Class PathLength

java.lang.Object

org.apache.batik.ext.awt.geom.PathLength

public class PathLength
extends Object

Utilitiy class for length calculations of paths.

PathLength is a utility class for calculating the length of a path, the location of a point at a particular length along the path, and the angle of the tangent to the path at a given length.

It uses a FlatteningPathIterator to create a flattened version of the Path. This means the values returned are not always exact (in fact, they rarely are), but in most cases they are reasonably accurate.

Version:

$Id$

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected static class	PathLength.PathSegment	A single path segment in the flattened version of the path.
protected static class	PathLength.SingleSegmentPathIterator	A PathIterator that returns only the next path segment from another PathIterator.

Field Summary

Fields

Modifier and Type	Field	Description
protected boolean	initialised	Whether this path been flattened yet.
protected Shape	path	The path to use for calculations.
protected float	pathLength	Cached copy of the path length.
protected int[]	segmentIndexes	Array where the index is the index of the original path segment and the value is the index of the first of the flattened segments in segments that corresponds to that original path segment.
protected List	segments	The list of flattened path segments.

Constructor Summary

Constructors

Constructor	Description
PathLength(Shape path)	Creates a new PathLength object for the specified Shape.

Method Summary

Modifier and Type	Method	Description
float	angleAtLength(float length)	Returns the slope of the path at the specified length.
float	angleAtLength(int index, float proportion)	Returns the slope of the path at the specified length.
int	findUpperIndex(float length)	Returns the index of the path segment that bounds the specified length along the path.
float	getLengthAtSegment(int index)	Returns the length at the start of the segment given by the specified index.
int	getNumberOfSegments()	Returns the number of segments in the path.
Shape	getPath()	Returns the path to use for calculations.
protected void	initialise()	Flattens the path and determines the path length.
float	lengthOfPath()	Returns the length of the path used by this PathLength object.
Point2D	pointAtLength(float length)	Returns the point that is at the given length along the path.
Point2D	pointAtLength(int index, float proportion)	Returns the point that is the given proportion along the path segment given by the specified index.
int	segmentAtLength(float length)	Returns the index of the segment at the given distance along the path.
void	setPath(Shape v)	Sets the path to use for calculations.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

path

protected Shape path

The path to use for calculations.

segments

protected List segments

The list of flattened path segments.

segmentIndexes

protected int[] segmentIndexes

Array where the index is the index of the original path segment and the value is the index of the first of the flattened segments in segments that corresponds to that original path segment.

pathLength

protected float pathLength

Cached copy of the path length.

initialised

protected boolean initialised

Whether this path been flattened yet.

Constructor Details

PathLength

public PathLength(Shape path)

Creates a new PathLength object for the specified Shape.

Parameters:

path - The Path (or Shape) to use.

Method Details

getPath

public Shape getPath()

Returns the path to use for calculations.

Returns:

Path used in calculations.

setPath

public void setPath(Shape v)

Sets the path to use for calculations.

Parameters:

v - Path to be used in calculations.

lengthOfPath

public float lengthOfPath()

Returns the length of the path used by this PathLength object.

Returns:

The length of the path.

initialise

protected void initialise()

Flattens the path and determines the path length.

getNumberOfSegments

public int getNumberOfSegments()

Returns the number of segments in the path.

getLengthAtSegment

public float getLengthAtSegment(int index)

Returns the length at the start of the segment given by the specified index.

segmentAtLength

public int segmentAtLength(float length)

Returns the index of the segment at the given distance along the path.

pointAtLength

public Point2D pointAtLength(int index,
 float proportion)

Returns the point that is the given proportion along the path segment given by the specified index.

pointAtLength

public Point2D pointAtLength(float length)

Returns the point that is at the given length along the path.

Parameters:

length - The length along the path

Returns:

The point at the given length

angleAtLength

public float angleAtLength(int index,
 float proportion)

Returns the slope of the path at the specified length.

Parameters:

index - The segment number

proportion - The proportion along the given segment

Returns:

the angle in radians, in the range [-Math.PI, Math.PI].

angleAtLength

public float angleAtLength(float length)

Returns the slope of the path at the specified length.

Parameters:

length - The length along the path

Returns:

the angle in radians, in the range [-Math.PI, Math.PI].

findUpperIndex

public int findUpperIndex(float length)

Returns the index of the path segment that bounds the specified length along the path.

Parameters:

length - The length along the path

Returns:

The path segment index, or -1 if there is not such segment