[CSS Regions] Elements in a region should be assignable to a named flow

Source/core/dom/NodeRenderingContext.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2011 Google Inc. 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
@@ skipping 156 matching lines @@
     if (m_parentFlowRenderer)
         return m_parentFlowRenderer;
 
     return m_renderingParent ? m_renderingParent->renderer() : 0;
 }
 
 bool NodeRenderingContext::shouldCreateRenderer() const
 {
     if (!m_renderingParent)
         return false;
+
     RenderObject* parentRenderer = this->parentRenderer();
     if (!parentRenderer)
         return false;
     if (!parentRenderer->canHaveChildren())
         return false;
     if (!m_renderingParent->childShouldCreateRenderer(*this))
         return false;
     return true;
 }
 
+bool NodeRenderingContext::elementInsideRegionNeedsRenderer()
+{
+    Element* element = toElement(m_node);
+    bool elementInsideRegionNeedsRenderer = false;
+    RenderObject* parentRenderer = this->parentRenderer();
+    if ((parentRenderer && !parentRenderer->canHaveChildren() && parentRenderer->isRenderRegion())
+        || (!parentRenderer && element->parentElement() && element->parentElement()->isInsideRegion())) {
+
+        if (!m_style)
+            m_style = element->styleForRenderer();
+
+        elementInsideRegionNeedsRenderer = element->shouldMoveToFlowThread(m_style.get());
+
+        // Children of this element will only be allowed to be flowed into other flow-threads if display is NOT none.
+        if (element->rendererIsNeeded(*this))
+            element->setIsInsideRegion(true);
+    }
+
+    return elementInsideRegionNeedsRenderer;
+}
+
 void NodeRenderingContext::moveToFlowThreadIfNeeded()
 {
-    ASSERT(m_node->isElementNode());
-    ASSERT(m_style);
     if (!RuntimeEnabledFeatures::cssRegionsEnabled())
         return;
 
-    if (m_style->flowThread().isEmpty())
+    Element* element = toElement(m_node);
+
+    if (!element->shouldMoveToFlowThread(m_style.get()))
         return;
 
-    // As per http://dev.w3.org/csswg/css3-regions/#flow-into, pseudo-elements such as ::first-line, ::first-letter, ::before or ::after
-    // cannot be directly collected into a named flow.
-    if (m_node->isPseudoElement())
-        return;
-
-    // FIXME: Do not collect elements if they are in shadow tree.
-    if (m_node->isInShadowTree())
-        return;
-
-    if (m_node->isElementNode() && FullscreenController::isActiveFullScreenElement(toElement(m_node)))
-        return;
-
-    // Allow only svg root elements to be directly collected by a render flow thread.
-    if (m_node->isSVGElement()
-        && (!(m_node->hasTagName(SVGNames::svgTag) && m_node->parentNode() && !m_node->parentNode()->isSVGElement())))
-        return;
-
-    m_flowThread = m_style->flowThread();
     ASSERT(m_node->document()->renderView());
     FlowThreadController* flowThreadController = m_node->document()->renderView()->flowThreadController();
-    m_parentFlowRenderer = flowThreadController->ensureRenderFlowThreadWithName(m_flowThread);
+    m_parentFlowRenderer = flowThreadController->ensureRenderFlowThreadWithName(m_style->flowThread());
     flowThreadController->registerNamedFlowContentNode(m_node, m_parentFlowRenderer);
 }
 
 bool NodeRenderingContext::isOnEncapsulationBoundary() const
 {
     return isOnUpperEncapsulationBoundary() || isLowerEncapsulationBoundary(m_parentDetails.insertionPoint()) || isLowerEncapsulationBoundary(m_node->parentNode());
 }
 
 bool NodeRenderingContext::isOnUpperEncapsulationBoundary() const
 {
     return m_node->parentNode() && m_node->parentNode()->isShadowRoot();
 }
 
 void NodeRenderingContext::createRendererForElementIfNeeded()
 {
     ASSERT(!m_node->renderer());
 
     Element* element = toElement(m_node);
 
-    if (!shouldCreateRenderer())
-        return;
+    element->setIsInsideRegion(false);

[esprehn, 2013/07/01 18:27:19]

You need to do this inside Node::detach too. Otherwise if I remove an element
from the tree it'll still claim it's inside a region.

+
+    if (!shouldCreateRenderer()) {
+        // Check the specific case of elements that are children of regions but are flowed into a flow thread themselves.
+        if (!elementInsideRegionNeedsRenderer())
+            return;

[esprehn, 2013/07/01 18:27:19]

if (!shouldCreateRenderer() && !elementInsideRegionNeedsRenderer())
  return;

Put the comment above the elementInsideRegionNeedsRenderer method.

+    }
+
     if (!m_style)
         m_style = element->styleForRenderer();
     ASSERT(m_style);
 
     moveToFlowThreadIfNeeded();
 
     if (!element->rendererIsNeeded(*this))
         return;
 
     RenderObject* parentRenderer = this->parentRenderer();
@@ skipping 59 matching lines @@
     newRenderer->setFlowThreadState(parentRenderer->flowThreadState());
 
     RenderObject* nextRenderer = this->nextRenderer();
     textNode->setRenderer(newRenderer);
     // Parent takes care of the animations, no need to call setAnimatableStyle.
     newRenderer->setStyle(m_style.release());
     parentRenderer->addChild(newRenderer, nextRenderer);
 }
 
 }