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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) 2006 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;

namespace Multimedia.Midi
{
	/// <summary>
	/// Provides functionality for building song position pointer messages.
	/// </summary>
	public class SongPositionPointerBuilder : IMessageBuilder
	{
        #region SongPositionPointerBuilder Members

        #region Constants

        // The number of ticks per 16th note.
        private const int TicksPer16thNote = 6;

        // Used for packing and unpacking the song position.
        private const int Shift = 7;

        // Used for packing and unpacking the song position.
        private const int Mask = 127;

        #endregion

        #region Fields

        // The scale used for converting from the song position to the position
        // in ticks.
        private int tickScale;

        // Pulses per quarter note resolution.
        private int ppqn;

        // Used for building the SysCommonMessage to represent the song
        // position pointer.
        private SysCommonMessageBuilder builder;

        #endregion

        #region Construction

        /// <summary>
        /// Initializes a new instance of the SongPositionPointerBuilder class.
        /// </summary>
        public SongPositionPointerBuilder()
        {
            builder = new SysCommonMessageBuilder();
            builder.Type = SysCommonType.SongPositionPointer;

            Ppqn = PpqnClock.PpqnMinValue;
        }

        /// <summary>
        /// Initializes a new instance of the SongPositionPointerBuilder class
        /// with the specified song position pointer message.
        /// </summary>
        /// <param name="message">
        /// The song position pointer message to use for initializing the 
        /// SongPositionPointerBuilder.
        /// </param>
        /// <exception cref="ArgumentException">
        /// If message is not a song position pointer message.
        /// </exception>
        public SongPositionPointerBuilder(SysCommonMessage message)
        {
            builder = new SysCommonMessageBuilder();
            builder.Type = SysCommonType.SongPositionPointer;

            Initialize(message);

            Ppqn = PpqnClock.PpqnMinValue;
        }

        #endregion

        #region Methods

        /// <summary>
        /// Initializes the SongPositionPointerBuilder with the specified 
        /// SysCommonMessage.
        /// </summary>
        /// <param name="message">
        /// The SysCommonMessage to use to initialize the 
        /// SongPositionPointerBuilder.
        /// </param>
        /// <exception cref="ArgumentException">
        /// If the SysCommonMessage is not a song position pointer message.
        /// </exception>
        public void Initialize(SysCommonMessage message)
        {
            #region Require

            if(message == null)
            {
                throw new ArgumentNullException("message");
            }
            else if(message.SysCommonType != SysCommonType.SongPositionPointer)
            {
                throw new ArgumentException(
                    "Message is not a song position pointer message.");
            }

            #endregion

            builder.Initialize(message);
        }

        #endregion

        #region Properties

        /// <summary>
        /// Gets or sets the sequence position in ticks.
        /// </summary>
        /// <exception cref="ArgumentOutOfRangeException">
        /// Value is set to less than zero.
        /// </exception>
        /// <remarks>
        /// Note: the position in ticks value is converted to the song position
        /// pointer value. Since the song position pointer has a lower 
        /// resolution than the position in ticks, there is a probable loss of 
        /// resolution when setting the position in ticks value.
        /// </remarks>
        public int PositionInTicks
        {
            get
            {
                return SongPosition * tickScale * TicksPer16thNote;
            }
            set
            {
                #region Require

                if(value < 0)
                {
                    throw new ArgumentOutOfRangeException("PositionInTicks", value,
                        "Position in ticks out of range.");
                }

                #endregion

                SongPosition = value / (tickScale * TicksPer16thNote);
            }
        }        

        /// <summary>
        /// Gets or sets the PulsesPerQuarterNote object.
        /// </summary>
        /// <exception cref="ArgumentOutOfRangeException">
        /// Value is not a multiple of 24.
        /// </exception>
        public int Ppqn
        {
            get
            {
                return ppqn;
            }
            set
            {
                #region Require

                if(value % PpqnClock.PpqnMinValue != 0)
                {
                    throw new ArgumentException(
                        "Invalid pulses per quarter note value.");
                }

                #endregion

                ppqn = value;

                tickScale = ppqn / PpqnClock.PpqnMinValue;
            }
        }

        /// <summary>
        /// Gets or sets the song position.
        /// </summary>
        /// <exception cref="ArgumentOutOfRangeException">
        /// Value is set to less than zero.
        /// </exception>
        public int SongPosition
        {
            get
            {
                return (builder.Data2 << Shift) | builder.Data1;                
            }
            set
            {
                #region Require

                if(value < 0)
                {
                    throw new ArgumentOutOfRangeException("SongPosition", value,
                        "Song position pointer out of range.");
                }

                #endregion

                builder.Data1 = value & Mask;
                builder.Data2 = value >> Shift;
            }
        }

        /// <summary>
        /// Gets the built song position pointer message.
        /// </summary>
        public SysCommonMessage Result
        {
            get
            {
                return builder.Result;
            }
        }

        #endregion

        #endregion

        #region IMessageBuilder Members

        /// <summary>
        /// Builds a song position pointer message.
        /// </summary>
        public void Build()
        {
            builder.Build();
        }

        #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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