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      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 CONTENT_RENDERER_MEDIA_MIDI_MESSAGE_FILTER_H_
      6 #define CONTENT_RENDERER_MEDIA_MIDI_MESSAGE_FILTER_H_
      7 
      8 #include <map>
      9 #include <vector>
     10 
     11 #include "base/memory/scoped_ptr.h"
     12 #include "content/common/content_export.h"
     13 #include "ipc/message_filter.h"
     14 #include "media/midi/midi_port_info.h"
     15 #include "media/midi/midi_result.h"
     16 #include "third_party/WebKit/public/platform/WebMIDIAccessorClient.h"
     17 
     18 namespace base {
     19 class MessageLoopProxy;
     20 }
     21 
     22 namespace content {
     23 
     24 // MessageFilter that handles MIDI messages.
     25 class CONTENT_EXPORT MidiMessageFilter : public IPC::MessageFilter {
     26  public:
     27   explicit MidiMessageFilter(
     28       const scoped_refptr<base::MessageLoopProxy>& io_message_loop);
     29 
     30   // Each client registers for MIDI access here.
     31   // If permission is granted, then the client's
     32   // addInputPort() and addOutputPort() methods will be called,
     33   // giving the client access to receive and send data.
     34   void StartSession(blink::WebMIDIAccessorClient* client);
     35   void RemoveClient(blink::WebMIDIAccessorClient* client);
     36 
     37   // A client will only be able to call this method if it has a suitable
     38   // output port (from addOutputPort()).
     39   void SendMidiData(uint32 port,
     40                     const uint8* data,
     41                     size_t length,
     42                     double timestamp);
     43 
     44   // IO message loop associated with this message filter.
     45   scoped_refptr<base::MessageLoopProxy> io_message_loop() const {
     46     return io_message_loop_;
     47   }
     48 
     49  protected:
     50   virtual ~MidiMessageFilter();
     51 
     52  private:
     53   // Sends an IPC message using |sender_|.
     54   void Send(IPC::Message* message);
     55 
     56   // IPC::MessageFilter override. Called on |io_message_loop|.
     57   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
     58   virtual void OnFilterAdded(IPC::Sender* sender) OVERRIDE;
     59   virtual void OnFilterRemoved() OVERRIDE;
     60   virtual void OnChannelClosing() OVERRIDE;
     61 
     62   // Called when the browser process has approved (or denied) access to
     63   // MIDI hardware.
     64   void OnSessionStarted(int client_id,
     65                         media::MidiResult result,
     66                         media::MidiPortInfoList inputs,
     67                         media::MidiPortInfoList outputs);
     68 
     69   // Called when the browser process has sent MIDI data containing one or
     70   // more messages.
     71   void OnDataReceived(uint32 port,
     72                       const std::vector<uint8>& data,
     73                       double timestamp);
     74 
     75   // From time-to-time, the browser incrementally informs us of how many bytes
     76   // it has successfully sent. This is part of our throttling process to avoid
     77   // sending too much data before knowing how much has already been sent.
     78   void OnAcknowledgeSentData(size_t bytes_sent);
     79 
     80   void HandleSessionStarted(int client_id,
     81                             media::MidiResult result,
     82                             media::MidiPortInfoList inputs,
     83                             media::MidiPortInfoList outputs);
     84 
     85   void HandleDataReceived(uint32 port,
     86                           const std::vector<uint8>& data,
     87                           double timestamp);
     88 
     89   void StartSessionOnIOThread(int client_id);
     90 
     91   void SendMidiDataOnIOThread(uint32 port,
     92                               const std::vector<uint8>& data,
     93                               double timestamp);
     94 
     95   blink::WebMIDIAccessorClient* GetClientFromId(int client_id);
     96 
     97   // IPC sender for Send(); must only be accessed on |io_message_loop_|.
     98   IPC::Sender* sender_;
     99 
    100   // Message loop on which IPC calls are driven.
    101   const scoped_refptr<base::MessageLoopProxy> io_message_loop_;
    102 
    103   // Main thread's message loop.
    104   scoped_refptr<base::MessageLoopProxy> main_message_loop_;
    105 
    106   // Keeps track of all MIDI clients.
    107   // We map client to "client id" used to track permission.
    108   // When access has been approved, we add the input and output ports to
    109   // the client, allowing it to actually receive and send MIDI data.
    110   typedef std::map<blink::WebMIDIAccessorClient*, int> ClientsMap;
    111   ClientsMap clients_;
    112 
    113   // Dishes out client ids.
    114   int next_available_id_;
    115 
    116   size_t unacknowledged_bytes_sent_;
    117 
    118   DISALLOW_COPY_AND_ASSIGN(MidiMessageFilter);
    119 };
    120 
    121 }  // namespace content
    122 
    123 #endif  // CONTENT_RENDERER_MEDIA_MIDI_MESSAGE_FILTER_H_
    124