third_party/WebKit/Source/core/layout/compositing/GraphicsLayerTreeBuilder.cpp

/*
 * Copyright (C) 2009, 2010 Apple Inc. All rights reserved.
 * Copyright (C) 2014 Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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#include "core/layout/compositing/GraphicsLayerTreeBuilder.h"

#include "core/html/HTMLMediaElement.h"
#include "core/html/HTMLVideoElement.h"
#include "core/layout/LayoutPart.h"
#include "core/layout/compositing/CompositedLayerMapping.h"
#include "core/layout/compositing/PaintLayerCompositor.h"
#include "core/paint/PaintLayer.h"

namespace blink {

GraphicsLayerTreeBuilder::GraphicsLayerTreeBuilder() {}

GraphicsLayerTreeBuilder::~GraphicsLayerTreeBuilder() {}

static bool shouldAppendLayer(const PaintLayer& layer) {
  Node* node = layer.layoutObject()->node();
  if (node && isHTMLVideoElement(*node)) {
    HTMLVideoElement* element = toHTMLVideoElement(node);
    if (element->isFullscreen() && element->usesOverlayFullscreenVideo())
      return false;
  }
  return true;
}

void GraphicsLayerTreeBuilder::rebuild(PaintLayer& layer, AncestorInfo info) {
  // Make the layer compositing if necessary, and set up clipping and content
  // layers.  Note that we can only do work here that is independent of whether
  // the descendant layers have been processed. computeCompositingRequirements()
  // will already have done the paint invalidation if necessary.

  layer.stackingNode()->updateLayerListsIfNeeded();

  const bool hasCompositedLayerMapping = layer.hasCompositedLayerMapping();
  CompositedLayerMapping* currentCompositedLayerMapping =
      layer.compositedLayerMapping();

  // If this layer has a compositedLayerMapping, then that is where we place
  // subsequent children GraphicsLayers.  Otherwise children continue to append
  // to the child list of the enclosing layer.
  GraphicsLayerVector layerChildren;
  AncestorInfo infoForChildren(info);
  if (hasCompositedLayerMapping) {
    infoForChildren.childLayersOfEnclosingCompositedLayer = &layerChildren;
    infoForChildren.enclosingCompositedLayer = &layer;
  }

#if ENABLE(ASSERT)
  LayerListMutationDetector mutationChecker(layer.stackingNode());
#endif

  if (layer.stackingNode()->isStackingContext()) {
    PaintLayerStackingNodeIterator iterator(*layer.stackingNode(),
                                            NegativeZOrderChildren);
    while (PaintLayerStackingNode* curNode = iterator.next())
      rebuild(*curNode->layer(), infoForChildren);

    // If a negative z-order child is compositing, we get a foreground layer
    // which needs to get parented.
    if (hasCompositedLayerMapping &&
        currentCompositedLayerMapping->foregroundLayer())
      infoForChildren.childLayersOfEnclosingCompositedLayer->append(
          currentCompositedLayerMapping->foregroundLayer());
  }

  PaintLayerStackingNodeIterator iterator(
      *layer.stackingNode(), NormalFlowChildren | PositiveZOrderChildren);
  while (PaintLayerStackingNode* curNode = iterator.next())
    rebuild(*curNode->layer(), infoForChildren);

  if (hasCompositedLayerMapping) {
    bool parented = false;
    if (layer.layoutObject()->isLayoutPart())
      parented = PaintLayerCompositor::attachFrameContentLayersToIframeLayer(
          toLayoutPart(layer.layoutObject()));

    if (!parented)
      currentCompositedLayerMapping->setSublayers(layerChildren);

    if (shouldAppendLayer(layer))
      info.childLayersOfEnclosingCompositedLayer->append(
          currentCompositedLayerMapping->childForSuperlayers());
  }

  if (layer.scrollParent() &&
      layer.scrollParent()->hasCompositedLayerMapping() &&
      layer.scrollParent()
          ->compositedLayerMapping()
          ->needsToReparentOverflowControls() &&
      layer.scrollParent()->getScrollableArea()->topmostScrollChild() == &layer)
    info.childLayersOfEnclosingCompositedLayer->append(
        layer.scrollParent()
            ->compositedLayerMapping()
            ->detachLayerForOverflowControls(*info.enclosingCompositedLayer));
}

}  // namespace blink