1 /*
   2  * Copyright (c) 1997, 2019, 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 sun.font;
  27 




  28 import java.awt.Font;
  29 import java.awt.FontMetrics;
  30 import java.awt.GraphicsEnvironment;



  31 import java.awt.font.FontRenderContext;
  32 import java.awt.font.TextLayout;
  33 import java.awt.geom.AffineTransform;
  34 import java.awt.geom.Rectangle2D;
  35 import java.io.IOException;
  36 import java.io.ObjectInputStream;
  37 import java.io.ObjectOutputStream;
  38 import java.lang.ref.ReferenceQueue;
  39 import java.lang.ref.SoftReference;
  40 import java.util.concurrent.ConcurrentHashMap;
  41 
  42 import sun.java2d.Disposer;
  43 import sun.java2d.DisposerRecord;
  44 
  45 /*
  46  * This class provides a summary of the glyph measurements  for a Font
  47  * and a set of hints that guide their display.  It provides more metrics
  48  * information for the Font than the java.awt.FontMetrics class. There
  49  * is also some redundancy with that class.
  50  * <p>
  51  * The design metrics for a Font are obtained from Font.getDesignMetrics().
  52  * The FontDesignMetrics object returned will be independent of the
  53  * point size of the Font.
  54  * Most users are familiar with the idea of using <i>point size</i> to
  55  * specify the size of glyphs in a font. This point size defines a
  56  * measurement between the baseline of one line to the baseline of the
  57  * following line in a single spaced text document. The point size is
  58  * based on <i>typographic points</i>, approximately 1/72 of an inch.
  59  * <p>
  60  * The Java2D API adopts the convention that one point is equivalent
  61  * to one unit in user coordinates.  When using a normalized transform
  62  * for converting user space coordinates to device space coordinates (see
  63  * GraphicsConfiguration.getDefaultTransform() and
  64  * GraphicsConfiguration.getNormalizingTransform()), 72 user space units
  65  * equal 1 inch in device space.  In this case one point is 1/72 of an inch.
  66  * <p>
  67  * The FontDesignMetrics class expresses font metrics in terms of arbitrary
  68  * <i>typographic units</i> (not points) chosen by the font supplier
  69  * and used in the underlying platform font representations.  These units are
  70  * defined by dividing the em-square into a grid.  The em-sqaure is the
  71  * theoretical square whose dimensions are the full body height of the
  72  * font.  A typographic unit is the smallest measurable unit in the
  73  * em-square.  The number of units-per-em is determined by the font
  74  * designer.  The greater the units-per-em, the greater the precision
  75  * in metrics.  For example, Type 1 fonts divide the em-square into a
  76  * 1000 x 1000 grid, while TrueType fonts typically use a 2048 x 2048
  77  * grid.  The scale of these units can be obtained by calling
  78  * getUnitsPerEm().
  79  * <p>
  80  * Typographic units are relative -- their absolute size changes as the
  81  * size of the of the em-square changes.  An em-square is 9 points high
  82  * in a 9-point font.  Because typographic units are relative to the
  83  * em-square, a given location on a glyph will have the same coordinates
  84  * in typographic units regardless of the point size.
  85  * <p>
  86  * Converting typographic units to pixels requires computing pixels-per-em
  87  * (ppem).  This can be computed as:
  88  * <pre>
  89          ppem = device_resolution * (inches-per-point) * pointSize
  90  * </pre>
  91  * where device resolution could be measured in pixels/inch and the point
  92  * size of a font is effectively points/em.  Using a normalized transform
  93  * from user space to device space (see above), results in 1/72 inch/point.
  94  * In this case, ppem is equal to the point size on a 72 dpi monitor, so
  95  * that an N point font displays N pixels high.  In general,
  96  * <pre>
  97         pixel_units = typographic_units * (ppem / units_per_em)
  98  * </pre>
  99  * @see java.awt.Font
 100  * @see java.awt.GraphicsConfiguration#getDefaultTransform
 101  * @see java.awt.GraphicsConfiguration#getNormalizingTransform
 102  */
 103 
 104 public final class FontDesignMetrics extends FontMetrics {
 105 
 106     static final long serialVersionUID = 4480069578560887773L;
 107 
 108     private static final float UNKNOWN_WIDTH = -1;
 109     private static final int CURRENT_VERSION = 1;
 110 
 111     // height, ascent, descent, leading are reported to the client
 112     // as an integer this value is added to the true fp value to
 113     // obtain a value which is usually going to result in a round up
 114     // to the next integer except for very marginal cases.
 115     private static float roundingUpValue = 0.95f;
 116 
 117     // These fields are all part of the old serialization representation
 118     private Font  font;
 119     private float ascent;
 120     private float descent;
 121     private float leading;
 122     private float maxAdvance;
 123     private double[] matrix;
 124     private int[] cache; // now unused, still here only for serialization
 125     // End legacy serialization fields
 126 
 127     private int serVersion = 0;  // If 1 in readObject, these fields are on the input stream:
 128     private boolean isAntiAliased;
 129     private boolean usesFractionalMetrics;
 130     private AffineTransform frcTx;
 131 
 132     private transient float[] advCache; // transient since values could change across runtimes
 133     private transient int height = -1;
 134 
 135     private transient FontRenderContext frc;
 136 
 137     private transient double[] devmatrix = null;
 138 
 139     private transient FontStrike fontStrike;
 140 
 141     private static FontRenderContext DEFAULT_FRC = null;
 142 
 143     private static FontRenderContext getDefaultFrc() {
 144 
 145         if (DEFAULT_FRC == null) {
 146             AffineTransform tx;
 147             if (GraphicsEnvironment.isHeadless()) {
 148                 tx = new AffineTransform();
 149             } else {
 150                 tx =  GraphicsEnvironment
 151                     .getLocalGraphicsEnvironment()
 152                     .getDefaultScreenDevice()
 153                     .getDefaultConfiguration()
 154                     .getDefaultTransform();
 155             }
 156             DEFAULT_FRC = new FontRenderContext(tx, false, false);
 157         }
 158         return DEFAULT_FRC;
 159     }
 160 
 161     /* Strongly cache up to 5 most recently requested FontMetrics objects,
 162      * and softly cache as many as GC allows. In practice this means we
 163      * should keep references around until memory gets low.
 164      * We key the cache either by a Font or a combination of the Font and
 165      * and FRC. A lot of callers use only the font so although there's code
 166      * duplication, we allow just a font to be a key implying a default FRC.
 167      * Also we put the references on a queue so that if they do get nulled
 168      * out we can clear the keys from the table.
 169      */
 170     private static class KeyReference extends SoftReference<Object>
 171         implements DisposerRecord, Disposer.PollDisposable {
 172 
 173         static ReferenceQueue<Object> queue = Disposer.getQueue();
 174 
 175         Object key;
 176 
 177         KeyReference(Object key, Object value) {
 178             super(value, queue);
 179             this.key = key;
 180             Disposer.addReference(this, this);
 181         }
 182 
 183         /* It is possible that since this reference object has been
 184          * enqueued, that a new metrics has been put into the table
 185          * for the same key value. So we'll test to see if the table maps
 186          * to THIS reference. If its a new one, we'll leave it alone.
 187          * It is possible that a new entry comes in after our test, but
 188          * it is unlikely and if this were a problem we would need to
 189          * synchronize all 'put' and 'remove' accesses to the cache which
 190          * I would prefer not to do.
 191          */
 192         public void dispose() {
 193             if (metricsCache.get(key) == this) {
 194                 metricsCache.remove(key);
 195             }
 196         }
 197     }
 198 
 199     private static class MetricsKey {
 200         Font font;
 201         FontRenderContext frc;
 202         int hash;
 203 
 204         MetricsKey() {
 205         }
 206 
 207         MetricsKey(Font font, FontRenderContext frc) {
 208             init(font, frc);
 209         }
 210 
 211         void init(Font font, FontRenderContext frc) {
 212             this.font = font;
 213             this.frc = frc;
 214             this.hash = font.hashCode() + frc.hashCode();
 215         }
 216 
 217         public boolean equals(Object key) {
 218             if (!(key instanceof MetricsKey)) {
 219                 return false;
 220             }
 221             return
 222                 font.equals(((MetricsKey)key).font) &&
 223                 frc.equals(((MetricsKey)key).frc);
 224         }
 225 
 226         public int hashCode() {
 227             return hash;
 228         }
 229 
 230         /* Synchronize access to this on the class */
 231         static final MetricsKey key = new MetricsKey();
 232     }
 233 
 234     /* All accesses to a CHM do not in general need to be synchronized,
 235      * as incomplete operations on another thread would just lead to
 236      * harmless cache misses.
 237      */
 238     private static final ConcurrentHashMap<Object, KeyReference>
 239         metricsCache = new ConcurrentHashMap<Object, KeyReference>();
 240 
 241     private static final int MAXRECENT = 5;
 242     private static final FontDesignMetrics[]
 243         recentMetrics = new FontDesignMetrics[MAXRECENT];
 244     private static int recentIndex = 0;
 245 
 246     public static FontDesignMetrics getMetrics(Font font) {
 247         return getMetrics(font, getDefaultFrc());
 248      }
 249 
 250     public static FontDesignMetrics getMetrics(Font font,
 251                                                FontRenderContext frc) {
 252 
 253 
 254         /* When using alternate composites, can't cache based just on
 255          * the java.awt.Font. Since this is rarely used and we can still
 256          * cache the physical fonts, its not a problem to just return a
 257          * new instance in this case.
 258          * Note that currently Swing native L&F composites are not handled
 259          * by this code as they use the metrics of the physical anyway.
 260          */
 261         SunFontManager fm = SunFontManager.getInstance();
 262         if (fm.usingAlternateCompositeFonts() &&
 263             FontUtilities.getFont2D(font) instanceof CompositeFont) {
 264             return new FontDesignMetrics(font, frc);
 265         }
 266 
 267         FontDesignMetrics m = null;
 268         KeyReference r;
 269 
 270         /* There are 2 possible keys used to perform lookups in metricsCache.
 271          * If the FRC is set to all defaults, we just use the font as the key.
 272          * If the FRC is non-default in any way, we construct a hybrid key
 273          * that combines the font and FRC.
 274          */
 275         boolean usefontkey = frc.equals(getDefaultFrc());
 276 
 277         if (usefontkey) {
 278             r = metricsCache.get(font);
 279         } else /* use hybrid key */ {
 280             // NB synchronization is not needed here because of updates to
 281             // the metrics cache but is needed for the shared key.
 282             synchronized (MetricsKey.class) {
 283                 MetricsKey.key.init(font, frc);
 284                 r = metricsCache.get(MetricsKey.key);
 285             }
 286         }
 287 
 288         if (r != null) {
 289             m = (FontDesignMetrics)r.get();
 290         }
 291 
 292         if (m == null) {
 293             /* either there was no reference, or it was cleared. Need a new
 294              * metrics instance. The key to use in the map is a new
 295              * MetricsKey instance when we've determined the FRC is
 296              * non-default. Its constructed from local vars so we are
 297              * thread-safe - no need to worry about the shared key changing.
 298              */
 299             m = new FontDesignMetrics(font, frc);
 300             if (usefontkey) {
 301                 metricsCache.put(font, new KeyReference(font, m));
 302             } else /* use hybrid key */ {
 303                 MetricsKey newKey = new MetricsKey(font, frc);
 304                 metricsCache.put(newKey, new KeyReference(newKey, m));
 305             }
 306         }
 307 
 308         /* Here's where we keep the recent metrics */
 309         for (int i=0; i<recentMetrics.length; i++) {
 310             if (recentMetrics[i]==m) {
 311                 return m;
 312             }
 313         }
 314 
 315         synchronized (recentMetrics) {
 316             recentMetrics[recentIndex++] = m;
 317             if (recentIndex == MAXRECENT) {
 318                 recentIndex = 0;
 319             }
 320         }
 321         return m;
 322     }
 323 
 324   /*
 325    * Constructs a new FontDesignMetrics object for the given Font.
 326    * Its private to enable caching - call getMetrics() instead.
 327    * @param font a Font object.
 328    */
 329 
 330     private FontDesignMetrics(Font font) {
 331 
 332         this(font, getDefaultFrc());
 333     }
 334 
 335     /* private to enable caching - call getMetrics() instead. */
 336     private FontDesignMetrics(Font font, FontRenderContext frc) {
 337       super(font);
 338       this.font = font;
 339       this.frc = frc;
 340 
 341       this.isAntiAliased = frc.isAntiAliased();
 342       this.usesFractionalMetrics = frc.usesFractionalMetrics();
 343 
 344       frcTx = frc.getTransform();
 345 
 346       matrix = new double[4];
 347       initMatrixAndMetrics();
 348 
 349       initAdvCache();
 350     }
 351 
 352     private void initMatrixAndMetrics() {
 353 
 354         Font2D font2D = FontUtilities.getFont2D(font);
 355         fontStrike = font2D.getStrike(font, frc);
 356         StrikeMetrics metrics = fontStrike.getFontMetrics();
 357         this.ascent = metrics.getAscent();
 358         this.descent = metrics.getDescent();
 359         this.leading = metrics.getLeading();
 360         this.maxAdvance = metrics.getMaxAdvance();
 361 
 362         devmatrix = new double[4];
 363         frcTx.getMatrix(devmatrix);
 364     }
 365 
 366     private void initAdvCache() {
 367         advCache = new float[256];
 368         // 0 is a valid metric so force it to -1
 369         for (int i = 0; i < 256; i++) {
 370             advCache[i] = UNKNOWN_WIDTH;
 371         }
 372     }
 373 
 374     private void readObject(ObjectInputStream in) throws IOException,
 375                                                   ClassNotFoundException {
 376 
 377         in.defaultReadObject();
 378         if (serVersion != CURRENT_VERSION) {
 379             frc = getDefaultFrc();
 380             isAntiAliased = frc.isAntiAliased();
 381             usesFractionalMetrics = frc.usesFractionalMetrics();
 382             frcTx = frc.getTransform();
 383         }
 384         else {
 385             frc = new FontRenderContext(frcTx, isAntiAliased, usesFractionalMetrics);
 386         }
 387 
 388         // when deserialized, members are set to their default values for their type--
 389         // not to the values assigned during initialization before the constructor
 390         // body!
 391         height = -1;
 392 
 393         cache = null;
 394 
 395         initMatrixAndMetrics();
 396         initAdvCache();
 397     }
 398 
 399     private void writeObject(ObjectOutputStream out) throws IOException {
 400 
 401         cache = new int[256];
 402         for (int i=0; i < 256; i++) {
 403             cache[i] = -1;
 404         }
 405         serVersion = CURRENT_VERSION;
 406 
 407         out.defaultWriteObject();
 408 
 409         cache = null;
 410     }
 411 
 412     private float handleCharWidth(int ch) {
 413         return fontStrike.getCodePointAdvance(ch); // x-component of result only
 414     }
 415 
 416     // Uses advCache to get character width
 417     // It is incorrect to call this method for ch > 255
 418     private float getLatinCharWidth(char ch) {
 419 
 420         float w = advCache[ch];
 421         if (w == UNKNOWN_WIDTH) {
 422             w = handleCharWidth(ch);
 423             advCache[ch] = w;
 424         }
 425         return w;
 426     }
 427 
 428 
 429     /* Override of FontMetrics.getFontRenderContext() */
 430     public FontRenderContext getFontRenderContext() {
 431         return frc;
 432     }
 433 
 434     public int charWidth(char ch) {
 435         // default metrics for compatibility with legacy code
 436         float w;
 437         if (ch < 0x100) {
 438             w = getLatinCharWidth(ch);
 439         }
 440         else {
 441             w = handleCharWidth(ch);
 442         }
 443         return (int)(0.5 + w);
 444     }
 445 
 446     public int charWidth(int ch) {
 447         if (!Character.isValidCodePoint(ch)) {
 448             ch = 0xffff;
 449         }
 450 
 451         float w = handleCharWidth(ch);
 452 
 453         return (int)(0.5 + w);
 454     }
 455 
 456     public int stringWidth(String str) {
 457 
 458         float width = 0;
 459         if (font.hasLayoutAttributes()) {
 460             /* TextLayout throws IAE for null, so throw NPE explicitly */
 461             if (str == null) {
 462                 throw new NullPointerException("str is null");
 463             }
 464             if (str.length() == 0) {
 465                 return 0;
 466             }
 467             width = new TextLayout(str, font, frc).getAdvance();
 468         } else {
 469             int length = str.length();
 470             for (int i=0; i < length; i++) {
 471                 char ch = str.charAt(i);
 472                 if (ch < 0x100) {
 473                     width += getLatinCharWidth(ch);
 474                 } else if (FontUtilities.isNonSimpleChar(ch)) {
 475                     width = new TextLayout(str, font, frc).getAdvance();
 476                     break;
 477                 } else {
 478                     width += handleCharWidth(ch);
 479                 }
 480             }
 481         }
 482 
 483         return (int) (0.5 + width);
 484     }
 485 
 486     public int charsWidth(char[] data, int off, int len) {
 487 
 488         float width = 0;
 489         if (font.hasLayoutAttributes()) {
 490             if (len == 0) {
 491                 return 0;
 492             }
 493             String str = new String(data, off, len);
 494             width = new TextLayout(str, font, frc).getAdvance();
 495         } else {
 496             /* Explicit test needed to satisfy superclass spec */
 497             if (len < 0) {
 498                 throw new IndexOutOfBoundsException("len="+len);
 499             }
 500             int limit = off + len;
 501             for (int i=off; i < limit; i++) {
 502                 char ch = data[i];
 503                 if (ch < 0x100) {
 504                     width += getLatinCharWidth(ch);
 505                 } else if (FontUtilities.isNonSimpleChar(ch)) {
 506                     String str = new String(data, off, len);
 507                     width = new TextLayout(str, font, frc).getAdvance();
 508                     break;
 509                 } else {
 510                     width += handleCharWidth(ch);
 511                 }
 512             }
 513         }
 514 
 515         return (int) (0.5 + width);
 516     }
 517 
 518     /**
 519      * This method is called from java.awt.Font only after verifying
 520      * the arguments and that the text is simple and there are no
 521      * layout attributes, font transform etc.
 522      */
 523     public Rectangle2D getSimpleBounds(char[] data, int off, int len) {
 524 
 525         float width = 0;
 526         int limit = off + len;
 527         for (int i=off; i < limit; i++) {
 528             char ch = data[i];
 529             if (ch < 0x100) {
 530                 width += getLatinCharWidth(ch);
 531             } else {
 532                 width += handleCharWidth(ch);
 533             }
 534         }
 535 
 536         float height = ascent + descent + leading;
 537         return new Rectangle2D.Float(0f, -ascent, width, height);
 538      }
 539 
 540     /**
 541      * Gets the advance widths of the first 256 characters in the
 542      * {@code Font}.  The advance is the
 543      * distance from the leftmost point to the rightmost point on the
 544      * character's baseline.  Note that the advance of a
 545      * {@code String} is not necessarily the sum of the advances
 546      * of its characters.
 547      * @return    an array storing the advance widths of the
 548      *                 characters in the {@code Font}
 549      *                 described by this {@code FontMetrics} object.
 550      */
 551     // More efficient than base class implementation - reuses existing cache
 552     public int[] getWidths() {
 553         int[] widths = new int[256];
 554         for (char ch = 0 ; ch < 256 ; ch++) {
 555             float w = advCache[ch];
 556             if (w == UNKNOWN_WIDTH) {
 557                 w = advCache[ch] = handleCharWidth(ch);
 558             }
 559             widths[ch] = (int) (0.5 + w);
 560         }
 561         return widths;
 562     }
 563 
 564     public int getMaxAdvance() {
 565         return (int)(0.99f + this.maxAdvance);
 566     }
 567 
 568   /*
 569    * Returns the typographic ascent of the font. This is the maximum distance
 570    * glyphs in this font extend above the base line (measured in typographic
 571    * units).
 572    */
 573     public int getAscent() {
 574         return (int)(roundingUpValue + this.ascent);
 575     }
 576 
 577   /*
 578    * Returns the typographic descent of the font. This is the maximum distance
 579    * glyphs in this font extend below the base line.
 580    */
 581     public int getDescent() {
 582         return (int)(roundingUpValue + this.descent);
 583     }
 584 
 585     public int getLeading() {
 586         // nb this ensures the sum of the results of the public methods
 587         // for leading, ascent & descent sum to height.
 588         // if the calculations in any other methods change this needs
 589         // to be changed too.
 590         // the 0.95 value used here and in the other methods allows some
 591         // tiny fraction of leeway before rouding up. A higher value (0.99)
 592         // caused some excessive rounding up.
 593         return
 594             (int)(roundingUpValue + descent + leading) -
 595             (int)(roundingUpValue + descent);
 596     }
 597 
 598     // height is calculated as the sum of two separately rounded up values
 599     // because typically clients use ascent to determine the y location to
 600     // pass to drawString etc and we need to ensure that the height has enough
 601     // space below the baseline to fully contain any descender.
 602     public int getHeight() {
 603 
 604         if (height < 0) {
 605             height = getAscent() + (int)(roundingUpValue + descent + leading);
 606         }
 607         return height;
 608     }
 609 }
--- EOF ---