chrome/browser/extensions/api/braille_display_private/brlapi_connection.h

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CHROME_BROWSER_EXTENSIONS_API_BRAILLE_DISPLAY_PRIVATE_BRLAPI_CONNECTION_H_
   6 #define CHROME_BROWSER_EXTENSIONS_API_BRAILLE_DISPLAY_PRIVATE_BRLAPI_CONNECTION_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/callback_forward.h"
  10 #include "base/memory/scoped_ptr.h"
  11 #include "library_loaders/libbrlapi.h"
  12
  13 namespace extensions {
  14 namespace api {
  15 namespace braille_display_private {
  16
  17 // A connection to the brlapi server.  See brlapi.h for more information
  18 // about the semantics of the methods in this class.
  19 class BrlapiConnection {
  20  public:
  21   typedef base::Closure OnDataReadyCallback;
  22
  23   enum ConnectResult {
  24     CONNECT_ERROR_RETRY,
  25     CONNECT_ERROR_NO_RETRY,
  26     CONNECT_SUCCESS,
  27   };
  28
  29   static scoped_ptr<BrlapiConnection> Create(LibBrlapiLoader* loader);
  30
  31   virtual ~BrlapiConnection();
  32
  33   virtual ConnectResult Connect(const OnDataReadyCallback& onDataReady) = 0;
  34
  35   virtual void Disconnect() = 0;
  36
  37   virtual bool Connected() = 0;
  38
  39   // Gets the last brlapi error on this thread.
  40   // This works ismilar to errno in C.  There's one thread-local error
  41   // value, meaning that this method should be called after any
  42   // other method of this class that can return an error without calling
  43   // another method in between.  This class is not thread safe.
  44   virtual brlapi_error_t* BrlapiError() = 0;
  45
  46   // Gets a description of the last brlapi error for this thread, useful
  47   // for logging.
  48   virtual std::string BrlapiStrError() = 0;
  49
  50   // Gets the total size of the display, which may be 0 if no display is
  51   // present, returning true on success.  Note that this is cached in the
  52   // brlapi client so it is cheap.
  53   virtual bool GetDisplaySize(size_t* size) = 0;
  54
  55   // Sends the specified cells to the display.  The array size must
  56   // be equal to what GetDisplaySize() last returned for this connection.
  57   virtual bool WriteDots(const unsigned char* cells) = 0;
  58
  59   // Reads the next keyboard command, returning true on success.
  60   // Returns < 0 on error, 0 if no more keys are pending and > 0
  61   // on success, in which case keyCode will be set to the key command
  62   // value.
  63   virtual int ReadKey(brlapi_keyCode_t* keyCode) = 0;
  64
  65  protected:
  66   BrlapiConnection();
  67   DISALLOW_COPY_AND_ASSIGN(BrlapiConnection);
  68 };
  69
  70 }  // namespace braille_display_private
  71 }  // namespace api
  72 }  // namespace extensions
  73
  74 #endif  // CHROME_BROWSER_EXTENSIONS_API_BRAILLE_DISPLAY_PRIVATE_BRLAPI_CONNECTION_H_