public abstract class

Line2D

extends Object
implements Shape Cloneable
java.lang.Object
   ↳ java.awt.geom.Line2D
Known Direct Subclasses

Class Overview

This Line2D represents a line segment in (x,y) coordinate space. This class, like all of the Java 2D API, uses a default coordinate system called user space in which the y-axis values increase downward and x-axis values increase to the right. For more information on the user space coordinate system, see the Coordinate Systems section of the Java 2D Programmer's Guide.

This class is only the abstract superclass for all objects that store a 2D line segment. The actual storage representation of the coordinates is left to the subclass.

Summary

Nested Classes
class Line2D.Double A line segment specified with double coordinates. 
class Line2D.Float A line segment specified with float coordinates. 
Protected Constructors
Line2D()
This is an abstract class that cannot be instantiated directly.
Public Methods
Object clone()
Creates a new object of the same class as this object.
boolean contains(double x, double y, double w, double h)
Tests if the interior of this Line2D entirely contains the specified set of rectangular coordinates.
boolean contains(Point2D p)
Tests if a given Point2D is inside the boundary of this Line2D.
boolean contains(double x, double y)
Tests if a specified coordinate is inside the boundary of this Line2D.
boolean contains(Rectangle2D r)
Tests if the interior of this Line2D entirely contains the specified Rectangle2D.
Rectangle getBounds()
Returns an integer Rectangle that completely encloses the Shape.
abstract Point2D getP1()
Returns the start Point2D of this Line2D.
abstract Point2D getP2()
Returns the end Point2D of this Line2D.
PathIterator getPathIterator(AffineTransform at)
Returns an iteration object that defines the boundary of this Line2D.
PathIterator getPathIterator(AffineTransform at, double flatness)
Returns an iteration object that defines the boundary of this flattened Line2D.
abstract double getX1()
Returns the X coordinate of the start point in double precision.
abstract double getX2()
Returns the X coordinate of the end point in double precision.
abstract double getY1()
Returns the Y coordinate of the start point in double precision.
abstract double getY2()
Returns the Y coordinate of the end point in double precision.
boolean intersects(double x, double y, double w, double h)
Tests if the interior of the Shape intersects the interior of a specified rectangular area.
boolean intersects(Rectangle2D r)
Tests if the interior of the Shape intersects the interior of a specified Rectangle2D.
boolean intersectsLine(Line2D l)
Tests if the specified line segment intersects this line segment.
boolean intersectsLine(double x1, double y1, double x2, double y2)
Tests if the line segment from (x1,y1) to (x2,y2) intersects this line segment.
static boolean linesIntersect(double x1, double y1, double x2, double y2, double x3, double y3, double x4, double y4)
Tests if the line segment from (x1,y1) to (x2,y2) intersects the line segment from (x3,y3) to (x4,y4).
double ptLineDist(Point2D pt)
Returns the distance from a Point2D to this line.
static double ptLineDist(double x1, double y1, double x2, double y2, double px, double py)
Returns the distance from a point to a line.
double ptLineDist(double px, double py)
Returns the distance from a point to this line.
static double ptLineDistSq(double x1, double y1, double x2, double y2, double px, double py)
Returns the square of the distance from a point to a line.
double ptLineDistSq(double px, double py)
Returns the square of the distance from a point to this line.
double ptLineDistSq(Point2D pt)
Returns the square of the distance from a specified Point2D to this line.
double ptSegDist(double px, double py)
Returns the distance from a point to this line segment.
static double ptSegDist(double x1, double y1, double x2, double y2, double px, double py)
Returns the distance from a point to a line segment.
double ptSegDist(Point2D pt)
Returns the distance from a Point2D to this line segment.
double ptSegDistSq(double px, double py)
Returns the square of the distance from a point to this line segment.
double ptSegDistSq(Point2D pt)
Returns the square of the distance from a Point2D to this line segment.
static double ptSegDistSq(double x1, double y1, double x2, double y2, double px, double py)
Returns the square of the distance from a point to a line segment.
static int relativeCCW(double x1, double y1, double x2, double y2, double px, double py)
Returns an indicator of where the specified point (px,py) lies with respect to the line segment from (x1,y1) to (x2,y2).
int relativeCCW(Point2D p)
Returns an indicator of where the specified Point2D lies with respect to this line segment.
int relativeCCW(double px, double py)
Returns an indicator of where the specified point (px,py) lies with respect to this line segment.
void setLine(Point2D p1, Point2D p2)
Sets the location of the end points of this Line2D to the specified Point2D coordinates.
abstract void setLine(double x1, double y1, double x2, double y2)
Sets the location of the end points of this Line2D to the specified double coordinates.
void setLine(Line2D l)
Sets the location of the end points of this Line2D to the same as those end points of the specified Line2D.
[Expand]
Inherited Methods
From class java.lang.Object
From interface java.awt.Shape

Protected Constructors

protected Line2D ()

This is an abstract class that cannot be instantiated directly. Type-specific implementation subclasses are available for instantiation and provide a number of formats for storing the information necessary to satisfy the various accessory methods below.

See Also

Public Methods

public Object clone ()

Creates a new object of the same class as this object.

Returns
  • a clone of this instance.
Throws
OutOfMemoryError if there is not enough memory.
See Also

public boolean contains (double x, double y, double w, double h)

Tests if the interior of this Line2D entirely contains the specified set of rectangular coordinates. This method is required to implement the Shape interface, but in the case of Line2D objects it always returns false since a line contains no area.

Parameters
x the X coordinate of the upper-left corner of the specified rectangular area
y the Y coordinate of the upper-left corner of the specified rectangular area
w the width of the specified rectangular area
h the height of the specified rectangular area
Returns
  • false because a Line2D contains no area.

public boolean contains (Point2D p)

Tests if a given Point2D is inside the boundary of this Line2D. This method is required to implement the Shape interface, but in the case of Line2D objects it always returns false since a line contains no area.

Parameters
p the specified Point2D to be tested
Returns
  • false because a Line2D contains no area.

public boolean contains (double x, double y)

Tests if a specified coordinate is inside the boundary of this Line2D. This method is required to implement the Shape interface, but in the case of Line2D objects it always returns false since a line contains no area.

Parameters
x the X coordinate of the specified point to be tested
y the Y coordinate of the specified point to be tested
Returns
  • false because a Line2D contains no area.

public boolean contains (Rectangle2D r)

Tests if the interior of this Line2D entirely contains the specified Rectangle2D. This method is required to implement the Shape interface, but in the case of Line2D objects it always returns false since a line contains no area.

Parameters
r the specified Rectangle2D to be tested
Returns
  • false because a Line2D contains no area.

public Rectangle getBounds ()

Returns an integer Rectangle that completely encloses the Shape. Note that there is no guarantee that the returned Rectangle is the smallest bounding box that encloses the Shape, only that the Shape lies entirely within the indicated Rectangle. The returned Rectangle might also fail to completely enclose the Shape if the Shape overflows the limited range of the integer data type. The getBounds2D method generally returns a tighter bounding box due to its greater flexibility in representation.

Returns
  • an integer Rectangle that completely encloses the Shape.

public abstract Point2D getP1 ()

Returns the start Point2D of this Line2D.

Returns
  • the start Point2D of this Line2D.

public abstract Point2D getP2 ()

Returns the end Point2D of this Line2D.

Returns
  • the end Point2D of this Line2D.

public PathIterator getPathIterator (AffineTransform at)

Returns an iteration object that defines the boundary of this Line2D. The iterator for this class is not multi-threaded safe, which means that this Line2D class does not guarantee that modifications to the geometry of this Line2D object do not affect any iterations of that geometry that are already in process.

Parameters
at the specified AffineTransform
Returns

public PathIterator getPathIterator (AffineTransform at, double flatness)

Returns an iteration object that defines the boundary of this flattened Line2D. The iterator for this class is not multi-threaded safe, which means that this Line2D class does not guarantee that modifications to the geometry of this Line2D object do not affect any iterations of that geometry that are already in process.

Parameters
at the specified AffineTransform
flatness the maximum amount that the control points for a given curve can vary from colinear before a subdivided curve is replaced by a straight line connecting the end points. Since a Line2D object is always flat, this parameter is ignored.
Returns
  • a PathIterator that defines the boundary of the flattened Line2D

public abstract double getX1 ()

Returns the X coordinate of the start point in double precision.

Returns
  • the X coordinate of the start point of this Line2D object.

public abstract double getX2 ()

Returns the X coordinate of the end point in double precision.

Returns
  • the X coordinate of the end point of this Line2D object.

public abstract double getY1 ()

Returns the Y coordinate of the start point in double precision.

Returns
  • the Y coordinate of the start point of this Line2D object.

public abstract double getY2 ()

Returns the Y coordinate of the end point in double precision.

Returns
  • the Y coordinate of the end point of this Line2D object.

public boolean intersects (double x, double y, double w, double h)

Tests if the interior of the Shape intersects the interior of a specified rectangular area. The rectangular area is considered to intersect the Shape if any point is contained in both the interior of the Shape and the specified rectangular area.

The Shape.intersects() method allows a Shape implementation to conservatively return true when:

  • there is a high probability that the rectangular area and the Shape intersect, but
  • the calculations to accurately determine this intersection are prohibitively expensive.
This means that for some Shapes this method might return true even though the rectangular area does not intersect the Shape. The Area class performs more accurate computations of geometric intersection than most Shape objects and therefore can be used if a more precise answer is required.

Parameters
x the X coordinate of the upper-left corner of the specified rectangular area
y the Y coordinate of the upper-left corner of the specified rectangular area
w the width of the specified rectangular area
h the height of the specified rectangular area
Returns
  • true if the interior of the Shape and the interior of the rectangular area intersect, or are both highly likely to intersect and intersection calculations would be too expensive to perform; false otherwise.

public boolean intersects (Rectangle2D r)

Tests if the interior of the Shape intersects the interior of a specified Rectangle2D. The Shape.intersects() method allows a Shape implementation to conservatively return true when:

  • there is a high probability that the Rectangle2D and the Shape intersect, but
  • the calculations to accurately determine this intersection are prohibitively expensive.
This means that for some Shapes this method might return true even though the Rectangle2D does not intersect the Shape. The Area class performs more accurate computations of geometric intersection than most Shape objects and therefore can be used if a more precise answer is required.

Parameters
r the specified Rectangle2D
Returns
  • true if the interior of the Shape and the interior of the specified Rectangle2D intersect, or are both highly likely to intersect and intersection calculations would be too expensive to perform; false otherwise.

public boolean intersectsLine (Line2D l)

Tests if the specified line segment intersects this line segment.

Parameters
l the specified Line2D
Returns
  • true if this line segment and the specified line segment intersect each other; false otherwise.

public boolean intersectsLine (double x1, double y1, double x2, double y2)

Tests if the line segment from (x1,y1) to (x2,y2) intersects this line segment.

Parameters
x1 the X coordinate of the start point of the specified line segment
y1 the Y coordinate of the start point of the specified line segment
x2 the X coordinate of the end point of the specified line segment
y2 the Y coordinate of the end point of the specified line segment
Returns
  • if this line segment and the specified line segment intersect each other; false otherwise.

public static boolean linesIntersect (double x1, double y1, double x2, double y2, double x3, double y3, double x4, double y4)

Tests if the line segment from (x1,y1) to (x2,y2) intersects the line segment from (x3,y3) to (x4,y4).

Parameters
x1 the X coordinate of the start point of the first specified line segment
y1 the Y coordinate of the start point of the first specified line segment
x2 the X coordinate of the end point of the first specified line segment
y2 the Y coordinate of the end point of the first specified line segment
x3 the X coordinate of the start point of the second specified line segment
y3 the Y coordinate of the start point of the second specified line segment
x4 the X coordinate of the end point of the second specified line segment
y4 the Y coordinate of the end point of the second specified line segment
Returns
  • true if the first specified line segment and the second specified line segment intersect each other; false otherwise.

public double ptLineDist (Point2D pt)

Returns the distance from a Point2D to this line. The distance measured is the distance between the specified point and the closest point on the infinitely-extended line defined by this Line2D. If the specified point intersects the line, this method returns 0.0.

Parameters
pt the specified Point2D being measured
Returns
  • a double value that is the distance from a specified Point2D to the current line.
See Also

public static double ptLineDist (double x1, double y1, double x2, double y2, double px, double py)

Returns the distance from a point to a line. The distance measured is the distance between the specified point and the closest point on the infinitely-extended line defined by the specified coordinates. If the specified point intersects the line, this method returns 0.0.

Parameters
x1 the X coordinate of the start point of the specified line
y1 the Y coordinate of the start point of the specified line
x2 the X coordinate of the end point of the specified line
y2 the Y coordinate of the end point of the specified line
px the X coordinate of the specified point being measured against the specified line
py the Y coordinate of the specified point being measured against the specified line
Returns
  • a double value that is the distance from the specified point to the specified line.
See Also

public double ptLineDist (double px, double py)

Returns the distance from a point to this line. The distance measured is the distance between the specified point and the closest point on the infinitely-extended line defined by this Line2D. If the specified point intersects the line, this method returns 0.0.

Parameters
px the X coordinate of the specified point being measured against this line
py the Y coordinate of the specified point being measured against this line
Returns
  • a double value that is the distance from a specified point to the current line.
See Also

public static double ptLineDistSq (double x1, double y1, double x2, double y2, double px, double py)

Returns the square of the distance from a point to a line. The distance measured is the distance between the specified point and the closest point on the infinitely-extended line defined by the specified coordinates. If the specified point intersects the line, this method returns 0.0.

Parameters
x1 the X coordinate of the start point of the specified line
y1 the Y coordinate of the start point of the specified line
x2 the X coordinate of the end point of the specified line
y2 the Y coordinate of the end point of the specified line
px the X coordinate of the specified point being measured against the specified line
py the Y coordinate of the specified point being measured against the specified line
Returns
  • a double value that is the square of the distance from the specified point to the specified line.
See Also

public double ptLineDistSq (double px, double py)

Returns the square of the distance from a point to this line. The distance measured is the distance between the specified point and the closest point on the infinitely-extended line defined by this Line2D. If the specified point intersects the line, this method returns 0.0.

Parameters
px the X coordinate of the specified point being measured against this line
py the Y coordinate of the specified point being measured against this line
Returns
  • a double value that is the square of the distance from a specified point to the current line.
See Also

public double ptLineDistSq (Point2D pt)

Returns the square of the distance from a specified Point2D to this line. The distance measured is the distance between the specified point and the closest point on the infinitely-extended line defined by this Line2D. If the specified point intersects the line, this method returns 0.0.

Parameters
pt the specified Point2D being measured against this line
Returns
  • a double value that is the square of the distance from a specified Point2D to the current line.
See Also

public double ptSegDist (double px, double py)

Returns the distance from a point to this line segment. The distance measured is the distance between the specified point and the closest point between the current line's end points. If the specified point intersects the line segment in between the end points, this method returns 0.0.

Parameters
px the X coordinate of the specified point being measured against this line segment
py the Y coordinate of the specified point being measured against this line segment
Returns
  • a double value that is the distance from the specified point to the current line segment.
See Also

public static double ptSegDist (double x1, double y1, double x2, double y2, double px, double py)

Returns the distance from a point to a line segment. The distance measured is the distance between the specified point and the closest point between the specified end points. If the specified point intersects the line segment in between the end points, this method returns 0.0.

Parameters
x1 the X coordinate of the start point of the specified line segment
y1 the Y coordinate of the start point of the specified line segment
x2 the X coordinate of the end point of the specified line segment
y2 the Y coordinate of the end point of the specified line segment
px the X coordinate of the specified point being measured against the specified line segment
py the Y coordinate of the specified point being measured against the specified line segment
Returns
  • a double value that is the distance from the specified point to the specified line segment.
See Also

public double ptSegDist (Point2D pt)

Returns the distance from a Point2D to this line segment. The distance measured is the distance between the specified point and the closest point between the current line's end points. If the specified point intersects the line segment in between the end points, this method returns 0.0.

Parameters
pt the specified Point2D being measured against this line segment
Returns
  • a double value that is the distance from the specified Point2D to the current line segment.
See Also

public double ptSegDistSq (double px, double py)

Returns the square of the distance from a point to this line segment. The distance measured is the distance between the specified point and the closest point between the current line's end points. If the specified point intersects the line segment in between the end points, this method returns 0.0.

Parameters
px the X coordinate of the specified point being measured against this line segment
py the Y coordinate of the specified point being measured against this line segment
Returns
  • a double value that is the square of the distance from the specified point to the current line segment.
See Also

public double ptSegDistSq (Point2D pt)

Returns the square of the distance from a Point2D to this line segment. The distance measured is the distance between the specified point and the closest point between the current line's end points. If the specified point intersects the line segment in between the end points, this method returns 0.0.

Parameters
pt the specified Point2D being measured against this line segment.
Returns
  • a double value that is the square of the distance from the specified Point2D to the current line segment.
See Also

public static double ptSegDistSq (double x1, double y1, double x2, double y2, double px, double py)

Returns the square of the distance from a point to a line segment. The distance measured is the distance between the specified point and the closest point between the specified end points. If the specified point intersects the line segment in between the end points, this method returns 0.0.

Parameters
x1 the X coordinate of the start point of the specified line segment
y1 the Y coordinate of the start point of the specified line segment
x2 the X coordinate of the end point of the specified line segment
y2 the Y coordinate of the end point of the specified line segment
px the X coordinate of the specified point being measured against the specified line segment
py the Y coordinate of the specified point being measured against the specified line segment
Returns
  • a double value that is the square of the distance from the specified point to the specified line segment.
See Also

public static int relativeCCW (double x1, double y1, double x2, double y2, double px, double py)

Returns an indicator of where the specified point (px,py) lies with respect to the line segment from (x1,y1) to (x2,y2). The return value can be either 1, -1, or 0 and indicates in which direction the specified line must pivot around its first end point, (x1,y1), in order to point at the specified point (px,py).

A return value of 1 indicates that the line segment must turn in the direction that takes the positive X axis towards the negative Y axis. In the default coordinate system used by Java 2D, this direction is counterclockwise.

A return value of -1 indicates that the line segment must turn in the direction that takes the positive X axis towards the positive Y axis. In the default coordinate system, this direction is clockwise.

A return value of 0 indicates that the point lies exactly on the line segment. Note that an indicator value of 0 is rare and not useful for determining colinearity because of floating point rounding issues.

If the point is colinear with the line segment, but not between the end points, then the value will be -1 if the point lies "beyond (x1,y1)" or 1 if the point lies "beyond (x2,y2)".

Parameters
x1 the X coordinate of the start point of the specified line segment
y1 the Y coordinate of the start point of the specified line segment
x2 the X coordinate of the end point of the specified line segment
y2 the Y coordinate of the end point of the specified line segment
px the X coordinate of the specified point to be compared with the specified line segment
py the Y coordinate of the specified point to be compared with the specified line segment
Returns
  • an integer that indicates the position of the third specified coordinates with respect to the line segment formed by the first two specified coordinates.

public int relativeCCW (Point2D p)

Returns an indicator of where the specified Point2D lies with respect to this line segment. See the method comments of relativeCCW(double, double, double, double, double, double) to interpret the return value.

Parameters
p the specified Point2D to be compared with this Line2D
Returns
  • an integer that indicates the position of the specified Point2D with respect to this Line2D
See Also

public int relativeCCW (double px, double py)

Returns an indicator of where the specified point (px,py) lies with respect to this line segment. See the method comments of relativeCCW(double, double, double, double, double, double) to interpret the return value.

Parameters
px the X coordinate of the specified point to be compared with this Line2D
py the Y coordinate of the specified point to be compared with this Line2D
Returns
  • an integer that indicates the position of the specified coordinates with respect to this Line2D
See Also

public void setLine (Point2D p1, Point2D p2)

Sets the location of the end points of this Line2D to the specified Point2D coordinates.

Parameters
p1 the start Point2D of the line segment
p2 the end Point2D of the line segment

public abstract void setLine (double x1, double y1, double x2, double y2)

Sets the location of the end points of this Line2D to the specified double coordinates.

Parameters
x1 the X coordinate of the start point
y1 the Y coordinate of the start point
x2 the X coordinate of the end point
y2 the Y coordinate of the end point

public void setLine (Line2D l)

Sets the location of the end points of this Line2D to the same as those end points of the specified Line2D.

Parameters
l the specified Line2D