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PathIterator.javaAPI DocJava SE 5 API7688Fri Aug 26 14:56:52 BST 2005java.awt.geom

PathIterator

public interface PathIterator
The PathIterator 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 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 {@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
version
1.16, 12/19/03
author
Jim Graham

Fields Summary
public static final int
WIND_EVEN_ODD
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.
public static final int
WIND_NON_ZERO
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.
public static final int
SEG_MOVETO
The segment type constant for a point that specifies the starting location for a new subpath.
public static final int
SEG_LINETO
The segment type constant for a point that specifies the end point of a line to be drawn from the most recently specified point.
public static final int
SEG_QUADTO
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)!)
public static final int
SEG_CUBICTO
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.
public static final int
SEG_CLOSE
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.
Constructors Summary
Methods Summary
public intcurrentSegment(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 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 intcurrentSegment(double[] 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.

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 intgetWindingRule()
Returns the winding rule for determining the interior of the path.

return
the winding rule.
see
#WIND_EVEN_ODD
see
#WIND_NON_ZERO

public booleanisDone()
Tests if the iteration is complete.

return
true if all the segments have been read; false otherwise.

public voidnext()
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.