Implement chrome.brailleDisplayPrivate API

chrome/browser/extensions/api/braille_display_private/braille_controller_brlapi.cc

+// 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.
+
+#include "chrome/browser/extensions/api/braille_display_private/braille_controller.h"
+
+#include <algorithm>
+#include <cerrno>
+#include <cstring>
+#include <vector>
+
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/files/file_path_watcher.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/singleton.h"
+#include "base/observer_list.h"
+#include "base/time/time.h"
+#include "chrome/browser/extensions/api/braille_display_private/brlapi_connection.h"
+#include "content/public/browser/browser_thread.h"
+#include "library_loaders/libbrlapi.h"
+
+namespace extensions {
+using content::BrowserThread;
+using base::TimeDelta;
+namespace api {
+namespace braille_display_private {
+
+namespace {
+// Delay between detecting a directory update and trying to connect
+// to the brlapi.
+const int64 kConnectionDelayMs = 1000;
+}
+
+class BrailleControllerImpl : public BrailleController {
+ public:
+  static BrailleControllerImpl* GetInstance();
+  virtual scoped_ptr<base::DictionaryValue> GetDisplayState() OVERRIDE;
+  virtual void WriteDots(const std::string& cells) OVERRIDE;
+  virtual void AddObserver(BrailleObserver* observer) OVERRIDE;
+  virtual void RemoveObserver(BrailleObserver* observer) OVERRIDE;
+  virtual void SetCreateBrlapiConnectionForTesting(
+      const CreateBrlapiConnectionFunction& callback) OVERRIDE;
+
+ private:
+  BrailleControllerImpl();
+  virtual ~BrailleControllerImpl();
+  void TryLoadLibBrlApi();
+  void StartConnecting();
+  void OnSocketDirChanged(const base::FilePath& path, bool error);
+  void TryToConnect();
+  scoped_ptr<BrlapiConnection> CreateBrlapiConnection();
+  void DispatchKeys();
+  scoped_ptr<KeyEvent> MapKeyCode(brlapi_keyCode_t code);
+  void DispatchKeyEvent(scoped_ptr<KeyEvent> event);
+
+  LibBrlapiLoader libbrlapi_loader_;
+  CreateBrlapiConnectionFunction create_brlapi_connection_function_;
+
+  // Manipulated on the IO thread.
+  scoped_ptr<BrlapiConnection> connection_;
+  base::FilePathWatcher file_path_watcher_;
+
+  // Manipulated on the UI thread.
+  ObserverList<BrailleObserver> observers_;
+  bool watching_dir_;
+
+  friend struct DefaultSingletonTraits<BrailleControllerImpl>;
+
+  DISALLOW_COPY_AND_ASSIGN(BrailleControllerImpl);
+};
+
+BrailleController::BrailleController() {
+}
+
+BrailleController::~BrailleController() {
+}
+
+// static
+BrailleController* BrailleController::GetInstance() {
+  return BrailleControllerImpl::GetInstance();
+}
+
+// static
+BrailleControllerImpl* BrailleControllerImpl::GetInstance() {
+  return Singleton<BrailleControllerImpl,
+                   LeakySingletonTraits<BrailleControllerImpl> >::get();
+}
+
+BrailleControllerImpl::BrailleControllerImpl()
+    : watching_dir_(false) {
+  create_brlapi_connection_function_ = base::Bind(
+      &BrailleControllerImpl::CreateBrlapiConnection,
+      base::Unretained(this));
+}
+
+BrailleControllerImpl::~BrailleControllerImpl() {
+}
+
+void BrailleControllerImpl::TryLoadLibBrlApi() {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
+  if (libbrlapi_loader_.loaded())
+    return;
+  // These versions of libbrlapi work the same for the functions we
+  // are using.  (0.6.0 adds brlapi_writeWText).
+  static const char* kSupportedVersions[] = {
+    "libbrlapi.so.0.5",
+    "libbrlapi.so.0.6"
+  };
+  for (size_t i = 0; i < arraysize(kSupportedVersions); ++i) {
+    if (libbrlapi_loader_.Load(kSupportedVersions[i]))
+      return;
+  }
+  LOG(WARNING) << "Couldn't load libbrlapi: " << strerror(errno);
+}
+
+scoped_ptr<base::DictionaryValue> BrailleControllerImpl::GetDisplayState() {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
+  if (!watching_dir_) {
+    watching_dir_ = true;
+    StartConnecting();
+  }
+  DisplayState displayState;
+  if (connection_.get() && connection_->Connected()) {
+    size_t size;
+    if (!connection_->GetDisplaySize(&size)) {
+      connection_->Disconnect();
+    } else if (size > 0) {  // size == 0 means no display present.
+      displayState.available = true;
+      displayState.text_cell_count.reset(new int(size));
+    }
+  }
+  return displayState.ToValue().Pass();
+}
+
+void BrailleControllerImpl::WriteDots(const std::string& cells) {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
+  if (connection_ && connection_->Connected()) {
+    size_t size;
+    if (!connection_->GetDisplaySize(&size)) {
+      connection_->Disconnect();
+    }
+    std::vector<unsigned char> sizedCells(size);
+    std::memcpy(&sizedCells[0], cells.data(), std::min(cells.size(), size));
+    if (size > cells.size())
+      std::fill(sizedCells.begin() + cells.size(), sizedCells.end(), 0);
+    if (!connection_->WriteDots(&sizedCells[0]))
+      connection_->Disconnect();
+  }
+}
+
+void BrailleControllerImpl::AddObserver(BrailleObserver* observer) {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  observers_.AddObserver(observer);
+}
+
+void BrailleControllerImpl::RemoveObserver(BrailleObserver* observer) {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  observers_.RemoveObserver(observer);
+}
+
+void BrailleControllerImpl::SetCreateBrlapiConnectionForTesting(
+    const CreateBrlapiConnectionFunction& function) {
+  if (function.is_null()) {
+    create_brlapi_connection_function_ = base::Bind(
+        &BrailleControllerImpl::CreateBrlapiConnection,
+        base::Unretained(this));
+  } else {
+    create_brlapi_connection_function_ = function;
+  }
+}
+
+void BrailleControllerImpl::StartConnecting() {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
+  TryLoadLibBrlApi();
+  if (!libbrlapi_loader_.loaded()) {
+    return;
+  }
+  base::FilePath brlapi_dir(BRLAPI_SOCKETPATH);
+  if (!file_path_watcher_.Watch(
+          brlapi_dir, false, base::Bind(
+              &BrailleControllerImpl::OnSocketDirChanged,
+              base::Unretained(this)))) {
+    LOG(WARNING) << "Couldn't watch brlapi directory " << BRLAPI_SOCKETPATH;
+    return;
+  }
+  TryToConnect();
+}
+
+void BrailleControllerImpl::OnSocketDirChanged(const base::FilePath& path,
+                                               bool error) {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
+  DCHECK(libbrlapi_loader_.loaded());
+  if (error) {
+    LOG(ERROR) << "Error watching brlapi directory: " << path.value();
+    return;
+  }
+  LOG(INFO) << "BrlAPI directory changed";
+  BrowserThread::PostDelayedTask(BrowserThread::IO, FROM_HERE,
+                                 base::Bind(
+                                     &BrailleControllerImpl::TryToConnect,
+                                     base::Unretained(this)),
+                                 TimeDelta::FromMilliseconds(
+                                     kConnectionDelayMs));
+}
+
+void BrailleControllerImpl::TryToConnect() {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO));
+  DCHECK(libbrlapi_loader_.loaded());
+  if (!connection_.get())
+    connection_ = create_brlapi_connection_function_.Run();
+  if (connection_.get() && !connection_->Connected()) {
+    if (!connection_->Connect(base::Bind(
+            &BrailleControllerImpl::DispatchKeys,
+            base::Unretained(this))))
+      LOG(WARNING) << "Couldn't connect to brlapi";
+  }
+}
+
+scoped_ptr<BrlapiConnection> BrailleControllerImpl::CreateBrlapiConnection() {
+  DCHECK(libbrlapi_loader_.loaded());
+  return BrlapiConnection::Create(&libbrlapi_loader_);
+}
+
+scoped_ptr<KeyEvent> BrailleControllerImpl::MapKeyCode(brlapi_keyCode_t code) {
+  brlapi_expandedKeyCode_t expanded;
+  if (libbrlapi_loader_.brlapi_expandKeyCode(code, &expanded) != 0) {
+    LOG(ERROR) << "Couldn't expand key code " << code;
+    return scoped_ptr<KeyEvent>();
+  }
+  scoped_ptr<KeyEvent> result(new KeyEvent);
+  result->command = KEY_COMMAND_NONE;
+  switch (expanded.type) {
+    case BRLAPI_KEY_TYPE_CMD:
+      switch (expanded.command) {
+        case BRLAPI_KEY_CMD_LNUP:
+          result->command = KEY_COMMAND_LINE_UP;
+          break;
+        case BRLAPI_KEY_CMD_LNDN:
+          result->command = KEY_COMMAND_LINE_DOWN;
+          break;
+        case BRLAPI_KEY_CMD_FWINLT:
+          result->command = KEY_COMMAND_PAN_LEFT;
+          break;
+        case BRLAPI_KEY_CMD_FWINRT:
+          result->command = KEY_COMMAND_PAN_RIGHT;
+          break;
+        case BRLAPI_KEY_CMD_TOP:
+          result->command = KEY_COMMAND_TOP;
+          break;
+        case BRLAPI_KEY_CMD_BOT:
+          result->command = KEY_COMMAND_BOTTOM;
+          break;
+        case BRLAPI_KEY_CMD_ROUTE:
+          result->command = KEY_COMMAND_ROUTING;
+          result->display_position.reset(new int(expanded.argument));
+          break;
+        case BRLAPI_KEY_CMD_PASSDOTS:
+          result->command = KEY_COMMAND_DOTS;
+          // The 8 low-order bits in the argument contains the dots.
+          result->braille_dots.reset(new int(expanded.argument & 0xf));
+          if ((expanded.argument & BRLAPI_DOTC) != 0)
+            result->space_key.reset(new bool(true));
+          break;
+      }
+      break;
+  }
+  if (result->command == KEY_COMMAND_NONE)
+    result.reset();
+  return result.Pass();
+}
+
+void BrailleControllerImpl::DispatchKeys() {
+  DCHECK(connection_.get());
+  brlapi_keyCode_t code;
+  while (true) {
+    int result = connection_->ReadKey(&code);
+    if (result < 0) {  // Error.
+      brlapi_error_t* err = connection_->BrlapiError();
+      if (err->brlerrno == BRLAPI_ERROR_LIBCERR && err->libcerrno == EINTR)
+        continue;
+      // Disconnect on other errors.
+      LOG(ERROR) << "BrlAPI error: " << connection_->BrlapiStrError();
+      connection_->Disconnect();
+      return;
+    } else if (result == 0) { // No more data.
+      return;
+    }
+    scoped_ptr<KeyEvent> event = MapKeyCode(code);
+    if (event)
+      DispatchKeyEvent(event.Pass());
+  }
+}
+
+void BrailleControllerImpl::DispatchKeyEvent(scoped_ptr<KeyEvent> event) {
+  if (!BrowserThread::CurrentlyOn(BrowserThread::UI)) {
+    BrowserThread::PostTask(BrowserThread::UI, FROM_HERE,
+                            base::Bind(
+                                &BrailleControllerImpl::DispatchKeyEvent,
+                                base::Unretained(this),
+                                base::Passed(&event)));
+    return;
+  }
+  FOR_EACH_OBSERVER(BrailleObserver, observers_, OnKeyEvent(*event));
+}
+
+}  // namespace braille_display_private
+}  // namespace api
+}  // namespace extensions