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/* QuadSegment.java -- QuadCurve segment used for BasicStroke

   Copyright (C) 2006 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 2, or (at your option)

any later version.

GNU Classpath 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 for more details.

You should have received a copy of the GNU General Public License

along with GNU Classpath; see the file COPYING.  If not, write to the

Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

02110-1301 USA.

Linking this library statically or dynamically with other modules is

making a combined work based on this library.  Thus, the terms and

conditions of the GNU General Public License cover the whole

combination.

As a special exception, the copyright holders of this library give you

permission to link this library with independent modules to produce an

executable, regardless of the license terms of these independent

modules, and to copy and distribute the resulting executable under

terms of your choice, provided that you also meet, for each linked

independent module, the terms and conditions of the license of that

module.  An independent module is a module which is not derived from

or based on this library.  If you modify this library, you may extend

this exception to your version of the library, but you are not

obligated to do so.  If you do not wish to do so, delete this

exception statement from your version. */

package gnu.java.awt.java2d;

import java.awt.geom.Point2D;

import java.awt.geom.QuadCurve2D;

/**

 * Quadratic Bezier curve segment

 *

 * Note: Most peers don't support quadratics directly, so it might make

 * sense to represent them as cubics internally and just be done with it.

 * I think we should be peer-agnostic, however, and stay faithful to the

 * input geometry types as far as possible.

 */

public class QuadSegment extends Segment

{

  public Point2D cp; // control point

  /**

   * Constructor, takes the coordinates of the start, control,

   * and end point, respectively.

   */

  public QuadSegment(double x1, double y1, double cx, double cy, double x2,

                     double y2)

  {

    super();

    P1 = new Point2D.Double(x1, y1);

    P2 = new Point2D.Double(x2, y2);

    cp = new Point2D.Double(cx, cy);

  }

  public QuadSegment(Point2D p1, Point2D cp, Point2D p2)

  {

    super();

    P1 = p1;

    P2 = p2;

    this.cp = cp;

  }

  public QuadSegment(QuadCurve2D curve)

  {

    super();

    P1 = curve.getP1();

    P2 = curve.getP2();

    this.cp = curve.getCtrlPt();

  }

  /**

   * Clones this segment

   */

  public Object clone()

  {

    QuadSegment segment = null;

    try

      {

        segment = (QuadSegment) super.clone();

        segment.P1 = (Point2D) P1.clone();

        segment.P2 = (Point2D) P2.clone();

        segment.cp = (Point2D) cp.clone();

      }

    catch (CloneNotSupportedException cnse)

      {

        InternalError ie = new InternalError();

        ie.initCause(cnse);

        throw ie;

      }

    return segment;

  }

  /**

   * Get the "top" and "bottom" segments of a given segment.

   * First array element is p0 + normal, second is p0 - normal.

   */

  public Segment[] getDisplacedSegments(double radius)

  {

    this.radius = radius;

    double x0 = P1.getX();

    double y0 = P1.getY();

    double x1 = cp.getX();

    double y1 = cp.getY();

    double x2 = P2.getX();

    double y2 = P2.getY();

    QuadCurve2D left = new QuadCurve2D.Double();

    QuadCurve2D right = new QuadCurve2D.Double();

    QuadCurve2D orig = new QuadCurve2D.Double(x0, y0, x1, y1, x2, y2);

    orig.subdivide(left, right);

    QuadSegment s1 = offsetSubdivided(left, true);

    QuadSegment s2 = offsetSubdivided(left, false);

    s1.add( offsetSubdivided(right, true) );

    s2.add( offsetSubdivided(right, false) );

    return new Segment[]{s1, s2};

  }

  private QuadSegment offsetSubdivided(QuadCurve2D curve, boolean plus)

  {

    double[] n1 = normal(curve.getX1(), curve.getY1(),

                         curve.getCtrlX(), curve.getCtrlY());

    double[] n2 = normal(curve.getCtrlX(), curve.getCtrlY(),

                         curve.getX2(), curve.getY2());

    Point2D cp;

    QuadSegment s;

    if(!plus)

      {

        n1[0] = -n1[0];

        n1[1] = -n1[1];

        n2[0] = -n2[0];

        n2[1] = -n2[1];

      }

    // Handle special cases where the control point is equal to an end point

    // or end points are equal (ie, straight lines)

    if (curve.getP1().equals(curve.getCtrlPt()))

      {

        cp = curve.getCtrlPt();

        cp.setLocation(cp.getX() + n2[0], cp.getY() + n2[1]);

        n1[0] = n2[0];

        n1[1] = n2[1];

      }

    else if (curve.getP2().equals(curve.getCtrlPt()))

      {

        cp = curve.getCtrlPt();

        cp.setLocation(cp.getX() + n1[0], cp.getY() + n1[1]);

        n2[0] = n1[0];

        n2[1] = n1[1];

      }

    else if (curve.getP1().equals(curve.getP2()))

      {

        cp = curve.getCtrlPt();

        double deltaX = curve.getX1() - curve.getCtrlX();

        double deltaY = curve.getY1() - curve.getCtrlY();

        double length = Math.sqrt((deltaX * deltaX) + (deltaY * deltaY));

        double ratio = radius / length;

        deltaX *= ratio;

        deltaY *= ratio;

        if (plus)

          cp.setLocation(cp.getX() + deltaX, cp.getY() + deltaY);

        else

          cp.setLocation(cp.getX() - deltaX, cp.getY() - deltaY);

      }

    else if (n1[0] == n2[0] && n1[1] == n2[1])

      {

        cp = curve.getCtrlPt();

        cp.setLocation(cp.getX() + n1[0], cp.getY() + n1[1]);

      }

    else

      {

        cp = lineIntersection(curve.getX1() + n1[0],

                              curve.getY1() + n1[1],

                              curve.getCtrlX() + n1[0],

                              curve.getCtrlY() + n1[1],

                              curve.getCtrlX() + n2[0],

                              curve.getCtrlY() + n2[1],

                              curve.getX2() + n2[0],

                              curve.getY2() + n2[1], true);

      }

    s = new QuadSegment(curve.getX1() + n1[0], curve.getY1() + n1[1],

                        cp.getX(), cp.getY(),

                        curve.getX2() + n2[0], curve.getY2() + n2[1]);

    return s;

  }

  private Point2D lineIntersection(double X1, double Y1,

                                   double X2, double Y2,

                                   double X3, double Y3,

                                   double X4, double Y4,

                                   boolean infinite)

  {

    double x1 = X1;

    double y1 = Y1;

    double rx = X2 - x1;

    double ry = Y2 - y1;

    double x2 = X3;

    double y2 = Y3;

    double sx = X4 - x2;

    double sy = Y4 - y2;

    double determinant = sx * ry - sy * rx;

    double nom = (sx * (y2 - y1) + sy * (x1 - x2));

    // lines can be considered parallel.

    if (Math.abs(determinant) < 1E-6)

      return null;

    nom = nom / determinant;

    // check if lines are within the bounds

    if(!infinite && (nom > 1.0 || nom < 0.0))

      return null;

    return new Point2D.Double(x1 + nom * rx, y1 + nom * ry);

  }

  public void reverse()

  {

    Point2D p = P1;

    P1 = P2;

    P2 = p;

  }

  public double[] cp1()

  {

    return new double[]{cp.getX(), cp.getY()};

  }

  public double[] cp2()

  {

    return new double[]{cp.getX(), cp.getY()};

  }

}