Print directly to CUPS using the IPP APIs

printing/metafile.h

 // Copyright (c) 2012 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_METAFILE_H_
 #define PRINTING_METAFILE_H_
 
 #include <stdint.h>
 
 #include <vector>
@@ skipping 68 matching lines @@
 #elif defined(OS_MACOSX)
   // Renders the given page into |rect| in the given context.
   // Pages use a 1-based index. The rendering uses the arguments in
   // |params| to determine scaling, translation, and rotation.
   virtual bool RenderPage(unsigned int page_number,
                           gfx::NativeDrawingContext context,
                           const CGRect rect,
                           const MacRenderPageParams& params) const = 0;
 #endif  // if defined(OS_WIN)
 
+#if defined(OS_CHROMEOS)
+  // Populates the buffer with the underlying data. This function should ONLY be
+  // called after the metafile is closed. Returns true if writing succeeded.
+  virtual bool GetDataAsVector(std::vector<char>* buffer) const = 0;
+#endif  // defined(OS_CHROMEOS)
+
   // Saves the underlying data to the given file. This function should ONLY be
   // called after the metafile is closed. Returns true if writing succeeded.
   virtual bool SaveTo(base::File* file) const = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MetafilePlayer);
 };
 
 // This class creates a graphics context that renders into a data stream
 // (usually PDF or EMF).
@@ skipping 49 matching lines @@
   // "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(gfx::NativeDrawingContext hdc,
                         const RECT* rect) const = 0;
 #endif  // OS_WIN
 
+#if defined(OS_CHROMEOS)
+  bool GetDataAsVector(std::vector<char>* buffer) const override;
+#else
   bool GetDataAsVector(std::vector<char>* buffer) const;

[Lei Zhang, 2016/07/20 01:26:56]

This feels a bit weird. Why don't we just remove the OS_CHROME ifdefs? I think
that's cleaner, even it it adds an extra method that does not get used on other
platforms.

[skau, 2016/07/22 23:36:13]

It happens that there's a Windows implementation of MetafilePlayer.  But I'll go
implement it there.

+#endif  // defined(OS_CHROMEOS)
 
   bool SaveTo(base::File* file) const override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(Metafile);
 };
 
 }  // namespace printing
 
 #endif  // PRINTING_METAFILE_H_