media/midi/midi_manager.h

   1 // Copyright (c) 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 MEDIA_MIDI_MIDI_MANAGER_H_
   6 #define MEDIA_MIDI_MIDI_MANAGER_H_
   7
   8 #include <set>
   9 #include <vector>
  10
  11 #include "base/basictypes.h"
  12 #include "base/memory/scoped_ptr.h"
  13 #include "base/message_loop/message_loop_proxy.h"
  14 #include "base/synchronization/lock.h"
  15 #include "media/base/media_export.h"
  16 #include "media/midi/midi_port_info.h"
  17
  18 namespace base {
  19 class Thread;
  20 }
  21
  22 namespace media {
  23
  24 // A MIDIManagerClient registers with the MIDIManager to receive MIDI data.
  25 // See MIDIManager::RequestAccess() and MIDIManager::ReleaseAccess()
  26 // for details.
  27 class MEDIA_EXPORT MIDIManagerClient {
  28  public:
  29    virtual ~MIDIManagerClient() {}
  30
  31   // ReceiveMIDIData() is called when MIDI data has been received from the
  32   // MIDI system.
  33   // |port_index| represents the specific input port from input_ports().
  34   // |data| represents a series of bytes encoding one or more MIDI messages.
  35   // |length| is the number of bytes in |data|.
  36   // |timestamp| is the time the data was received, in seconds.
  37   virtual void ReceiveMIDIData(uint32 port_index,
  38                                const uint8* data,
  39                                size_t length,
  40                                double timestamp) = 0;
  41
  42   // AccumulateMIDIBytesSent() is called to acknowledge when bytes have
  43   // successfully been sent to the hardware.
  44   // This happens as a result of the client having previously called
  45   // MIDIManager::DispatchSendMIDIData().
  46   virtual void AccumulateMIDIBytesSent(size_t n) = 0;
  47 };
  48
  49 // Manages access to all MIDI hardware.
  50 class MEDIA_EXPORT MIDIManager {
  51  public:
  52   static MIDIManager* Create();
  53
  54   MIDIManager();
  55   virtual ~MIDIManager();
  56
  57   // A client calls StartSession() to receive and send MIDI data.
  58   // If the session is ready to start, the MIDI system is lazily initialized
  59   // and the client is registered to receive MIDI data.
  60   // Returns |true| if the session succeeds to start.
  61   bool StartSession(MIDIManagerClient* client);
  62
  63   // A client calls ReleaseSession() to stop receiving MIDI data.
  64   void EndSession(MIDIManagerClient* client);
  65
  66   // DispatchSendMIDIData() schedules one or more messages to be sent
  67   // at the given time on a dedicated thread.
  68   // |port_index| represents the specific output port from output_ports().
  69   // |data| represents a series of bytes encoding one or more MIDI messages.
  70   // |length| is the number of bytes in |data|.
  71   // |timestamp| is the time to send the data, in seconds. A value of 0
  72   // means send "now" or as soon as possible.
  73   void DispatchSendMIDIData(MIDIManagerClient* client,
  74                             uint32 port_index,
  75                             const std::vector<uint8>& data,
  76                             double timestamp);
  77
  78   // input_ports() is a list of MIDI ports for receiving MIDI data.
  79   // Each individual port in this list can be identified by its
  80   // integer index into this list.
  81   const MIDIPortInfoList& input_ports() { return input_ports_; }
  82
  83   // output_ports() is a list of MIDI ports for sending MIDI data.
  84   // Each individual port in this list can be identified by its
  85   // integer index into this list.
  86   const MIDIPortInfoList& output_ports() { return output_ports_; }
  87
  88  protected:
  89   // Initializes the MIDI system, returning |true| on success.
  90   virtual bool Initialize() = 0;
  91
  92   // Implements the platform-specific details of sending MIDI data.
  93   // This function runs on MIDISendThread.
  94   virtual void SendMIDIData(MIDIManagerClient* client,
  95                             uint32 port_index,
  96                             const std::vector<uint8>& data,
  97                             double timestamp) = 0;
  98
  99   void AddInputPort(const MIDIPortInfo& info);
 100   void AddOutputPort(const MIDIPortInfo& info);
 101
 102   // Dispatches to all clients.
 103   void ReceiveMIDIData(uint32 port_index,
 104                        const uint8* data,
 105                        size_t length,
 106                        double timestamp);
 107
 108   // Checks if current thread is MIDISendThread.
 109   bool CurrentlyOnMIDISendThread();
 110
 111   bool initialized_;
 112
 113   // Keeps track of all clients who wish to receive MIDI data.
 114   typedef std::set<MIDIManagerClient*> ClientList;
 115   ClientList clients_;
 116
 117   // Protects access to our clients.
 118   base::Lock clients_lock_;
 119
 120   MIDIPortInfoList input_ports_;
 121   MIDIPortInfoList output_ports_;
 122
 123   // |send_thread_| is used to send MIDI data by calling the platform-specific
 124   // API.
 125   scoped_ptr<base::Thread> send_thread_;
 126   scoped_refptr<base::MessageLoopProxy> send_message_loop_;
 127
 128   DISALLOW_COPY_AND_ASSIGN(MIDIManager);
 129 };
 130
 131 }  // namespace media
 132
 133 #endif  // MEDIA_MIDI_MIDI_MANAGER_H_