critical_images_beacon_filter.h

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/*
 * Copyright 2013 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http:///www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


#ifndef NET_INSTAWEB_REWRITER_PUBLIC_CRITICAL_IMAGES_BEACON_FILTER_H_
#define NET_INSTAWEB_REWRITER_PUBLIC_CRITICAL_IMAGES_BEACON_FILTER_H_

#include "net/instaweb/rewriter/public/common_filter.h"
#include "net/instaweb/rewriter/public/critical_finder_support_util.h"
#include "net/instaweb/rewriter/public/rewrite_driver.h"
#include "pagespeed/kernel/base/basictypes.h"
#include "pagespeed/kernel/base/statistics.h"
#include "pagespeed/kernel/base/string.h"
#include "pagespeed/kernel/base/string_util.h"
#include "pagespeed/kernel/html/html_element.h"
#include "pagespeed/kernel/html/html_filter.h"

namespace net_instaweb {

class CriticalImagesBeaconFilter : public CommonFilter {
 public:
  static const char* kImageOnloadCode;
  static const char kCriticalImagesBeaconAddedCount[];

  explicit CriticalImagesBeaconFilter(RewriteDriver* driver);
  virtual ~CriticalImagesBeaconFilter();

  virtual void DetermineEnabled(GoogleString* disabled_reason);

  static void InitStats(Statistics* statistics);

  virtual void StartDocumentImpl() { }
  virtual void EndDocument();
  virtual void StartElementImpl(HtmlElement* element) { }
  virtual void EndElementImpl(HtmlElement* element);
  virtual const char* Name() const { return "CriticalImagesBeacon"; }
  ScriptUsage GetScriptUsage() const override { return kWillInjectScripts; }

  static bool ShouldApply(RewriteDriver* rewrite_driver);

 private:
  void Clear();

  void MaybeAddBeaconJavascript(HtmlElement* element);

  BeaconMetadata beacon_metadata_;
  StringSet image_url_hashes_;
  bool insert_beacon_js_;
  Variable* critical_images_beacon_added_count_;

  bool added_beacon_js_;

  
};

}  

#endif