Add support to extract viewer preference

core/include/fpdfdoc/fpdf_doc.h

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
  
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #ifndef _FPDF_DOC_H_
 #define _FPDF_DOC_H_
 #ifndef _FPDF_PARSER_
 #include "../fpdfapi/fpdf_parser.h"
@@ skipping 1639 matching lines @@
     CPDF_ViewerPreferences(CPDF_Document *pDoc);
 
 
     ~CPDF_ViewerPreferences();
 
 
     FX_BOOL IsDirectionR2L() const;
 
     FX_BOOL PrintScaling() const;
 
+    FX_INT32 NumCopies() const;
+
+    CPDF_Array* PrintPageRange() const;
+
+    CFX_ByteString Duplex() const;
 
 protected:
     CPDF_Document*      m_pDoc;
 };
 class CPDF_ApSettings : public CFX_Object
 {
 public:
 
     CPDF_ApSettings(CPDF_Dictionary* pDict = NULL)
     {
@@ skipping 113 matching lines @@
     FX_FLOAT                            GetOriginalColor(int index, FX_BSTR csEntry);
 
     void                                        GetOriginalColor(int& iColorType, FX_FLOAT fc[4], FX_BSTR csEntry);
 
     CFX_WideString                      GetCaption(FX_BSTR csEntry);
 
     CPDF_Stream*                        GetIcon(FX_BSTR csEntry);
     friend class                        CPDF_FormControl;
 };
 #endif