line2d.java

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	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 :
						throw new NoSuchElementException("line iterator out of bounds");
				}
				if (at != null)
					at.transform(coords, 0, coords, 0, 1);
				return result;
			}
		};
	}

	/**