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C# MIDI Toolkit

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18 Apr 2007MIT18 min read 3.1M   41.7K   303  
A toolkit for creating MIDI applications with C#.
#region License

/* Copyright (c) 2005 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.
 */

#endregion

#region Contact

/*
 * Leslie Sanford
 * Email: jabberdabber@hotmail.com
 */

#endregion

using System;
using System.Collections;
using System.Runtime.InteropServices;

namespace Sanford.Multimedia.Midi
{
	/// <summary>
	/// Builds a pointer to a MidiHeader structure.
	/// </summary>
	internal class MidiHeaderBuilder
	{
        // The length of the system exclusive buffer.
        private int bufferLength;

        // The system exclusive data.
        private byte[] data;

        // Indicates whether the pointer to the MidiHeader has been built.
        private bool built = false;

        // The built pointer to the MidiHeader.
        private IntPtr result;

        /// <summary>
        /// Initializes a new instance of the MidiHeaderBuilder.
        /// </summary>
		public MidiHeaderBuilder()
		{
            BufferLength = 1;
		}

        #region Methods

        /// <summary>
        /// Builds the pointer to the MidiHeader structure.
        /// </summary>
        public void Build()
        {
            MidiHeader header = new MidiHeader();

            // Initialize the MidiHeader.
            header.bufferLength = BufferLength;
            header.bytesRecorded = 0;
            header.data = Marshal.AllocHGlobal(BufferLength);
            header.flags = 0;

            // Write data to the MidiHeader.
            for(int i = 0; i < BufferLength; i++)
            {
                Marshal.WriteByte(header.data, i, data[i]);
            }

            try
            {
                result = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(MidiHeader)));
            }
            catch(Exception)
            {
                Marshal.FreeHGlobal(header.data);

                throw;
            }

            try
            {
                Marshal.StructureToPtr(header, result, false);
            }
            catch(Exception)
            {
                Marshal.FreeHGlobal(header.data);
                Marshal.FreeHGlobal(result);

                throw;
            }

            built = true;
        }

        /// <summary>
        /// Initializes the MidiHeaderBuilder with the specified SysExMessage.
        /// </summary>
        /// <param name="message">
        /// The SysExMessage to use for initializing the MidiHeaderBuilder.
        /// </param>
        public void InitializeBuffer(SysExMessage message)
        {
            // If this is a start system exclusive message.
            if(message.SysExType == SysExType.Start)
            {
                BufferLength = message.Length;

                // Copy entire message.
                for(int i = 0; i < BufferLength; i++)
                {
                    data[i] = message[i];
                }
            }
            // Else this is a continuation message.
            else
            {
                BufferLength = message.Length - 1;

                // Copy all but the first byte of message.
                for(int i = 0; i < BufferLength; i++)
                {
                    data[i] = message[i + 1];
                }
            }
        }

        public void InitializeBuffer(ICollection events)
        {
            #region Require

            if(events == null)
            {
                throw new ArgumentNullException("events");
            }
            else if(events.Count % 4 != 0)
            {
                throw new ArgumentException("Stream events not word aligned.");
            }

            #endregion

            #region Guard

            if(events.Count == 0)
            {
                return;
            }

            #endregion

            BufferLength = events.Count;

            events.CopyTo(data, 0);
        }

        /// <summary>
        /// Releases the resources associated with the built MidiHeader pointer.
        /// </summary>
        public void Destroy()
        {
            #region Require

            if(!built)
            {
                throw new InvalidOperationException("Cannot destroy MidiHeader");
            }

            #endregion

            Destroy(result);
        }

        /// <summary>
        /// Releases the resources associated with the specified MidiHeader pointer.
        /// </summary>
        /// <param name="headerPtr">
        /// The MidiHeader pointer.
        /// </param>
        public void Destroy(IntPtr headerPtr)
        {
            MidiHeader header = (MidiHeader)Marshal.PtrToStructure(headerPtr, typeof(MidiHeader));

            Marshal.FreeHGlobal(header.data);
            Marshal.FreeHGlobal(headerPtr);
        }

        #endregion

        #region Properties

        /// <summary>
        /// The length of the system exclusive buffer.
        /// </summary>
        public int BufferLength
        {
            get
            {
                return bufferLength;
            }
            set
            {
                #region Require

                if(value <= 0)
                {
                    throw new ArgumentOutOfRangeException("BufferLength", value, 
                        "MIDI header buffer length out of range.");
                }

                #endregion

                bufferLength = value;
                data = new byte[value];
            }
        }

        /// <summary>
        /// Gets the pointer to the MidiHeader.
        /// </summary>
        public IntPtr Result
        {
            get
            {
                return result;
            }
        }

        #endregion
	}
}

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License

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


Written By
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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