/**
 * equalTemperedBentPitchFactory.java
 *
 * Generates a bentPitch object which is part of an equal tempered scale.
 *
 *
 *
 * Given the base MIDI pitch, number of divisions per octave,
 * and step position,
 * this class creates a bentPitch object with the base MIDI pitch
 * and two status bytes set correctly
 *
 * This module is part of Karl Brown's MIDI programming project.
 *
 */
package MidiApps;

import java.io.*;
import java.util.*;
import javax.sound.midi.*;
/**
 *
 * @author  Karl Brown
 * @version 1.0
 * last updated 2/16/2003
 */


public  class equalTemperedBentPitchFactory
			extends bentPitchFactory	{


//This constant assumes MIDI instrument's pitch bend range
//is set to the normal value of two semitones up and down.
	private static int HALF_STEP_PITCH_BEND = 0x1000;

    private short divisionsPerOctave;
    private short stepPosition;
    private byte baseMidiPitch;


    private double octaveFraction;
    private double totalHalfsteps;
    private short wholeHalfsteps;
    private double fractionalHalfsteps;

	public void setBaseMidiPitch (byte pitch)
	{
		baseMidiPitch = pitch;
	}

	protected void setDivisions(short div)
	{
		divisionsPerOctave = div;
	}

	protected void setStepPosition (short pos)
	{
		stepPosition = pos;
	}

	public byte getBaseMidiPitch()
	{
		return baseMidiPitch;
	}

	public short getDivisionsPerOctave()
	{
		return divisionsPerOctave;
	}

	public short getStepPosition()
	{
		return stepPosition;
	}

/**
 *
 * calculate bend amount relative to pitch bend center
 * from bend amount relative to pitch bend center
 * It is assumed that the MIDI instrument playing the output
 * has a pitch bend range of two semitones up and down.
 *
 */

	public void calculateBendAmount()
		throws Exception
	{

//calculate portion of octave represented by the interval,
//where one half step on an ordinary keyboard is one twelfth of an octave
	    octaveFraction = (double)( (double)getStepPosition() / (double)getDivisionsPerOctave() );

//translate the fraction of an octave into whole and fractional half steps
	    totalHalfsteps = octaveFraction * 12;
	    wholeHalfsteps = (short)totalHalfsteps;
	    fractionalHalfsteps = (double)((double)totalHalfsteps - (double)wholeHalfsteps );

//set the pitch value to which the note on / off event status byte will be set.
	    setMidiPitchOut( (byte)( wholeHalfsteps + (short)getBaseMidiPitch() ) );

//set the pitch bend amount, from which the pitch bend event status bytes will be calulated
	    setBendAmount((int)(fractionalHalfsteps * (double)HALF_STEP_PITCH_BEND));
/*
		tr.trace("step position: " + getStepPosition()
		+ " divisions: "  + getDivisionsPerOctave()
		+ " octave fraction: " + octaveFraction);
		tr.trace("total half steps: " + totalHalfsteps
		+ " whole half steps "  + wholeHalfsteps
		+ " fractional half steps: " + fractionalHalfsteps);
		tr.trace("bend amount: " + getBendAmount()
		+ " midi pitch out "  + getMidiPitchOut());
*/
	}

}