java.awt.geom

Interface PathIterator

Known Implementing Classes:
FlatteningPathIterator

public interface PathIterator

This interface provides a directed path over the boundary of a shape. The path can contain 1st through 3rd order Bezier curves (lines, and quadratic and cubic splines). A shape can have multiple disjoint paths via the MOVETO directive, and can close a circular path back to the previos MOVETO via the CLOSE directive.
Since:
1.2
See Also:
Shape, Stroke, FlatteningPathIterator

Field Summary

static int
SEG_CLOSE
The current segment closes a loop by an implicit line to the previous SEG_MOVETO coordinate.
static int
SEG_CUBICTO
The current segment is a cubic parametric curve (more commonly known as a Bezier curve).
static int
SEG_LINETO
The current segment is a line.
static int
SEG_MOVETO
Starts a new subpath.
static int
SEG_QUADTO
The current segment is a quadratic parametric curve.
static int
WIND_EVEN_ODD
The even-odd winding mode: a point is internal to the shape if a ray from the point to infinity (in any direction) crosses an odd number of segments.
static int
WIND_NON_ZERO
The non-zero winding mode: a point is internal to the shape if a ray from the point to infinity (in any direction) crosses a different number of segments headed clockwise than those headed counterclockwise.

Method Summary

int
currentSegment(double[] coords)
Returns the coordinates of the next point(s), as well as the type of line segment.
int
currentSegment(float[] coords)
Returns the coordinates of the next point(s), as well as the type of line segment.
int
getWindingRule()
Returns the winding rule to determine which points are inside this path.
boolean
isDone()
Tests if the iterator is exhausted.
void
next()
Advance to the next segment in the iteration.

Field Details

SEG_CLOSE

public static final int SEG_CLOSE
The current segment closes a loop by an implicit line to the previous SEG_MOVETO coordinate.
Field Value:
4

SEG_CUBICTO

public static final int SEG_CUBICTO
The current segment is a cubic parametric curve (more commonly known as a Bezier curve). It is interpolated as t varies from 0 to 1 over the current point (CP), first control point (P1), the second control point (P2), and final interpolated control point (P3):
  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)!)
 
Field Value:
3

SEG_LINETO

public static final int SEG_LINETO
The current segment is a line.
Field Value:
1

SEG_MOVETO

public static final int SEG_MOVETO
Starts a new subpath. There is no segment from the previous vertex.
Field Value:
0

SEG_QUADTO

public static final int SEG_QUADTO
The current segment is a quadratic parametric curve. It is interpolated as t varies from 0 to 1 over the current point (CP), first control point (P1), and final interpolated control point (P2):
  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)!)
 
Field Value:
2

WIND_EVEN_ODD

public static final int WIND_EVEN_ODD
The even-odd winding mode: a point is internal to the shape if a ray from the point to infinity (in any direction) crosses an odd number of segments.
Field Value:
0

WIND_NON_ZERO

public static final int WIND_NON_ZERO
The non-zero winding mode: a point is internal to the shape if a ray from the point to infinity (in any direction) crosses a different number of segments headed clockwise than those headed counterclockwise.
Field Value:
1

Method Details

currentSegment

public int currentSegment(double[] coords)
Returns the coordinates of the next point(s), as well as the type of line segment. The input array must be at least a double[6], to accomodate up to three (x,y) point pairs (although if you know the iterator is flat, you can probably get by with a double[2]). If the returned type is SEG_MOVETO or SEG_LINETO, the first point in the array is modified; if the returned type is SEG_QUADTO, the first two points are modified; if the returned type is SEG_CUBICTO, all three points are modified; and if the returned type is SEG_CLOSE, the array is untouched.
Parameters:
coords - the array to place the point coordinates in
Returns:
the segment type
Throws:
NullPointerException - if coords is null
ArrayIndexOutOfBoundsException - if coords is too small
NoSuchElementException - optional when isDone() is true

currentSegment

public int currentSegment(float[] coords)
Returns the coordinates of the next point(s), as well as the type of line segment. The input array must be at least a float[6], to accomodate up to three (x,y) point pairs (although if you know the iterator is flat, you can probably get by with a float[2]). If the returned type is SEG_MOVETO or SEG_LINETO, the first point in the array is modified; if the returned type is SEG_QUADTO, the first two points are modified; if the returned type is SEG_CUBICTO, all three points are modified; and if the returned type is SEG_CLOSE, the array is untouched.
Parameters:
coords - the array to place the point coordinates in
Returns:
the segment type
Throws:
NullPointerException - if coords is null
ArrayIndexOutOfBoundsException - if coords is too small
NoSuchElementException - optional when isDone() is true

getWindingRule

public int getWindingRule()
Returns the winding rule to determine which points are inside this path.
Returns:
the winding rule

isDone

public boolean isDone()
Tests if the iterator is exhausted. If this returns true, currentSegment and next may throw a NoSuchElementException (although this is not required).
Returns:
true if the iteration is complete

next

public void next()
Advance to the next segment in the iteration. It is not specified what this does if called when isDone() returns true.
Throws:
NoSuchElementException - optional when isDone() is true

PathIterator.java -- describes a shape by iterating over its vertices Copyright (C) 2000, 2002, 2003 Free Software Foundation This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.