSchedulingEnabled)
         return;
     if (!needsLayout())
         return;
     if (!m_frame->document()->shouldScheduleLayout())
         return;
@@ skipping 2299 matching lines @@
     return m_hiddenForThrottling && m_crossOriginForThrottling;
 }
 
 LayoutBox& FrameView::boxForScrollControlPaintInvalidation() const
 {
     ASSERT(layoutView());
     return *layoutView();
 }
 
 } // namespace blink