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+//  writer.hh -- putting PDF objects in a file
+//  Copyright (C) 2008  SEIKO EPSON CORPORATION
+//
+//  This file is part of the 'iscan' program.
+//
+//  The 'iscan' program is free-ish software.
+//  You can redistribute it and/or modify it under the terms of the GNU
+//  General Public License as published by the Free Software Foundation;
+//  either version 2 of the License or at your option any later version.
+//
+//  This program is distributed in the hope that it will be useful, but
+//  WITHOUT ANY WARRANTY;  without even the implied warranty of FITNESS
+//  FOR A PARTICULAR PURPOSE or MERCHANTABILITY.
+//  See the GNU General Public License for more details.
+//
+//  You should have received a verbatim copy of the GNU General Public
+//  License along with this program; if not, write to:
+//
+//      Free Software Foundation, Inc.
+//      59 Temple Place, Suite 330
+//      Boston, MA  02111-1307  USA
+//
+//  As a special exception, the copyright holders give permission
+//  to link the code of this program with the esmod library and
+//  distribute linked combinations including the two.  You must obey
+//  the GNU General Public License in all respects for all of the
+//  code used other than esmod.
+
+#ifndef iscan_pdf_writer_hh_included
+#define iscan_pdf_writer_hh_included
+
+#ifndef __cplusplus
+#error "This is a C++ header file; use a C++ compiler to compile it."
+#endif
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include "object.hh"
+#include "primitive.hh"
+#include "dictionary.hh"
+
+#include <map>
+
+namespace iscan
+{
+
+namespace pdf
+{
+  using std::string;
+
+/*! Writes PDF objects to a file.
+ * See section 3.4 of the PDF Reference version 1.7 for details on the basic
+ * file structure of a PDF file.
+ *
+ * There are two writing modes: object mode and stream mode.
+ * The default mode is object mode. When begin_stream() is called, the current
+ * mode is set to stream mode. When end_stream() is called, the mode is reset
+ * to object mode.
+ *
+ * In object mode, PDF objects are written all at once. Stream mode allows the
+ * writing of PDF stream objects which can be written incrementally.
+ */
+class writer
+{
+private:
+  typedef std::map<size_t, size_t> xref;
+
+  xref _xref;
+  size_t _xref_pos;
+  size_t _last_xref_pos;
+
+  FILE *_file;
+  size_t _saved_pos;
+
+  primitive* _stream_len_obj;
+
+  typedef enum {
+    object_mode,
+    stream_mode
+  } write_mode;
+
+  write_mode _mode;
+
+public:
+  /*! Creates a new pdf::writer object which will write to the given stream.
+   */
+  writer (FILE *file);
+
+  ~writer ();
+
+  /*! Writes a pdf::object to the file as an indirect object [p 63].
+   *
+   * Recursively writes any child objects to the file.
+   * Can only be called while in object mode, which is the default
+   * mode. If this method is called between calls to begin_stream() and
+   * end_stream() a std::runtime_error exception is thrown.
+   */
+  void write (object& object);
+
+  /*! Initializes a PDF stream [p 60] and sets the current mode to stream mode.
+   *
+   *  Pass a pdf::dictionary object, \a dict, defining the stream properties,
+   *  omitting the mandatory "Length" property which is automatically
+   *  calculated and written to the file. If this method is called when already
+   *  in stream mode, a std::runtime_error exception is thrown.
+   */
+  void begin_stream (dictionary& dict);
+
+  /*! Writes \a n bytes from \a buf to the file as part of a PDF stream.
+   *
+   *  Can only be called while in stream mode.
+   *  Calls to this method must be contained within calls to
+   *  begin_stream() and end_stream(). If not, a std::runtime_error
+   *  exception is thrown.
+   */
+  void write (const char* buf, size_t n);
+
+  /*! Writes a string \a s to the file as part of a PDF stream.
+   *
+   *  Can only be called while in stream mode.
+   *  Calls to this method must be contained within calls to
+   *  begin_stream() and end_stream(). If not, a std::runtime_error
+   *  exception is thrown.
+   */
+  void write (const string& s);
+
+  /*! Finishes writing a PDF stream and sets the current mode to object mode.
+   *
+   *  The "Length" property of the stream is written at this point as an
+   *  indirect object. Can only be called when in stream mode, if not, a
+   *  std::runtime_error exception is thrown.
+   */
+  void end_stream ();
+
+  /*! Writes the PDF header [p 92].
+   *
+   *  A std::runtime_error exception is thrown if this method is called while
+   *  in stream mode.
+   */
+  void header ();
+
+  /*! Writes the PDF trailer [p 96] and xref table [p 93].
+   *
+   * Also sets the "Prev" entry in \a trailer_dict and clears the internal
+   * xref table. A std::runtime_error exception is thrown if this method is
+   * called while in stream mode.
+   *
+   * \param trailer_dict The trailer entries to be written.
+   */
+  void trailer (dictionary& trailer_dict);
+
+private:
+  // Writes the cross-reference table [p 93].
+  void write_xref ();
+
+  // Writes the file trailer [p 96].
+  void write_trailer (dictionary& trailer_dict);
+};
+
+}       // namespace pdf
+}       // namespace iscan
+
+#endif  // iscan_pdf_writer_hh_included