arc2d.java

gcc的组建

  {
    double start = getAngleStart();
    double extent = getAngleExtent();
    double end = start + extent;

    if (extent == 0)
      return false;

    if (extent >= 360 || extent <= -360)
      return true;

    if (extent < 0)
      {
	end = start;
	start += extent;
      }

    start %= 360;
    while (start < 0)
      start += 360;

    end %= 360;
    while (end < start)
      end += 360;

    a %= 360;
    while (a < start)
      a += 360;

    return a >= start && a < end; // starting angle included, ending angle not
  }

  /**
   * Determines if the arc contains the given point. If the bounding box
   * is empty, then this will return false.
   *
   * The area considered 'inside' an arc of type OPEN is the same as the
   * area inside an equivalent filled CHORD-type arc. The area considered
   * 'inside' a CHORD-type arc is the same as the filled area.
   *
   * @param x the x coordinate to test
   * @param y the y coordinate to test
   * @return true if the point is inside the arc
   */
  public boolean contains(double x, double y)
  {
    double w = getWidth();
    double h = getHeight();
    double extent = getAngleExtent();
    if (w <= 0 || h <= 0 || extent == 0)
      return false;

    double mx = getX() + w / 2;
    double my = getY() + h / 2;
    double dx = (x - mx) * 2 / w;
    double dy = (y - my) * 2 / h;
    if ((dx * dx + dy * dy) >= 1.0)
      return false;

    double angle = Math.toDegrees(Math.atan2(-dy, dx));
    if (getArcType() == PIE)
      return containsAngle(angle);

    double a1 = Math.toRadians(getAngleStart());
    double a2 = Math.toRadians(getAngleStart() + extent);
    double x1 = mx + getWidth() * Math.cos(a1) / 2;
    double y1 = my - getHeight() * Math.sin(a1) / 2;
    double x2 = mx + getWidth() * Math.cos(a2) / 2;
    double y2 = my - getHeight() * Math.sin(a2) / 2;
    double sgn = ((x2 - x1) * (my - y1) - (mx - x1) * (y2 - y1)) * ((x2 - x1) * (y
                 - y1) - (x - x1) * (y2 - y1));

    if (Math.abs(extent) > 180)
      {
	if (containsAngle(angle))
	  return true;
	return sgn > 0;
      }
    else
      {
	if (! containsAngle(angle))
	  return false;
	return sgn < 0;
      }
  }

  /**
   * Tests if a given rectangle intersects the area of the arc.
   *
   * For a definition of the 'inside' area, see the contains() method.
   * @see #contains(double, double)
   *
   * @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 two shapes share common points
   */
  public boolean intersects(double x, double y, double w, double h)
  {
    double extent = getAngleExtent();
    if (extent == 0)
      return false;

    if (contains(x, y) || contains(x, y + h) || contains(x + w, y)
        || contains(x + w, y + h))
      return true;

    Rectangle2D rect = new Rectangle2D.Double(x, y, w, h);

    double a = getWidth() / 2.0;
    double b = getHeight() / 2.0;

    double mx = getX() + a;
    double my = getY() + b;
    double x1 = mx + a * Math.cos(Math.toRadians(getAngleStart()));
    double y1 = my - b * Math.sin(Math.toRadians(getAngleStart()));
    double x2 = mx + a * Math.cos(Math.toRadians(getAngleStart() + extent));
    double y2 = my - b * Math.sin(Math.toRadians(getAngleStart() + extent));

    if (getArcType() != CHORD)
      {
	// check intersections against the pie radii
	if (rect.intersectsLine(mx, my, x1, y1))
	  return true;
	if (rect.intersectsLine(mx, my, x2, y2))
	  return true;
      }
    else// check the chord
    if (rect.intersectsLine(x1, y1, x2, y2))
      return true;

    // Check the Arc segment against the four edges
    double dx;

    // Check the Arc segment against the four edges
    double dy;
    dy = y - my;
    dx = a * Math.sqrt(1 - ((dy * dy) / (b * b)));
    if (! java.lang.Double.isNaN(dx))
      {
	if (mx + dx >= x && mx + dx <= x + w
	    && containsAngle(Math.toDegrees(Math.atan2(-dy, dx))))
	  return true;
	if (mx - dx >= x && mx - dx <= x + w
	    && containsAngle(Math.toDegrees(Math.atan2(-dy, -dx))))
	  return true;
      }
    dy = (y + h) - my;
    dx = a * Math.sqrt(1 - ((dy * dy) / (b * b)));
    if (! java.lang.Double.isNaN(dx))
      {
	if (mx + dx >= x && mx + dx <= x + w
	    && containsAngle(Math.toDegrees(Math.atan2(-dy, dx))))
	  return true;
	if (mx - dx >= x && mx - dx <= x + w
	    && containsAngle(Math.toDegrees(Math.atan2(-dy, -dx))))
	  return true;
      }
    dx = x - mx;
    dy = b * Math.sqrt(1 - ((dx * dx) / (a * a)));
    if (! java.lang.Double.isNaN(dy))
      {
	if (my + dy >= y && my + dy <= y + h
	    && containsAngle(Math.toDegrees(Math.atan2(-dy, dx))))
	  return true;
	if (my - dy >= y && my - dy <= y + h
	    && containsAngle(Math.toDegrees(Math.atan2(dy, dx))))
	  return true;
      }

    dx = (x + w) - mx;
    dy = b * Math.sqrt(1 - ((dx * dx) / (a * a)));
    if (! java.lang.Double.isNaN(dy))
      {
	if (my + dy >= y && my + dy <= y + h
	    && containsAngle(Math.toDegrees(Math.atan2(-dy, dx))))
	  return true;
	if (my - dy >= y && my - dy <= y + h
	    && containsAngle(Math.toDegrees(Math.atan2(dy, dx))))
	  return true;
      }

    // Check whether the arc is contained within the box
    if (rect.contains(mx, my))
      return true;

    return false;
  }

  /**
   * Tests if a given rectangle is contained in the area of the arc.
   *
   * @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 arc contains the rectangle
   */
  public boolean contains(double x, double y, double w, double h)
  {
    double extent = getAngleExtent();
    if (extent == 0)
      return false;

    if (! (contains(x, y) && contains(x, y + h) && contains(x + w, y)
        && contains(x + w, y + h)))
      return false;

    Rectangle2D rect = new Rectangle2D.Double(x, y, w, h);

    double a = getWidth() / 2.0;
    double b = getHeight() / 2.0;

    double mx = getX() + a;
    double my = getY() + b;
    double x1 = mx + a * Math.cos(Math.toRadians(getAngleStart()));
    double y1 = my - b * Math.sin(Math.toRadians(getAngleStart()));
    double x2 = mx + a * Math.cos(Math.toRadians(getAngleStart() + extent));
    double y2 = my - b * Math.sin(Math.toRadians(getAngleStart() + extent));
    if (getArcType() != CHORD)
      {
	// check intersections against the pie radii
	if (rect.intersectsLine(mx, my, x1, y1))
	  return false;

	if (rect.intersectsLine(mx, my, x2, y2))
	  return false;
      }
    else if (rect.intersectsLine(x1, y1, x2, y2))
      return false;
    return true;
  }

  /**
   * Tests if a given rectangle is contained in the area of the arc.
   *
   * @param r the rectangle
   * @return true if the arc contains the rectangle
   */
  public boolean contains(Rectangle2D r)
  {
    return contains(r.getX(), r.getY(), r.getWidth(), r.getHeight());
  }

  /**
   * Returns an iterator over this arc, with an optional transformation.
   * This iterator is threadsafe, so future modifications to the arc do not
   * affect the iteration.
   *
   * @param at the transformation, or null
   * @return a path iterator
   */
  public PathIterator getPathIterator(AffineTransform at)
  {
    return new ArcIterator(this, at);
  }

  /**
   * This class is used to iterate over an arc. Since ellipses are a subclass
   * of arcs, this is used by Ellipse2D as well.
   *
   * @author Eric Blake ([e-mail])
   */
  static final class ArcIterator implements PathIterator
  {
    /** The current iteration. */
    private int current;

    /** The last iteration. */
    private final int limit;

    /** The optional transformation. */
    private final AffineTransform xform;

    /** The x coordinate of the bounding box. */
    private final double x;

    /** The y coordinate of the bounding box. */
    private final double y;

    /** The width of the bounding box. */
    private final double w;

    /** The height of the bounding box. */
    private final double h;

    /** The start angle, in radians (not degrees). */
    private final double start;

    /** The extent angle, in radians (not degrees). */
    private final double extent;

    /** The arc closure type. */
    private final int type;

    /**
     * Construct a new iterator over an arc.
     *
     * @param a the arc
     * @param xform the transform
     */
    public ArcIterator(Arc2D a, AffineTransform xform)
    {
      this.xform = xform;
      x = a.getX();
      y = a.getY();
      w = a.getWidth();
      h = a.getHeight();
      double start = a.getAngleStart() * (Math.PI / 180);
      double extent = a.getAngleExtent() * (Math.PI / 180);

      if (extent < 0)
        {
	  extent = -extent;
	  start = 2 * Math.PI - extent + start;
        }
      this.start = start;
      this.extent = extent;

      type = a.type;
      if (w < 0 || h < 0)
	limit = -1;
      else if (extent == 0)
	limit = type;
      else if (extent <= Math.PI / 2.0)
	limit = type + 1;
      else if (extent <= Math.PI)
	limit = type + 2;
      else if (extent <= 3.0 * (Math.PI / 2.0))
	limit = type + 3;
      else
	limit = type + 4;
    }

    /**
     * Construct a new iterator over an ellipse.
     *
     * @param e the ellipse
     * @param xform the transform
     */
    public ArcIterator(Ellipse2D e, AffineTransform xform)
    {
      this.xform = xform;
      x = e.getX();
      y = e.getY();
      w = e.getWidth();
      h = e.getHeight();
      start = 0;
      extent = 2 * Math.PI;
      type = CHORD;
      limit = (w < 0 || h < 0) ? -1 : 5;
    }

    /**
     * Return the winding rule.
     *
     * @return {@link PathIterator#WIND_NON_ZERO}
     */
    public int getWindingRule()
    {
      return WIND_NON_ZERO;
    }

    /**
     * Test if the iteration is complete.
     *
     * @return true if more segments exist
     */
    public boolean isDone()
    {
      return current > limit;
    }

    /**
     * Advance the iterator.
     */
    public void next()
    {
      current++;
    }

    /**
     * Put the current segment into the array, and return the segment type.
     *
     * @param coords an array of 6 elements
     * @return the segment type
     * @throws NullPointerException if coords is null
     * @throws ArrayIndexOutOfBoundsException if coords is too small
     */
    public int currentSegment(float[] coords)
    {
      double[] double_coords = new double[6];
      int code = currentSegment(double_coords);
      for (int i = 0; i < 6; ++i)
	coords[i] = (float) double_coords[i];
      return code;
    }

    /**
     * Put the current segment into the array, and return the segment type.
     *
     * @param coords an array of 6 elements
     * @return the segment type
     * @throws NullPointerException if coords is null
     * @throws ArrayIndexOutOfBoundsException if coords is too small
     */
    public int currentSegment(double[] coords)
    {
      double rx = w / 2;
      double ry = h / 2;
      double xmid = x + rx;
      double ymid = y + ry;

      if (current > limit)
	throw new NoSuchElementException("arc iterator out of bounds");

      if (current == 0)
        {
	  coords[0] = xmid + rx * Math.cos(start);
	  coords[1] = ymid - ry * Math.sin(start);
	  if (xform != null)
	    xform.transform(coords, 0, coords, 0, 1);
	  return SEG_MOVETO;
        }

      if (type != OPEN && current == limit)
	return SEG_CLOSE;

      if ((current == limit - 1) && (type == PIE))
        {
	  coords[0] = xmid;
	  coords[1] = ymid;
	  if (xform != null)
	    xform.transform(coords, 0, coords, 0, 1);
	  return SEG_LINETO;
        }

      // note that this produces a cubic approximation of the arc segment,
      // not a true ellipsoid. there's no ellipsoid path segment code,
      // unfortunately. the cubic approximation looks about right, though.
      double kappa = (Math.sqrt(2.0) - 1.0) * (4.0 / 3.0);
      double quad = (Math.PI / 2.0);

      double curr_begin = start + (current - 1) * quad;
      double curr_extent = Math.min((start + extent) - curr_begin, quad);
      double portion_of_a_quadrant = curr_extent / quad;

      double x0 = xmid + rx * Math.cos(curr_begin);
      double y0 = ymid - ry * Math.sin(curr_begin);

      double x1 = xmid + rx * Math.cos(curr_begin + curr_extent);
      double y1 = ymid - ry * Math.sin(curr_begin + curr_extent);

      AffineTransform trans = new AffineTransform();
      double[] cvec = new double[2];
      double len = kappa * portion_of_a_quadrant;
      double angle = curr_begin;

      // in a hypothetical "first quadrant" setting, our first control
      // vector would be sticking up, from [1,0] to [1,kappa].
      //
      // let us recall however that in java2d, y coords are upside down
      // from what one would consider "normal" first quadrant rules, so we
      // will *subtract* the y value of this control vector from our first
      // point.
      cvec[0] = 0;