third_party/blink/renderer/core/frame/frame_serializer.h

/*
 * Copyright (C) 2011 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.
 *     * 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.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promo te 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,
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef THIRD_PARTY_BLINK_RENDERER_CORE_FRAME_FRAME_SERIALIZER_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_FRAME_FRAME_SERIALIZER_H_

#include "third_party/blink/renderer/core/core_export.h"
#include "third_party/blink/renderer/core/dom/attribute.h"
#include "third_party/blink/renderer/core/html/html_template_element.h"
#include "third_party/blink/renderer/platform/weborigin/kurl.h"
#include "third_party/blink/renderer/platform/weborigin/kurl_hash.h"
#include "third_party/blink/renderer/platform/wtf/allocator/allocator.h"
#include "third_party/blink/renderer/platform/wtf/deque.h"
#include "third_party/blink/renderer/platform/wtf/forward.h"
#include "third_party/blink/renderer/platform/wtf/hash_set.h"
#include "third_party/blink/renderer/platform/wtf/vector.h"

namespace blink {

class CSSPropertyValueSet;
class CSSRule;
class CSSStyleSheet;
class CSSValue;
class Document;
class Element;
class FontResource;
class HTMLTemplateElement;
class ImageResourceContent;
class LocalFrame;
class ShadowRoot;

struct SerializedResource;

class FrameSerializerResourceDelegate {
 public:
  virtual ~FrameSerializerResourceDelegate() = default;

  // Adds the resource needed to serialize an element.
  virtual void AddResourceForElement(Document&, const Element&) = 0;

  // Serializes the stylesheet back to text and adds it to the resources if
  // URL is not-empty.  It also adds any resources included in that stylesheet
  // (including any imported stylesheets and their own resources).
  virtual void SerializeCSSStyleSheet(CSSStyleSheet&, const KURL&) = 0;
};

// This class is used to serialize frame's contents back to text (typically
// HTML).  It serializes frame's document and resources such as images and CSS
// stylesheets.
class CORE_EXPORT FrameSerializer : public FrameSerializerResourceDelegate {
  STACK_ALLOCATED();

 public:
  class Delegate {
   public:
    virtual ~Delegate() = default;

    // Controls whether HTML serialization should skip the given element.
    virtual bool ShouldIgnoreElement(const Element&) { return false; }

    // Controls whether HTML serialization should skip the given attribute.
    virtual bool ShouldIgnoreAttribute(const Element&, const Attribute&) {
      return false;
    }

    // Method allowing the Delegate control which URLs are written into the
    // generated html document.
    //
    // When URL of the element needs to be rewritten, this method should
    // return true and populate |rewrittenLink| with a desired value of the
    // html attribute value to be used in place of the original link.
    // (i.e. in place of img.src or iframe.src or object.data).
    //
    // If no link rewriting is desired, this method should return false.
    virtual bool RewriteLink(const Element&, String& rewritten_link) {
      return false;
    }

    // Tells whether to skip serialization of a subresource or CSSStyleSheet
    // with a given URI. Used to deduplicate resources across multiple frames.
    virtual bool ShouldSkipResourceWithURL(const KURL&) { return false; }

    // Returns custom attributes that need to add in order to serialize the
    // element.
    virtual Vector<Attribute> GetCustomAttributes(const Element&) {
      return Vector<Attribute>();
    }

    // Returns a shadow tree that needs to be serialized.
    virtual std::pair<ShadowRoot*, HTMLTemplateElement*> GetShadowTree(
        const Element&) const {
      return std::pair<ShadowRoot*, HTMLTemplateElement*>();
    }
  };

  // Constructs a serializer that will write output to the given deque of
  // SerializedResources and uses the Delegate for controlling some
  // serialization aspects.  Callers need to ensure that both arguments stay
  // alive until the FrameSerializer gets destroyed.
  FrameSerializer(Deque<SerializedResource>&, Delegate&);

  // Initiates the serialization of the frame. All serialized content and
  // retrieved resources are added to the Deque passed to the constructor.
  // The first resource in that deque is the frame's serialized content.
  // Subsequent resources are images, css, etc.
  void SerializeFrame(const LocalFrame&);

  static String MarkOfTheWebDeclaration(const KURL&);

 private:
  void AddResourceForElement(Document&, const Element&) override;
  void SerializeCSSStyleSheet(CSSStyleSheet&, const KURL&) override;

  // Serializes the css rule (including any imported stylesheets), adding
  // referenced resources.
  void SerializeCSSRule(CSSRule*);

  bool ShouldAddURL(const KURL&);

  void AddToResources(const String& mime_type,
                      scoped_refptr<const SharedBuffer>,
                      const KURL&);
  void AddImageToResources(ImageResourceContent*, const KURL&);
  void AddFontToResources(FontResource&);

  void RetrieveResourcesForProperties(const CSSPropertyValueSet*, Document&);
  void RetrieveResourcesForCSSValue(const CSSValue&, Document&);

  Deque<SerializedResource>* resources_;
  // This hashset is only used for de-duplicating resources to be serialized.
  HashSet<KURL> resource_urls_;

  Delegate& delegate_;
};

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_CORE_FRAME_FRAME_SERIALIZER_H_