Create a Factory for NativeMetafile.

printing/pdf_ps_metafile_cairo.h

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef PRINTING_PDF_PS_METAFILE_CAIRO_H_
 #define PRINTING_PDF_PS_METAFILE_CAIRO_H_
 
 #include <string>
 
 #include "base/basictypes.h"
+#include "printing/metafile_factory.h"
+#include "printing/native_metafile_linux.h"
 
 typedef struct _cairo_surface cairo_surface_t;
 typedef struct _cairo cairo_t;
 
 namespace base {
 struct FileDescriptor;
 }
 
 class FilePath;
 
 namespace printing {
 
 // This class uses Cairo graphics library to generate PostScript/PDF stream
 // and stores rendering results in a string buffer.
-class PdfPsMetafile {
+class PdfPsMetafile: public NativeMetafile  {
+
+  friend class MetafileFactory;
+
  public:
-  enum FileFormat {
-    PDF,
-    PS,
-  };
 
-  PdfPsMetafile();
-
+  //TODO dpapad: move it to protected (or delete, PDF is supported only anyway)
   // In the renderer process, callers should also call Init(void) to see if the
   // metafile can obtain all necessary rendering resources.
   // In the browser process, callers should also call Init(const void*, uint32)
   // to initialize the buffer |data_| to use SaveTo().
   explicit PdfPsMetafile(const FileFormat& format);
 
-  ~PdfPsMetafile();
+  virtual ~PdfPsMetafile();
 
   // Initializes to a fresh new metafile. Returns true on success.
   // Note: Only call in the renderer to allocate rendering resources.
-  bool Init();
+  virtual bool Init();
 
   // Initializes a copy of metafile from PDF/PS stream data.
   // Returns true on success.
   // |src_buffer| should point to the shared memory which stores PDF/PS
   // contents generated in the renderer.
   // Note: Only call in the browser to initialize |data_|.
-  bool Init(const void* src_buffer, uint32 src_buffer_size);
+  virtual bool Init(const void* src_buffer, uint32 src_buffer_size);
 
   // Sets raw PS/PDF data for the document. This is used when a cairo drawing
   // surface has already been created. This method will cause all subsequent
   // drawing on the surface to be discarded (in Close()). If Init() has not yet
   // been called this method simply calls the second version of Init.
-  bool SetRawData(const void* src_buffer, uint32 src_buffer_size);
+  virtual bool SetRawData(const void* src_buffer, uint32 src_buffer_size);
 
-  FileFormat GetFileFormat() const { return format_; }
+  virtual FileFormat GetFileFormat() const { return format_; }
 
   // Prepares a new cairo surface/context for rendering a new page.
   // The unit is in point (=1/72 in).
   // Returns NULL when failed.
-  cairo_t* StartPage(double width_in_points,
+  virtual cairo_t* StartPage(double width_in_points,
                      double height_in_points,
                      double margin_top_in_points,
                      double margin_right_in_points,
                      double margin_bottom_in_points,
                      double margin_left_in_points);
 
   // Destroys the surface and the context used in rendering current page.
   // The results of current page will be appended into buffer |data_|.
   // Returns true on success.
-  bool FinishPage();
+  virtual bool FinishPage();
 
   // Closes resulting PDF/PS file. No further rendering is allowed.
-  void Close();
+  virtual void Close();
 
   // Returns size of PDF/PS contents stored in buffer |data_|.
   // This function should ONLY be called after PDF/PS file is closed.
-  uint32 GetDataSize() const;
+  virtual uint32 GetDataSize() const;
 
   // Copies PDF/PS contents stored in buffer |data_| into |dst_buffer|.
   // This function should ONLY be called after PDF/PS file is closed.
   // Returns true only when success.
-  bool GetData(void* dst_buffer, uint32 dst_buffer_size) const;
+  virtual bool GetData(void* dst_buffer, uint32 dst_buffer_size) const;
 
   // Saves PDF/PS contents stored in buffer |data_| into the file
   // associated with |fd|.
   // This function should ONLY be called after PDF/PS file is closed.
-  bool SaveTo(const base::FileDescriptor& fd) const;
+  virtual bool SaveTo(const base::FileDescriptor& fd) const;
 
   // The hardcoded margins, in points. These values are based on 72 dpi,
   // with 0.25 margins on top, left, and right, and 0.56 on bottom.
   static const double kTopMarginInInch;
   static const double kRightMarginInInch;
   static const double kBottomMarginInInch;
   static const double kLeftMarginInInch;
 
   // Returns the PdfPsMetafile object that owns the given context. Returns NULL
   // if the context was not created by a PdfPdMetafile object.
   static PdfPsMetafile* FromCairoContext(cairo_t* context);
 
+ protected:
+  PdfPsMetafile();
+
  private:
   // Cleans up all resources.
-  void CleanUpAll();
+  virtual void CleanUpAll();
 
   FileFormat format_;
 
   // Cairo surface and context for entire PDF/PS file.
   cairo_surface_t* surface_;
   cairo_t* context_;
 
   // Buffer stores PDF/PS contents for entire PDF/PS file.
   std::string data_;
   // Buffer stores raw PDF/PS contents set by SetRawPageData.
   std::string raw_override_data_;
 
   DISALLOW_COPY_AND_ASSIGN(PdfPsMetafile);
 };
 
 }  // namespace printing
 
 #endif  // PRINTING_PDF_PS_METAFILE_CAIRO_H_