text: // 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 CONTENT_BROWSER_GAMEPAD_GAMEPAD_PROVIDER_H_
  #define CONTENT_BROWSER_GAMEPAD_GAMEPAD_PROVIDER_H_
  
  #include <utility>
  #include <vector>
  
  #include "base/callback_forward.h"
  #include "base/memory/ref_counted.h"
  #include "base/memory/scoped_ptr.h"
  #include "base/memory/shared_memory.h"
  #include "base/memory/weak_ptr.h"
  #include "base/message_loop/message_loop_proxy.h"
  #include "base/synchronization/lock.h"
  #include "base/system_monitor/system_monitor.h"
  #include "content/common/content_export.h"
  #include "third_party/WebKit/public/platform/WebGamepads.h"
  
  namespace base {
  class MessageLoopProxy;
  class Thread;
  }
  
  namespace content {
  
  class GamepadDataFetcher;
  struct GamepadHardwareBuffer;
  
  class CONTENT_EXPORT GamepadProvider :
    public base::SystemMonitor::DevicesChangedObserver {
   public:
    GamepadProvider();
  
    // Manually specifies the data fetcher. Used for testing.
    explicit GamepadProvider(scoped_ptr<GamepadDataFetcher> fetcher);
  
    ~GamepadProvider() override;
  
    // Returns the shared memory handle of the gamepad data duplicated into the
    // given process.
    base::SharedMemoryHandle GetSharedMemoryHandleForProcess(
        base::ProcessHandle renderer_process);
  
    void GetCurrentGamepadData(blink::WebGamepads* data);
  
    // Pause and resume the background polling thread. Can be called from any
    // thread.
    void Pause();
    void Resume();
  
    // Registers the given closure for calling when the user has interacted with
    // the device. This callback will only be issued once.
    void RegisterForUserGesture(const base::Closure& closure);
  
    // base::SystemMonitor::DevicesChangedObserver implementation.
    void OnDevicesChanged(base::SystemMonitor::DeviceType type) override;
  
   private:
    void Initialize(scoped_ptr<GamepadDataFetcher> fetcher);
  
    // Method for setting up the platform-specific data fetcher. Takes ownership
    // of |fetcher|.
    void DoInitializePollingThread(scoped_ptr<GamepadDataFetcher> fetcher);
  
    // Method for sending pause hints to the low-level data fetcher. Runs on
    // polling_thread_.
    void SendPauseHint(bool paused);
  
    // Method for polling a GamepadDataFetcher. Runs on the polling_thread_.
    void DoPoll();
    void ScheduleDoPoll();
  
    void OnGamepadConnectionChange(bool connected,
                                   int index,
                                   const blink::WebGamepad& pad);
    void DispatchGamepadConnectionChange(bool connected,
                                         int index,
                                         const blink::WebGamepad& pad);
  
    GamepadHardwareBuffer* SharedMemoryAsHardwareBuffer();
  
    // Checks the gamepad state to see if the user has interacted with it.
    void CheckForUserGesture();
  
    enum { kDesiredSamplingIntervalMs = 16 };
  
    // Keeps track of when the background thread is paused. Access to is_paused_
    // must be guarded by is_paused_lock_.
    base::Lock is_paused_lock_;
    bool is_paused_;
  
    // Keep track of when a polling task is schedlued, so as to prevent us from
    // accidentally scheduling more than one at any time, when rapidly toggling
    // |is_paused_|.
    bool have_scheduled_do_poll_;
  
    // Lists all observers registered for user gestures, and the thread which
    // to issue the callbacks on. Since we always issue the callback on the
    // thread which the registration happened, and this class lives on the I/O
    // thread, the message loop proxies will normally just be the I/O thread.
    // However, this will be the main thread for unit testing.
    base::Lock user_gesture_lock_;
    struct ClosureAndThread {
      ClosureAndThread(const base::Closure& c,
                       const scoped_refptr<base::MessageLoopProxy>& m);
      ~ClosureAndThread();
  
      base::Closure closure;
      scoped_refptr<base::MessageLoopProxy> message_loop;
    };
    typedef std::vector<ClosureAndThread> UserGestureObserverVector;
    UserGestureObserverVector user_gesture_observers_;
  
    // Updated based on notification from SystemMonitor when the system devices
    // have been updated, and this notification is passed on to the data fetcher
    // to enable it to avoid redundant (and possibly expensive) is-connected
    // tests. Access to devices_changed_ must be guarded by
    // devices_changed_lock_.
    base::Lock devices_changed_lock_;
    bool devices_changed_;
  
    bool ever_had_user_gesture_;
  
    class PadState {
     public:
      PadState() {
        SetDisconnected();
      }
  
      bool Match(const blink::WebGamepad& pad) const;
      void SetPad(const blink::WebGamepad& pad);
      void SetDisconnected();
      void AsWebGamepad(blink::WebGamepad* pad);
  
      bool connected() const { return connected_; }
  
     private:
      bool connected_;
      unsigned axes_length_;
      unsigned buttons_length_;
      blink::WebUChar id_[blink::WebGamepad::idLengthCap];
      blink::WebUChar mapping_[blink::WebGamepad::mappingLengthCap];
    };
  
    // Used to detect connections and disconnections.
    scoped_ptr<PadState[]> pad_states_;
  
    // Only used on the polling thread.
    scoped_ptr<GamepadDataFetcher> data_fetcher_;
  
    base::Lock shared_memory_lock_;
    base::SharedMemory gamepad_shared_memory_;
  
    // Polling is done on this background thread.
    scoped_ptr<base::Thread> polling_thread_;
  
    static GamepadProvider* instance_;
  
    DISALLOW_COPY_AND_ASSIGN(GamepadProvider);
  };
  
  }  // namespace content
  
  #endif  // CONTENT_BROWSER_GAMEPAD_GAMEPAD_PROVIDER_H_
  