third_party/WebKit/Source/core/dom/ElementShadow.cpp

/*
 * Copyright (C) 2012 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:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "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 THE COPYRIGHT
 * OWNER 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 OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#include "core/dom/ElementShadow.h"

#include "core/css/StyleChangeReason.h"
#include "core/css/StyleSheetList.h"
#include "core/css/resolver/ScopedStyleResolver.h"
#include "core/dom/ElementShadowV0.h"
#include "core/dom/NodeTraversal.h"
#include "core/frame/Deprecation.h"
#include "core/probe/CoreProbes.h"
#include "platform/EventDispatchForbiddenScope.h"
#include "platform/bindings/ScriptForbiddenScope.h"

namespace blink {

ElementShadow* ElementShadow::Create() {
  return new ElementShadow();
}

ElementShadow::ElementShadow() : needs_distribution_recalc_(false) {}

ShadowRoot& ElementShadow::YoungestShadowRoot() const {
  ShadowRoot* current = shadow_root_;
  DCHECK(current);
  while (current->YoungerShadowRoot())
    current = current->YoungerShadowRoot();
  return *current;
}

ShadowRoot& ElementShadow::AddShadowRoot(Element& shadow_host,
                                         ShadowRootType type) {
  EventDispatchForbiddenScope assert_no_event_dispatch;
  ScriptForbiddenScope forbid_script;

  // Multiple ShadowRoots are removed.
  // TODO(kochi): Further cleanup of unnecessary code for multiple shadow.
  DCHECK(!shadow_root_);

  if (shadow_root_) {
    // TODO(hayato): Is the order, from the youngest to the oldest, important?
    for (ShadowRoot* root = &YoungestShadowRoot(); root;
         root = root->OlderShadowRoot())
      root->LazyReattachIfAttached();
  } else if (type == ShadowRootType::V0 || type == ShadowRootType::kUserAgent) {
    DCHECK(!element_shadow_v0_);
    element_shadow_v0_ = ElementShadowV0::Create(*this);
  }

  ShadowRoot* shadow_root = ShadowRoot::Create(shadow_host.GetDocument(), type);
  shadow_root->SetParentOrShadowHostNode(&shadow_host);
  shadow_root->SetParentTreeScope(shadow_host.GetTreeScope());
  AppendShadowRoot(*shadow_root);
  if (type == ShadowRootType::V0) {
    SetNeedsDistributionRecalc();
  } else {
    for (Node& child : NodeTraversal::ChildrenOf(shadow_host))
      child.LazyReattachIfAttached();
  }

  shadow_root->InsertedInto(&shadow_host);
  shadow_host.SetChildNeedsStyleRecalc();
  shadow_host.SetNeedsStyleRecalc(
      kSubtreeStyleChange,
      StyleChangeReasonForTracing::Create(StyleChangeReason::kShadow));

  probe::didPushShadowRoot(&shadow_host, shadow_root);

  return *shadow_root;
}

void ElementShadow::AppendShadowRoot(ShadowRoot& shadow_root) {
  if (!shadow_root_) {
    shadow_root_ = &shadow_root;
    return;
  }
  ShadowRoot& youngest = YoungestShadowRoot();
  DCHECK(shadow_root.GetType() == ShadowRootType::V0);
  DCHECK(youngest.GetType() == ShadowRootType::V0);
  youngest.SetYoungerShadowRoot(shadow_root);
  shadow_root.SetOlderShadowRoot(youngest);
}

void ElementShadow::Attach(const Node::AttachContext& context) {
  Node::AttachContext children_context(context);
  children_context.resolved_style = nullptr;

  for (ShadowRoot* root = &YoungestShadowRoot(); root;
       root = root->OlderShadowRoot()) {
    if (root->NeedsAttach())
      root->AttachLayoutTree(children_context);
  }
}

void ElementShadow::Detach(const Node::AttachContext& context) {
  Node::AttachContext children_context(context);
  children_context.resolved_style = nullptr;

  for (ShadowRoot* root = &YoungestShadowRoot(); root;
       root = root->OlderShadowRoot())
    root->DetachLayoutTree(children_context);
}

void ElementShadow::SetNeedsDistributionRecalc() {
  if (needs_distribution_recalc_)
    return;
  needs_distribution_recalc_ = true;
  Host().MarkAncestorsWithChildNeedsDistributionRecalc();
  if (!IsV1())
    V0().ClearDistribution();
}

bool ElementShadow::HasSameStyles(const ElementShadow& other) const {
  ShadowRoot* root = &YoungestShadowRoot();
  ShadowRoot* other_root = &other.YoungestShadowRoot();
  while (root || other_root) {
    if (!root || !other_root)
      return false;

    if (!ScopedStyleResolver::HaveSameStyles(
            root->GetScopedStyleResolver(),
            other_root->GetScopedStyleResolver())) {
      return false;
    }

    root = root->OlderShadowRoot();
    other_root = other_root->OlderShadowRoot();
  }

  return true;
}

void ElementShadow::Distribute() {
  if (IsV1())
    YoungestShadowRoot().DistributeV1();
  else
    V0().Distribute();
}

void ElementShadow::Trace(blink::Visitor* visitor) {
  visitor->Trace(element_shadow_v0_);
  visitor->Trace(shadow_root_);
}

void ElementShadow::TraceWrappers(const ScriptWrappableVisitor* visitor) const {
  visitor->TraceWrappers(element_shadow_v0_);
  visitor->TraceWrappers(shadow_root_);
}

}  // namespace blink