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package java.awt.geom;

import java.lang.annotation.Native;


The PathIterator interface provides the mechanism for objects that implement the Shape interface to return the geometry of their boundary by allowing a caller to retrieve the path of that boundary a segment at a time. This interface allows these objects to retrieve the path of their boundary a segment at a time by using 1st through 3rd order Bézier curves, which are lines and quadratic or cubic Bézier splines. 

Multiple subpaths can be expressed by using a "MOVETO" segment to
create a discontinuity in the geometry to move from the end of
one subpath to the beginning of the next.

 Each subpath can be closed manually by ending the last segment in the subpath on the same coordinate as the beginning "MOVETO" segment for that subpath or by using a "CLOSE" segment to append a line segment from the last point back to the first. Be aware that manually closing an outline as opposed to using a "CLOSE" segment to close the path might result in different line style decorations being used at the end points of the subpath. For example, the BasicStroke object uses a line "JOIN" decoration to connect the first and last points if a "CLOSE" segment is encountered, whereas simply ending the path on the same coordinate as the beginning coordinate results in line "CAP" decorations being used at the ends. 
Author:Jim Graham
See Also:
/**
 * The <code>PathIterator</code> interface provides the mechanism
 * for objects that implement the {@link java.awt.Shape Shape}
 * interface to return the geometry of their boundary by allowing
 * a caller to retrieve the path of that boundary a segment at a
 * time.  This interface allows these objects to retrieve the path of
 * their boundary a segment at a time by using 1st through 3rd order
 * B&eacute;zier curves, which are lines and quadratic or cubic
 * B&eacute;zier splines.
 * <p>
 * Multiple subpaths can be expressed by using a "MOVETO" segment to
 * create a discontinuity in the geometry to move from the end of
 * one subpath to the beginning of the next.
 * <p>
 * Each subpath can be closed manually by ending the last segment in
 * the subpath on the same coordinate as the beginning "MOVETO" segment
 * for that subpath or by using a "CLOSE" segment to append a line
 * segment from the last point back to the first.
 * Be aware that manually closing an outline as opposed to using a
 * "CLOSE" segment to close the path might result in different line
 * style decorations being used at the end points of the subpath.
 * For example, the {@link java.awt.BasicStroke BasicStroke} object
 * uses a line "JOIN" decoration to connect the first and last points
 * if a "CLOSE" segment is encountered, whereas simply ending the path
 * on the same coordinate as the beginning coordinate results in line
 * "CAP" decorations being used at the ends.
 *
 * @see java.awt.Shape
 * @see java.awt.BasicStroke
 *
 * @author Jim Graham
 */
public interface PathIterator {
    
The winding rule constant for specifying an even-odd rule
for determining the interior of a path.
The even-odd rule specifies that a point lies inside the
path if a ray drawn in any direction from that point to
infinity is crossed by path segments an odd number of times.

/**
     * The winding rule constant for specifying an even-odd rule
     * for determining the interior of a path.
     * The even-odd rule specifies that a point lies inside the
     * path if a ray drawn in any direction from that point to
     * infinity is crossed by path segments an odd number of times.
     */
    @Native public static final int WIND_EVEN_ODD       = 0;

    
The winding rule constant for specifying a non-zero rule
for determining the interior of a path.
The non-zero rule specifies that a point lies inside the
path if a ray drawn in any direction from that point to
infinity is crossed by path segments a different number
of times in the counter-clockwise direction than the
clockwise direction.

/**
     * The winding rule constant for specifying a non-zero rule
     * for determining the interior of a path.
     * The non-zero rule specifies that a point lies inside the
     * path if a ray drawn in any direction from that point to
     * infinity is crossed by path segments a different number
     * of times in the counter-clockwise direction than the
     * clockwise direction.
     */
    @Native public static final int WIND_NON_ZERO       = 1;

    
The segment type constant for a point that specifies the
starting location for a new subpath.

/**
     * The segment type constant for a point that specifies the
     * starting location for a new subpath.
     */
    @Native public static final int SEG_MOVETO          = 0;

    
The segment type constant for a point that specifies the
end point of a line to be drawn from the most recently
specified point.

/**
     * The segment type constant for a point that specifies the
     * end point of a line to be drawn from the most recently
     * specified point.
     */
    @Native public static final int SEG_LINETO          = 1;

    
The segment type constant for the pair of points that specify
a quadratic parametric curve to be drawn from the most recently
specified point.
The curve is interpolated by solving the parametric control
equation in the range (t=[0..1]) using
the most recently specified (current) point (CP),
the first control point (P1),
and the final interpolated control point (P2).
The parametric control equation for this curve is:

         P(t) = B(2,0)*CP + B(2,1)*P1 + B(2,2)*P2
         0 <= t <= 1
       B(n,m) = mth coefficient of nth degree Bernstein polynomial
              = C(n,m) * t^(m) * (1 - t)^(n-m)
       C(n,m) = Combinations of n things, taken m at a time
              = n! / (m! * (n-m)!)



/**
     * The segment type constant for the pair of points that specify
     * a quadratic parametric curve to be drawn from the most recently
     * specified point.
     * The curve is interpolated by solving the parametric control
     * equation in the range <code>(t=[0..1])</code> using
     * the most recently specified (current) point (CP),
     * the first control point (P1),
     * and the final interpolated control point (P2).
     * The parametric control equation for this curve is:
     * <pre>
     *          P(t) = B(2,0)*CP + B(2,1)*P1 + B(2,2)*P2
     *          0 &lt;= t &lt;= 1
     *
     *        B(n,m) = mth coefficient of nth degree Bernstein polynomial
     *               = C(n,m) * t^(m) * (1 - t)^(n-m)
     *        C(n,m) = Combinations of n things, taken m at a time
     *               = n! / (m! * (n-m)!)
     * </pre>
     */
    @Native public static final int SEG_QUADTO          = 2;

    
The segment type constant for the set of 3 points that specify
a cubic parametric curve to be drawn from the most recently
specified point.
The curve is interpolated by solving the parametric control
equation in the range (t=[0..1]) using
the most recently specified (current) point (CP),
the first control point (P1),
the second control point (P2),
and the final interpolated control point (P3).
The parametric control equation for this curve is:

         P(t) = B(3,0)*CP + B(3,1)*P1 + B(3,2)*P2 + B(3,3)*P3
         0 <= t <= 1
       B(n,m) = mth coefficient of nth degree Bernstein polynomial
              = C(n,m) * t^(m) * (1 - t)^(n-m)
       C(n,m) = Combinations of n things, taken m at a time
              = n! / (m! * (n-m)!)


This form of curve is commonly known as a Bézier curve.

/**
     * The segment type constant for the set of 3 points that specify
     * a cubic parametric curve to be drawn from the most recently
     * specified point.
     * The curve is interpolated by solving the parametric control
     * equation in the range <code>(t=[0..1])</code> using
     * the most recently specified (current) point (CP),
     * the first control point (P1),
     * the second control point (P2),
     * and the final interpolated control point (P3).
     * The parametric control equation for this curve is:
     * <pre>
     *          P(t) = B(3,0)*CP + B(3,1)*P1 + B(3,2)*P2 + B(3,3)*P3
     *          0 &lt;= t &lt;= 1
     *
     *        B(n,m) = mth coefficient of nth degree Bernstein polynomial
     *               = C(n,m) * t^(m) * (1 - t)^(n-m)
     *        C(n,m) = Combinations of n things, taken m at a time
     *               = n! / (m! * (n-m)!)
     * </pre>
     * This form of curve is commonly known as a B&eacute;zier curve.
     */
    @Native public static final int SEG_CUBICTO         = 3;

    
The segment type constant that specifies that
the preceding subpath should be closed by appending a line segment
back to the point corresponding to the most recent SEG_MOVETO.

/**
     * The segment type constant that specifies that
     * the preceding subpath should be closed by appending a line segment
     * back to the point corresponding to the most recent SEG_MOVETO.
     */
    @Native public static final int SEG_CLOSE           = 4;

    
Returns the winding rule for determining the interior of the
path.

See Also:
Returns:the winding rule.
/**
     * Returns the winding rule for determining the interior of the
     * path.
     * @return the winding rule.
     * @see #WIND_EVEN_ODD
     * @see #WIND_NON_ZERO
     */
    public int getWindingRule();

    
Tests if the iteration is complete.

Returns:true if all the segments have
been read; false otherwise.
/**
     * Tests if the iteration is complete.
     * @return <code>true</code> if all the segments have
     * been read; <code>false</code> otherwise.
     */
    public boolean isDone();

    
Moves the iterator to the next segment of the path forwards
along the primary direction of traversal as long as there are
more points in that direction.

/**
     * Moves the iterator to the next segment of the path forwards
     * along the primary direction of traversal as long as there are
     * more points in that direction.
     */
    public void next();

    
Returns the coordinates and type of the current path segment in
the iteration.
The return value is the path-segment type:
SEG_MOVETO, SEG_LINETO, SEG_QUADTO, SEG_CUBICTO, or SEG_CLOSE.
A float array of length 6 must be passed in and can be used to
store the coordinates of the point(s).
Each point is stored as a pair of float x,y coordinates.
SEG_MOVETO and SEG_LINETO types returns one point,
SEG_QUADTO returns two points,
SEG_CUBICTO returns 3 points
and SEG_CLOSE does not return any points.

Params:
  • coords – an array that holds the data returned from
this method
See Also:
Returns:the path-segment type of the current path segment.
/**
     * Returns the coordinates and type of the current path segment in
     * the iteration.
     * The return value is the path-segment type:
     * SEG_MOVETO, SEG_LINETO, SEG_QUADTO, SEG_CUBICTO, or SEG_CLOSE.
     * A float array of length 6 must be passed in and can be used to
     * store the coordinates of the point(s).
     * Each point is stored as a pair of float x,y coordinates.
     * SEG_MOVETO and SEG_LINETO types returns one point,
     * SEG_QUADTO returns two points,
     * SEG_CUBICTO returns 3 points
     * and SEG_CLOSE does not return any points.
     * @param coords an array that holds the data returned from
     * this method
     * @return the path-segment type of the current path segment.
     * @see #SEG_MOVETO
     * @see #SEG_LINETO
     * @see #SEG_QUADTO
     * @see #SEG_CUBICTO
     * @see #SEG_CLOSE
     */
    public int currentSegment(float[] coords);

    
Returns the coordinates and type of the current path segment in
the iteration.
The return value is the path-segment type:
SEG_MOVETO, SEG_LINETO, SEG_QUADTO, SEG_CUBICTO, or SEG_CLOSE.
A double array of length 6 must be passed in and can be used to
store the coordinates of the point(s).
Each point is stored as a pair of double x,y coordinates.
SEG_MOVETO and SEG_LINETO types returns one point,
SEG_QUADTO returns two points,
SEG_CUBICTO returns 3 points
and SEG_CLOSE does not return any points.

Params:
  • coords – an array that holds the data returned from
this method
See Also:
Returns:the path-segment type of the current path segment.
/**
     * Returns the coordinates and type of the current path segment in
     * the iteration.
     * The return value is the path-segment type:
     * SEG_MOVETO, SEG_LINETO, SEG_QUADTO, SEG_CUBICTO, or SEG_CLOSE.
     * A double array of length 6 must be passed in and can be used to
     * store the coordinates of the point(s).
     * Each point is stored as a pair of double x,y coordinates.
     * SEG_MOVETO and SEG_LINETO types returns one point,
     * SEG_QUADTO returns two points,
     * SEG_CUBICTO returns 3 points
     * and SEG_CLOSE does not return any points.
     * @param coords an array that holds the data returned from
     * this method
     * @return the path-segment type of the current path segment.
     * @see #SEG_MOVETO
     * @see #SEG_LINETO
     * @see #SEG_QUADTO
     * @see #SEG_CUBICTO
     * @see #SEG_CLOSE
     */
    public int currentSegment(double[] coords);
}