org.geotools.renderer.label

Class LineStringCursor

Object

LineStringCursor

public class LineStringCursor
extends Object

Allows to move a point cursor along the path of a LineString using a curvilinear coordinate system and either absolute distances (from the start of the line) or offsets relative to the current position, to return the absolute position of the cursor as a Point, and to get the orientation of the current segment.

Author:

Andrea Aime

Constructor Summary

Constructors

Constructor and Description
LineStringCursor(LineString ls) Builds a new cursor
LineStringCursor(LineStringCursor cursor) Copy constructor

Method Summary

Modifier and Type	Method and Description
double	getCurrentAngle() Returns the current segment direction as an angle expressed in radians
double	getCurrentOrdinate()
Coordinate	getCurrentPosition() Returns the Point representing the current position along the LineString
Coordinate	getCurrentPosition(Coordinate c) Returns the Point representing the current position along the LineString
double	getLabelOrientation() Returns the current segment direction as an angle expressed in radians
LineString	getLineString() The linestrings wrapped by this cursor
double	getLineStringLength() Returns the line string length
double	getMaxAngleChange(double startOrdinate, double endOrdinate) Returns the maximum angle change (in radians) between two subsequent segments between the specified curvilinear coordinates.
double	getMaxAngleChange(double startOrdinate, double endOrdinate, double step) A variant of getMaxAngleChange(double, double) taking a step and evaluating angle differences at such step.
double	getMaxDistanceFromStraightLine(double startOrdinate, double endOrdinate) Returns the maximum distance between the curve and a straight line connecting the start and end ordinates.
protected double	getSegmentAngle(int segmentIdx)
LineString	getSubLineString(double startOrdinate, double endOrdinate) Returns the linestring that starts and ends at the specified curvilinear coordinates.
boolean	moveRelative(double offset) Moves of the specified distance from the current position.
void	moveTo(double ordinate) Moves the current position to the
LineStringCursor	reverse() Returns a line string cursor based on the opposite walking direction.

Methods inherited from class Object

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

Constructor Detail

LineStringCursor

public LineStringCursor(LineString ls)

Builds a new cursor

Parameters:

ls -

LineStringCursor

public LineStringCursor(LineStringCursor cursor)

Copy constructor

Parameters:

cursor -

Method Detail

getLineStringLength

public double getLineStringLength()

Returns the line string length

Returns:

moveTo

public void moveTo(double ordinate)

Moves the current position to the

Parameters:

ordinate -

moveRelative

public boolean moveRelative(double offset)

Moves of the specified distance from the current position.

Parameters:

offset -

Returns:

true if it was possible to move to the desired offset, false if the movement stopped because the start or end of the LineString was reached

getCurrentPosition

public Coordinate getCurrentPosition()

Returns the Point representing the current position along the LineString

getCurrentPosition

public Coordinate getCurrentPosition(Coordinate c)

Returns the Point representing the current position along the LineString

getCurrentOrdinate

public double getCurrentOrdinate()

getCurrentAngle

public double getCurrentAngle()

Returns the current segment direction as an angle expressed in radians

Returns:

getSegmentAngle

protected double getSegmentAngle(int segmentIdx)

getLabelOrientation

public double getLabelOrientation()

Returns the current segment direction as an angle expressed in radians

Returns:

getMaxAngleChange

public double getMaxAngleChange(double startOrdinate,
                                double endOrdinate)

Returns the maximum angle change (in radians) between two subsequent segments between the specified curvilinear coordinates.

Parameters:

startOrdinate -

endOrdinate -

Returns:

getMaxAngleChange

public double getMaxAngleChange(double startOrdinate,
                                double endOrdinate,
                                double step)

A variant of getMaxAngleChange(double, double) taking a step and evaluating angle differences at such step. This helps when a line has many little segments and chars would end up showing several segments apart (so the full angle change needs to be considered)

Parameters:

startOrdinate -

endOrdinate -

step -

Returns:

getMaxDistanceFromStraightLine

public double getMaxDistanceFromStraightLine(double startOrdinate,
                                             double endOrdinate)

Returns the maximum distance between the curve and a straight line connecting the start and end ordinates.

Parameters:

startOrdinate -

endOrdinate -

Returns:

reverse

public LineStringCursor reverse()

Returns a line string cursor based on the opposite walking direction.

Returns:

getLineString

public LineString getLineString()

The linestrings wrapped by this cursor

Returns:

getSubLineString

public LineString getSubLineString(double startOrdinate,
                                   double endOrdinate)

Returns the linestring that starts and ends at the specified curvilinear coordinates.

Parameters:

startOrdinate -

endOrdinate -

Returns: