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Wrapper Library for Windows MIDI API

, 28 Jan 2008 MIT 494.6K 12.6K 141
A small library encapsulating the Windows MIDI API
mididevdemo.zip
MIDIDeviceDemo.exe
mididevdemo_v2.zip
MIDIDevDemo v2
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MIDIDevDemo v2.dsw
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MIDIDevDemo v2.opt
MIDIDevDemo v2.plg
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MIDIDevDemo v2.ico
midiwrapper.zip
MIDIDeviceDemo.zip
MIDIWrapperSrc.zip
midiwrappersource.zip
MIDIWrapper Source
midiwrapper_demo.zip
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MIDIDevDemo v2.dsp
MIDIDevDemo v2.dsw
MIDIDevDemo v2.ico
midiwrapper_source.zip
MIDIWrapper_Source
MIDIWrapper Source
midiwrapper_src.zip
/*******************************************************************************
 * MIDIOutDevice.cpp - Implementation for CMIDIOutDevice and related 
 *                     classes.
 *
     Copyright (c) 2008 Leslie Sanford

    Permission is hereby granted, free of charge, to any person
    obtaining a copy of this software and associated documentation
    files (the "Software"), to deal in the Software without
    restriction, including without limitation the rights to use,
    copy, modify, merge, publish, distribute, sublicense, and/or sell
    copies of the Software, and to permit persons to whom the
    Software is furnished to do so, subject to the following
    conditions:

    The above copyright notice and this permission notice shall be
    included in all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
    OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
    NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
    HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
    WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
    OTHER DEALINGS IN THE SOFTWARE.

    Contact: Leslie Sanford (jabberdabber@hotmail.com)

    Last modified: 01/23/2008
 ******************************************************************************/


//--------------------------------------------------------------------
// Dependencies
//--------------------------------------------------------------------


#include "MIDIOutDevice.h"
#include "midi.h"


//--------------------------------------------------------------------
// Using declarations
//--------------------------------------------------------------------


using midi::CMIDIOutDevice;
using midi::CMIDIOutException;


//--------------------------------------------------------------------
// CMIDIOutHeader implementation
//--------------------------------------------------------------------


// Constructor
CMIDIOutDevice::CMIDIOutHeader::CMIDIOutHeader(HMIDIOUT DevHandle,
                                               LPSTR Msg, 
                                               DWORD MsgLength) :
m_DevHandle(DevHandle)
{
    // Initialize header
    m_MIDIHdr.lpData         = Msg;
    m_MIDIHdr.dwBufferLength = MsgLength;
    m_MIDIHdr.dwFlags        = 0;

    // Prepare header
    MMRESULT Result = ::midiOutPrepareHeader(DevHandle, &m_MIDIHdr,
                                             sizeof m_MIDIHdr);

    // If an error occurred, throw exception
    if(Result != MMSYSERR_NOERROR)
    {
        throw CMIDIOutException(Result);
    }
}


// Destructor
CMIDIOutDevice::CMIDIOutHeader::~CMIDIOutHeader()
{
    ::midiOutUnprepareHeader(m_DevHandle, &m_MIDIHdr, 
                             sizeof m_MIDIHdr);
}


// Sends long message
void CMIDIOutDevice::CMIDIOutHeader::SendMsg()
{
    MMRESULT Result = ::midiOutLongMsg(m_DevHandle, &m_MIDIHdr,
                                       sizeof m_MIDIHdr);

    if(Result != MMSYSERR_NOERROR)
    {
        throw CMIDIOutException(Result);
    }
}


//--------------------------------------------------------------------
// CHeaderQueue implementation
//--------------------------------------------------------------------


// Constructor
CMIDIOutDevice::CHeaderQueue::CHeaderQueue()
{
    ::InitializeCriticalSection(&m_CriticalSection);
}


// Destructor
CMIDIOutDevice::CHeaderQueue::~CHeaderQueue()
{
    RemoveAll();

    ::DeleteCriticalSection(&m_CriticalSection);
}


// Add header to queue
void CMIDIOutDevice::CHeaderQueue::AddHeader(
                               CMIDIOutDevice::CMIDIOutHeader *Header)
{
    ::EnterCriticalSection(&m_CriticalSection);

    m_HdrQueue.push(Header);

    ::LeaveCriticalSection(&m_CriticalSection);
}


// Remove header from queue
void CMIDIOutDevice::CHeaderQueue::RemoveHeader()
{
    ::EnterCriticalSection(&m_CriticalSection);

    if(!m_HdrQueue.empty())
    {
        delete m_HdrQueue.front();
        m_HdrQueue.pop();
    }

    ::LeaveCriticalSection(&m_CriticalSection);
}


// Empty header queue
void CMIDIOutDevice::CHeaderQueue::RemoveAll()
{
    ::EnterCriticalSection(&m_CriticalSection);

    while(!m_HdrQueue.empty())
    {
        delete m_HdrQueue.front();
        m_HdrQueue.pop();
    }

    ::LeaveCriticalSection(&m_CriticalSection);
}


// Determines if the header queue is empty
bool CMIDIOutDevice::CHeaderQueue::IsEmpty()
{
    bool Result;

    ::EnterCriticalSection(&m_CriticalSection);

    Result = m_HdrQueue.empty();

    ::LeaveCriticalSection(&m_CriticalSection);

    return Result;
}


//--------------------------------------------------------------------
// CMIDIOutDevice implementation
//--------------------------------------------------------------------


// Constructs CMIDIOutDevice object in an closed state
CMIDIOutDevice::CMIDIOutDevice() :
m_State(CLOSED)
{
    // If we are unable to create signalling event, throw exception
    if(!CreateEvent())
    {
        throw CMIDIOutEventFailure();
    }
}


// Constructs CMIDIOutDevice object in an opened state
CMIDIOutDevice::CMIDIOutDevice(UINT DeviceId) :
m_State(CLOSED)
{
    // Open device
    Open(DeviceId);

    // If we are unable to create signalling event, throw exception
    if(!CreateEvent())
    {
        Close();
        throw CMIDIOutEventFailure();
    }
}


// Destruction
CMIDIOutDevice::~CMIDIOutDevice()
{
    // Close device
    Close();

    // Close handle to signalling event
    ::CloseHandle(m_Event);
}


// Opens the MIDI output device
void CMIDIOutDevice::Open(UINT DeviceId)
{
    // Makes sure the previous device, if any, is closed before 
    // opening another one
    Close();

    // Open MIDI output device
    MMRESULT Result = ::midiOutOpen(&m_DevHandle, DeviceId, 
                                 reinterpret_cast<DWORD>(MidiOutProc),
                                 reinterpret_cast<DWORD>(this),
                                 CALLBACK_FUNCTION);

    // If we are able to open the device, change state
    if(Result == MMSYSERR_NOERROR)
    {
        m_State = OPENED;
        m_WorkerThread = AfxBeginThread(
            reinterpret_cast<AFX_THREADPROC>(HeaderProc), this);
    }
    // Else opening failed, throw exception
    else
    {
        ::SetEvent(m_Event);
        ::WaitForSingleObject(m_WorkerThread->m_hThread, INFINITE);

        throw CMIDIOutException(Result);
    }
}


// Closes the MIDI output device
void CMIDIOutDevice::Close()
{
    // Only close an already opened device
    if(m_State == OPENED)
    {
        // Change state
        m_State = CLOSED;

        // Notify our worker thread and wait for it to finish
        ::SetEvent(m_Event);
        ::WaitForSingleObject(m_WorkerThread->m_hThread, INFINITE);

        // Empty header queue - we're finished with the headers
        m_HdrQueue.RemoveAll();

        // Close the MIDI output device
        ::midiOutClose(m_DevHandle);
    }
}


// Sends short message
void CMIDIOutDevice::SendMsg(DWORD Msg)
{
    if(m_State == OPENED)
    {
        MMRESULT Result = ::midiOutShortMsg(m_DevHandle, Msg);

        if(Result != MMSYSERR_NOERROR)
        {
            throw CMIDIOutException(Result);
        }
    }
}


// Sends long message
void CMIDIOutDevice::SendMsg(LPSTR Msg, DWORD MsgLength)
{
    if(m_State == OPENED)
    {  
        CMIDIOutHeader *Header;

        try
        {
            // Create new header to send system exclusive message
            Header = new CMIDIOutHeader(m_DevHandle, Msg, MsgLength);
        }
        // If memory allocation failed, throw exception
        catch(const std::bad_alloc &)
        {
            throw CMIDIOutMemFailure();
        }
        // If preparing the header failed, rethrow exception
        catch(const CMIDIOutException &)
        {
            throw;
        }

        try
        {
            // Send system exclusive data
            Header->SendMsg();

            // Add header to queue
            m_HdrQueue.AddHeader(Header);
        }
        // If sending system exclusive msg failed, release header
        // and rethrow exception
        catch(const CMIDIOutException &)
        {
            delete Header;
            throw;
        }
    }
}


// Determines if the MIDI output device is opened
bool CMIDIOutDevice::IsOpen() const
{
    return (m_State == OPENED);
}


// Gets the Id for this device
UINT CMIDIOutDevice::GetDevID() const
{
    UINT DeviceID;
    MMRESULT Result = ::midiOutGetID(m_DevHandle, &DeviceID);

    if(Result != MMSYSERR_NOERROR)
    {
        throw CMIDIOutException(Result);
    }

    return DeviceID;
}


// Gets the capabilities of a particular MIDI output device
void CMIDIOutDevice::GetDevCaps(UINT DeviceId, MIDIOUTCAPS &Caps)
{
    MMRESULT Result = ::midiOutGetDevCaps(DeviceId, &Caps, 
                                          sizeof Caps);

    // If we are not able to retrieve device capabilities, throw 
    // exception
    if(Result != MMSYSERR_NOERROR)
    {
        throw CMIDIOutException(Result);
    }
}


// Creates event for signalling header thread
bool CMIDIOutDevice::CreateEvent()
{
    bool Result = true;

    m_Event = ::CreateEvent(NULL, FALSE, FALSE, NULL);

    // If event creation failed, record failure
    if(m_Event == NULL)
    {
        Result = false;
    }

    return Result;
}

// Called by Windows when a MIDI input event occurs
void CALLBACK CMIDIOutDevice::MidiOutProc(HMIDIOUT MidiOut, UINT Msg,
                                          DWORD_PTR Instance, DWORD_PTR Param1,
                                          DWORD_PTR Param2)
{
    CMIDIOutDevice *Device;
    
    Device = reinterpret_cast<CMIDIOutDevice *>(Instance);

    if(Msg == MOM_DONE)
    {
        ::SetEvent(Device->m_Event);
    }
}


// Header worker thread
DWORD CMIDIOutDevice::HeaderProc(LPVOID Parameter)
{
    CMIDIOutDevice *Device; 
    
    Device = reinterpret_cast<CMIDIOutDevice *>(Parameter);

    // Continue while the MIDI output device is open
    while(Device->m_State == OPENED)
    {
        ::WaitForSingleObject(Device->m_Event, INFINITE);

        // Make sure the device is still open
        if(Device->m_State == OPENED)
        {
            // Remove the finished header
            Device->m_HdrQueue.RemoveHeader();
        }
    }

    return 0;
}



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This article, along with any associated source code and files, is licensed under The MIT License

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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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