org.openstreetmap.josm.data.osm.visitor.paint

Class LineClip

java.lang.Object

org.openstreetmap.josm.data.osm.visitor.paint.LineClip

public class LineClip
extends Object

Computes the part of a line that is visible in a given rectangle. Using int leads to overflow, so we need long int.

Field Summary

Fields

Modifier and Type	Field and Description
private Rectangle	clipBounds
private Point	p1
private Point	p2

Constructor Summary

Constructors

Constructor and Description
LineClip(Point p1, Point p2, Rectangle clipBounds) Constructs a new LineClip.

Method Summary

Modifier and Type	Method and Description
private boolean	cohenSutherland(long x1, long y1, long x2, long y2, long xmin, long ymin, long xmax, long ymax) Cohen–Sutherland algorithm.
private static int	computeOutCode(long x, long y, long xmin, long ymin, long xmax, long ymax) The outcode of the point.
boolean	execute() run the clipping algorithm
Point	getP1()
Point	getP2()

Methods inherited from class java.lang.Object

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

Field Detail

p1

private Point p1

p2

private Point p2

clipBounds

private final Rectangle clipBounds

Constructor Detail

LineClip

public LineClip(Point p1,
                Point p2,
                Rectangle clipBounds)

Constructs a new LineClip.

Parameters:

p1 - start point of the clipped line

p2 - end point of the clipped line

clipBounds - Clip bounds

Method Detail

execute

public boolean execute()

run the clipping algorithm

Returns:

true if the some parts of the line lies within the clip bounds

getP1

public Point getP1()

Returns:

start point of the clipped line

getP2

public Point getP2()

Returns:

end point of the clipped line

cohenSutherland

private boolean cohenSutherland(long x1,
                                long y1,
                                long x2,
                                long y2,
                                long xmin,
                                long ymin,
                                long xmax,
                                long ymax)

Cohen–Sutherland algorithm. See Wikipedia article

Parameters:

x1 - X coordinate of first point

y1 - Y coordinate of first point

x2 - X coordinate of second point

y2 - Y coordinate of second point

xmin - minimal X coordinate

ymin - minimal Y coordinate

xmax - maximal X coordinate

ymax - maximal Y coordinate

Returns:

true, if line is visible in the given clip region

computeOutCode

private static int computeOutCode(long x,
                                  long y,
                                  long xmin,
                                  long ymin,
                                  long xmax,
                                  long ymax)

The outcode of the point. We cannot use Rectangle.outcode(double, double) since it does not work with long ints.

Parameters:

x - X coordinate

y - Y coordinate

xmin - minimal X coordinate

ymin - minimal Y coordinate

xmax - maximal X coordinate

ymax - maximal Y coordinate

Returns:

outcode