Module java.desktop
Package 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 Transform 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.

See Also:
Graphics2D
  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final int
    Ends unclosed subpaths and dash segments with no added decoration.
    static final int
    Ends unclosed subpaths and dash segments with a round decoration that has a radius equal to half of the width of the pen.
    static final int
    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.
    static final int
    Joins path segments by connecting the outer corners of their wide outlines with a straight segment.
    static final int
    Joins path segments by extending their outside edges until they meet.
    static final int
    Joins path segments by rounding off the corner at a radius of half the line width.
  • Constructor Summary

    Constructors
    Constructor
    Description
    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

    Modifier and Type
    Method
    Description
    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[]
    Returns the array representing the lengths of the dash segments.
    float
    Returns the current dash phase.
    int
    Returns the end cap style.
    int
    Returns the line join style.
    float
    Returns the line width.
    float
    Returns the limit of miter joins.
    int
    Returns the hashcode for this stroke.

    Methods declared in class java.lang.Object

    clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait
  • Field Details

    • JOIN_MITER

      @Native public static final int JOIN_MITER
      Joins path segments by extending their outside edges until they meet.
      See Also:
      Constant Field Values
    • JOIN_ROUND

      @Native 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

      @Native 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

      @Native public static final int CAP_BUTT
      Ends unclosed subpaths and dash segments with no added decoration.
      See Also:
      Constant Field Values
    • CAP_ROUND

      @Native 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

      @Native 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
  • Constructor Details

    • BasicStroke

      @ConstructorProperties({"lineWidth","endCap","lineJoin","miterLimit","dashArray","dashPhase"}) 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 Details

    • 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.
      Throws:
      NullPointerException - if s is null
    • 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), System.identityHashCode(java.lang.Object)
    • 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(), HashMap