uk.ac.starlink.ttools.plot

Class PointIterator

java.lang.Object

uk.ac.starlink.ttools.plot.PointIterator

Direct Known Subclasses:

PlotDataPointIterator

public abstract class PointIterator
extends Object

Iterates over the points which have actually been plotted to the screen.

Since:

19 Jan 2006

Author:

Mark Taylor

Field Summary

Fields

Modifier and Type	Field and Description
static PointIterator	EMPTY PointIterator instance with no points.

Constructor Summary

Constructors

Constructor and Description
PointIterator()

Method Summary

Modifier and Type	Method and Description
BitSet	getAllPoints() Returns a bit vector with bits set for every point index visited by this iterator.
int	getClosestPoint(Point p, int error) Returns the index of the closest plotted point to a given screen point.
BitSet	getContainedPoints(Shape shape) Returns a bit vector with bits set for every point index which falls within a given shape on the screen.
int	getIndex() Returns the most recently read point index.
int	getX() Returns the most recently read screen X coordinate.
int	getY() Returns the most recently read Y coordinate.
protected abstract int[]	nextPoint() Returns a triple giving point index, screen X coordinate and screen Y coordinate.
boolean	readNextPoint() Loads the data for the next point if there is one.

Methods inherited from class java.lang.Object

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

Field Detail

EMPTY

public static PointIterator EMPTY

PointIterator instance with no points.

Constructor Detail

PointIterator

public PointIterator()

Method Detail

nextPoint

protected abstract int[] nextPoint()

Returns a triple giving point index, screen X coordinate and screen Y coordinate. Returns null if there are no more points. It is permissible to return the same int[] array with different contents each time. Invoked by readNextPoint().

Returns:

ip, xp, yp triple

getIndex

public int getIndex()

Returns the most recently read point index.

Returns:

ip

getX

public int getX()

Returns the most recently read screen X coordinate.

Returns:

xp

getY

public int getY()

Returns the most recently read Y coordinate.

Returns:

yp

readNextPoint

public boolean readNextPoint()

Loads the data for the next point if there is one.

Returns:

true if the data are loaded for the next point; false if the iteration is at an end

getContainedPoints

public BitSet getContainedPoints(Shape shape)

Returns a bit vector with bits set for every point index which falls within a given shape on the screen.

Parameters:

shape - shape defining inclusion criterion

Returns:

bit vector locating points inside shape

getAllPoints

public BitSet getAllPoints()

Returns a bit vector with bits set for every point index visited by this iterator.

Returns:

bit vector locating included points

getClosestPoint

public int getClosestPoint(Point p,
                           int error)

Returns the index of the closest plotted point to a given screen point. Only points within a given error box are eligible; if none can be found, -1 is returned.

Parameters:

p - screen point near which plotted points should be located

error - number of pixels in any direction which defines the error box within which a point may be found

Returns:

index of closest point to p, or -1 if none are nearby