Make cluster creation independent of fingerprinting. Keep track of current

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 847 matching lines @@
     }
 
     // If there is any pagination to apply, it will affect the RenderView's style, so we should
     // take care of that now.
     applyPaginationToViewport();
 
     // Always ensure our style info is up-to-date. This can happen in situations where
     // the layout beats any sort of style recalc update that needs to occur.
     TemporaryChange<bool> changeDoingPreLayoutStyleUpdate(m_doingPreLayoutStyleUpdate, true);
     document->updateStyleIfNeeded();
-
-    if (FastTextAutosizer* textAutosizer = document->fastTextAutosizer())
-        textAutosizer->prepareForLayout();

[pdr., 2013/12/21 01:46:57]

I think we still need a mechanism for calling setNeedsLayout() on all blocks
that may depend on a multiplier change. For example, imagine blocks A, B, and C
all depend on a common multiplier but only blocks A and B get called for
layout().

[skobes, 2014/01/07 03:12:37]

I'm not sure I follow.  There are three issues I can think of:

(1) For global changes (autosizing enabled/disabled via inspector, font scale
factor changed in preferences, window resize) we have to make sure the
multipliers get recomputed.  But I thought TextAutosizer::recalculateMultipliers
would handle this already?

(2) If there is a partial layout, we need to make sure the cluster stack has all
the ancestor clusters of the element being processed.  I think we talked about
walking up the tree from beginLayout in this case?  Let's sync tomorrow about
this.

(3) If one cluster in a supercluster is modified or removed, we won't recompute
the multiplier on the other clusters.  I'm not sure this is actually a problem,
it just means we might ignore the fingerprints if a page is adding and removing
stuff via script.

 }
 
 void FrameView::performLayout(RenderObject* rootForThisLayout, bool inSubtreeLayout)
 {
     // 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.
     FrameView::DeferredRepaintScope deferRepaints(*this);
 
     {
@@ skipping 2600 matching lines @@
 void FrameView::willRemoveScrollbar(Scrollbar* scrollbar, ScrollbarOrientation orientation)
 {
     ScrollableArea::willRemoveScrollbar(scrollbar, orientation);
     if (AXObjectCache* cache = axObjectCache()) {
         cache->remove(scrollbar);
         cache->handleScrollbarUpdate(this);
     }
 }
 
 } // namespace WebCore