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

printing/emf_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_EMF_WIN_H_
 #define PRINTING_EMF_WIN_H_
 
 #include <windows.h>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/gtest_prod_util.h"
-#include "printing/native_metafile_win.h"
+#include "printing/native_metafile.h"
 
 class FilePath;
 
-namespace gfx {
-class Rect;
-}
-
 namespace printing {
 
-// Simple wrapper class that manage an EMF data stream and its virtual HDC.
 class Emf : public NativeMetafile {
  public:
   class Record;
   class Enumerator;
   struct EnumerationContext;
 
   virtual ~Emf();
 
-  // Initializes the Emf with the data in |src_buffer|. Returns true on success.
+  //NativeMetafile methods.
+  virtual bool Init() { return true; }
   virtual bool Init(const void* src_buffer, uint32 src_buffer_size);
 
-  // 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);
+  virtual uint32 GetDataSize() const;
+  virtual bool GetData(void* buffer, uint32 size) const;
 
-  // Similar to the above method but the metafile is backed by a file.
-  virtual bool CreateFileBackedDc(HDC sibling,
+  virtual bool FinishPage();
+  virtual void Close();
+
+  // 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 FilePath& file_path) const;
+
+  // Should be passed to Playback to keep the exact same size.
+  virtual gfx::Rect GetPageBounds(unsigned int page_number) const;
+
+  virtual unsigned int GetPageCount() const {
+    return 1;
+  }
+
+  virtual bool StartPage();
+
+  virtual bool CreateDc(PlatformContext sibling, const RECT* rect);
+  virtual bool CreateFileBackedDc(PlatformContext sibling,
                                   const RECT* rect,
                                   const FilePath& path);
+  virtual bool CreateFromFile(const FilePath& file_path);
 
-    // Load an EMF file.
-  virtual bool CreateFromFile(const FilePath& metafile_path);
-
-  // 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 or PS.
-
-  // Closes the HDC created by CreateDc() and generates the compiled EMF
-  // data.
   virtual bool CloseDc();
 
-  // Closes the EMF data handle when it is not needed anymore.
-  virtual void CloseEmf();
+  virtual bool Playback(PlatformContext hdc, const RECT* rect) const;
+  virtual bool SafePlayback(PlatformContext hdc) const;
 
-  // "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;
-
-  // 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;
-
-  // 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;
-
-  // Retrieves the EMF stream size.
-  virtual uint32 GetDataSize() const;
-
-  // Retrieves the EMF stream.
-  virtual bool GetData(void* buffer, uint32 size) const;
-
-  // Retrieves the EMF stream. It is an helper function.
   virtual bool GetData(std::vector<uint8>* buffer) const;
 
   virtual HENHMETAFILE emf() const {
     return emf_;
   }
 
-  virtual HDC hdc() const {
+  virtual PlatformContext hdc() const {
     return hdc_;
   }
 
-  // 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();
-  virtual bool EndPage();
-
-  // 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;
-
  protected:
   Emf();
 
  private:
   friend class NativeMetafileFactory;
   FRIEND_TEST_ALL_PREFIXES(EmfTest, DC);
   FRIEND_TEST_ALL_PREFIXES(EmfTest, FileBackedDC);
   FRIEND_TEST_ALL_PREFIXES(EmfPrintingTest, Enumerate);
   FRIEND_TEST_ALL_PREFIXES(EmfPrintingTest, PageBreak);
 
   // Playbacks safely one EMF record.
-  static int CALLBACK SafePlaybackProc(HDC hdc,
+  static int CALLBACK SafePlaybackProc(PlatformContext hdc,
                                        HANDLETABLE* handle_table,
                                        const ENHMETARECORD* record,
                                        int objects_count,
                                        LPARAM param);
 
   // Compiled EMF data handle.
   HENHMETAFILE emf_;
 
   // Valid when generating EMF data through a virtual HDC.
-  HDC hdc_;
+  PlatformContext hdc_;
 
   DISALLOW_COPY_AND_ASSIGN(Emf);
 };
 
 struct Emf::EnumerationContext {
   HANDLETABLE* handle_table;
   int objects_count;
-  HDC hdc;
+  PlatformContext hdc;
 };
 
 // One EMF record. It keeps pointers to the EMF buffer held by Emf::emf_.
-// The entries become invalid once Emf::CloseEmf() is called.
+// The entries become invalid once Emf::Close() is called.
 class Emf::Record {
  public:
   // Plays the record.
   bool Play() const;
 
   // Plays the record working around quirks with SetLayout,
   // SetWorldTransform and ModifyWorldTransform. See implementation for details.
   bool SafePlayback(const XFORM* base_matrix) const;
 
   // Access the underlying EMF record.
@@ skipping 14 matching lines @@
 // over records that are unsupported on a specific printer or to play back
 // only a part of an EMF buffer.
 class Emf::Enumerator {
  public:
   // Iterator type used for iterating the records.
   typedef std::vector<Record>::const_iterator const_iterator;
 
   // Enumerates the records at construction time. |hdc| and |rect| are
   // both optional at the same time or must both be valid.
   // Warning: |emf| must be kept valid for the time this object is alive.
-  Enumerator(const Emf& emf, HDC hdc, const RECT* rect);
+  Enumerator(const Emf& emf, PlatformContext hdc, const RECT* rect);
 
   // Retrieves the first Record.
   const_iterator begin() const;
 
   // Retrieves the end of the array.
   const_iterator end() const;
 
  private:
   // Processes one EMF record and saves it in the items_ array.
-  static int CALLBACK EnhMetaFileProc(HDC hdc,
+  static int CALLBACK EnhMetaFileProc(PlatformContext hdc,
                                       HANDLETABLE* handle_table,
                                       const ENHMETARECORD* record,
                                       int objects_count,
                                       LPARAM param);
 
   // The collection of every EMF records in the currently loaded EMF buffer.
   // Initialized by Enumerate(). It keeps pointers to the EMF buffer held by
-  // Emf::emf_. The entries become invalid once Emf::CloseEmf() is called.
+  // Emf::emf_. The entries become invalid once Emf::Close() is called.
   std::vector<Record> items_;
 
   EnumerationContext context_;
 
   DISALLOW_COPY_AND_ASSIGN(Enumerator);
 };
 
 }  // namespace printing
 
 #endif  // PRINTING_EMF_WIN_H_