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BasicStroke.javaAPI DocJava SE 6 API19564Tue Jun 10 00:25:12 BST 2008java.awt

BasicStroke

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 {@link 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 {@link 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 {@link java.awt.geom.PathIterator#SEG_CLOSE SEG_CLOSE} for more information on the CLOSE segment. The three different decorations are: {@link #CAP_BUTT}, {@link #CAP_ROUND}, and {@link #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 {@link java.awt.geom.PathIterator#SEG_CLOSE SEG_CLOSE}. The three different decorations are: {@link #JOIN_BEVEL}, {@link #JOIN_MITER}, and {@link #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.

see
Graphics2D
version
1.43, 03/09/06
author
Jim Graham

Fields Summary
public static final int
JOIN_MITER
Joins path segments by extending their outside edges until they meet.
public static final int
JOIN_ROUND
Joins path segments by rounding off the corner at a radius of half the line width.
public static final int
JOIN_BEVEL
Joins path segments by connecting the outer corners of their wide outlines with a straight segment.
public static final int
CAP_BUTT
Ends unclosed subpaths and dash segments with no added decoration.
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.
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.
float
width
int
join
int
cap
float
miterlimit
float[]
dash
float
dash_phase
private static final int[]
RasterizerCaps
private static final int[]
RasterizerCorners
Constructors Summary
public BasicStroke(float width, int cap, int join, float miterlimit, float[] dash, float dash_phase)
Constructs a new BasicStroke with the specified attributes.

param
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.
param
cap the decoration of the ends of a BasicStroke
param
join the decoration applied where path segments meet
param
miterlimit the limit to trim the miter join. The miterlimit must be greater than or equal to 1.0f.
param
dash the array representing the dashing pattern
param
dash_phase the offset to start the dashing pattern
throws
IllegalArgumentException if width is negative
throws
IllegalArgumentException if cap is not either CAP_BUTT, CAP_ROUND or CAP_SQUARE
throws
IllegalArgumentException if miterlimit is less than 1 and join is JOIN_MITER
throws
IllegalArgumentException if join is not either JOIN_ROUND, JOIN_BEVEL, or JOIN_MITER
throws
IllegalArgumentException if dash_phase is negative and dash is not null
throws
IllegalArgumentException if the length of dash is zero
throws
IllegalArgumentException if dash lengths are all zero.


                                                                                                                                                                                                                                                                       
            
		           
	if (width < 0.0f) {
	    throw new IllegalArgumentException("negative width");
	}
	if (cap != CAP_BUTT && cap != CAP_ROUND && cap != CAP_SQUARE) {
	    throw new IllegalArgumentException("illegal end cap value");
	}
	if (join == JOIN_MITER) {
	    if (miterlimit < 1.0f) {
		throw new IllegalArgumentException("miter limit < 1");
	    }
	} else if (join != JOIN_ROUND && join != JOIN_BEVEL) {
	    throw new IllegalArgumentException("illegal line join value");
	}
	if (dash != null) {
	    if (dash_phase < 0.0f) {
		throw new IllegalArgumentException("negative dash phase");
	    }
	    boolean allzero = true;
	    for (int i = 0; i < dash.length; i++) {
		float d = dash[i];
		if (d > 0.0) {
		    allzero = false;
		} else if (d < 0.0) {
		    throw new IllegalArgumentException("negative dash length");
		}
	    }
	    if (allzero) {
		throw new IllegalArgumentException("dash lengths all zero");
	    }
	}
	this.width	= width;
	this.cap	= cap;
	this.join	= join;
	this.miterlimit	= miterlimit;
        if (dash != null) {
            this.dash = (float []) dash.clone();
        }
	this.dash_phase	= dash_phase;
    
public BasicStroke(float width, int cap, int join, float miterlimit)
Constructs a solid BasicStroke with the specified attributes.

param
width the width of the BasicStroke
param
cap the decoration of the ends of a BasicStroke
param
join the decoration applied where path segments meet
param
miterlimit the limit to trim the miter join
throws
IllegalArgumentException if width is negative
throws
IllegalArgumentException if cap is not either CAP_BUTT, CAP_ROUND or CAP_SQUARE
throws
IllegalArgumentException if miterlimit is less than 1 and join is JOIN_MITER
throws
IllegalArgumentException if join is not either JOIN_ROUND, JOIN_BEVEL, or JOIN_MITER

	this(width, cap, join, miterlimit, null, 0.0f);
    
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.

param
width the width of the BasicStroke
param
cap the decoration of the ends of a BasicStroke
param
join the decoration applied where path segments meet
throws
IllegalArgumentException if width is negative
throws
IllegalArgumentException if cap is not either CAP_BUTT, CAP_ROUND or CAP_SQUARE
throws
IllegalArgumentException if join is not either JOIN_ROUND, JOIN_BEVEL, or JOIN_MITER

	this(width, cap, join, 10.0f, null, 0.0f);
    
public BasicStroke(float width)
Constructs a solid BasicStroke with the specified line width and with default values for the cap and join styles.

param
width the width of the BasicStroke
throws
IllegalArgumentException if width is negative

	this(width, CAP_SQUARE, JOIN_MITER, 10.0f, null, 0.0f);
    
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.

	this(1.0f, CAP_SQUARE, JOIN_MITER, 10.0f, null, 0.0f);
    
Methods Summary
public java.awt.ShapecreateStrokedShape(java.awt.Shape s)
Returns a Shape whose interior defines the stroked outline of a specified Shape.

param
s the Shape boundary be stroked
return
the Shape of the stroked outline.

	FillAdapter filler = new FillAdapter();
	PathStroker stroker = new PathStroker(filler);
	PathDasher dasher = null;

	try {
	    PathConsumer consumer;

	    stroker.setPenDiameter(width);
	    stroker.setPenT4(null);
	    stroker.setCaps(RasterizerCaps[cap]);
	    stroker.setCorners(RasterizerCorners[join], miterlimit);
	    if (dash != null) {
		dasher = new PathDasher(stroker);
		dasher.setDash(dash, dash_phase);
		dasher.setDashT4(null);
		consumer = dasher;
	    } else {
		consumer = stroker;
	    }

	    feedConsumer(consumer, s.getPathIterator(null));
	} finally {
	    stroker.dispose();
	    if (dasher != null) {
		dasher.dispose();
	    }
	}

	return filler.getShape();
    
public booleanequals(java.lang.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.

param
obj the specified object to compare to this BasicStroke
return
true if the width, join, cap, miter limit, dash, and dash phase are the same for both objects; false otherwise.

        if (!(obj instanceof BasicStroke)) {
            return false;
        }

        BasicStroke bs = (BasicStroke) obj;
        if (width != bs.width) {
            return false;
        }

        if (join != bs.join) {
            return false;
        }

        if (cap != bs.cap) {
            return false;
        }

        if (miterlimit != bs.miterlimit) {
            return false;
        }

        if (dash != null) {
	    if (dash_phase != bs.dash_phase) {
		return false;
	    }

	    if (!java.util.Arrays.equals(dash, bs.dash)) {
		return false;
	    }
        }
        else if (bs.dash != null) {
            return false;
        }

        return true;
    
private voidfeedConsumer(sun.dc.path.PathConsumer consumer, java.awt.geom.PathIterator pi)

	try {
	    consumer.beginPath();
	    boolean pathClosed = false;
	    float mx = 0.0f;
	    float my = 0.0f;
	    float point[]  = new float[6];

	    while (!pi.isDone()) {
		int type = pi.currentSegment(point);
		if (pathClosed == true) {
		    pathClosed = false;
		    if (type != PathIterator.SEG_MOVETO) {
			// Force current point back to last moveto point
			consumer.beginSubpath(mx, my);
		    }
		}
		switch (type) {
		case PathIterator.SEG_MOVETO:
		    mx = point[0];
		    my = point[1];
		    consumer.beginSubpath(point[0], point[1]);
		    break;
		case PathIterator.SEG_LINETO:
		    consumer.appendLine(point[0], point[1]);
		    break;
		case PathIterator.SEG_QUADTO:
		    // Quadratic curves take two points
		    consumer.appendQuadratic(point[0], point[1],
					     point[2], point[3]);
		    break;
		case PathIterator.SEG_CUBICTO:
		    // Cubic curves take three points
		    consumer.appendCubic(point[0], point[1],
					 point[2], point[3],
					 point[4], point[5]);
		    break;
		case PathIterator.SEG_CLOSE:
		    consumer.closedSubpath();
		    pathClosed = true;
		    break;
		}
		pi.next();
	    }

	    consumer.endPath();
	} catch (PathException e) {
	    throw new InternalError("Unable to Stroke shape ("+
				    e.getMessage()+")");
	}
    
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.

return
the dash array.

        if (dash == null) {
            return null;
        }

        return (float[]) dash.clone();
    
public floatgetDashPhase()
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.

return
the dash phase as a float value.

	return dash_phase;
    
public intgetEndCap()
Returns the end cap style.

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

	return cap;
    
public intgetLineJoin()
Returns the line join style.

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

	return join;
    
public floatgetLineWidth()
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.

return
the line width of this BasicStroke.
see
Graphics2D

	return width;
    
public floatgetMiterLimit()
Returns the limit of miter joins.

return
the limit of miter joins of the BasicStroke.

	return miterlimit;
    
public inthashCode()
Returns the hashcode for this stroke.

return
a hash code for this stroke.

	int hash = Float.floatToIntBits(width);
	hash = hash * 31 + join;
	hash = hash * 31 + cap;
	hash = hash * 31 + Float.floatToIntBits(miterlimit);
	if (dash != null) {
	    hash = hash * 31 + Float.floatToIntBits(dash_phase);
	    for (int i = 0; i < dash.length; i++) {
		hash = hash * 31 + Float.floatToIntBits(dash[i]);
	    }
	}
	return hash;