/* Polygon.java -- Class representing a polygon
   Copyright (C) 1999 Free Software Foundation, Inc.

This file is part of the non-peer AWT libraries of GNU Classpath.

This library is free software; you can redistribute it and/or modify
it under the terms of the GNU Library General Public License as published 
by the Free Software Foundation, either version 2 of the License, or
(at your option) any later verion.

This library 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 Library General Public License for more details.

You should have received a copy of the GNU Library General Public License
along with this library; if not, write to the Free Software Foundation
Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307 USA. */


package java.awt;

/**
  * This class represents a polygon
  *
  * @author Aaron M. Renn (arenn@urbanophile.com)
  */
public class Polygon implements Shape, java.io.Serializable
{

/*
 * Instance Variables
 */

/**
  * This total number of endpoints 
  */
public int npoints;

/**
  * The array of X coordinates of endpoints.
  */
public int xpoints[];

/**
  * The array of Y coordinates of endpoints.
  */
public int ypoints[];

/**
  * The bounding box of this polygon
  */
protected Rectangle bounds;

/*************************************************************************/

/*
 * Constructors
 */

/**
  * Initializes a new instance of <code>Polygon</code> that is empty.
  */
public
Polygon()
{
  xpoints = new int[0];
  ypoints = new int[0];

  bounds = new Rectangle(0,0,0,0);
}

/*************************************************************************/

/**
  * Initializes a new instance of <code>Polygon</code> that has the
  * specified endpoints.
  *
  * @param xpoints The array of X coordinates for this polygon.
  * @param ypoints The array of Y coordinates for this polygon.
  * @param npoints The total number of endpoints in this polygon.
  *
  * @exception NegativeArraySizeException If <code>npoints</code> is negative.
  */
public
Polygon(int[] xpoints, int[] ypoints, int npoints)
{
  if (npoints < 0)
    throw new NegativeArraySizeException();

  this.xpoints = xpoints;
  this.ypoints = ypoints;
  this.npoints = npoints;

  calculateBounds();
}

/*************************************************************************/

/*
 * Instance Methods
 */

/**
  * Calculates the bounding rectangle of this polygon.
  */
public void
calculateBounds()
{
  int minx = xpoints[0], maxx = xpoints[0];
  int miny = ypoints[0], maxy = ypoints[0];

  for (int i = 0; i < npoints; i++)
    {
      if (xpoints[i] < minx)
        minx = xpoints[i];

      if (xpoints[i] > maxx)
        maxx = xpoints[i];

      if (ypoints[i] < miny)
        miny = ypoints[i];

      if (ypoints[i] > maxy)
        maxy = ypoints[i];
    }

  bounds = new Rectangle(minx, maxy, maxx-minx, maxy-miny);
}

/*************************************************************************/

/**
  * Translates the polygon by adding the specified values to all X and Y
  * coordinates.
  *
  * @param dx The amount to add to all X coordinates.
  * @param dy The amount to add to all Y coordinates.
  */
public void
translate(int dx, int dy)
{
  for (int i = 0; i < npoints; i++)
    {
      xpoints[i] += dx;
      xpoints[i] += dy;
    }

  calculateBounds();
}

/*************************************************************************/

/**
  * Adds the specified endpoint to the polygon.
  *
  * @param x The X coordinate of the point to add.
  * @param y The Y coordiante of the point to add.
  */
public void
addPoint(int x, int y)
{
  int newxpoints[] = new int[npoints + 1];
  int newypoints[] = new int[npoints + 1];

  System.arraycopy(xpoints, 0, newxpoints, 0, npoints);
  System.arraycopy(ypoints, 0, newypoints, 0, npoints);

  newxpoints[npoints] = x;
  newypoints[npoints] = y;

  xpoints = newxpoints;
  ypoints = newypoints;
  ++npoints;
}

/*************************************************************************/

/**
  * Returns the bounding box of this polygon.  This is the smallest 
  * rectangle with sides parallel to the X axis that will contain this
  * polygon.
  *
  * @return The bounding box for this polygon.
  */
public Rectangle
getBounds()
{
  return(bounds);
}

/*************************************************************************/

/**
  * Returns the bounding box of this polygon.  This is the smallest 
  * rectangle with sides parallel to the X axis that will contain this
  * polygon.
  *
  * @return The bounding box for this polygon.
  *
  * @deprecated This method has been replaced by <code>getBounds()</code>.
  */
public Rectangle
getBoundingBox()
{
  return(bounds);
}

/*************************************************************************/

/**
  * Tests whether or not the specified point is inside this polygon.
  *
  * @param x The X coordinate of the point to test.
  * @param y the Y coordinate of the point to test.
  *
  * @return <code>true</code> if the point is inside this polygon,
  * <code>false</code> otherwise.
  */
public boolean
contains(int x, int y)
{
  // Is inside bounding box.
  if (!bounds.contains(x, y))
    return(false);

  int sign = 0;
  for (int i = 0; i < npoints; i ++)
    {
      int nx = xpoints[(i + 1) % npoints] - xpoints[i];
      int ny = ypoints[(i + 1) % npoints] - ypoints[i];

      int dx = x - xpoints[i];
      int dy = y - ypoints[i];

      int val = (dx*nx) + (dy*nx);

      if (sign == 0)
        {
          if (val < 1)
            sign = -1;
          else if (val > 1)
            sign = 1;
        }

      if ((val > 1) && (sign < 1))
        return(false);
      if ((val < 1) && (sign > 1))
        return(false);
    }

  return(true);
}

/*************************************************************************/

/**
  * Tests whether or not the specified point is inside this polygon.
  *
  * @param x The X coordinate of the point to test.
  * @param y the Y coordinate of the point to test.
  *
  * @return <code>true</code> if the point is inside this polygon,
  * <code>false</code> otherwise.
  *
  * @deprecated This method has been replaced by <code>contains()</code>.
  */
public boolean
inside(int x, int y)
{
  return(contains(x, y));
}

} // class Polygon