Page Speed Optimization Libraries  1.7.30.1
net/instaweb/rewriter/public/dedup_inlined_images_filter.h
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00001 /*
00002  * Copyright 2013 Google Inc.
00003  *
00004  * Licensed under the Apache License, Version 2.0 (the "License");
00005  * you may not use this file except in compliance with the License.
00006  * You may obtain a copy of the License at
00007  *
00008  *      http:///www.apache.org/licenses/LICENSE-2.0
00009  *
00010  * Unless required by applicable law or agreed to in writing, software
00011  * distributed under the License is distributed on an "AS IS" BASIS,
00012  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
00013  * See the License for the specific language governing permissions and
00014  * limitations under the License.
00015  */
00016 
00018 
00019 #ifndef NET_INSTAWEB_REWRITER_PUBLIC_DEDUP_INLINED_IMAGES_FILTER_H_
00020 #define NET_INSTAWEB_REWRITER_PUBLIC_DEDUP_INLINED_IMAGES_FILTER_H_
00021 
00022 #include "net/instaweb/util/public/basictypes.h"
00023 #include "net/instaweb/rewriter/public/common_filter.h"
00024 #include "net/instaweb/util/public/string_util.h"
00025 
00026 namespace net_instaweb {
00027 
00028 class HtmlElement;
00029 class RewriteDriver;
00030 class Statistics;
00031 class Variable;
00032 
00033 /*
00034  * The Dedup Inlined Images filter replaces the second & subsequent occurences
00035  * a repeated inlined image (data:image/... URL) with JavaScript that loads
00036  * the image from the first occurence. This requires the first occurence to be
00037  * tagged with a unique id; if it already has an id then that's used instead.
00038  */
00039 class DedupInlinedImagesFilter : public CommonFilter {
00040  public:
00041   static const unsigned int kMinimumImageCutoff; 
00042 
00043   static const char kDiiInitializer[]; 
00044 
00046   static const char kCandidatesFound[]; 
00047   static const char kCandidatesReplaced[]; 
00048 
00049   explicit DedupInlinedImagesFilter(RewriteDriver* driver);
00050   virtual ~DedupInlinedImagesFilter();
00051 
00053   static void InitStats(Statistics* statistics);
00054 
00055   virtual void StartDocumentImpl();
00056   virtual void EndDocument();
00057   virtual void StartElementImpl(HtmlElement* element);
00058   virtual void EndElementImpl(HtmlElement* element);
00059   virtual void DetermineEnabled();
00060 
00061   virtual const char* Name() const { return "DedupInlinedImages"; }
00062 
00063  private:
00064   bool IsDedupCandidate(HtmlElement* element, StringPiece* src_iff_true);
00065   void InsertOurScriptElement(HtmlElement* before);
00066 
00067   bool script_inserted_; 
00068   StringStringMap hash_to_id_map_; 
00069   int snippet_id_; 
00070 
00072   Variable* num_dedup_inlined_images_candidates_found_;
00074   Variable* num_dedup_inlined_images_candidates_replaced_;
00075 
00076   DISALLOW_COPY_AND_ASSIGN(DedupInlinedImagesFilter);
00077 };
00078 
00079 }  
00080 
00081 #endif  ///< NET_INSTAWEB_REWRITER_PUBLIC_DEDUP_INLINED_IMAGES_FILTER_H_
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