Overview

Package

Class

Use

Tree

Deprecated

Index

Help

Java Platform 1.2
Beta 4

PREV CLASS NEXT CLASS

FRAMES NO FRAMES

SUMMARY: INNER | FIELD | CONSTR | METHOD

DETAIL: FIELD | CONSTR | METHOD

Interface java.awt.geom.PathIterator

All Known Implementing Classes:

FlatteningPathIterator

public abstract interface PathIterator

The iteration interface for objects which traverse the geometric outline of the boundary of an object which implements the Shape interface. This interface allows the iteration objects to return the geometry a single path segment at a time using 1st through 3rd order Bezier curves (lines and quadratic or cubic Bezier 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 may result in different line style decorations being used at the end points of the subpath. In particular, the BasicStroke object will use 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 will result in line "CAP" decorations being used at the ends.

See Also:

Shape, BasicStroke

Field Summary

static 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.
static 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.
static 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.
static int	SEG_MOVETO The segment type constant for a point that specifies the starting location for a new subpath.
static 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.
static int	WIND_EVEN_ODD The winding rule constant for specifying an even-odd rule for determining the interior of a path.
static int	WIND_NON_ZERO The winding rule constant for specifying a non-zero rule for determining the interior of a path.

Method Summary

int	currentSegment(double[] coords) Returns the coordinates and type of the current path segment in the iteration.
int	currentSegment(float[] coords) Returns the coordinates and type of the current path segment in the iteration.
int	getWindingRule() Return the winding rule for determining the interior of the path.
boolean	isDone() Tests if there are more points to read.
void	next() 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.

Field Detail

WIND_EVEN_ODD

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.

WIND_NON_ZERO

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.

SEG_MOVETO

public static final int SEG_MOVETO

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

SEG_LINETO

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.

SEG_QUADTO

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)!)
 

SEG_CUBICTO

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.

SEG_CLOSE

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.

Method Detail

getWindingRule

public int getWindingRule()

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

See Also:

WIND_EVEN_ODD, WIND_NON_ZERO

isDone

public boolean isDone()

Tests if there are more points to read.

Returns:

true if there are no more points to read

next

public void next()

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.

currentSegment

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 float array of length 6 must be passed in and may 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 will return one point, SEG_QUADTO will return two points, SEG_CUBICTO will return 3 points and SEG_CLOSE will not return any points.

See Also:

SEG_MOVETO, SEG_LINETO, SEG_QUADTO, SEG_CUBICTO, SEG_CLOSE

currentSegment

public int currentSegment(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 may 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 will return one point, SEG_QUADTO will return two points, SEG_CUBICTO will return 3 points and SEG_CLOSE will not return any points.

See Also:

SEG_MOVETO, SEG_LINETO, SEG_QUADTO, SEG_CUBICTO, SEG_CLOSE