Add infrastructure for partial layouts

Source/core/rendering/RenderBlock.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) Research In Motion Limited 2010. 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
  * License as published by the Free Software Foundation; either
@@ skipping 1369 matching lines @@
     StackStats::LayoutCheckPoint layoutCheckPoint;
     OverflowEventDispatcher dispatcher(this);
 
     // Update our first letter info now.
     updateFirstLetter();
 
     // Table cells call layoutBlock directly, so don't add any logic here.  Put code into
     // layoutBlock().
     layoutBlock(false);
 
+    if (frameView()->partialLayout().shouldStop())
+        return;
+
     // It's safe to check for control clip here, since controls can never be table cells.
     // If we have a lightweight clip, there can never be any overflow from children.
     if (hasControlClip() && m_overflow)
         clearLayoutOverflow();
 
     invalidateBackgroundObscurationStatus();
 }
 
 void RenderBlock::imageChanged(WrappedImagePtr image, const IntRect*)
 {
@@ skipping 190 matching lines @@
     LayoutUnit repaintLogicalTop = 0;
     LayoutUnit repaintLogicalBottom = 0;
     LayoutUnit maxFloatLogicalBottom = 0;
     if (!firstChild() && !isAnonymousBlock())
         setChildrenInline(true);
     if (childrenInline())
         layoutInlineChildren(relayoutChildren, repaintLogicalTop, repaintLogicalBottom);
     else
         layoutBlockChildren(relayoutChildren, maxFloatLogicalBottom, layoutScope);
 
+    if (frameView()->partialLayout().shouldStop()) {
+        statePusher.pop();
+        return;
+    }
+
     // Expand our intrinsic height to encompass floats.
     LayoutUnit toAdd = borderAfter() + paddingAfter() + scrollbarLogicalHeight();
     if (lowestFloatLogicalBottom() > (logicalHeight() - toAdd) && expandsToEncloseOverhangingFloats())
         setLogicalHeight(lowestFloatLogicalBottom() + toAdd);
 
     if (relayoutForPagination(hasSpecifiedPageLogicalHeight, pageLogicalHeight, statePusher))
         return;
 
     // Calculate our new height.
     LayoutUnit oldHeight = logicalHeight();
@@ skipping 27 matching lines @@
 
     updateRegionsAndShapesAfterChildLayout(flowThread, heightChanged);
 
     // Add overflow from children (unless we're multi-column, since in that case all our child overflow is clipped anyway).
     computeOverflow(oldClientAfterEdge);
 
     statePusher.pop();
 
     fitBorderToLinesIfNeeded();
 
+    if (frameView()->partialLayout().shouldStop())
+        return;
+
     if (renderView->layoutState()->m_pageLogicalHeight)
         setPageLogicalOffset(renderView->layoutState()->pageLogicalOffset(this, logicalTop()));
 
     updateLayerTransform();
 
     // Update our scroll information if we're overflow:auto/scroll/hidden now that we know if
     // we overflow or not.
     updateScrollInfoAfterLayout();
 
     // FIXME: This repaint logic should be moved into a separate helper function!
@@ skipping 852 matching lines @@
             continue;
         }
         if (child->isFloating()) {
             insertFloatingObject(child);
             adjustFloatingBlock(marginInfo);
             continue;
         }
 
         // Lay out the child.
         layoutBlockChild(child, marginInfo, previousFloatLogicalBottom, maxFloatLogicalBottom);
+
+        // If doing a partial layout and the child was the target renderer, early exit here.
+        if (frameView()->partialLayout().checkPartialLayoutComplete(child))
+            break;
     }
 
     // Now do the handling of the bottom of the block, adding in our bottom border/padding and
     // determining the correct collapsed bottom margin information.
     handleAfterSideOfBlock(beforeEdge, afterEdge, marginInfo);
 }
 
 void RenderBlock::layoutBlockChild(RenderBox* child, MarginInfo& marginInfo, LayoutUnit& previousFloatLogicalBottom, LayoutUnit& maxFloatLogicalBottom)
 {
     LayoutUnit oldPosMarginBefore = maxPositiveMarginBefore();
@@ skipping 45 matching lines @@
 
     SubtreeLayoutScope layoutScope(child);
     if (!child->needsLayout())
         child->markForPaginationRelayoutIfNeeded(layoutScope);
 
     bool childHadLayout = child->everHadLayout();
     bool childNeededLayout = child->needsLayout();
     if (childNeededLayout)
         child->layout();
 
+    if (frameView()->partialLayout().shouldStop())
+        return;
+
     // Cache if we are at the top of the block right now.
     bool atBeforeSideOfBlock = marginInfo.atBeforeSideOfBlock();
 
     // Now determine the correct ypos based off examination of collapsing margin
     // values.
     LayoutUnit logicalTopBeforeClear = collapseMargins(child, marginInfo);
 
     // Now check for clear.
     LayoutUnit logicalTopAfterClear = clearFloatsIfNeeded(child, marginInfo, oldPosMarginBefore, oldNegMarginBefore, logicalTopBeforeClear);
 
@@ skipping 5384 matching lines @@
 void RenderBlock::showLineTreeAndMark(const InlineBox* markedBox1, const char* markedLabel1, const InlineBox* markedBox2, const char* markedLabel2, const RenderObject* obj) const
 {
     showRenderObject();
     for (const RootInlineBox* root = firstRootBox(); root; root = root->nextRootBox())
         root->showLineTreeAndMark(markedBox1, markedLabel1, markedBox2, markedLabel2, obj, 1);
 }
 
 #endif
 
 } // namespace WebCore