Unifying NativeMetafile class interface (as much as possible) for Linux, Mac, Win

printing/native_metafile_win.h

-// Copyright (c) 2011 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_NATIVE_METAFILE_WIN_H_
-#define PRINTING_NATIVE_METAFILE_WIN_H_
-
-#include <windows.h>
-#include <vector>
-
-#include "base/basictypes.h"
-
-class FilePath;
-
-namespace gfx {
-class Rect;
-}
-
-namespace printing {
-
-// Simple wrapper class that manages a data stream and its virtual HDC.
-class NativeMetafile {
- public:
-  virtual ~NativeMetafile() {}
-
-  // Initializes the data stream with the data in |src_buffer|. Returns
-  // true on success.
-  virtual bool Init(const void* src_buffer, uint32 src_buffer_size) = 0;
-
-  // Generates a virtual HDC that will record every GDI commands and compile it
-  // in a EMF data stream.
-  // hdc is used to setup the default DPI and color settings. hdc is optional.
-  // rect specifies the dimensions (in .01-millimeter units) of the EMF. rect is
-  // optional.
-  virtual bool CreateDc(HDC sibling, const RECT* rect) = 0;
-
-  // Similar to the above method but the metafile is backed by a file.
-  virtual bool CreateFileBackedDc(HDC sibling,
-                                  const RECT* rect,
-                                  const FilePath& path) = 0;
-
-  // Load a data stream from file.
-  virtual bool CreateFromFile(const FilePath& metafile_path) = 0;
-
-  // TODO(maruel): CreateFromFile(). If ever used. Maybe users would like to
-  // have the ability to save web pages to an EMF file? Afterward, it is easy to
-  // convert to PDF.
-
-  // Closes the HDC created by CreateDc() and generates the compiled EMF
-  // data.
-  virtual bool CloseDc() = 0;
-
-  // Closes the EMF data handle when it is not needed anymore.
-  virtual void CloseEmf() = 0;
-
-  // "Plays" the EMF buffer in a HDC. It is the same effect as calling the
-  // original GDI function that were called when recording the EMF. |rect| is in
-  // "logical units" and is optional. If |rect| is NULL, the natural EMF bounds
-  // are used.
-  // Note: Windows has been known to have stack buffer overflow in its GDI
-  // functions, whether used directly or indirectly through precompiled EMF
-  // data. We have to accept the risk here. Since it is used only for printing,
-  // it requires user intervention.
-  virtual bool Playback(HDC hdc, const RECT* rect) const = 0;
-
-  // The slow version of Playback(). It enumerates all the records and play them
-  // back in the HDC. The trick is that it skip over the records known to have
-  // issue with some printers. See Emf::Record::SafePlayback implementation for
-  // details.
-  virtual bool SafePlayback(HDC hdc) const = 0;
-
-  // Retrieves the bounds of the painted area by this EMF buffer. This value
-  // should be passed to Playback to keep the exact same size.
-  virtual gfx::Rect GetBounds() const = 0;
-
-  // Retrieves the data stream size.
-  virtual uint32 GetDataSize() const = 0;
-
-  // Retrieves the data stream.
-  virtual bool GetData(void* buffer, uint32 size) const = 0;
-
-  // Retrieves the data stream. It is an helper function.
-  virtual bool GetData(std::vector<uint8>* buffer) const = 0;
-
-  virtual HENHMETAFILE emf() const = 0;
-
-  virtual HDC hdc() const = 0;
-
-  // Inserts a custom GDICOMMENT records indicating StartPage/EndPage calls
-  // (since StartPage and EndPage do not work in a metafile DC). Only valid
-  // when hdc_ is non-NULL.
-  virtual bool StartPage() = 0;
-  virtual bool EndPage() = 0;
-
-  // Saves the EMF data to a file as-is. It is recommended to use the .emf file
-  // extension but it is not enforced. This function synchronously writes to the
-  // file. For testing only.
-  virtual bool SaveTo(const std::wstring& filename) const = 0;
-};
-
-}  // namespace printing
-
-#endif  // PRINTING_NATIVE_METAFILE_WIN_H_