java.awt
Class BasicStroke

java.lang.Object
  java.awt.BasicStroke

All Implemented Interfaces:

Stroke

public class BasicStroke

extends Object

implements Stroke

The BasicStroke class defines a basic set of rendering attributes for the outlines of graphics primitives, which are rendered with a Graphics2D object that has its Stroke attribute set to this BasicStroke. The rendering attributes defined by BasicStroke describe the shape of the mark made by a pen drawn along the outline of a Shape and the decorations applied at the ends and joins of path segments of the Shape. These rendering attributes include:

width

The pen width, measured perpendicularly to the pen trajectory.

end caps

The decoration applied to the ends of unclosed subpaths and dash segments. Subpaths that start and end on the same point are still considered unclosed if they do not have a CLOSE segment. See SEG_CLOSE for more information on the CLOSE segment. The three different decorations are: CAP_BUTT, CAP_ROUND, and CAP_SQUARE.

line joins

The decoration applied at the intersection of two path segments and at the intersection of the endpoints of a subpath that is closed using SEG_CLOSE. The three different decorations are: JOIN_BEVEL, JOIN_MITER, and JOIN_ROUND.

miter limit

The limit to trim a line join that has a JOIN_MITER decoration. A line join is trimmed when the ratio of miter length to stroke width is greater than the miterlimit value. The miter length is the diagonal length of the miter, which is the distance between the inside corner and the outside corner of the intersection. The smaller the angle formed by two line segments, the longer the miter length and the sharper the angle of intersection. The default miterlimit value of 10.0f causes all angles less than 11 degrees to be trimmed. Trimming miters converts the decoration of the line join to bevel.

dash attributes

The definition of how to make a dash pattern by alternating between opaque and transparent sections.

All attributes that specify measurements and distances controlling the shape of the returned outline are measured in the same coordinate system as the original unstroked Shape argument. When a Graphics2D object uses a Stroke object to redefine a path during the execution of one of its draw methods, the geometry is supplied in its original form before the Graphics2D transform attribute is applied. Therefore, attributes such as the pen width are interpreted in the user space coordinate system of the Graphics2D object and are subject to the scaling and shearing effects of the user-space-to-device-space transform in that particular Graphics2D. For example, the width of a rendered shape's outline is determined not only by the width attribute of this BasicStroke, but also by the transform attribute of the Graphics2D object. Consider this code:

// sets the Graphics2D object's Tranform attribute g2d.scale(10, 10); // sets the Graphics2D object's Stroke attribute g2d.setStroke(new BasicStroke(1.5f));

Assuming there are no other scaling transforms added to the Graphics2D object, the resulting line will be approximately 15 pixels wide. As the example code demonstrates, a floating-point line offers better precision, especially when large transforms are used with a Graphics2D object. When a line is diagonal, the exact width depends on how the rendering pipeline chooses which pixels to fill as it traces the theoretical widened outline. The choice of which pixels to turn on is affected by the antialiasing attribute because the antialiasing rendering pipeline can choose to color partially-covered pixels.

For more information on the user space coordinate system and the rendering process, see the Graphics2D class comments.

Author:

Jim Graham

See Also:

Graphics2D

Nested Class Summary

private class

BasicStroke.FillAdapter

Field Summary

(package private) int	cap
static int	CAP_BUTT Ends unclosed subpaths and dash segments with no added decoration.
static int	CAP_ROUND Ends unclosed subpaths and dash segments with a round decoration that has a radius equal to half of the width of the pen.
static int	CAP_SQUARE Ends unclosed subpaths and dash segments with a square projection that extends beyond the end of the segment to a distance equal to half of the line width.
(package private) float[]	dash
(package private) float	dash_phase
(package private) int	join
static int	JOIN_BEVEL Joins path segments by connecting the outer corners of their wide outlines with a straight segment.
static int	JOIN_MITER Joins path segments by extending their outside edges until they meet.
static int	JOIN_ROUND Joins path segments by rounding off the corner at a radius of half the line width.
(package private) float	miterlimit
private static int[]	RasterizerCaps
private static int[]	RasterizerCorners
(package private) float	width

Constructor Summary

BasicStroke()
Constructs a new BasicStroke with defaults for all attributes.

BasicStroke(float width)
Constructs a solid BasicStroke with the specified line width and with default values for the cap and join styles.

BasicStroke(float width, int cap, int join)
Constructs a solid BasicStroke with the specified attributes.

BasicStroke(float width, int cap, int join, float miterlimit)
Constructs a solid BasicStroke with the specified attributes.

BasicStroke(float width, int cap, int join, float miterlimit, float[] dash, float dash_phase)
Constructs a new BasicStroke with the specified attributes.

Method Summary

Shape	createStrokedShape(Shape s) Returns a Shape whose interior defines the stroked outline of a specified Shape.
boolean	equals(Object obj) Tests if a specified object is equal to this BasicStroke by first testing if it is a BasicStroke and then comparing its width, join, cap, miter limit, dash, and dash phase attributes with those of this BasicStroke.
float[]	getDashArray() Returns the array representing the lengths of the dash segments.
float	getDashPhase() Returns the current dash phase.
int	getEndCap() Returns the end cap style.
int	getLineJoin() Returns the line join style.
float	getLineWidth() Returns the line width.
float	getMiterLimit() Returns the limit of miter joins.
int	hashCode() Returns the hashcode for this stroke.

Methods inherited from class java.lang.Object

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

Field Detail

JOIN_MITER

public static final int JOIN_MITER

Joins path segments by extending their outside edges until they meet.

See Also:

Constant Field Values

JOIN_ROUND

public static final int JOIN_ROUND

Joins path segments by rounding off the corner at a radius of half the line width.

See Also:

Constant Field Values

JOIN_BEVEL

public static final int JOIN_BEVEL

Joins path segments by connecting the outer corners of their wide outlines with a straight segment.

See Also:

Constant Field Values

CAP_BUTT

public static final int CAP_BUTT

Ends unclosed subpaths and dash segments with no added decoration.

See Also:

Constant Field Values

CAP_ROUND

public static final int CAP_ROUND

Ends unclosed subpaths and dash segments with a round decoration that has a radius equal to half of the width of the pen.

See Also:

Constant Field Values

CAP_SQUARE

public static final int CAP_SQUARE

Ends unclosed subpaths and dash segments with a square projection that extends beyond the end of the segment to a distance equal to half of the line width.

See Also:

Constant Field Values

width

float width

join

int join

cap

int cap

miterlimit

float miterlimit

dash

float[] dash

dash_phase

float dash_phase

RasterizerCaps

private static final int[] RasterizerCaps

RasterizerCorners

private static final int[] RasterizerCorners

Constructor Detail

BasicStroke

public BasicStroke(float width,
                   int cap,
                   int join,
                   float miterlimit,
                   float[] dash,
                   float dash_phase)

Constructs a new BasicStroke with the specified attributes.

Parameters:

width - the width of this BasicStroke. The width must be greater than or equal to 0.0f. If width is set to 0.0f, the stroke is rendered as the thinnest possible line for the target device and the antialias hint setting.

cap - the decoration of the ends of a BasicStroke

join - the decoration applied where path segments meet

miterlimit - the limit to trim the miter join. The miterlimit must be greater than or equal to 1.0f.

dash - the array representing the dashing pattern

dash_phase - the offset to start the dashing pattern

Throws:

IllegalArgumentException - if width is negative

IllegalArgumentException - if cap is not either CAP_BUTT, CAP_ROUND or CAP_SQUARE

IllegalArgumentException - if miterlimit is less than 1 and join is JOIN_MITER

IllegalArgumentException - if join is not either JOIN_ROUND, JOIN_BEVEL, or JOIN_MITER

IllegalArgumentException - if dash_phase is negative and dash is not null

IllegalArgumentException - if the length of dash is zero

IllegalArgumentException - if dash lengths are all zero.

BasicStroke

public BasicStroke(float width,
                   int cap,
                   int join,
                   float miterlimit)

Constructs a solid BasicStroke with the specified attributes.

Parameters:

width - the width of the BasicStroke

cap - the decoration of the ends of a BasicStroke

join - the decoration applied where path segments meet

miterlimit - the limit to trim the miter join

Throws:

IllegalArgumentException - if width is negative

IllegalArgumentException - if cap is not either CAP_BUTT, CAP_ROUND or CAP_SQUARE

IllegalArgumentException - if miterlimit is less than 1 and join is JOIN_MITER

IllegalArgumentException - if join is not either JOIN_ROUND, JOIN_BEVEL, or JOIN_MITER

BasicStroke

public BasicStroke(float width,
                   int cap,
                   int join)

Constructs a solid BasicStroke with the specified attributes. The miterlimit parameter is unnecessary in cases where the default is allowable or the line joins are not specified as JOIN_MITER.

Parameters:

width - the width of the BasicStroke

cap - the decoration of the ends of a BasicStroke

join - the decoration applied where path segments meet

Throws:

IllegalArgumentException - if width is negative

IllegalArgumentException - if cap is not either CAP_BUTT, CAP_ROUND or CAP_SQUARE

IllegalArgumentException - if join is not either JOIN_ROUND, JOIN_BEVEL, or JOIN_MITER

BasicStroke

public BasicStroke(float width)

Constructs a solid BasicStroke with the specified line width and with default values for the cap and join styles.

Parameters:

width - the width of the BasicStroke

Throws:

IllegalArgumentException - if width is negative

BasicStroke

public BasicStroke()

Constructs a new BasicStroke with defaults for all attributes. The default attributes are a solid line of width 1.0, CAP_SQUARE, JOIN_MITER, a miter limit of 10.0.

Method Detail

createStrokedShape

public Shape createStrokedShape(Shape s)

Returns a Shape whose interior defines the stroked outline of a specified Shape.

Specified by:

createStrokedShape in interface Stroke

Parameters:

s - the Shape boundary be stroked

Returns:

the Shape of the stroked outline.

getLineWidth

public float getLineWidth()

Returns the line width. Line width is represented in user space, which is the default-coordinate space used by Java 2D. See the Graphics2D class comments for more information on the user space coordinate system.

Returns:

the line width of this BasicStroke.

See Also:

Graphics2D

getEndCap

public int getEndCap()

Returns the end cap style.

Returns:

the end cap style of this BasicStroke as one of the static int values that define possible end cap styles.

getLineJoin

public int getLineJoin()

Returns the line join style.

Returns:

the line join style of the BasicStroke as one of the static int values that define possible line join styles.

getMiterLimit

public float getMiterLimit()

Returns the limit of miter joins.

Returns:

the limit of miter joins of the BasicStroke.

getDashArray

public float[] getDashArray()

Returns the array representing the lengths of the dash segments. Alternate entries in the array represent the user space lengths of the opaque and transparent segments of the dashes. As the pen moves along the outline of the Shape to be stroked, the user space distance that the pen travels is accumulated. The distance value is used to index into the dash array. The pen is opaque when its current cumulative distance maps to an even element of the dash array and transparent otherwise.

Returns:

the dash array.

getDashPhase

public float getDashPhase()

Returns the current dash phase. The dash phase is a distance specified in user coordinates that represents an offset into the dashing pattern. In other words, the dash phase defines the point in the dashing pattern that will correspond to the beginning of the stroke.

Returns:

the dash phase as a float value.

hashCode

public int hashCode()

Returns the hashcode for this stroke.

Overrides:

hashCode in class Object

Returns:

a hash code for this stroke.

See Also:

Object.equals(java.lang.Object), Hashtable

equals

public boolean equals(Object obj)

Tests if a specified object is equal to this BasicStroke by first testing if it is a BasicStroke and then comparing its width, join, cap, miter limit, dash, and dash phase attributes with those of this BasicStroke.

Overrides:

equals in class Object

Parameters:

obj - the specified object to compare to this BasicStroke

Returns:

true if the width, join, cap, miter limit, dash, and dash phase are the same for both objects; false otherwise.

See Also:

Object.hashCode(), Hashtable