/*
 * $Id: LinearTransform.java,v 1.3 2002/12/03 16:35:50 oz Exp $
 *
 * This software is provided by NOAA for full, free and open release.  It is
 * understood by the recipient/user that NOAA assumes no liability for any
 * errors contained in the code.  Although this software is released without
 * conditions or restrictions in its use, it is expected that appropriate
 * credit be given to its author and to the National Oceanic and Atmospheric
 * Administration should the software be included by the recipient as an
 * element in other product development.
 */
 
package sgtplot.util;

import java.beans.PropertyChangeListener;

import sgtplot.Transform;
import sgtplot.util.Range2D;
 
/**
 * LinearTransform defines a liniear transformations between 
 * user and physical coordinates defined between two end points.
 *
 * @see AxisTransform
 *
 * @author Donald Denbo
 * @version $Revision: 1.3 $, $Date: 2002/12/03 16:35:50 $
 */
public class LinearTransform implements Transform {
	Range2D mPhysRange = null;
	Range2D mUserRange = null;
	double mPUSlope, mPUYintercept;
	double mUPSlope, mUPYintercept;

	public LinearTransform(double p1, double p2, double u1, double u2) {
		setRangeP(p1, p2);
		setRangeU(u1, u2);
		computeTransforms();
	}

	public LinearTransform(Range2D prange, Range2D urange) {
		setRangeP(prange);
		setRangeU(urange);
		computeTransforms();
	}

	public LinearTransform() {
	}
	
	/**
	* Set physical coordinate range.
	*
	* @param p1 minimum value, physical coordinates
	* @param p2 maximum value, physical coordinates
	* @see LinearTransform
	**/
	public void setRangeP(double p1,double p2) {
		mPhysRange = new Range2D(p1, p2);
	}

	/**
	* Set physical coordinate range.
	*
	* @param prange physcial coordinate range
	* @see Range2D
	* @see LinearTransform
	**/
	public void setRangeP(Range2D prange) {
		mPhysRange = null;
		mPhysRange = new Range2D();
		mPhysRange.add(prange);
	}

	/**
	* Get the physical coordinate range.
	*
	* @return physcial coordinate range
	* @see Range2D
	**/
	public Range2D getRangeP() {
		return mPhysRange;
	}

	/**
	* Set the user coordinate range for double values.
	*
	* @param u1 minimum value, user coordinates
	* @param u2 maximum value, user coordinates
	* @see LinearTransform
	**/
	public void setRangeU(double u1,double u2) {
		mUserRange = new Range2D(u1, u2);
	}

	/**
	* Set the user coordinate range for double values.
	*
	* @param urange user coordinate range
	* @see Range2D
	* @see LinearTransform
	**/
	public void setRangeU(Range2D urange) {
		mUserRange = null;
		mUserRange = new Range2D();
		mUserRange.add(urange);
		computeTransforms();
	}

	/**
	* Get the user coordinate range for double values.
	*
	* @return user range
	* @see Range2D
	**/
	public Range2D getRangeU() {
		return mUserRange;
	}

	/**
	* Transform from user to physical coordinates.
	*
	* @param u user value
	* @return physical value
	*/
	public double getTransP(double u) {
		return (mUPSlope * u) + mUPYintercept;
	}

	/**
	* Transform from physical to user coordinates.
	*
	* @param p physical value
	* @return user value
	*/
	public double getTransU(double p) {
		return (mPUSlope *p) + mPUYintercept;
	}

	/**
	* Add listener for changes to transform properties.
	*/
	public void addPropertyChangeListener(PropertyChangeListener listener) {

	}

	public void removePropertyChangeListener(PropertyChangeListener listener) {

	}
	
	public void computeTransforms() {
		computePULine();
		computeUPLine();
	}
	
	private void computePULine() {
		double denom = mPhysRange.start - mPhysRange.end;
		double num = mUserRange.start - mUserRange.end;
		mPUSlope = num/denom;
		mPUYintercept = mUserRange.start - (mPUSlope * mPhysRange.start);
	}
	
	private void computeUPLine() {
		double num = mPhysRange.start - mPhysRange.end;
		double denom = mUserRange.start - mUserRange.end;
		mUPSlope = num/denom;
		mUPYintercept = mPhysRange.start - (mPUSlope * mUserRange.start);
	}
}