Get semantic capabilities from Print Backend.

printing/backend/print_backend.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_BACKEND_PRINT_BACKEND_H_
 #define PRINTING_BACKEND_PRINT_BACKEND_H_
 
 #include <map>
 #include <string>
 #include <vector>
 
 #include "base/memory/ref_counted.h"
+#include "printing/print_job_constants.h"
 #include "printing/printing_export.h"
 
 namespace base {
 class DictionaryValue;
 }
 
 // This is the interface for platform-specific code for a print backend
 namespace printing {
 
 struct PRINTING_EXPORT PrinterBasicInfo {
   PrinterBasicInfo();
   ~PrinterBasicInfo();
 
   std::string printer_name;
   std::string printer_description;
   int printer_status;
   int is_default;
   std::map<std::string, std::string> options;
 };
 
 typedef std::vector<PrinterBasicInfo> PrinterList;
 
+struct PRINTING_EXPORT PrinterSemanticCapsAndDefaults {
+  PrinterSemanticCapsAndDefaults();
+  ~PrinterSemanticCapsAndDefaults();
+
+  std::string GetAsJson() const;
+
+  // Capabilities.
+  bool color_capable;
+  bool duplex_capable;
+
+  // Current defaults.
+  bool color_default;
+  DuplexMode duplex_default;
+};
+
 struct PRINTING_EXPORT PrinterCapsAndDefaults {
   PrinterCapsAndDefaults();
   ~PrinterCapsAndDefaults();
 
   std::string printer_capabilities;
   std::string caps_mime_type;
   std::string printer_defaults;
   std::string defaults_mime_type;
 };
 
 // PrintBackend class will provide interface for different print backends
 // (Windows, CUPS) to implement. User will call CreateInstance() to
 // obtain available print backend.
 // Please note, that PrintBackend is not platform specific, but rather
 // print system specific. For example, CUPS is available on both Linux and Mac,
 // but not available on ChromeOS, etc. This design allows us to add more
 // functionality on some platforms, while reusing core (CUPS) functions.
 class PRINTING_EXPORT PrintBackend
     : public base::RefCountedThreadSafe<PrintBackend> {
  public:
   // Enumerates the list of installed local and network printers.
   virtual bool EnumeratePrinters(PrinterList* printer_list) = 0;
 
   // Get the default printer name. Empty string if no default printer.
   virtual std::string GetDefaultPrinterName() = 0;
 
+  // Gets the semantic capabilities and defaults for a specific printer.
+  // This is usually a lighter implementation than GetPrinterCapsAndDefaults().
+  // NOTE: on some old platforms (WinXP without XPS pack)
+  // GetPrinterCapsAndDefaults() will fail, while this function will succeed.
+  virtual bool GetPrinterSemanticCapsAndDefaults(
+      const std::string& printer_name,
+      PrinterSemanticCapsAndDefaults* printer_info) = 0;
+
   // Gets the capabilities and defaults for a specific printer.
   virtual bool GetPrinterCapsAndDefaults(

[Albert Bodenhamer, 2012/08/29 23:54:26]

Do we need to keep both?

[gene, 2012/08/30 03:19:03]

Definitely yes. This function is used by CloudPrint. The idea to have 2
functions, one returning semantic subset of caps, while another return a full
list of capabilities.

       const std::string& printer_name,
       PrinterCapsAndDefaults* printer_info) = 0;
 
   // Gets the information about driver for a specific printer.
   virtual std::string GetPrinterDriverInfo(
       const std::string& printer_name) = 0;
 
   // Returns true if printer_name points to a valid printer.
   virtual bool IsValidPrinter(const std::string& printer_name) = 0;
 
   // Allocate a print backend. If |print_backend_settings| is NULL, default
   // settings will be used.
   // Return NULL if no print backend available.
   static scoped_refptr<PrintBackend> CreateInstance(
       const base::DictionaryValue* print_backend_settings);
 
  protected:
   friend class base::RefCountedThreadSafe<PrintBackend>;
   virtual ~PrintBackend();
 };
 
 }  // namespace printing
 
 #endif  // PRINTING_BACKEND_PRINT_BACKEND_H_