generalpath.java

gcc的组建

   * within the path, <code>false</code> otherwise
   */
  public boolean contains(Rectangle2D r)
  {
    return contains(r.getX(), r.getY(), r.getWidth(), r.getHeight());
  }

  /**
   * Evaluates if a rectangle intersects the path.
   * @param x x coordinate of the rectangle
   * @param y y coordinate of the rectangle
   * @param w width of the rectangle
   * @param h height of the rectangle
   * @return <code>true</code> if the rectangle intersects the path,
   * <code>false</code> otherwise
   */
  public boolean intersects(double x, double y, double w, double h)
  {
    /* Does any edge intersect? */
    if (getAxisIntersections(x, y, false, w) != 0 /* top */
        || getAxisIntersections(x, y + h, false, w) != 0 /* bottom */
        || getAxisIntersections(x + w, y, true, h) != 0 /* right */
        || getAxisIntersections(x, y, true, h) != 0) /* left */
      return true;

    /* No intersections, is any point inside? */
    if (getWindingNumber(x, y) != 0)
      return true;

    return false;
  }

  /**
   * Evaluates if a Rectangle2D intersects the path.
   * @param r The rectangle
   * @return <code>true</code> if the rectangle intersects the path,
   * <code>false</code> otherwise
   */
  public boolean intersects(Rectangle2D r)
  {
    return intersects(r.getX(), r.getY(), r.getWidth(), r.getHeight());
  }

  /**
   * A PathIterator that iterates over the segments of a GeneralPath.
   *
   * @author Sascha Brawer ([e-mail])
   */
  private static class GeneralPathIterator implements PathIterator
  {
    /**
     * The number of coordinate values for each segment type.
     */
    private static final int[] NUM_COORDS = { 
                                            /* 0: SEG_MOVETO */ 1, 
                                            /* 1: SEG_LINETO */ 1, 
                                            /* 2: SEG_QUADTO */ 2, 
                                            /* 3: SEG_CUBICTO */ 3, 
                                            /* 4: SEG_CLOSE */ 0};

    /**
     * The GeneralPath whose segments are being iterated.
     * This is package-private to avoid an accessor method.
     */
    final GeneralPath path;

    /**
     * The affine transformation used to transform coordinates.
     */
    private final AffineTransform transform;

    /**
     * The current position of the iterator.
     */
    private int pos;

    /**
     * Constructs a new iterator for enumerating the segments of a
     * GeneralPath.
     *
     * @param path the path to enumerate
     * @param transform an affine transformation for projecting the returned
     * points, or <code>null</code> to return the original points
     * without any mapping.
     */
    GeneralPathIterator(GeneralPath path, AffineTransform transform)
    {
      this.path = path;
      this.transform = transform;
    }

    /**
     * Returns the current winding rule of the GeneralPath.
     */
    public int getWindingRule()
    {
      return path.rule;
    }

    /**
     * Determines whether the iterator has reached the last segment in
     * the path.
     */
    public boolean isDone()
    {
      return pos >= path.index;
    }

    /**
     * Advances the iterator position by one segment.
     */
    public void next()
    {
      int seg;

      /*
       * Increment pos by the number of coordinate pairs.
       */
      seg = path.types[pos];
      if (seg == SEG_CLOSE)
	pos++;
      else
	pos += NUM_COORDS[seg];
    }

    /**
     * Returns the current segment in float coordinates.
     */
    public int currentSegment(float[] coords)
    {
      int seg;
      int numCoords;

      seg = path.types[pos];
      numCoords = NUM_COORDS[seg];
      if (numCoords > 0)
        {
	  for (int i = 0; i < numCoords; i++)
	    {
	      coords[i << 1] = path.xpoints[pos + i];
	      coords[(i << 1) + 1] = path.ypoints[pos + i];
	    }

	  if (transform != null)
	    transform.transform( /* src */
	    coords, /* srcOffset */
	    0, /* dest */ coords, /* destOffset */
	    0, /* numPoints */ numCoords);
        }
      return seg;
    }

    /**
     * Returns the current segment in double coordinates.
     */
    public int currentSegment(double[] coords)
    {
      int seg;
      int numCoords;

      seg = path.types[pos];
      numCoords = NUM_COORDS[seg];
      if (numCoords > 0)
        {
	  for (int i = 0; i < numCoords; i++)
	    {
	      coords[i << 1] = (double) path.xpoints[pos + i];
	      coords[(i << 1) + 1] = (double) path.ypoints[pos + i];
	    }
	  if (transform != null)
	    transform.transform( /* src */
	    coords, /* srcOffset */
	    0, /* dest */ coords, /* destOffset */
	    0, /* numPoints */ numCoords);
        }
      return seg;
    }
  }

  /**
   * Creates a PathIterator for iterating along the segments of the path.
   *
   * @param at an affine transformation for projecting the returned
   * points, or <code>null</code> to let the created iterator return
   * the original points without any mapping.
   */
  public PathIterator getPathIterator(AffineTransform at)
  {
    return new GeneralPathIterator(this, at);
  }

  /**
   * Creates a new FlatteningPathIterator for the path
   */
  public PathIterator getPathIterator(AffineTransform at, double flatness)
  {
    return new FlatteningPathIterator(getPathIterator(at), flatness);
  }

  /**
   * Creates a new shape of the same run-time type with the same contents 
   * as this one.
   *
   * @return the clone
   *
   * @exception OutOfMemoryError If there is not enough memory available.
   *
   * @since 1.2
   */
  public Object clone()
  {
    // This class is final; no need to use super.clone().
    return new GeneralPath(this);
  }

  /**
   * Helper method - ensure the size of the data arrays,
   * otherwise, reallocate new ones twice the size
   */
  private void ensureSize(int size)
  {
    if (subpath < 0)
      throw new IllegalPathStateException("need initial moveto");
    if (size <= xpoints.length)
      return;
    byte[] b = new byte[types.length << 1];
    System.arraycopy(types, 0, b, 0, index);
    types = b;
    float[] f = new float[xpoints.length << 1];
    System.arraycopy(xpoints, 0, f, 0, index);
    xpoints = f;
    f = new float[ypoints.length << 1];
    System.arraycopy(ypoints, 0, f, 0, index);
    ypoints = f;
  }

  /**
   * Helper method - Get the total number of intersections from (x,y) along 
   * a given axis, within a given distance.
   */
  private int getAxisIntersections(double x, double y, boolean useYaxis,
                                   double distance)
  {
    return (evaluateCrossings(x, y, false, useYaxis, distance));
  }

  /**
   * Helper method - returns the winding number of a point.
   */
  private int getWindingNumber(double x, double y)
  {
    /* Evaluate the crossings from x,y to infinity on the y axis (arbitrary 
       choice). Note that we don't actually use Double.INFINITY, since that's 
       slower, and may cause problems. */
    return (evaluateCrossings(x, y, true, true, BIG_VALUE));
  }

  /**
   * Helper method - evaluates the number of intersections on an axis from 
   * the point (x,y) to the point (x,y+distance) or (x+distance,y).
   * @param x x coordinate.
   * @param y y coordinate.
   * @param neg True if opposite-directed intersections should cancel, 
   * false to sum all intersections.
   * @param useYaxis Use the Y axis, false uses the X axis.
   * @param distance Interval from (x,y) on the selected axis to find 
   * intersections.
   */
  private int evaluateCrossings(double x, double y, boolean neg,
                                boolean useYaxis, double distance)
  {
    float cx = 0.0f;
    float cy = 0.0f;
    float firstx = 0.0f;
    float firsty = 0.0f;

    int negative = (neg) ? -1 : 1;
    double x0;
    double x1;
    double x2;
    double x3;
    double y0;
    double y1;
    double y2;
    double y3;
    double[] r = new double[4];
    int nRoots;
    double epsilon = 0.0;
    int pos = 0;
    int windingNumber = 0;
    boolean pathStarted = false;

    if (index == 0)
      return (0);
    if (useYaxis)
      {
	float[] swap1;
	swap1 = ypoints;
	ypoints = xpoints;
	xpoints = swap1;
	double swap2;
	swap2 = y;
	y = x;
	x = swap2;
      }

    /* Get a value which is hopefully small but not insignificant relative
     the path. */
    epsilon = ypoints[0] * 1E-7;

    if(epsilon == 0) 
      epsilon = 1E-7;

    pos = 0;
    while (pos < index)
      {
	switch (types[pos])
	  {
	  case PathIterator.SEG_MOVETO:
	    if (pathStarted) // close old path
	      {
		x0 = cx;
		y0 = cy;
		x1 = firstx;
		y1 = firsty;

		if (y0 == 0.0)
		  y0 -= epsilon;
		if (y1 == 0.0)
		  y1 -= epsilon;
		if (Line2D.linesIntersect(x0, y0, x1, y1, 
					  epsilon, 0.0, distance, 0.0))
		  windingNumber += (y1 < y0) ? 1 : negative;

		cx = firstx;
		cy = firsty;
	      }
	    cx = firstx = xpoints[pos] - (float) x;
	    cy = firsty = ypoints[pos++] - (float) y;
	    pathStarted = true;
	    break;
	  case PathIterator.SEG_CLOSE:
	    x0 = cx;
	    y0 = cy;
	    x1 = firstx;
	    y1 = firsty;

	    if (y0 == 0.0)
	      y0 -= epsilon;
	    if (y1 == 0.0)
	      y1 -= epsilon;
	    if (Line2D.linesIntersect(x0, y0, x1, y1, 
				      epsilon, 0.0, distance, 0.0))
	      windingNumber += (y1 < y0) ? 1 : negative;

	    cx = firstx;
	    cy = firsty;
	    pos++;
	    pathStarted = false;
	    break;
	  case PathIterator.SEG_LINETO:
	    x0 = cx;
	    y0 = cy;
	    x1 = xpoints[pos] - (float) x;
	    y1 = ypoints[pos++] - (float) y;

	    if (y0 == 0.0)
	      y0 -= epsilon;
	    if (y1 == 0.0)
	      y1 -= epsilon;
	    if (Line2D.linesIntersect(x0, y0, x1, y1, 
				      epsilon, 0.0, distance, 0.0))
	      windingNumber += (y1 < y0) ? 1 : negative;

	    cx = xpoints[pos - 1] - (float) x;
	    cy = ypoints[pos - 1] - (float) y;
	    break;
	  case PathIterator.SEG_QUADTO:
	    x0 = cx;
	    y0 = cy;
	    x1 = xpoints[pos] - x;
	    y1 = ypoints[pos++] - y;
	    x2 = xpoints[pos] - x;
	    y2 = ypoints[pos++] - y;

	    /* check if curve may intersect X+ axis. */
	    if ((x0 > 0.0 || x1 > 0.0 || x2 > 0.0)
	        && (y0 * y1 <= 0 || y1 * y2 <= 0))
	      {
		if (y0 == 0.0)
		  y0 -= epsilon;
		if (y2 == 0.0)
		  y2 -= epsilon;

		r[0] = y0;
		r[1] = 2 * (y1 - y0);
		r[2] = (y2 - 2 * y1 + y0);

		/* degenerate roots (=tangent points) do not
		   contribute to the winding number. */
		if ((nRoots = QuadCurve2D.solveQuadratic(r)) == 2)
		  for (int i = 0; i < nRoots; i++)
		    {
		      float t = (float) r[i];
		      if (t > 0.0f && t < 1.0f)
		        {
			  double crossing = t * t * (x2 - 2 * x1 + x0)
			                    + 2 * t * (x1 - x0) + x0;
			  if (crossing >= 0.0 && crossing <= distance)
			    windingNumber += (2 * t * (y2 - 2 * y1 + y0)
			                   + 2 * (y1 - y0) < 0) ? 1 : negative;
		        }
		    }
	      }

	    cx = xpoints[pos - 1] - (float) x;
	    cy = ypoints[pos - 1] - (float) y;
	    break;
	  case PathIterator.SEG_CUBICTO:
	    x0 = cx;
	    y0 = cy;
	    x1 = xpoints[pos] - x;
	    y1 = ypoints[pos++] - y;
	    x2 = xpoints[pos] - x;
	    y2 = ypoints[pos++] - y;
	    x3 = xpoints[pos] - x;
	    y3 = ypoints[pos++] - y;

	    /* check if curve may intersect X+ axis. */
	    if ((x0 > 0.0 || x1 > 0.0 || x2 > 0.0 || x3 > 0.0)
	        && (y0 * y1 <= 0 || y1 * y2 <= 0 || y2 * y3 <= 0))
	      {
		if (y0 == 0.0)
		  y0 -= epsilon;
		if (y3 == 0.0)
		  y3 -= epsilon;

		r[0] = y0;
		r[1] = 3 * (y1 - y0);
		r[2] = 3 * (y2 + y0 - 2 * y1);
		r[3] = y3 - 3 * y2 + 3 * y1 - y0;

		if ((nRoots = CubicCurve2D.solveCubic(r)) != 0)
		  for (int i = 0; i < nRoots; i++)
		    {
		      float t = (float) r[i];
		      if (t > 0.0 && t < 1.0)
		        {
			  double crossing = -(t * t * t) * (x0 - 3 * x1
			                    + 3 * x2 - x3)
			                    + 3 * t * t * (x0 - 2 * x1 + x2)
			                    + 3 * t * (x1 - x0) + x0;
			  if (crossing >= 0 && crossing <= distance)
			    windingNumber += (3 * t * t * (y3 + 3 * y1
			                     - 3 * y2 - y0)
			                     + 6 * t * (y0 - 2 * y1 + y2)
			                   + 3 * (y1 - y0) < 0) ? 1 : negative;
		        }
		    }
	      }

	    cx = xpoints[pos - 1] - (float) x;
	    cy = ypoints[pos - 1] - (float) y;
	    break;
	  }
      }

    // swap coordinates back
    if (useYaxis)
      {
	float[] swap;
	swap = ypoints;
	ypoints = xpoints;
	xpoints = swap;
      }
    return (windingNumber);
  }
} // class GeneralPath