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	/*
	* Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package java.awt.geom;

	import java.awt.Shape;
	import java.awt.Rectangle;
	import java.io.Serializable;

	/**
	* This <code>Line2D</code> represents a line segment in {@code (x,y)}
	* coordinate space. This class, like all of the Java 2D API, uses a
	* default coordinate system called <i>user space</i> in which the y-axis
	* values increase downward and x-axis values increase to the right. For
	* more information on the user space coordinate system, see the
	* <a href="https://docs.oracle.com/javase/1.3/docs/guide/2d/spec/j2d-intro.fm2.html#61857">
	* Coordinate Systems</a> section of the Java 2D Programmer's Guide.
	* <p>
	* This class is only the abstract superclass for all objects that
	* store a 2D line segment.
	* The actual storage representation of the coordinates is left to
	* the subclass.
	*
	* @author Jim Graham
	* @since 1.2
	*/
	public abstract class Line2D implements Shape, Cloneable {

	/**
	* A line segment specified with float coordinates.
	* @since 1.2
	*/
	public static class Float extends Line2D implements Serializable {
	/**
	* The X coordinate of the start point of the line segment.
	* @since 1.2
	* @serial
	*/
	public float x1;

	/**
	* The Y coordinate of the start point of the line segment.
	* @since 1.2
	* @serial
	*/
	public float y1;

	/**
	* The X coordinate of the end point of the line segment.
	* @since 1.2
	* @serial
	*/
	public float x2;

	/**
	* The Y coordinate of the end point of the line segment.
	* @since 1.2
	* @serial
	*/
	public float y2;

	/**
	* Constructs and initializes a Line with coordinates (0, 0) → (0, 0).
	* @since 1.2
	*/
	public Float() {
	}

	/**
	* Constructs and initializes a Line from the specified coordinates.
	* @param x1 the X coordinate of the start point
	* @param y1 the Y coordinate of the start point
	* @param x2 the X coordinate of the end point
	* @param y2 the Y coordinate of the end point
	* @since 1.2
	*/
	public Float(float x1, float y1, float x2, float y2) {
	setLine(x1, y1, x2, y2);
	}

	/**
	* Constructs and initializes a <code>Line2D</code> from the
	* specified <code>Point2D</code> objects.
	* @param p1 the start <code>Point2D</code> of this line segment
	* @param p2 the end <code>Point2D</code> of this line segment
	* @since 1.2
	*/
	public Float(Point2D p1, Point2D p2) {
	setLine(p1, p2);
	}

	/**
	* {@inheritDoc}
	* @since 1.2
	*/
	public double getX1() {
	return (double) x1;
	}

	/**
	* {@inheritDoc}
	* @since 1.2
	*/
	public double getY1() {
	return (double) y1;
	}

	/**
	* {@inheritDoc}
	* @since 1.2
	*/
	public Point2D getP1() {
	return new Point2D.Float(x1, y1);
	}

	/**
	* {@inheritDoc}
	* @since 1.2
	*/
	public double getX2() {
	return (double) x2;
	}

	/**
	* {@inheritDoc}
	* @since 1.2
	*/
	public double getY2() {
	return (double) y2;
	}

	/**
	* {@inheritDoc}
	* @since 1.2
	*/
	public Point2D getP2() {
	return new Point2D.Float(x2, y2);
	}

	/**
	* {@inheritDoc}
	* @since 1.2
	*/
	public void setLine(double x1, double y1, double x2, double y2) {
	this.x1 = (float) x1;
	this.y1 = (float) y1;
	this.x2 = (float) x2;
	this.y2 = (float) y2;
	}

	/**
	* Sets the location of the end points of this <code>Line2D</code>
	* to the specified float coordinates.
	* @param x1 the X coordinate of the start point
	* @param y1 the Y coordinate of the start point
	* @param x2 the X coordinate of the end point
	* @param y2 the Y coordinate of the end point
	* @since 1.2
	*/
	public void setLine(float x1, float y1, float x2, float y2) {
	this.x1 = x1;
	this.y1 = y1;
	this.x2 = x2;
	this.y2 = y2;
	}

	/**
	* {@inheritDoc}
	* @since 1.2
	*/
	public Rectangle2D getBounds2D() {
	float x, y, w, h;
	if (x1 < x2) {
	x = x1;
	w = x2 - x1;
	} else {
	x = x2;
	w = x1 - x2;
	}
	if (y1 < y2) {
	y = y1;
	h = y2 - y1;
	} else {
	y = y2;
	h = y1 - y2;
	}
	return new Rectangle2D.Float(x, y, w, h);
	}

	/*
	* JDK 1.6 serialVersionUID
	*/
	private static final long serialVersionUID = 6161772511649436349L;
	}

	/**
	* A line segment specified with double coordinates.
	* @since 1.2
	*/
	public static class Double extends Line2D implements Serializable {
	/**
	* The X coordinate of the start point of the line segment.
	* @since 1.2
	* @serial
	*/
	public double x1;

	/**
	* The Y coordinate of the start point of the line segment.
	* @since 1.2
	* @serial
	*/
	public double y1;

	/**
	* The X coordinate of the end point of the line segment.
	* @since 1.2
	* @serial
	*/
	public double x2;

	/**
	* The Y coordinate of the end point of the line segment.
	* @since 1.2
	* @serial
	*/
	public double y2;

	/**
	* Constructs and initializes a Line with coordinates (0, 0) → (0, 0).
	* @since 1.2
	*/
	public Double() {
	}

	/**
	* Constructs and initializes a <code>Line2D</code> from the
	* specified coordinates.
	* @param x1 the X coordinate of the start point
	* @param y1 the Y coordinate of the start point
	* @param x2 the X coordinate of the end point
	* @param y2 the Y coordinate of the end point
	* @since 1.2
	*/
	public Double(double x1, double y1, double x2, double y2) {
	setLine(x1, y1, x2, y2);
	}

	/**
	* Constructs and initializes a <code>Line2D</code> from the
	* specified <code>Point2D</code> objects.
	* @param p1 the start <code>Point2D</code> of this line segment
	* @param p2 the end <code>Point2D</code> of this line segment
	* @since 1.2
	*/
	public Double(Point2D p1, Point2D p2) {
	setLine(p1, p2);
	}

	/**
	* {@inheritDoc}
	* @since 1.2
	*/
	public double getX1() {
	return x1;
	}

	/**
	* {@inheritDoc}
	* @since 1.2
	*/
	public double getY1() {
	return y1;
	}

	/**
	* {@inheritDoc}
	* @since 1.2
	*/
	public Point2D getP1() {
	return new Point2D.Double(x1, y1);
	}

	/**
	* {@inheritDoc}
	* @since 1.2
	*/
	public double getX2() {
	return x2;
	}

	/**
	* {@inheritDoc}
	* @since 1.2
	*/
	public double getY2() {
	return y2;
	}

	/**
	* {@inheritDoc}
	* @since 1.2
	*/
	public Point2D getP2() {
	return new Point2D.Double(x2, y2);
	}

	/**
	* {@inheritDoc}
	* @since 1.2
	*/
	public void setLine(double x1, double y1, double x2, double y2) {
	this.x1 = x1;
	this.y1 = y1;
	this.x2 = x2;
	this.y2 = y2;
	}

	/**
	* {@inheritDoc}
	* @since 1.2
	*/
	public Rectangle2D getBounds2D() {
	double x, y, w, h;
	if (x1 < x2) {
	x = x1;
	w = x2 - x1;
	} else {
	x = x2;
	w = x1 - x2;
	}
	if (y1 < y2) {
	y = y1;
	h = y2 - y1;
	} else {
	y = y2;
	h = y1 - y2;
	}
	return new Rectangle2D.Double(x, y, w, h);
	}

	/*
	* JDK 1.6 serialVersionUID
	*/
	private static final long serialVersionUID = 7979627399746467499L;
	}

	/**
	* This is an abstract class that cannot be instantiated directly.
	* Type-specific implementation subclasses are available for
	* instantiation and provide a number of formats for storing
	* the information necessary to satisfy the various accessory
	* methods below.
	*
	* @see java.awt.geom.Line2D.Float
	* @see java.awt.geom.Line2D.Double
	* @since 1.2
	*/
	protected Line2D() {
	}

	/**
	* Returns the X coordinate of the start point in double precision.
	* @return the X coordinate of the start point of this
	* {@code Line2D} object.
	* @since 1.2
	*/
	public abstract double getX1();

	/**
	* Returns the Y coordinate of the start point in double precision.
	* @return the Y coordinate of the start point of this
	* {@code Line2D} object.
	* @since 1.2
	*/
	public abstract double getY1();

	/**
	* Returns the start <code>Point2D</code> of this <code>Line2D</code>.
	* @return the start <code>Point2D</code> of this <code>Line2D</code>.
	* @since 1.2
	*/
	public abstract Point2D getP1();

	/**
	* Returns the X coordinate of the end point in double precision.
	* @return the X coordinate of the end point of this
	* {@code Line2D} object.
	* @since 1.2
	*/
	public abstract double getX2();

	/**
	* Returns the Y coordinate of the end point in double precision.
	* @return the Y coordinate of the end point of this
	* {@code Line2D} object.
	* @since 1.2
	*/
	public abstract double getY2();

	/**
	* Returns the end <code>Point2D</code> of this <code>Line2D</code>.
	* @return the end <code>Point2D</code> of this <code>Line2D</code>.
	* @since 1.2
	*/
	public abstract Point2D getP2();

	/**
	* Sets the location of the end points of this <code>Line2D</code> to
	* the specified double coordinates.
	* @param x1 the X coordinate of the start point
	* @param y1 the Y coordinate of the start point
	* @param x2 the X coordinate of the end point
	* @param y2 the Y coordinate of the end point
	* @since 1.2
	*/
	public abstract void setLine(double x1, double y1, double x2, double y2);

	/**
	* Sets the location of the end points of this <code>Line2D</code> to
	* the specified <code>Point2D</code> coordinates.
	* @param p1 the start <code>Point2D</code> of the line segment
	* @param p2 the end <code>Point2D</code> of the line segment
	* @since 1.2
	*/
	public void setLine(Point2D p1, Point2D p2) {
	setLine(p1.getX(), p1.getY(), p2.getX(), p2.getY());
	}

	/**
	* Sets the location of the end points of this <code>Line2D</code> to
	* the same as those end points of the specified <code>Line2D</code>.
	* @param l the specified <code>Line2D</code>
	* @since 1.2
	*/
	public void setLine(Line2D l) {
	setLine(l.getX1(), l.getY1(), l.getX2(), l.getY2());
	}

	/**
	* Returns an indicator of where the specified point
	* {@code (px,py)} lies with respect to the line segment from
	* {@code (x1,y1)} to {@code (x2,y2)}.
	* The return value can be either 1, -1, or 0 and indicates
	* in which direction the specified line must pivot around its
	* first end point, {@code (x1,y1)}, in order to point at the
	* specified point {@code (px,py)}.
	* <p>A return value of 1 indicates that the line segment must
	* turn in the direction that takes the positive X axis towards
	* the negative Y axis. In the default coordinate system used by
	* Java 2D, this direction is counterclockwise.
	* <p>A return value of -1 indicates that the line segment must
	* turn in the direction that takes the positive X axis towards
	* the positive Y axis. In the default coordinate system, this
	* direction is clockwise.
	* <p>A return value of 0 indicates that the point lies
	* exactly on the line segment. Note that an indicator value
	* of 0 is rare and not useful for determining collinearity
	* because of floating point rounding issues.
	* <p>If the point is colinear with the line segment, but
	* not between the end points, then the value will be -1 if the point
	* lies "beyond {@code (x1,y1)}" or 1 if the point lies
	* "beyond {@code (x2,y2)}".
	*
	* @param x1 the X coordinate of the start point of the
	* specified line segment
	* @param y1 the Y coordinate of the start point of the
	* specified line segment
	* @param x2 the X coordinate of the end point of the
	* specified line segment
	* @param y2 the Y coordinate of the end point of the
	* specified line segment
	* @param px the X coordinate of the specified point to be
	* compared with the specified line segment
	* @param py the Y coordinate of the specified point to be
	* compared with the specified line segment
	* @return an integer that indicates the position of the third specified
	* coordinates with respect to the line segment formed
	* by the first two specified coordinates.
	* @since 1.2
	*/
	public static int relativeCCW(double x1, double y1,
	double x2, double y2,
	double px, double py)
	{
	x2 -= x1;
	y2 -= y1;
	px -= x1;
	py -= y1;
	double ccw = px * y2 - py * x2;
	if (ccw == 0.0) {
	// The point is colinear, classify based on which side of
	// the segment the point falls on. We can calculate a
	// relative value using the projection of px,py onto the
	// segment - a negative value indicates the point projects
	// outside of the segment in the direction of the particular
	// endpoint used as the origin for the projection.
	ccw = px * x2 + py * y2;
	if (ccw > 0.0) {
	// Reverse the projection to be relative to the original x2,y2
	// x2 and y2 are simply negated.
	// px and py need to have (x2 - x1) or (y2 - y1) subtracted
	// from them (based on the original values)
	// Since we really want to get a positive answer when the
	// point is "beyond (x2,y2)", then we want to calculate
	// the inverse anyway - thus we leave x2 & y2 negated.
	px -= x2;
	py -= y2;
	ccw = px * x2 + py * y2;
	if (ccw < 0.0) {
	ccw = 0.0;
	}
	}
	}
	return (ccw < 0.0) ? -1 : ((ccw > 0.0) ? 1 : 0);
	}

	/**
	* Returns an indicator of where the specified point
	* {@code (px,py)} lies with respect to this line segment.
	* See the method comments of
	* {@link #relativeCCW(double, double, double, double, double, double)}
	* to interpret the return value.
	* @param px the X coordinate of the specified point
	* to be compared with this <code>Line2D</code>
	* @param py the Y coordinate of the specified point
	* to be compared with this <code>Line2D</code>
	* @return an integer that indicates the position of the specified
	* coordinates with respect to this <code>Line2D</code>
	* @see #relativeCCW(double, double, double, double, double, double)
	* @since 1.2
	*/
	public int relativeCCW(double px, double py) {
	return relativeCCW(getX1(), getY1(), getX2(), getY2(), px, py);
	}

	/**
	* Returns an indicator of where the specified <code>Point2D</code>
	* lies with respect to this line segment.
	* See the method comments of
	* {@link #relativeCCW(double, double, double, double, double, double)}
	* to interpret the return value.
	* @param p the specified <code>Point2D</code> to be compared
	* with this <code>Line2D</code>
	* @return an integer that indicates the position of the specified
	* <code>Point2D</code> with respect to this <code>Line2D</code>
	* @see #relativeCCW(double, double, double, double, double, double)
	* @since 1.2
	*/
	public int relativeCCW(Point2D p) {
	return relativeCCW(getX1(), getY1(), getX2(), getY2(),
	p.getX(), p.getY());
	}

	/**
	* Tests if the line segment from {@code (x1,y1)} to
	* {@code (x2,y2)} intersects the line segment from {@code (x3,y3)}
	* to {@code (x4,y4)}.
	*
	* @param x1 the X coordinate of the start point of the first
	* specified line segment
	* @param y1 the Y coordinate of the start point of the first
	* specified line segment
	* @param x2 the X coordinate of the end point of the first
	* specified line segment
	* @param y2 the Y coordinate of the end point of the first
	* specified line segment
	* @param x3 the X coordinate of the start point of the second
	* specified line segment
	* @param y3 the Y coordinate of the start point of the second
	* specified line segment
	* @param x4 the X coordinate of the end point of the second
	* specified line segment
	* @param y4 the Y coordinate of the end point of the second
	* specified line segment
	* @return <code>true</code> if the first specified line segment
	* and the second specified line segment intersect
	* each other; <code>false</code> otherwise.
	* @since 1.2
	*/
	public static boolean linesIntersect(double x1, double y1,
	double x2, double y2,
	double x3, double y3,
	double x4, double y4)
	{
	return ((relativeCCW(x1, y1, x2, y2, x3, y3) *
	relativeCCW(x1, y1, x2, y2, x4, y4) <= 0)
	&& (relativeCCW(x3, y3, x4, y4, x1, y1) *
	relativeCCW(x3, y3, x4, y4, x2, y2) <= 0));
	}

	/**
	* Tests if the line segment from {@code (x1,y1)} to
	* {@code (x2,y2)} intersects this line segment.
	*
	* @param x1 the X coordinate of the start point of the
	* specified line segment
	* @param y1 the Y coordinate of the start point of the
	* specified line segment
	* @param x2 the X coordinate of the end point of the
	* specified line segment
	* @param y2 the Y coordinate of the end point of the
	* specified line segment
	* @return {@code <true>} if this line segment and the specified line segment
	* intersect each other; <code>false</code> otherwise.
	* @since 1.2
	*/
	public boolean intersectsLine(double x1, double y1, double x2, double y2) {
	return linesIntersect(x1, y1, x2, y2,
	getX1(), getY1(), getX2(), getY2());
	}

	/**
	* Tests if the specified line segment intersects this line segment.
	* @param l the specified <code>Line2D</code>
	* @return <code>true</code> if this line segment and the specified line
	* segment intersect each other;
	* <code>false</code> otherwise.
	* @since 1.2
	*/
	public boolean intersectsLine(Line2D l) {
	return linesIntersect(l.getX1(), l.getY1(), l.getX2(), l.getY2(),
	getX1(), getY1(), getX2(), getY2());
	}

	/**
	* Returns the square of the distance from a point to a line segment.
	* The distance measured is the distance between the specified
	* point and the closest point between the specified end points.
	* If the specified point intersects the line segment in between the
	* end points, this method returns 0.0.
	*
	* @param x1 the X coordinate of the start point of the
	* specified line segment
	* @param y1 the Y coordinate of the start point of the
	* specified line segment
	* @param x2 the X coordinate of the end point of the
	* specified line segment
	* @param y2 the Y coordinate of the end point of the
	* specified line segment
	* @param px the X coordinate of the specified point being
	* measured against the specified line segment
	* @param py the Y coordinate of the specified point being
	* measured against the specified line segment
	* @return a double value that is the square of the distance from the
	* specified point to the specified line segment.
	* @see #ptLineDistSq(double, double, double, double, double, double)
	* @since 1.2
	*/
	public static double ptSegDistSq(double x1, double y1,
	double x2, double y2,
	double px, double py)
	{
	// Adjust vectors relative to x1,y1
	// x2,y2 becomes relative vector from x1,y1 to end of segment
	x2 -= x1;
	y2 -= y1;
	// px,py becomes relative vector from x1,y1 to test point
	px -= x1;
	py -= y1;
	double dotprod = px * x2 + py * y2;
	double projlenSq;
	if (dotprod <= 0.0) {
	// px,py is on the side of x1,y1 away from x2,y2
	// distance to segment is length of px,py vector
	// "length of its (clipped) projection" is now 0.0
	projlenSq = 0.0;
	} else {
	// switch to backwards vectors relative to x2,y2
	// x2,y2 are already the negative of x1,y1=>x2,y2
	// to get px,py to be the negative of px,py=>x2,y2
	// the dot product of two negated vectors is the same
	// as the dot product of the two normal vectors
	px = x2 - px;
	py = y2 - py;
	dotprod = px * x2 + py * y2;
	if (dotprod <= 0.0) {
	// px,py is on the side of x2,y2 away from x1,y1
	// distance to segment is length of (backwards) px,py vector
	// "length of its (clipped) projection" is now 0.0
	projlenSq = 0.0;
	} else {
	// px,py is between x1,y1 and x2,y2
	// dotprod is the length of the px,py vector
	// projected on the x2,y2=>x1,y1 vector times the
	// length of the x2,y2=>x1,y1 vector
	projlenSq = dotprod * dotprod / (x2 * x2 + y2 * y2);
	}
	}
	// Distance to line is now the length of the relative point
	// vector minus the length of its projection onto the line
	// (which is zero if the projection falls outside the range
	// of the line segment).
	double lenSq = px * px + py * py - projlenSq;
	if (lenSq < 0) {
	lenSq = 0;
	}
	return lenSq;
	}

	/**
	* Returns the distance from a point to a line segment.
	* The distance measured is the distance between the specified
	* point and the closest point between the specified end points.
	* If the specified point intersects the line segment in between the
	* end points, this method returns 0.0.
	*
	* @param x1 the X coordinate of the start point of the
	* specified line segment
	* @param y1 the Y coordinate of the start point of the
	* specified line segment
	* @param x2 the X coordinate of the end point of the
	* specified line segment
	* @param y2 the Y coordinate of the end point of the
	* specified line segment
	* @param px the X coordinate of the specified point being
	* measured against the specified line segment
	* @param py the Y coordinate of the specified point being
	* measured against the specified line segment
	* @return a double value that is the distance from the specified point
	* to the specified line segment.
	* @see #ptLineDist(double, double, double, double, double, double)
	* @since 1.2
	*/
	public static double ptSegDist(double x1, double y1,
	double x2, double y2,
	double px, double py)
	{
	return Math.sqrt(ptSegDistSq(x1, y1, x2, y2, px, py));
	}

	/**
	* Returns the square of the distance from a point to this line segment.
	* The distance measured is the distance between the specified
	* point and the closest point between the current line's end points.
	* If the specified point intersects the line segment in between the
	* end points, this method returns 0.0.
	*
	* @param px the X coordinate of the specified point being
	* measured against this line segment
	* @param py the Y coordinate of the specified point being
	* measured against this line segment
	* @return a double value that is the square of the distance from the
	* specified point to the current line segment.
	* @see #ptLineDistSq(double, double)
	* @since 1.2
	*/
	public double ptSegDistSq(double px, double py) {
	return ptSegDistSq(getX1(), getY1(), getX2(), getY2(), px, py);
	}

	/**
	* Returns the square of the distance from a <code>Point2D</code> to
	* this line segment.
	* The distance measured is the distance between the specified
	* point and the closest point between the current line's end points.
	* If the specified point intersects the line segment in between the
	* end points, this method returns 0.0.
	* @param pt the specified <code>Point2D</code> being measured against
	* this line segment.
	* @return a double value that is the square of the distance from the
	* specified <code>Point2D</code> to the current
	* line segment.
	* @see #ptLineDistSq(Point2D)
	* @since 1.2
	*/
	public double ptSegDistSq(Point2D pt) {
	return ptSegDistSq(getX1(), getY1(), getX2(), getY2(),
	pt.getX(), pt.getY());
	}

	/**
	* Returns the distance from a point to this line segment.
	* The distance measured is the distance between the specified
	* point and the closest point between the current line's end points.
	* If the specified point intersects the line segment in between the
	* end points, this method returns 0.0.
	*
	* @param px the X coordinate of the specified point being
	* measured against this line segment
	* @param py the Y coordinate of the specified point being
	* measured against this line segment
	* @return a double value that is the distance from the specified
	* point to the current line segment.
	* @see #ptLineDist(double, double)
	* @since 1.2
	*/
	public double ptSegDist(double px, double py) {
	return ptSegDist(getX1(), getY1(), getX2(), getY2(), px, py);
	}

	/**
	* Returns the distance from a <code>Point2D</code> to this line
	* segment.
	* The distance measured is the distance between the specified
	* point and the closest point between the current line's end points.
	* If the specified point intersects the line segment in between the
	* end points, this method returns 0.0.
	* @param pt the specified <code>Point2D</code> being measured
	* against this line segment
	* @return a double value that is the distance from the specified
	* <code>Point2D</code> to the current line
	* segment.
	* @see #ptLineDist(Point2D)
	* @since 1.2
	*/
	public double ptSegDist(Point2D pt) {
	return ptSegDist(getX1(), getY1(), getX2(), getY2(),
	pt.getX(), pt.getY());
	}

	/**
	* Returns the square of the distance from a point to a line.
	* The distance measured is the distance between the specified
	* point and the closest point on the infinitely-extended line
	* defined by the specified coordinates. If the specified point
	* intersects the line, this method returns 0.0.
	*
	* @param x1 the X coordinate of the start point of the specified line
	* @param y1 the Y coordinate of the start point of the specified line
	* @param x2 the X coordinate of the end point of the specified line
	* @param y2 the Y coordinate of the end point of the specified line
	* @param px the X coordinate of the specified point being
	* measured against the specified line
	* @param py the Y coordinate of the specified point being
	* measured against the specified line
	* @return a double value that is the square of the distance from the
	* specified point to the specified line.
	* @see #ptSegDistSq(double, double, double, double, double, double)
	* @since 1.2
	*/
	public static double ptLineDistSq(double x1, double y1,
	double x2, double y2,
	double px, double py)
	{
	// Adjust vectors relative to x1,y1
	// x2,y2 becomes relative vector from x1,y1 to end of segment
	x2 -= x1;
	y2 -= y1;
	// px,py becomes relative vector from x1,y1 to test point
	px -= x1;
	py -= y1;
	double dotprod = px * x2 + py * y2;
	// dotprod is the length of the px,py vector
	// projected on the x1,y1=>x2,y2 vector times the
	// length of the x1,y1=>x2,y2 vector
	double projlenSq = dotprod * dotprod / (x2 * x2 + y2 * y2);
	// Distance to line is now the length of the relative point
	// vector minus the length of its projection onto the line
	double lenSq = px * px + py * py - projlenSq;
	if (lenSq < 0) {
	lenSq = 0;
	}
	return lenSq;
	}

	/**
	* Returns the distance from a point to a line.
	* The distance measured is the distance between the specified
	* point and the closest point on the infinitely-extended line
	* defined by the specified coordinates. If the specified point
	* intersects the line, this method returns 0.0.
	*
	* @param x1 the X coordinate of the start point of the specified line
	* @param y1 the Y coordinate of the start point of the specified line
	* @param x2 the X coordinate of the end point of the specified line
	* @param y2 the Y coordinate of the end point of the specified line
	* @param px the X coordinate of the specified point being
	* measured against the specified line
	* @param py the Y coordinate of the specified point being
	* measured against the specified line
	* @return a double value that is the distance from the specified
	* point to the specified line.
	* @see #ptSegDist(double, double, double, double, double, double)
	* @since 1.2
	*/
	public static double ptLineDist(double x1, double y1,
	double x2, double y2,
	double px, double py)
	{
	return Math.sqrt(ptLineDistSq(x1, y1, x2, y2, px, py));
	}

	/**
	* Returns the square of the distance from a point to this line.
	* The distance measured is the distance between the specified
	* point and the closest point on the infinitely-extended line
	* defined by this <code>Line2D</code>. If the specified point
	* intersects the line, this method returns 0.0.
	*
	* @param px the X coordinate of the specified point being
	* measured against this line
	* @param py the Y coordinate of the specified point being
	* measured against this line
	* @return a double value that is the square of the distance from a
	* specified point to the current line.
	* @see #ptSegDistSq(double, double)
	* @since 1.2
	*/
	public double ptLineDistSq(double px, double py) {
	return ptLineDistSq(getX1(), getY1(), getX2(), getY2(), px, py);
	}

	/**
	* Returns the square of the distance from a specified
	* <code>Point2D</code> to this line.
	* The distance measured is the distance between the specified
	* point and the closest point on the infinitely-extended line
	* defined by this <code>Line2D</code>. If the specified point
	* intersects the line, this method returns 0.0.
	* @param pt the specified <code>Point2D</code> being measured
	* against this line
	* @return a double value that is the square of the distance from a
	* specified <code>Point2D</code> to the current
	* line.
	* @see #ptSegDistSq(Point2D)
	* @since 1.2
	*/
	public double ptLineDistSq(Point2D pt) {
	return ptLineDistSq(getX1(), getY1(), getX2(), getY2(),
	pt.getX(), pt.getY());
	}

	/**
	* Returns the distance from a point to this line.
	* The distance measured is the distance between the specified
	* point and the closest point on the infinitely-extended line
	* defined by this <code>Line2D</code>. If the specified point
	* intersects the line, this method returns 0.0.
	*
	* @param px the X coordinate of the specified point being
	* measured against this line
	* @param py the Y coordinate of the specified point being
	* measured against this line
	* @return a double value that is the distance from a specified point
	* to the current line.
	* @see #ptSegDist(double, double)
	* @since 1.2
	*/
	public double ptLineDist(double px, double py) {
	return ptLineDist(getX1(), getY1(), getX2(), getY2(), px, py);
	}

	/**
	* Returns the distance from a <code>Point2D</code> to this line.
	* The distance measured is the distance between the specified
	* point and the closest point on the infinitely-extended line
	* defined by this <code>Line2D</code>. If the specified point
	* intersects the line, this method returns 0.0.
	* @param pt the specified <code>Point2D</code> being measured
	* @return a double value that is the distance from a specified
	* <code>Point2D</code> to the current line.
	* @see #ptSegDist(Point2D)
	* @since 1.2
	*/
	public double ptLineDist(Point2D pt) {
	return ptLineDist(getX1(), getY1(), getX2(), getY2(),
	pt.getX(), pt.getY());
	}

	/**
	* Tests if a specified coordinate is inside the boundary of this
	* <code>Line2D</code>. This method is required to implement the
	* {@link Shape} interface, but in the case of <code>Line2D</code>
	* objects it always returns <code>false</code> since a line contains
	* no area.
	* @param x the X coordinate of the specified point to be tested
	* @param y the Y coordinate of the specified point to be tested
	* @return <code>false</code> because a <code>Line2D</code> contains
	* no area.
	* @since 1.2
	*/
	public boolean contains(double x, double y) {
	return false;
	}

	/**
	* Tests if a given <code>Point2D</code> is inside the boundary of
	* this <code>Line2D</code>.
	* This method is required to implement the {@link Shape} interface,
	* but in the case of <code>Line2D</code> objects it always returns
	* <code>false</code> since a line contains no area.
	* @param p the specified <code>Point2D</code> to be tested
	* @return <code>false</code> because a <code>Line2D</code> contains
	* no area.
	* @since 1.2
	*/
	public boolean contains(Point2D p) {
	return false;
	}

	/**
	* {@inheritDoc}
	* @since 1.2
	*/
	public boolean intersects(double x, double y, double w, double h) {
	return intersects(new Rectangle2D.Double(x, y, w, h));
	}

	/**
	* {@inheritDoc}
	* @since 1.2
	*/
	public boolean intersects(Rectangle2D r) {
	return r.intersectsLine(getX1(), getY1(), getX2(), getY2());
	}

	/**
	* Tests if the interior of this <code>Line2D</code> entirely contains
	* the specified set of rectangular coordinates.
	* This method is required to implement the <code>Shape</code> interface,
	* but in the case of <code>Line2D</code> objects it always returns
	* false since a line contains no area.
	* @param x the X coordinate of the upper-left corner of the
	* specified rectangular area
	* @param y the Y coordinate of the upper-left corner of the
	* specified rectangular area
	* @param w the width of the specified rectangular area
	* @param h the height of the specified rectangular area
	* @return <code>false</code> because a <code>Line2D</code> contains
	* no area.
	* @since 1.2
	*/
	public boolean contains(double x, double y, double w, double h) {
	return false;
	}

	/**
	* Tests if the interior of this <code>Line2D</code> entirely contains
	* the specified <code>Rectangle2D</code>.
	* This method is required to implement the <code>Shape</code> interface,
	* but in the case of <code>Line2D</code> objects it always returns
	* <code>false</code> since a line contains no area.
	* @param r the specified <code>Rectangle2D</code> to be tested
	* @return <code>false</code> because a <code>Line2D</code> contains
	* no area.
	* @since 1.2
	*/
	public boolean contains(Rectangle2D r) {
	return false;
	}

	/**
	* {@inheritDoc}
	* @since 1.2
	*/
	public Rectangle getBounds() {
	return getBounds2D().getBounds();
	}

	/**
	* Returns an iteration object that defines the boundary of this
	* <code>Line2D</code>.
	* The iterator for this class is not multi-threaded safe,
	* which means that this <code>Line2D</code> class does not
	* guarantee that modifications to the geometry of this
	* <code>Line2D</code> object do not affect any iterations of that
	* geometry that are already in process.
	* @param at the specified {@link AffineTransform}
	* @return a {@link PathIterator} that defines the boundary of this
	* <code>Line2D</code>.
	* @since 1.2
	*/
	public PathIterator getPathIterator(AffineTransform at) {
	return new LineIterator(this, at);
	}

	/**
	* Returns an iteration object that defines the boundary of this
	* flattened <code>Line2D</code>.
	* The iterator for this class is not multi-threaded safe,
	* which means that this <code>Line2D</code> class does not
	* guarantee that modifications to the geometry of this
	* <code>Line2D</code> object do not affect any iterations of that
	* geometry that are already in process.
	* @param at the specified <code>AffineTransform</code>
	* @param flatness the maximum amount that the control points for a
	* given curve can vary from colinear before a subdivided
	* curve is replaced by a straight line connecting the
	* end points. Since a <code>Line2D</code> object is
	* always flat, this parameter is ignored.
	* @return a <code>PathIterator</code> that defines the boundary of the
	* flattened <code>Line2D</code>
	* @since 1.2
	*/
	public PathIterator getPathIterator(AffineTransform at, double flatness) {
	return new LineIterator(this, at);
	}

	/**
	* Creates a new object of the same class as this object.
	*
	* @return a clone of this instance.
	* @exception OutOfMemoryError if there is not enough memory.
	* @see java.lang.Cloneable
	* @since 1.2
	*/
	public Object clone() {
	try {
	return super.clone();
	} catch (CloneNotSupportedException e) {
	// this shouldn't happen, since we are Cloneable
	throw new InternalError(e);
	}
	}
	}

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