Create a Factory for NativeMetafile.

printing/native_metafile_linux.h

Index: printing/native_metafile_linux.h
diff --git a/printing/native_metafile_linux.h b/printing/native_metafile_linux.h
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+// Copyright (c) 2009 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 NATIVE_METAFILE_LINUX_H_
+#define NATIVE_METAFILE_LINUX_H_
+
+#include <string>
+
+#include "base/basictypes.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 NativeMetafile  {
+ public:
+  enum FileFormat {
+    PDF,
+    PS,
+  };
+
+  virtual ~NativeMetafile() {};
+
+  // Initializes to a fresh new metafile. Returns true on success.
+  // Note: Only call in the renderer to allocate rendering resources.
+  virtual bool Init() = 0;
+
+  // 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_|.
+  virtual bool Init(const void* src_buffer, uint32 src_buffer_size) = 0;
+
+  // 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.
+  virtual bool SetRawData(const void* src_buffer, uint32 src_buffer_size) = 0;
+
+  virtual FileFormat GetFileFormat() const  = 0;
+
+  // Prepares a new cairo surface/context for rendering a new page.
+  // The unit is in point (=1/72 in).
+  // Returns NULL when failed.
+  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) = 0;
+
+  // 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.
+  virtual bool FinishPage() = 0;
+
+  // Closes resulting PDF/PS file. No further rendering is allowed.
+  virtual void Close() = 0;
+
+  // Returns size of PDF/PS contents stored in buffer |data_|.
+  // This function should ONLY be called after PDF/PS file is closed.
+  virtual uint32 GetDataSize() const = 0;
+
+  // 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.
+  virtual bool GetData(void* dst_buffer, uint32 dst_buffer_size) const = 0;
+
+  // 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.
+  virtual bool SaveTo(const base::FileDescriptor& fd) const = 0;
+
+};
+
+}  // namespace printing
+
+#endif /* NATIVE_METAFILE_LINUX_H_ */