First version of new merge algorithm (not enabled yet)

Source/core/paint/BlockPainter.cpp

 // Copyright 2014 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 "config.h"
 #include "core/paint/BlockPainter.h"
 
 #include "core/editing/Caret.h"
 #include "core/editing/FrameSelection.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Settings.h"
 #include "core/page/Page.h"
 #include "core/paint/BoxClipper.h"
 #include "core/paint/BoxPainter.h"
 #include "core/paint/GraphicsContextAnnotator.h"
 #include "core/paint/InlinePainter.h"
 #include "core/paint/LineBoxListPainter.h"
 #include "core/paint/RenderDrawingRecorder.h"
 #include "core/paint/ScrollRecorder.h"
 #include "core/paint/ScrollableAreaPainter.h"
+#include "core/paint/SubtreeInfoRecorder.h"
 #include "core/rendering/PaintInfo.h"
 #include "core/rendering/RenderBlock.h"
 #include "core/rendering/RenderFlexibleBox.h"
 #include "core/rendering/RenderInline.h"
 #include "core/rendering/RenderLayer.h"
 #include "core/rendering/RenderView.h"
 #include "platform/geometry/LayoutPoint.h"
 #include "platform/geometry/LayoutRect.h"
 #include "platform/graphics/paint/ClipRecorder.h"
 
 namespace blink {
 
 void BlockPainter::paint(const PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 {
     PaintInfo localPaintInfo(paintInfo);
+    SubtreeInfoRecorder subtreeInfoRecorder(paintInfo.context, m_renderBlock, localPaintInfo.phase);

[chrishtr, 2015/02/03 22:30:47]

Just to be sure, this is just one example right?

[Xianzhu, 2015/02/04 00:13:24]

Yes. This looks the most common case of subtree painting. Adding of this code
can be incremental. For other subtree painting code if any, we'll repaint the
subtree when it appears the next time.

I'll find other places and add this code, perhaps in later changes.

 
     ANNOTATE_GRAPHICS_CONTEXT(localPaintInfo, &m_renderBlock);
 
     LayoutPoint adjustedPaintOffset = paintOffset + m_renderBlock.location();
 
     PaintPhase originalPhase = localPaintInfo.phase;
 
     // Check if we need to do anything at all.
     // FIXME: Could eliminate the isDocumentElement() check if we fix background painting so that the RenderView
     // paints the root's background.
     if (!m_renderBlock.isDocumentElement()) {
         LayoutRect overflowBox = overflowRectForPaintRejection();
         m_renderBlock.flipForWritingMode(overflowBox);
         overflowBox.moveBy(adjustedPaintOffset);
         if (!overflowBox.intersects(localPaintInfo.rect))
             return;
     }
 
+    subtreeInfoRecorder.begin();
+
     // There are some cases where not all clipped visual overflow is accounted for.
     // FIXME: reduce the number of such cases.
     ContentsClipBehavior contentsClipBehavior = ForceContentsClip;
     if (m_renderBlock.hasOverflowClip() && !m_renderBlock.hasControlClip() && !(m_renderBlock.shouldPaintSelectionGaps() && originalPhase == PaintPhaseForeground) && !hasCaret())
         contentsClipBehavior = SkipContentsClipIfPossible;
 
     if (localPaintInfo.phase == PaintPhaseOutline) {
         localPaintInfo.phase = PaintPhaseChildOutlines;
     } else if (localPaintInfo.phase == PaintPhaseChildBlockBackground) {
         localPaintInfo.phase = PaintPhaseBlockBackground;
@@ skipping 446 matching lines @@
         RenderBlock* block = flow->containingBlock();
         for ( ; block && block != &m_renderBlock; block = block->containingBlock())
             accumulatedPaintOffset.moveBy(block->location());
         ASSERT(block);
         InlinePainter(*flow).paintOutline(info, accumulatedPaintOffset);
     }
 }
 
 
 } // namespace blink