line2d.java

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  {
    return Math.sqrt(ptSegDistSq(x1, y1, x2, y2, px, py));
  }

  /**
   * Measures the square of the shortest distance from the reference point
   * to a point on this line segment. If the point is on the segment, the
   * result will be 0.
   *
   * @param px the x coordinate of the point
   * @param py the y coordinate of the point
   * @return the square of the distance from the point to the segment
   * @see #ptSegDistSq(double, double, double, double, double, double)
   */
  public double ptSegDistSq(double px, double py)
  {
    return ptSegDistSq(getX1(), getY1(), getX2(), getY2(), px, py);
  }

  /**
   * Measures the square of the shortest distance from the reference point
   * to a point on this line segment. If the point is on the segment, the
   * result will be 0.
   *
   * @param p the point
   * @return the square of the distance from the point to the segment
   * @throws NullPointerException if p is null
   * @see #ptSegDistSq(double, double, double, double, double, double)
   */
  public double ptSegDistSq(Point2D p)
  {
    return ptSegDistSq(getX1(), getY1(), getX2(), getY2(), p.getX(), p.getY());
  }

  /**
   * Measures the shortest distance from the reference point to a point on
   * this line segment. If the point is on the segment, the result will be 0.
   *
   * @param px the x coordinate of the point
   * @param py the y coordinate of the point
   * @return the distance from the point to the segment
   * @see #ptSegDist(double, double, double, double, double, double)
   */
  public double ptSegDist(double px, double py)
  {
    return ptSegDist(getX1(), getY1(), getX2(), getY2(), px, py);
  }

  /**
   * Measures the shortest distance from the reference point to a point on
   * this line segment. If the point is on the segment, the result will be 0.
   *
   * @param p the point
   * @return the distance from the point to the segment
   * @throws NullPointerException if p is null
   * @see #ptSegDist(double, double, double, double, double, double)
   */
  public double ptSegDist(Point2D p)
  {
    return ptSegDist(getX1(), getY1(), getX2(), getY2(), p.getX(), p.getY());
  }

  /**
   * Measures the square of the shortest distance from the reference point
   * to a point on the infinite line extended from the segment. If the point
   * is on the segment, the result will be 0. If the segment is length 0,
   * the distance is to the common endpoint.
   *
   * @param x1 the first x coordinate of the segment
   * @param y1 the first y coordinate of the segment
   * @param x2 the second x coordinate of the segment
   * @param y2 the second y coordinate of the segment
   * @param px the x coordinate of the point
   * @param py the y coordinate of the point
   * @return the square of the distance from the point to the extended line
   * @see #ptLineDist(double, double, double, double, double, double)
   * @see #ptSegDistSq(double, double, double, double, double, double)
   */
  public static double ptLineDistSq(double x1, double y1, double x2, double y2,
                                    double px, double py)
  {
    double pd2 = (x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2);

    double x, y;
    if (pd2 == 0)
      {
        // Points are coincident.
        x = x1;
        y = y2;
      }
    else
      {
        double u = ((px - x1) * (x2 - x1) + (py - y1) * (y2 - y1)) / pd2;
        x = x1 + u * (x2 - x1);
        y = y1 + u * (y2 - y1);
      }

    return (x - px) * (x - px) + (y - py) * (y - py);
  }

  /**
   * Measures the shortest distance from the reference point to a point on
   * the infinite line extended from the segment. If the point is on the
   * segment, the result will be 0. If the segment is length 0, the distance
   * is to the common endpoint.
   *
   * @param x1 the first x coordinate of the segment
   * @param y1 the first y coordinate of the segment
   * @param x2 the second x coordinate of the segment
   * @param y2 the second y coordinate of the segment
   * @param px the x coordinate of the point
   * @param py the y coordinate of the point
   * @return the distance from the point to the extended line
   * @see #ptLineDistSq(double, double, double, double, double, double)
   * @see #ptSegDist(double, double, double, double, double, double)
   */
  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));
  }

  /**
   * Measures the square of the shortest distance from the reference point
   * to a point on the infinite line extended from this segment. If the point
   * is on the segment, the result will be 0. If the segment is length 0,
   * the distance is to the common endpoint.
   *
   * @param px the x coordinate of the point
   * @param py the y coordinate of the point
   * @return the square of the distance from the point to the extended line
   * @see #ptLineDistSq(double, double, double, double, double, double)
   */
  public double ptLineDistSq(double px, double py)
  {
    return ptLineDistSq(getX1(), getY1(), getX2(), getY2(), px, py);
  }

  /**
   * Measures the square of the shortest distance from the reference point
   * to a point on the infinite line extended from this segment. If the point
   * is on the segment, the result will be 0. If the segment is length 0,
   * the distance is to the common endpoint.
   *
   * @param p the point
   * @return the square of the distance from the point to the extended line
   * @throws NullPointerException if p is null
   * @see #ptLineDistSq(double, double, double, double, double, double)
   */
  public double ptLineDistSq(Point2D p)
  {
    return ptLineDistSq(getX1(), getY1(), getX2(), getY2(),
                        p.getX(), p.getY());
  }

  /**
   * Measures the shortest distance from the reference point to a point on
   * the infinite line extended from this segment. If the point is on the
   * segment, the result will be 0. If the segment is length 0, the distance
   * is to the common endpoint.
   *
   * @param px the x coordinate of the point
   * @param py the y coordinate of the point
   * @return the distance from the point to the extended line
   * @see #ptLineDist(double, double, double, double, double, double)
   */
  public double ptLineDist(double px, double py)
  {
    return ptLineDist(getX1(), getY1(), getX2(), getY2(), px, py);
  }

  /**
   * Measures the shortest distance from the reference point to a point on
   * the infinite line extended from this segment. If the point is on the
   * segment, the result will be 0. If the segment is length 0, the distance
   * is to the common endpoint.
   *
   * @param p the point
   * @return the distance from the point to the extended line
   * @throws NullPointerException if p is null
   * @see #ptLineDist(double, double, double, double, double, double)
   */
  public double ptLineDist(Point2D p)
  {
    return ptLineDist(getX1(), getY1(), getX2(), getY2(), p.getX(), p.getY());
  }

  /**
   * Test if a point is contained inside the line. Since a line has no area,
   * this returns false.
   *
   * @param x the x coordinate
   * @param y the y coordinate
   * @return false; the line does not contain points
   */
  public boolean contains(double x, double y)
  {
    return false;
  }

  /**
   * Test if a point is contained inside the line. Since a line has no area,
   * this returns false.
   *
   * @param p the point
   * @return false; the line does not contain points
   */
  public boolean contains(Point2D p)
  {
    return false;
  }

  /**
   * Tests if this line intersects the interior of the specified rectangle.
   *
   * @param x the x coordinate of the rectangle
   * @param y the y coordinate of the rectangle
   * @param w the width of the rectangle
   * @param h the height of the rectangle
   * @return true if the line intersects the rectangle
   */
  public boolean intersects(double x, double y, double w, double h)
  {
    if (w <= 0 || h <= 0)
      return false;
    double x1 = getX1();
    double y1 = getY1();
    double x2 = getX2();
    double y2 = getY2();

    if (x1 >= x && x1 <= x + w && y1 >= y && y1 <= y + h)
      return true;
    if (x2 >= x && x2 <= x + w && y2 >= y && y2 <= y + h)
      return true;

    double x3 = x + w;
    double y3 = y + h;

    return (linesIntersect(x1, y1, x2, y2, x, y, x, y3)
            || linesIntersect(x1, y1, x2, y2, x, y3, x3, y3)
            || linesIntersect(x1, y1, x2, y2, x3, y3, x3, y)
            || linesIntersect(x1, y1, x2, y2, x3, y, x, y));
  }

  /**
   * Tests if this line intersects the interior of the specified rectangle.
   *
   * @param r the rectangle
   * @return true if the line intersects the rectangle
   * @throws NullPointerException if r is null
   */
  public boolean intersects(Rectangle2D r)
  {
    return intersects(r.getX(), r.getY(), r.getWidth(), r.getHeight());
  }

  /**
   * Tests if the line contains a rectangle. Since lines have no area, this
   * always returns false.
   *
   * @param x the x coordinate of the rectangle
   * @param y the y coordinate of the rectangle
   * @param w the width of the rectangle
   * @param h the height of the rectangle
   * @return false; the line does not contain points
   */
  public boolean contains(double x, double y, double w, double h)
  {
    return false;
  }

  /**
   * Tests if the line contains a rectangle. Since lines have no area, this
   * always returns false.
   *
   * @param r the rectangle
   * @return false; the line does not contain points
   */
  public boolean contains(Rectangle2D r)
  {
    return false;
  }

  /**
   * Gets a bounding box (not necessarily minimal) for this line.
   *
   * @return the integer bounding box
   * @see #getBounds2D()
   */
  public Rectangle getBounds()
  {
    return getBounds2D().getBounds();
  }

  /**
   * Return a path iterator, possibly applying a transform on the result. This
   * iterator is not threadsafe.
   *
   * @param at the transform, or null
   * @return a new path iterator
   */
  public PathIterator getPathIterator(final AffineTransform at)
  {
    return new PathIterator()
    {
      /** Current coordinate. */
      private int current;

      public int getWindingRule()
      {
        return WIND_NON_ZERO;
      }

      public boolean isDone()
      {
        return current < 2;
      }

      public void next()
      {
        current++;
      }

      public int currentSegment(float[] coords)
      {
        int result;
        switch (current)
          {
          case 0:
            coords[0] = (float) getX1();
            coords[1] = (float) getY1();
            result = SEG_MOVETO;
            break;
          case 1:
            coords[0] = (float) getX2();
            coords[1] = (float) getY2();
            result = SEG_LINETO;
            break;
          default:
            throw new NoSuchElementException("line iterator out of bounds");
          }
        if (at != null)
          at.transform(coords, 0, coords, 0, 1);
        return result;
      }

      public int currentSegment(double[] coords)
      {
        int result;
        switch (current)
          {
          case 0:
            coords[0] = getX1();
            coords[1] = getY1();
            result = SEG_MOVETO;
            break;
          case 1:
            coords[0] = getX2();
            coords[1] = getY2();
            result = SEG_LINETO;
            break;
          default: