SkPDF: in-place font subsetting

src/pdf/SkPDFDocument.h

 /*
  * Copyright 2016 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #ifndef SkPDFDocument_DEFINED
 #define SkPDFDocument_DEFINED
 
 #include "SkDocument.h"
 #include "SkPDFCanon.h"
 #include "SkPDFMetadata.h"
 #include "SkPDFFont.h"
 
 class SkPDFDevice;
 
 sk_sp<SkDocument> SkPDFMakeDocument(SkWStream* stream,
                                     void (*doneProc)(SkWStream*, bool),
                                     SkScalar rasterDpi,
                                     const SkDocument::PDFMetadata&,
                                     sk_sp<SkPixelSerializer>,
                                     bool pdfa);
 
 // Logically part of SkPDFDocument (like SkPDFCanon), but separate to
 // keep similar functionality together.
 struct SkPDFObjectSerializer : SkNoncopyable {
     SkPDFObjNumMap fObjNumMap;
-    SkPDFSubstituteMap fSubstituteMap;
     SkTDArray<int32_t> fOffsets;
     sk_sp<SkPDFObject> fInfoDict;
     size_t fBaseOffset;
     int32_t fNextToBeSerialized;  // index in fObjNumMap
 
     SkPDFObjectSerializer();
     ~SkPDFObjectSerializer();
     void addObjectRecursively(const sk_sp<SkPDFObject>&);
     void serializeHeader(SkWStream*, const SkDocument::PDFMetadata&);
     void serializeObjects(SkWStream*);
@@ skipping 24 matching lines @@
                      const SkTime::DateTime*) override;
 #endif  // SK_SUPPORT_LEGACY_DOCUMENT_API
     /**
        Serialize the object, as well as any other objects it
        indirectly refers to.  If any any other objects have been added
        to the SkPDFObjNumMap without serializing them, they will be
        serialized as well.
 
        It might go without saying that objects should not be changed
        after calling serialize, since those changes will be too late.
-       The same goes for changes to the SkPDFSubstituteMap that effect
-       the object or its dependencies.
      */
     void serialize(const sk_sp<SkPDFObject>&);
     SkPDFCanon* canon() { return &fCanon; }
-    SkPDFGlyphSetMap* getGlyphUsage() { return &fGlyphUsage; }
+    void registerFont(SkPDFFont* f) { fFonts.add(f); }
 
 private:
     SkPDFObjectSerializer fObjectSerializer;
     SkPDFCanon fCanon;
-    SkPDFGlyphSetMap fGlyphUsage;
     SkTArray<sk_sp<SkPDFDict>> fPages;
+    SkTHashSet<SkPDFFont*> fFonts;
     sk_sp<SkPDFDict> fDests;
     sk_sp<SkPDFDevice> fPageDevice;
     sk_sp<SkCanvas> fCanvas;
     sk_sp<SkPDFObject> fID;
     sk_sp<SkPDFObject> fXMP;
     SkScalar fRasterDpi;
     SkDocument::PDFMetadata fMetadata;
     bool fPDFA;
+
+    void reset();
 };
 
 #endif  // SkPDFDocument_DEFINED