[devtools] Add DOMSnapshot domain for dom+layout+style snapshots.

third_party/WebKit/Source/core/inspector/InspectorDOMSnapshotAgent.cpp

+// Copyright 2017 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 "core/inspector/InspectorDOMSnapshotAgent.h"
+
+#include "core/css/CSSComputedStyleDeclaration.h"
+#include "core/dom/Attribute.h"
+#include "core/dom/AttributeCollection.h"
+#include "core/dom/DOMNodeIds.h"
+#include "core/dom/Document.h"
+#include "core/dom/DocumentType.h"
+#include "core/dom/Element.h"
+#include "core/dom/Node.h"
+#include "core/dom/PseudoElement.h"
+#include "core/dom/QualifiedName.h"
+#include "core/frame/LocalFrame.h"
+#include "core/html/HTMLFrameOwnerElement.h"
+#include "core/html/HTMLLinkElement.h"
+#include "core/html/HTMLTemplateElement.h"
+#include "core/inspector/IdentifiersFactory.h"
+#include "core/inspector/InspectedFrames.h"
+#include "core/inspector/InspectorDOMAgent.h"
+#include "core/layout/LayoutObject.h"
+#include "core/layout/LayoutText.h"
+#include "core/layout/line/InlineTextBox.h"
+#include "platform/wtf/PtrUtil.h"
+
+namespace blink {
+
+using protocol::Maybe;
+using protocol::Response;
+
+namespace {
+
+std::unique_ptr<protocol::DOM::Rect> BuildRectForFloatRect(
+    const FloatRect& rect) {
+  return protocol::DOM::Rect::create()
+      .setX(rect.X())
+      .setY(rect.Y())
+      .setWidth(rect.Width())
+      .setHeight(rect.Height())
+      .build();
+}
+
+protocol::DOMSnapshot::AuxiliaryProperties* GetAux(
+    protocol::DOMSnapshot::DOMNode* node) {
+  if (!node->hasAuxProperties()) {
+    node->setAuxProperties(
+        protocol::DOMSnapshot::AuxiliaryProperties::create().build());
+  }
+  return node->getAuxProperties(nullptr);

[alex clarke (OOO till 29th), 2017/06/07 12:56:44]

I wonder if the compiler is smart enough to compile the following to the same
code?

node->getAuxProperties(protocol::DOMSnapshot::AuxiliaryProperties::create().build())

[Eric Seckler, 2017/06/07 13:05:17]

Probably not, but even if it would, that doesn't actually result in the same
logic - getAuxProperties() doesn't set the default value in the object if it
didn't have a value. It just returns it. So you'd still have to call
setAuxProperties() afterwards.

+}
+
+}  // namespace
+
+struct InspectorDOMSnapshotAgent::VectorStringHashTraits
+    : public WTF::GenericHashTraits<Vector<String>> {
+  static unsigned GetHash(const Vector<String>& vec) {
+    unsigned h = DefaultHash<size_t>::Hash::GetHash(vec.size());
+    for (size_t i = 0; i < vec.size(); i++) {
+      h = WTF::HashInts(h, DefaultHash<String>::Hash::GetHash(vec[i]));
+    }
+    return h;
+  }
+
+  static bool Equal(const Vector<String>& a, const Vector<String>& b) {
+    if (a.size() != b.size())
+      return false;
+    for (size_t i = 0; i < a.size(); i++) {
+      if (a[i] != b[i])
+        return false;
+    }
+    return true;
+  }
+
+  static void ConstructDeletedValue(Vector<String>& vec, bool) {
+    vec.clear();
+    vec.push_back(String(WTF::kHashTableDeletedValue));
+  }
+
+  static bool IsDeletedValue(const Vector<String>& vec) {
+    return !vec.IsEmpty() && vec[0].IsHashTableDeletedValue();
+  }
+
+  static bool IsEmptyValue(const Vector<String>& vec) { return vec.IsEmpty(); }
+
+  static const bool kEmptyValueIsZero = false;
+  static const bool safe_to_compare_to_empty_or_deleted = false;
+  static const bool kHasIsEmptyValueFunction = true;
+};
+
+InspectorDOMSnapshotAgent::InspectorDOMSnapshotAgent(
+    InspectedFrames* inspected_frames)
+    : inspected_frames_(inspected_frames) {}
+
+InspectorDOMSnapshotAgent::~InspectorDOMSnapshotAgent() {}
+
+Response InspectorDOMSnapshotAgent::getSnapshot(
+    std::unique_ptr<protocol::Array<String>> style_whitelist,
+    std::unique_ptr<protocol::Array<protocol::DOMSnapshot::DOMNode>>* dom_nodes,
+    std::unique_ptr<protocol::Array<protocol::DOMSnapshot::LayoutTreeNode>>*
+        layout_tree_nodes,
+    std::unique_ptr<protocol::Array<protocol::DOMSnapshot::ComputedStyle>>*
+        computed_styles) {
+  DCHECK(!dom_nodes_ && !layout_tree_nodes_ && !computed_styles_);
+
+  Document* document = inspected_frames_->Root()->GetDocument();
+  if (!document)
+    return Response::Error("Document is not available");
+
+  // Setup snapshot.
+  dom_nodes_ = protocol::Array<protocol::DOMSnapshot::DOMNode>::create();
+  layout_tree_nodes_ =
+      protocol::Array<protocol::DOMSnapshot::LayoutTreeNode>::create();
+  computed_styles_ =
+      protocol::Array<protocol::DOMSnapshot::ComputedStyle>::create();
+  computed_styles_map_ = WTF::MakeUnique<ComputedStylesMap>();
+  css_property_whitelist_ = WTF::MakeUnique<CSSPropertyWhitelist>();
+
+  // Look up the CSSPropertyIDs for each entry in |style_whitelist|.
+  for (size_t i = 0; i < style_whitelist->length(); i++) {
+    CSSPropertyID property_id = cssPropertyID(style_whitelist->get(i));
+    if (property_id == CSSPropertyInvalid)
+      continue;
+    css_property_whitelist_->push_back(
+        std::make_pair(style_whitelist->get(i), property_id));
+  }
+
+  // Actual traversal.
+  VisitNode(document);
+
+  // Extract results from state and reset.
+  *dom_nodes = std::move(dom_nodes_);
+  *layout_tree_nodes = std::move(layout_tree_nodes_);
+  *computed_styles = std::move(computed_styles_);
+  computed_styles_map_.reset();
+  css_property_whitelist_.reset();
+  return Response::OK();
+}
+
+int InspectorDOMSnapshotAgent::VisitNode(Node* node) {
+  if (node->IsDocumentNode()) {
+    // Update layout tree before traversal of document so that we inspect a
+    // current and consistent state of all trees.
+    node->GetDocument().UpdateStyleAndLayoutTree();
+  }
+
+  String node_value;
+  switch (node->getNodeType()) {
+    case Node::kTextNode:
+    case Node::kAttributeNode:
+    case Node::kCommentNode:
+    case Node::kCdataSectionNode:
+      node_value = node->nodeValue();
+      break;
+    default:
+      break;
+  }
+
+  // Create DOMNode object and add it to the result array before traversing
+  // children, so that parents appear before their children in the array.
+  std::unique_ptr<protocol::DOMSnapshot::DOMNode> owned_value =
+      protocol::DOMSnapshot::DOMNode::create()
+          .setNodeType(static_cast<int>(node->getNodeType()))
+          .setNodeName(node->nodeName())
+          .setNodeValue(node_value)
+          .setBackendNodeId(DOMNodeIds::IdForNode(node))
+          .setAuxProperties(
+              protocol::DOMSnapshot::AuxiliaryProperties::create().build())
+          .build();
+  protocol::DOMSnapshot::DOMNode* value = owned_value.get();
+  int index = dom_nodes_->length();
+  dom_nodes_->addItem(std::move(owned_value));
+
+  int layoutNodeIndex = VisitLayoutTreeNode(node, index);
+  if (layoutNodeIndex != -1)
+    value->setLayoutNodeIndex(layoutNodeIndex);
+
+  if (node->IsElementNode()) {
+    Element* element = ToElement(node);
+    value->setAttributes(BuildArrayForElementAttributes(element));
+
+    if (node->IsFrameOwnerElement()) {
+      HTMLFrameOwnerElement* frame_owner = ToHTMLFrameOwnerElement(node);
+      if (LocalFrame* frame =
+              frame_owner->ContentFrame() &&
+                      frame_owner->ContentFrame()->IsLocalFrame()
+                  ? ToLocalFrame(frame_owner->ContentFrame())
+                  : nullptr) {
+        GetAux(value)->setFrameId(IdentifiersFactory::FrameId(frame));
+      }
+      if (Document* doc = frame_owner->contentDocument()) {
+        GetAux(value)->setContentDocumentIndex(VisitNode(doc));
+      }
+    }
+
+    if (node->parentNode() && node->parentNode()->IsDocumentNode()) {
+      LocalFrame* frame = node->GetDocument().GetFrame();
+      if (frame)
+        GetAux(value)->setFrameId(IdentifiersFactory::FrameId(frame));
+    }
+
+    if (isHTMLLinkElement(*element)) {
+      HTMLLinkElement& link_element = toHTMLLinkElement(*element);
+      if (link_element.IsImport() && link_element.import() &&
+          InspectorDOMAgent::InnerParentNode(link_element.import()) ==
+              link_element) {
+        GetAux(value)->setImportedDocumentIndex(
+            VisitNode(link_element.import()));
+      }
+    }
+
+    if (isHTMLTemplateElement(*element)) {
+      GetAux(value)->setTemplateContentIndex(
+          VisitNode(toHTMLTemplateElement(*element).content()));
+    }
+
+    if (element->GetPseudoId()) {
+      protocol::DOM::PseudoType pseudo_type;
+      if (InspectorDOMAgent::GetPseudoElementType(element->GetPseudoId(),
+                                                  &pseudo_type)) {
+        GetAux(value)->setPseudoType(pseudo_type);
+      }
+    } else {
+      value->setPseudoElementIndexes(VisitPseudoElements(element));
+    }
+  } else if (node->IsDocumentNode()) {
+    Document* document = ToDocument(node);
+    GetAux(value)->setDocumentURL(
+        InspectorDOMAgent::DocumentURLString(document));
+    GetAux(value)->setBaseURL(
+        InspectorDOMAgent::DocumentBaseURLString(document));
+  } else if (node->IsDocumentTypeNode()) {
+    DocumentType* doc_type = ToDocumentType(node);
+    GetAux(value)->setPublicId(doc_type->publicId());
+    GetAux(value)->setSystemId(doc_type->systemId());
+  }
+
+  if (node->IsContainerNode())
+    value->setChildNodeIndexes(VisitContainerChildren(node));
+
+  return index;
+}
+
+std::unique_ptr<protocol::Array<int>>
+InspectorDOMSnapshotAgent::VisitContainerChildren(Node* container) {
+  auto children = protocol::Array<int>::create();
+
+  if (!FlatTreeTraversal::HasChildren(*container))
+    return nullptr;
+
+  Node* child = FlatTreeTraversal::FirstChild(*container);
+  while (child) {
+    children->addItem(VisitNode(child));
+    child = FlatTreeTraversal::NextSibling(*child);
+  }
+
+  return children;
+}
+
+std::unique_ptr<protocol::Array<int>>
+InspectorDOMSnapshotAgent::VisitPseudoElements(Element* parent) {
+  if (!parent->GetPseudoElement(kPseudoIdBefore) &&
+      !parent->GetPseudoElement(kPseudoIdAfter)) {
+    return nullptr;
+  }
+
+  auto pseudo_elements = protocol::Array<int>::create();
+
+  if (parent->GetPseudoElement(kPseudoIdBefore)) {
+    pseudo_elements->addItem(
+        VisitNode(parent->GetPseudoElement(kPseudoIdBefore)));
+  }
+  if (parent->GetPseudoElement(kPseudoIdAfter)) {
+    pseudo_elements->addItem(
+        VisitNode(parent->GetPseudoElement(kPseudoIdAfter)));
+  }
+
+  return pseudo_elements;
+}
+
+std::unique_ptr<protocol::Array<protocol::DOMSnapshot::NameValue>>
+InspectorDOMSnapshotAgent::BuildArrayForElementAttributes(Element* element) {
+  auto attributes_value =
+      protocol::Array<protocol::DOMSnapshot::NameValue>::create();
+  AttributeCollection attributes = element->Attributes();
+  for (const auto& attribute : attributes) {
+    attributes_value->addItem(protocol::DOMSnapshot::NameValue::create()
+                                  .setName(attribute.GetName().ToString())
+                                  .setValue(attribute.Value())
+                                  .build());
+  }
+  return attributes_value;
+}
+
+int InspectorDOMSnapshotAgent::VisitLayoutTreeNode(Node* node, int node_index) {
+  LayoutObject* layout_object = node->GetLayoutObject();
+  if (!layout_object)
+    return -1;
+
+  auto layout_tree_node =
+      protocol::DOMSnapshot::LayoutTreeNode::create()
+          .setDomNodeIndex(node_index)
+          .setBoundingBox(BuildRectForFloatRect(
+              node->IsElementNode()
+                  ? FloatRect(ToElement(node)->BoundsInViewport())
+                  : layout_object->AbsoluteBoundingBoxRect()))
+          .build();
+
+  int style_index = GetStyleIndexForNode(node);
+  if (style_index != -1)
+    layout_tree_node->setStyleIndex(style_index);
+
+  if (layout_object->IsText()) {
+    LayoutText* layout_text = ToLayoutText(layout_object);
+    layout_tree_node->setLayoutText(layout_text->GetText());
+    if (layout_text->HasTextBoxes()) {
+      std::unique_ptr<protocol::Array<protocol::CSS::InlineTextBox>>
+          inline_text_nodes =
+              protocol::Array<protocol::CSS::InlineTextBox>::create();
+      for (const InlineTextBox* text_box = layout_text->FirstTextBox();
+           text_box; text_box = text_box->NextTextBox()) {
+        FloatRect local_coords_text_box_rect(text_box->FrameRect());
+        FloatRect absolute_coords_text_box_rect =
+            layout_object->LocalToAbsoluteQuad(local_coords_text_box_rect)
+                .BoundingBox();
+        inline_text_nodes->addItem(
+            protocol::CSS::InlineTextBox::create()
+                .setStartCharacterIndex(text_box->Start())
+                .setNumCharacters(text_box->Len())
+                .setBoundingBox(
+                    BuildRectForFloatRect(absolute_coords_text_box_rect))
+                .build());
+      }
+      layout_tree_node->setInlineTextNodes(std::move(inline_text_nodes));
+    }
+  }
+
+  int index = layout_tree_nodes_->length();
+  layout_tree_nodes_->addItem(std::move(layout_tree_node));
+  return index;
+}
+
+int InspectorDOMSnapshotAgent::GetStyleIndexForNode(Node* node) {
+  CSSComputedStyleDeclaration* computed_style_info =
+      CSSComputedStyleDeclaration::Create(node, true);
+
+  Vector<String> style;
+  bool all_properties_empty = true;
+  for (const auto& pair : *css_property_whitelist_) {
+    String value = computed_style_info->GetPropertyValue(pair.second);
+    if (!value.IsEmpty())
+      all_properties_empty = false;
+    style.push_back(value);
+  }
+
+  // -1 means an empty style.
+  if (all_properties_empty)
+    return -1;
+
+  ComputedStylesMap::iterator it = computed_styles_map_->find(style);
+  if (it != computed_styles_map_->end())
+    return it->value;
+
+  // It's a distinct style, so append to |computedStyles|.
+  auto style_properties =
+      protocol::Array<protocol::DOMSnapshot::NameValue>::create();
+
+  for (size_t i = 0; i < style.size(); i++) {
+    if (style[i].IsEmpty())
+      continue;
+    style_properties->addItem(protocol::DOMSnapshot::NameValue::create()
+                                  .setName((*css_property_whitelist_)[i].first)
+                                  .setValue(style[i])
+                                  .build());
+  }
+
+  size_t index = computed_styles_->length();
+  computed_styles_->addItem(protocol::DOMSnapshot::ComputedStyle::create()
+                                .setProperties(std::move(style_properties))
+                                .build());
+  computed_styles_map_->insert(std::move(style), index);
+  return index;
+}
+
+DEFINE_TRACE(InspectorDOMSnapshotAgent) {
+  visitor->Trace(inspected_frames_);
+  InspectorBaseAgent::Trace(visitor);
+}
+
+}  // namespace blink