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Posted 16 Aug 2002

Wrapper Library for Windows MIDI API

, 28 Jan 2008
A small library encapsulating the Windows MIDI API
MIDIDevDemo v2
MIDIDevDemo v2.clw
MIDIDevDemo v2.dsp
MIDIDevDemo v2.dsw
MIDIDevDemo v2.ncb
MIDIDevDemo v2.opt
MIDIDevDemo v2.plg
MIDIDevDemo v2.ico
MIDIWrapper Source
MIDIDevDemo v2.clw
MIDIDevDemo v2.dsp
MIDIDevDemo v2.dsw
MIDIDevDemo v2.ico
MIDIWrapper Source

 * MIDIOutDevice.h - Interface for CMIDIOutDevice and related classes.
 * Copyright (C) 2002 Leslie Sanford
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * Lesser General Public License for more details.
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 * Contact:
 * Last modified: 08/19/2003
 * Note: You must link to the winmm.lib to use these classes.

#pragma warning(disable:4786) // Disable annoying template warnings

// Dependencies

// Necessary for Windows data types
#include "stdafx.h"
#include <mmsystem.h>

// Necessary for exception classes derived from std::exception
#include <exception> 

// Necessary for header queue used by CHeaderQueue
#include <queue>

namespace midi
    // Class declarations

    // CMIDIOutDevice exception classes

    // Encapsulates the midiOutGetErrorText messages
    class CMIDIOutException : public std::exception
        CMIDIOutException(MMRESULT ErrCode) throw()
        { ::midiOutGetErrorText(ErrCode, m_ErrMsg, sizeof m_ErrMsg); }

        const char *what() const throw() { return m_ErrMsg; }

        char m_ErrMsg[128];

    // Thrown when memory allocation fails within a CMIDIOutDevice 
    // object
    class CMIDIOutMemFailure : public std::bad_alloc
        const char *what() const throw()
        { return "Memory allocation within a CMIDIOutDevice object "
                 "failed."; }

    // Thrown when a CMIDIOutDevice is unable to create a signalling 
    // event
    class CMIDIOutEventFailure : public std::exception
        const char *what() const throw()
        { return "Unable to create a signalling event for "
                 "CMIDIOutDevice object."; }

    // Thrown when a CMIDIOutDevice is unable to create a worker 
    // thread
    class CMIDIOutThreadFailure : public std::exception
        const char *what() const throw()
        { return "Unable to create worker thread for CMIDIOutDevice "
                 "object."; }

    // CMIDIOutDevice
    // This class represents MIDI output devices.

    class CMIDIOutDevice
        // For constructing a CMIDIOutDevice in an closed state

        // For constructing a CMIDIOutDevice in an opened state
        CMIDIOutDevice(UINT DeviceId);

        // Destruction

        // Opens the MIDI output device
        void Open(UINT DeviceId);

        // Closes the MIDI output device
        void Close();

        // Sends short message
        void SendMsg(DWORD Msg);

        // Sends long message
        void SendMsg(LPSTR Msg, DWORD MsgLength);

        // Returns true if the device is open
        bool IsOpen() const;

        // Gets the Id for this device
        UINT GetDevID() const;

        // Gets the number of MIDI output devices on this system
        static UINT GetNumDevs() { return midiOutGetNumDevs(); }

        // Gets the capabilities of a particular MIDI output device
        // The results are stored in the MIDIOUTCAPS parameter.
        static void GetDevCaps(UINT DeviceId, MIDIOUTCAPS &Caps);

    // Private methods
        // Copying and assignment not allowed
        CMIDIOutDevice(const CMIDIOutDevice &);
        CMIDIOutDevice &operator = (const CMIDIOutDevice &);

        // Creates an event for signalling the header thread
        bool CreateEvent();

        // Called by Windows when a MIDI output event occurs
        static void CALLBACK MidiOutProc(HMIDIOUT MidiOut, UINT Msg,
                                         DWORD Instance, DWORD Param1, 
                                         DWORD Param2);

        // Thread function for managing headers
        static DWORD WINAPI HeaderProc(LPVOID Parameter);

    // Private class declarations
        // Encapsulates the MIDIHDR structure for MIDI output
        class CMIDIOutHeader
            CMIDIOutHeader(HMIDIOUT DevHandle, LPSTR Msg, 
                           DWORD MsgLength);

            void SendMsg();

            HMIDIOUT m_DevHandle;
            MIDIHDR  m_MIDIHdr;

        // Thread safe queue for storing CMIDIOutHeader objects
        class CHeaderQueue

            void AddHeader(CMIDIOutHeader *Header);
            void RemoveHeader();
            void RemoveAll();
            bool IsEmpty();

            std::queue<CMIDIOutHeader *> m_HdrQueue;
            CRITICAL_SECTION m_CriticalSection;

    // Private attributes and constants
        HMIDIOUT       m_DevHandle;
        HANDLE         m_Event;
        CWinThread    *m_WorkerThread;
        CHeaderQueue   m_HdrQueue;
        enum State { CLOSED, OPENED } m_State;


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About the Author

Leslie Sanford
United States United States
Aside from dabbling in BASIC on his old Atari 1040ST years ago, Leslie's programming experience didn't really begin until he discovered the Internet in the late 90s. There he found a treasure trove of information about two of his favorite interests: MIDI and sound synthesis.

After spending a good deal of time calculating formulas he found on the Internet for creating new sounds by hand, he decided that an easier way would be to program the computer to do the work for him. This led him to learn C. He discovered that beyond using programming as a tool for synthesizing sound, he loved programming in and of itself.

Eventually he taught himself C++ and C#, and along the way he immersed himself in the ideas of object oriented programming. Like many of us, he gotten bitten by the design patterns bug and a copy of GOF is never far from his hands.

Now his primary interest is in creating a complete MIDI toolkit using the C# language. He hopes to create something that will become an indispensable tool for those wanting to write MIDI applications for the .NET framework.

Besides programming, his other interests are photography and playing his Les Paul guitars.

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