Implement chrome.brailleDisplayPrivate API

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

+// Copyright (c) 2013 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 CHROME_BROWSER_EXTENSIONS_API_BRAILLE_DISPLAY_PRIVATE_BRLAPI_BRLAPI_CONNECTION_H_
+#define CHROME_BROWSER_EXTENSIONS_API_BRAILLE_DISPLAY_PRIVATE_BRLAPI_BRLLAPI_CONNECTION_H_
+
+#include "base/basictypes.h"
+#include "base/callback_forward.h"
+#include "base/memory/scoped_ptr.h"
+#include "library_loaders/libbrlapi.h"
+
+namespace extensions {
+namespace api {
+namespace braille_display_private {
+
+// A connection to the brlapi server.  See brlapi.h for more information
+// about the semantics of the methods in this class.
+class BrlapiConnection {
+ public:
+  typedef base::Closure OnDataReadyCallback;
+
+  static scoped_ptr<BrlapiConnection> Create(LibBrlapiLoader* loader);
+
+  virtual ~BrlapiConnection();
+
+  virtual bool Connect(const OnDataReadyCallback& onDataReady) = 0;
+
+  virtual void Disconnect() = 0;
+
+  virtual bool Connected() = 0;
+
+  // Gets the last brlapi error on this thread.
+  // This works ismilar to errno in C.  There's one thread-local error
+  // value, meaning that this method should be called after any
+  // other method of this class that can return an error without calling
+  // another method in between.  This class is not thread safe.
+  virtual brlapi_error_t* BrlapiError() = 0;
+
+  // Gets a description of the last brlapi error for this thread, useful
+  // for logging.
+  virtual std::string BrlapiStrError() = 0;
+
+  // Gets the total size of the display, which may be 0 if no display is
+  // present, returning true on success.  Note that this is cached in the
+  // brlapi client so it is cheap.
+  virtual bool GetDisplaySize(size_t* size) = 0;
+
+  // Sends the specified cells to the display.  The array size must
+  // be equal to what GetDisplaySize() last returned for this connection.
+  virtual bool WriteDots(const unsigned char* cells) = 0;
+
+  // Reads the next keyboard command, returning true on success.
+  // Returns < 0 on error, 0 if no more keys are pending and > 0
+  // on success, in which case keyCode will be set to the key command
+  // value.
+  virtual int ReadKey(brlapi_keyCode_t* keyCode) = 0;
+
+ protected:
+  BrlapiConnection();
+  DISALLOW_COPY_AND_ASSIGN(BrlapiConnection);
+};
+
+}  // braille_display_private
+}  // api
+}  // extensions
+
+#endif // CHROME_BROWSER_EXTENSIONS_API_BRAILLE_DISPLAY_PRIVATE_BRLAPI_BRLAPI_CONNECTION_H_