1 /*
   2  * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package java.awt;
  27 
  28 import java.beans.ConstructorProperties;
  29 
  30 import java.lang.annotation.Native;
  31 
  32 /**
  33  * The {@code BasicStroke} class defines a basic set of rendering
  34  * attributes for the outlines of graphics primitives, which are rendered
  35  * with a {@link Graphics2D} object that has its Stroke attribute set to
  36  * this {@code BasicStroke}.
  37  * The rendering attributes defined by {@code BasicStroke} describe
  38  * the shape of the mark made by a pen drawn along the outline of a
  39  * {@link Shape} and the decorations applied at the ends and joins of
  40  * path segments of the {@code Shape}.
  41  * These rendering attributes include:
  42  * <dl>
  43  * <dt><i>width</i>
  44  * <dd>The pen width, measured perpendicularly to the pen trajectory.
  45  * <dt><i>end caps</i>
  46  * <dd>The decoration applied to the ends of unclosed subpaths and
  47  * dash segments.  Subpaths that start and end on the same point are
  48  * still considered unclosed if they do not have a CLOSE segment.
  49  * See {@link java.awt.geom.PathIterator#SEG_CLOSE SEG_CLOSE}
  50  * for more information on the CLOSE segment.
  51  * The three different decorations are: {@link #CAP_BUTT},
  52  * {@link #CAP_ROUND}, and {@link #CAP_SQUARE}.
  53  * <dt><i>line joins</i>
  54  * <dd>The decoration applied at the intersection of two path segments
  55  * and at the intersection of the endpoints of a subpath that is closed
  56  * using {@link java.awt.geom.PathIterator#SEG_CLOSE SEG_CLOSE}.
  57  * The three different decorations are: {@link #JOIN_BEVEL},
  58  * {@link #JOIN_MITER}, and {@link #JOIN_ROUND}.
  59  * <dt><i>miter limit</i>
  60  * <dd>The limit to trim a line join that has a JOIN_MITER decoration.
  61  * A line join is trimmed when the ratio of miter length to stroke
  62  * width is greater than the miterlimit value.  The miter length is
  63  * the diagonal length of the miter, which is the distance between
  64  * the inside corner and the outside corner of the intersection.
  65  * The smaller the angle formed by two line segments, the longer
  66  * the miter length and the sharper the angle of intersection.  The
  67  * default miterlimit value of 10.0f causes all angles less than
  68  * 11 degrees to be trimmed.  Trimming miters converts
  69  * the decoration of the line join to bevel.
  70  * <dt><i>dash attributes</i>
  71  * <dd>The definition of how to make a dash pattern by alternating
  72  * between opaque and transparent sections.
  73  * </dl>
  74  * All attributes that specify measurements and distances controlling
  75  * the shape of the returned outline are measured in the same
  76  * coordinate system as the original unstroked {@code Shape}
  77  * argument.  When a {@code Graphics2D} object uses a
  78  * {@code Stroke} object to redefine a path during the execution
  79  * of one of its {@code draw} methods, the geometry is supplied
  80  * in its original form before the {@code Graphics2D} transform
  81  * attribute is applied.  Therefore, attributes such as the pen width
  82  * are interpreted in the user space coordinate system of the
  83  * {@code Graphics2D} object and are subject to the scaling and
  84  * shearing effects of the user-space-to-device-space transform in that
  85  * particular {@code Graphics2D}.
  86  * For example, the width of a rendered shape's outline is determined
  87  * not only by the width attribute of this {@code BasicStroke},
  88  * but also by the transform attribute of the
  89  * {@code Graphics2D} object.  Consider this code:
  90  * <blockquote><pre>{@code
  91  *      // sets the Graphics2D object's Transform attribute
  92  *      g2d.scale(10, 10);
  93  *      // sets the Graphics2D object's Stroke attribute
  94  *      g2d.setStroke(new BasicStroke(1.5f));
  95  * }</pre></blockquote>
  96  * Assuming there are no other scaling transforms added to the
  97  * {@code Graphics2D} object, the resulting line
  98  * will be approximately 15 pixels wide.
  99  * As the example code demonstrates, a floating-point line
 100  * offers better precision, especially when large transforms are
 101  * used with a {@code Graphics2D} object.
 102  * When a line is diagonal, the exact width depends on how the
 103  * rendering pipeline chooses which pixels to fill as it traces the
 104  * theoretical widened outline.  The choice of which pixels to turn
 105  * on is affected by the antialiasing attribute because the
 106  * antialiasing rendering pipeline can choose to color
 107  * partially-covered pixels.
 108  * <p>
 109  * For more information on the user space coordinate system and the
 110  * rendering process, see the {@code Graphics2D} class comments.
 111  * @see Graphics2D
 112  * @author Jim Graham
 113  */
 114 public class BasicStroke implements Stroke {
 115 
 116     /**
 117      * Joins path segments by extending their outside edges until
 118      * they meet.
 119      */
 120     @Native public static final int JOIN_MITER = 0;
 121 
 122     /**
 123      * Joins path segments by rounding off the corner at a radius
 124      * of half the line width.
 125      */
 126     @Native public static final int JOIN_ROUND = 1;
 127 
 128     /**
 129      * Joins path segments by connecting the outer corners of their
 130      * wide outlines with a straight segment.
 131      */
 132     @Native public static final int JOIN_BEVEL = 2;
 133 
 134     /**
 135      * Ends unclosed subpaths and dash segments with no added
 136      * decoration.
 137      */
 138     @Native public static final int CAP_BUTT = 0;
 139 
 140     /**
 141      * Ends unclosed subpaths and dash segments with a round
 142      * decoration that has a radius equal to half of the width
 143      * of the pen.
 144      */
 145     @Native public static final int CAP_ROUND = 1;
 146 
 147     /**
 148      * Ends unclosed subpaths and dash segments with a square
 149      * projection that extends beyond the end of the segment
 150      * to a distance equal to half of the line width.
 151      */
 152     @Native public static final int CAP_SQUARE = 2;
 153 
 154     float width;
 155 
 156     int join;
 157     int cap;
 158     float miterlimit;
 159 
 160     float[] dash;
 161     float dash_phase;
 162 
 163     /**
 164      * Constructs a new {@code BasicStroke} with the specified
 165      * attributes.
 166      * @param width the width of this {@code BasicStroke}.  The
 167      *         width must be greater than or equal to 0.0f.  If width is
 168      *         set to 0.0f, the stroke is rendered as the thinnest
 169      *         possible line for the target device and the antialias
 170      *         hint setting.
 171      * @param cap the decoration of the ends of a {@code BasicStroke}
 172      * @param join the decoration applied where path segments meet
 173      * @param miterlimit the limit to trim the miter join.  The miterlimit
 174      *        must be greater than or equal to 1.0f.
 175      * @param dash the array representing the dashing pattern
 176      * @param dash_phase the offset to start the dashing pattern
 177      * @throws IllegalArgumentException if {@code width} is negative
 178      * @throws IllegalArgumentException if {@code cap} is not either
 179      *         CAP_BUTT, CAP_ROUND or CAP_SQUARE
 180      * @throws IllegalArgumentException if {@code miterlimit} is less
 181      *         than 1 and {@code join} is JOIN_MITER
 182      * @throws IllegalArgumentException if {@code join} is not
 183      *         either JOIN_ROUND, JOIN_BEVEL, or JOIN_MITER
 184      * @throws IllegalArgumentException if {@code dash_phase}
 185      *         is negative and {@code dash} is not {@code null}
 186      * @throws IllegalArgumentException if the length of
 187      *         {@code dash} is zero
 188      * @throws IllegalArgumentException if dash lengths are all zero.
 189      */
 190     @ConstructorProperties({ "lineWidth", "endCap", "lineJoin", "miterLimit", "dashArray", "dashPhase" })
 191     public BasicStroke(float width, int cap, int join, float miterlimit,
 192                        float[] dash, float dash_phase) {
 193         if (width < 0.0f) {
 194             throw new IllegalArgumentException("negative width");
 195         }
 196         if (cap != CAP_BUTT && cap != CAP_ROUND && cap != CAP_SQUARE) {
 197             throw new IllegalArgumentException("illegal end cap value");
 198         }
 199         if (join == JOIN_MITER) {
 200             if (miterlimit < 1.0f) {
 201                 throw new IllegalArgumentException("miter limit < 1");
 202             }
 203         } else if (join != JOIN_ROUND && join != JOIN_BEVEL) {
 204             throw new IllegalArgumentException("illegal line join value");
 205         }
 206         if (dash != null) {
 207             if (dash_phase < 0.0f) {
 208                 throw new IllegalArgumentException("negative dash phase");
 209             }
 210             boolean allzero = true;
 211             for (int i = 0; i < dash.length; i++) {
 212                 float d = dash[i];
 213                 if (d > 0.0) {
 214                     allzero = false;
 215                 } else if (d < 0.0) {
 216                     throw new IllegalArgumentException("negative dash length");
 217                 }
 218             }
 219             if (allzero) {
 220                 throw new IllegalArgumentException("dash lengths all zero");
 221             }
 222         }
 223         this.width      = width;
 224         this.cap        = cap;
 225         this.join       = join;
 226         this.miterlimit = miterlimit;
 227         if (dash != null) {
 228             this.dash = dash.clone();
 229         }
 230         this.dash_phase = dash_phase;
 231     }
 232 
 233     /**
 234      * Constructs a solid {@code BasicStroke} with the specified
 235      * attributes.
 236      * @param width the width of the {@code BasicStroke}
 237      * @param cap the decoration of the ends of a {@code BasicStroke}
 238      * @param join the decoration applied where path segments meet
 239      * @param miterlimit the limit to trim the miter join
 240      * @throws IllegalArgumentException if {@code width} is negative
 241      * @throws IllegalArgumentException if {@code cap} is not either
 242      *         CAP_BUTT, CAP_ROUND or CAP_SQUARE
 243      * @throws IllegalArgumentException if {@code miterlimit} is less
 244      *         than 1 and {@code join} is JOIN_MITER
 245      * @throws IllegalArgumentException if {@code join} is not
 246      *         either JOIN_ROUND, JOIN_BEVEL, or JOIN_MITER
 247      */
 248     public BasicStroke(float width, int cap, int join, float miterlimit) {
 249         this(width, cap, join, miterlimit, null, 0.0f);
 250     }
 251 
 252     /**
 253      * Constructs a solid {@code BasicStroke} with the specified
 254      * attributes.  The {@code miterlimit} parameter is
 255      * unnecessary in cases where the default is allowable or the
 256      * line joins are not specified as JOIN_MITER.
 257      * @param width the width of the {@code BasicStroke}
 258      * @param cap the decoration of the ends of a {@code BasicStroke}
 259      * @param join the decoration applied where path segments meet
 260      * @throws IllegalArgumentException if {@code width} is negative
 261      * @throws IllegalArgumentException if {@code cap} is not either
 262      *         CAP_BUTT, CAP_ROUND or CAP_SQUARE
 263      * @throws IllegalArgumentException if {@code join} is not
 264      *         either JOIN_ROUND, JOIN_BEVEL, or JOIN_MITER
 265      */
 266     public BasicStroke(float width, int cap, int join) {
 267         this(width, cap, join, 10.0f, null, 0.0f);
 268     }
 269 
 270     /**
 271      * Constructs a solid {@code BasicStroke} with the specified
 272      * line width and with default values for the cap and join
 273      * styles.
 274      * @param width the width of the {@code BasicStroke}
 275      * @throws IllegalArgumentException if {@code width} is negative
 276      */
 277     public BasicStroke(float width) {
 278         this(width, CAP_SQUARE, JOIN_MITER, 10.0f, null, 0.0f);
 279     }
 280 
 281     /**
 282      * Constructs a new {@code BasicStroke} with defaults for all
 283      * attributes.
 284      * The default attributes are a solid line of width 1.0, CAP_SQUARE,
 285      * JOIN_MITER, a miter limit of 10.0.
 286      */
 287     public BasicStroke() {
 288         this(1.0f, CAP_SQUARE, JOIN_MITER, 10.0f, null, 0.0f);
 289     }
 290 
 291 
 292     /**
 293      * Returns a {@code Shape} whose interior defines the
 294      * stroked outline of a specified {@code Shape}.
 295      * @param s the {@code Shape} boundary be stroked
 296      * @return the {@code Shape} of the stroked outline.
 297      */
 298     public Shape createStrokedShape(Shape s) {
 299         sun.java2d.pipe.RenderingEngine re =
 300             sun.java2d.pipe.RenderingEngine.getInstance();
 301         return re.createStrokedShape(s, width, cap, join, miterlimit,
 302                                      dash, dash_phase);
 303     }
 304 
 305     /**
 306      * Returns the line width.  Line width is represented in user space,
 307      * which is the default-coordinate space used by Java 2D.  See the
 308      * {@code Graphics2D} class comments for more information on
 309      * the user space coordinate system.
 310      * @return the line width of this {@code BasicStroke}.
 311      * @see Graphics2D
 312      */
 313     public float getLineWidth() {
 314         return width;
 315     }
 316 
 317     /**
 318      * Returns the end cap style.
 319      * @return the end cap style of this {@code BasicStroke} as one
 320      * of the static {@code int} values that define possible end cap
 321      * styles.
 322      */
 323     public int getEndCap() {
 324         return cap;
 325     }
 326 
 327     /**
 328      * Returns the line join style.
 329      * @return the line join style of the {@code BasicStroke} as one
 330      * of the static {@code int} values that define possible line
 331      * join styles.
 332      */
 333     public int getLineJoin() {
 334         return join;
 335     }
 336 
 337     /**
 338      * Returns the limit of miter joins.
 339      * @return the limit of miter joins of the {@code BasicStroke}.
 340      */
 341     public float getMiterLimit() {
 342         return miterlimit;
 343     }
 344 
 345     /**
 346      * Returns the array representing the lengths of the dash segments.
 347      * Alternate entries in the array represent the user space lengths
 348      * of the opaque and transparent segments of the dashes.
 349      * As the pen moves along the outline of the {@code Shape}
 350      * to be stroked, the user space
 351      * distance that the pen travels is accumulated.  The distance
 352      * value is used to index into the dash array.
 353      * The pen is opaque when its current cumulative distance maps
 354      * to an even element of the dash array and transparent otherwise.
 355      * @return the dash array.
 356      */
 357     public float[] getDashArray() {
 358         if (dash == null) {
 359             return null;
 360         }
 361 
 362         return dash.clone();
 363     }
 364 
 365     /**
 366      * Returns the current dash phase.
 367      * The dash phase is a distance specified in user coordinates that
 368      * represents an offset into the dashing pattern. In other words, the dash
 369      * phase defines the point in the dashing pattern that will correspond to
 370      * the beginning of the stroke.
 371      * @return the dash phase as a {@code float} value.
 372      */
 373     public float getDashPhase() {
 374         return dash_phase;
 375     }
 376 
 377     /**
 378      * Returns the hashcode for this stroke.
 379      * @return      a hash code for this stroke.
 380      */
 381     public int hashCode() {
 382         int hash = Float.floatToIntBits(width);
 383         hash = hash * 31 + join;
 384         hash = hash * 31 + cap;
 385         hash = hash * 31 + Float.floatToIntBits(miterlimit);
 386         if (dash != null) {
 387             hash = hash * 31 + Float.floatToIntBits(dash_phase);
 388             for (int i = 0; i < dash.length; i++) {
 389                 hash = hash * 31 + Float.floatToIntBits(dash[i]);
 390             }
 391         }
 392         return hash;
 393     }
 394 
 395     /**
 396      * Returns true if this BasicStroke represents the same
 397      * stroking operation as the given argument.
 398      */
 399    /**
 400     * Tests if a specified object is equal to this {@code BasicStroke}
 401     * by first testing if it is a {@code BasicStroke} and then comparing
 402     * its width, join, cap, miter limit, dash, and dash phase attributes with
 403     * those of this {@code BasicStroke}.
 404     * @param  obj the specified object to compare to this
 405     *              {@code BasicStroke}
 406     * @return {@code true} if the width, join, cap, miter limit, dash, and
 407     *            dash phase are the same for both objects;
 408     *            {@code false} otherwise.
 409     */
 410     public boolean equals(Object obj) {
 411         if (!(obj instanceof BasicStroke)) {
 412             return false;
 413         }
 414 
 415         BasicStroke bs = (BasicStroke) obj;
 416         if (width != bs.width) {
 417             return false;
 418         }
 419 
 420         if (join != bs.join) {
 421             return false;
 422         }
 423 
 424         if (cap != bs.cap) {
 425             return false;
 426         }
 427 
 428         if (miterlimit != bs.miterlimit) {
 429             return false;
 430         }
 431 
 432         if (dash != null) {
 433             if (dash_phase != bs.dash_phase) {
 434                 return false;
 435             }
 436 
 437             if (!java.util.Arrays.equals(dash, bs.dash)) {
 438                 return false;
 439             }
 440         }
 441         else if (bs.dash != null) {
 442             return false;
 443         }
 444 
 445         return true;
 446     }
 447 }