Web MIDI API back-end (work-in-progress)

media/midi/midi_manager.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 MEDIA_MIDI_MIDI_MANAGER_H_
+#define MEDIA_MIDI_MIDI_MANAGER_H_
+
+#include <set>
+
+#include "base/basictypes.h"
+#include "base/synchronization/lock.h"
+#include "media/base/media_export.h"
+#include "media/midi/midi_port_info.h"
+
+namespace media {
+
+// Manages access to all MIDI hardware.
+class MEDIA_EXPORT MIDIManager {
+ public:
+  enum AccessType {
+    kNoSystemExclusive,
+    kSystemExclusive
+  };
+
+  class Client {

[scherkus (not reviewing), 2013/06/12 01:28:47]

although it is prevalent elsewhere in media code, inner classes like this are
discouraged since they can't be forward declared

typical recommendation is to go with class MIDIManagerClient { ... };

[Chris Rogers, 2013/06/12 20:34:35]

Done.

+   public:
+     virtual ~Client() {}
+     virtual void ReceiveMIDIData(

[scherkus (not reviewing), 2013/06/12 01:28:47]

needs docs

[Chris Rogers, 2013/06/12 20:34:35]

Added comments for this and similar methods in this file.

+         int port_index,
+         const uint8* data,
+         size_t length,
+         double timestamp) = 0;
+  };
+
+  static MIDIManager* Create();
+
+  MIDIManager();
+  virtual ~MIDIManager();
+
+  // If access is approved, lazily initializes the MIDI system
+  // and registers the client to receive MIDI data.
+  // Returns |true| if access is approved.
+  bool RequestAccess(Client* client, int access);
+  void ReleaseAccess(Client* client);
+
+  // Send one or more messages at the given time.
+  virtual void SendMIDIData(int port_index,
+                            const uint8* data,
+                            size_t length,
+                            double timestamp) = 0;
+
+  const MIDIPortInfoList& input_ports() { return input_ports_; }
+  const MIDIPortInfoList& output_ports() { return output_ports_; }
+
+ protected:
+  // Initializes the MIDI system, returning |true| on success.
+  virtual bool Initialize() = 0;
+
+  void AddInputPort(const MIDIPortInfo& info);
+  void AddOutputPort(const MIDIPortInfo& info);
+
+  // Dispatches to all clients.
+  void ReceiveMIDIData(
+      int port_index,
+      const uint8* data,
+      size_t length,
+      double timestamp);
+
+  bool initialized_;
+
+  // Keeps track of all clients who wish to receive MIDI data.
+  typedef std::set<Client*> ClientList;
+  ClientList clients_;
+
+  // Protects access to our clients.
+  base::Lock clients_lock_;
+
+  MIDIPortInfoList input_ports_;
+  MIDIPortInfoList output_ports_;
+
+  DISALLOW_COPY_AND_ASSIGN(MIDIManager);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_MIDI_MIDI_MANAGER_H_