1 /*
   2  * Copyright (c) 2007, 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.geom.GeneralPath;
  29 import java.awt.geom.Point2D;
  30 import java.awt.geom.Rectangle2D;
  31 import java.lang.ref.WeakReference;
  32 import java.lang.reflect.Constructor;
  33 
  34 import sun.java2d.Disposer;
  35 import sun.java2d.DisposerRecord;
  36 
  37 /* FontScaler is "internal interface" to font rasterizer library.
  38  *
  39  * Access to native rasterizers without going through this interface is
  40  * strongly discouraged. In particular, this is important because native
  41  * data could be disposed due to runtime font processing error at any time.
  42  *
  43  * FontScaler represents combination of particular rasterizer implementation
  44  * and particular font. It does not include rasterization attributes such as
  45  * transform. These attributes are part of native scalerContext object.
  46  * This approach allows to share same scaler for different requests related
  47  * to the same font file.
  48  *
  49  * Note that scaler may throw FontScalerException on any operation.
  50  * Generally this means that runtime error had happened and scaler is not
  51  * usable.  Subsequent calls to this scaler should not cause crash but will
  52  * likely cause exceptions to be thrown again.
  53  *
  54  * It is recommended that callee should replace its reference to the scaler
  55  * with something else. For instance it could be FontManager.getNullScaler().
  56  * Note that NullScaler is trivial and will not actually rasterize anything.
  57  *
  58  * Alternatively, callee can use more sophisticated error recovery strategies
  59  * and for instance try to substitute failed scaler with new scaler instance
  60  * using another font.
  61  *
  62  * Note that in case of error there is no need to call dispose(). Moreover,
  63  * dispose() generally is called by Disposer thread and explicit calls to
  64  * dispose might have unexpected sideeffects because scaler can be shared.
  65  *
  66  * Current disposing logic is the following:
  67  *   - scaler is registered in the Disposer by the FontManager (on creation)
  68  *   - scalers are disposed when associated Font2D object (e.g. TruetypeFont)
  69  *     is garbage collected. That's why this object implements DisposerRecord
  70  *     interface directly (as it is not used as indicator when it is safe
  71  *     to release native state) and that's why we have to use WeakReference
  72  *     to Font internally.
  73  *   - Majority of Font2D objects are linked from various mapping arrays
  74  *     (e.g. FontManager.localeFullNamesToFont). So, they are not collected.
  75  *     This logic only works for fonts created with Font.createFont()
  76  *
  77  *  Notes:
  78  *   - Eventually we may consider releasing some of the scaler resources if
  79  *     it was not used for a while but we do not want to be too aggressive on
  80  *     this (and this is probably more important for Type1 fonts).
  81  */
  82 public abstract class FontScaler implements DisposerRecord {
  83 
  84     private static FontScaler nullScaler = null;
  85     private static Constructor<FontScaler> scalerConstructor = null;
  86 
  87     //Find preferred font scaler
  88     //
  89     //NB: we can allow property based preferences
  90     //   (theoretically logic can be font type specific)
  91     static {
  92         Class scalerClass = null;
  93         Class arglst[] = new Class[] {Font2D.class, int.class,
  94         boolean.class, int.class};
  95 
  96         try {
  97             if (FontUtilities.isOpenJDK) {
  98                 scalerClass = Class.forName("sun.font.FreetypeFontScaler");
  99             } else {
 100                 scalerClass = Class.forName("sun.font.T2KFontScaler");
 101             }
 102         } catch (ClassNotFoundException e) {
 103                 scalerClass = NullFontScaler.class;
 104         }
 105 
 106         //NB: rewrite using factory? constructor is ugly way
 107         try {
 108             scalerConstructor = scalerClass.getConstructor(arglst);
 109         } catch (NoSuchMethodException e) {
 110             //should not happen
 111         }
 112     }
 113 
 114     /* This is the only place to instantiate new FontScaler.
 115      * Therefore this is very convinient place to register
 116      * scaler with Disposer as well as trigger deregistring bad font
 117      * in case when scaler reports this.
 118      */
 119     public static FontScaler getScaler(Font2D font,
 120                                 int indexInCollection,
 121                                 boolean supportsCJK,
 122                                 int filesize) {
 123         FontScaler scaler = null;
 124 
 125         try {
 126             Object args[] = new Object[] {font, indexInCollection,
 127                                           supportsCJK, filesize};
 128             scaler = scalerConstructor.newInstance(args);
 129             Disposer.addObjectRecord(font, scaler);
 130         } catch (Throwable e) {
 131             scaler = nullScaler;
 132 
 133             //if we can not instantiate scaler assume bad font
 134             //NB: technically it could be also because of internal scaler
 135             //    error but here we are assuming scaler is ok.
 136             FontManager fm = FontManagerFactory.getInstance();
 137             fm.deRegisterBadFont(font);
 138         }
 139         return scaler;
 140     }
 141 
 142     /*
 143      * At the moment it is harmless to create 2 null scalers so, technically,
 144      * syncronized keyword is not needed.
 145      *
 146      * But it is safer to keep it to avoid subtle problems if we will be adding
 147      * checks like whether scaler is null scaler.
 148      */
 149     public static synchronized FontScaler getNullScaler() {
 150         if (nullScaler == null) {
 151             nullScaler = new NullFontScaler();
 152         }
 153         return nullScaler;
 154     }
 155 
 156     protected WeakReference<Font2D> font = null;
 157     protected long nativeScaler = 0; //used by decendants
 158                                      //that have native state
 159     protected boolean disposed = false;
 160 
 161     abstract StrikeMetrics getFontMetrics(long pScalerContext)
 162                 throws FontScalerException;
 163 
 164     abstract float getGlyphAdvance(long pScalerContext, int glyphCode)
 165                 throws FontScalerException;
 166 
 167     abstract void getGlyphMetrics(long pScalerContext, int glyphCode,
 168                                   Point2D.Float metrics)
 169                 throws FontScalerException;
 170 
 171     /*
 172      *  Returns pointer to native GlyphInfo object.
 173      *  Callee is responsible for freeing this memory.
 174      *
 175      *  Note:
 176      *   currently this method has to return not 0L but pointer to valid
 177      *   GlyphInfo object. Because Strike and drawing releated logic does
 178      *   expect that.
 179      *   In the future we may want to rework this to allow 0L here.
 180      */
 181     abstract long getGlyphImage(long pScalerContext, int glyphCode)
 182                 throws FontScalerException;
 183 
 184     abstract Rectangle2D.Float getGlyphOutlineBounds(long pContext,
 185                                                      int glyphCode)
 186                 throws FontScalerException;
 187 
 188     abstract GeneralPath getGlyphOutline(long pScalerContext, int glyphCode,
 189                                          float x, float y)
 190                 throws FontScalerException;
 191 
 192     abstract GeneralPath getGlyphVectorOutline(long pScalerContext, int[] glyphs,
 193                                                int numGlyphs, float x, float y)
 194                 throws FontScalerException;
 195 
 196     /* Used by Java2D disposer to ensure native resources are released.
 197        Note: this method does not release any of created
 198              scaler context objects! */
 199     public void dispose() {}
 200 
 201     /* At the moment these 3 methods are needed for Type1 fonts only.
 202      * For Truetype fonts we extract required info outside of scaler
 203      * on java layer.
 204      */
 205     abstract int getNumGlyphs() throws FontScalerException;
 206     abstract int getMissingGlyphCode() throws FontScalerException;
 207     abstract int getGlyphCode(char charCode) throws FontScalerException;
 208 
 209     /* This method returns table cache used by native layout engine.
 210      * This cache is essentially just small collection of
 211      * pointers to various truetype tables. See definition of TTLayoutTableCache
 212      * in the fontscalerdefs.h for more details.
 213      *
 214      * Note that tables themselves have same format as defined in the truetype
 215      * specification, i.e. font scaler do not need to perform any preprocessing.
 216      *
 217      * Probably it is better to have API to request pointers to each table
 218      * separately instead of requesting pointer to some native structure.
 219      * (then there is not need to share its definition by different
 220      * implementations of scaler).
 221      * However, this means multiple JNI calls and potential impact on performance.
 222      *
 223      * Note: return value 0 is legal.
 224      *   This means tables are not available (e.g. type1 font).
 225      */
 226     abstract long getLayoutTableCache() throws FontScalerException;
 227 
 228     /* Used by the OpenType engine for mark positioning. */
 229     abstract Point2D.Float getGlyphPoint(long pScalerContext,
 230                                 int glyphCode, int ptNumber)
 231         throws FontScalerException;
 232 
 233     abstract long getUnitsPerEm();
 234 
 235     /* Returns pointer to native structure describing rasterization attributes.
 236        Format of this structure is scaler-specific.
 237 
 238        Callee is responsible for freeing scaler context (using free()).
 239 
 240        Note:
 241          Context is tightly associated with strike and it is actually
 242         freed when corresponding strike is being released.
 243      */
 244     abstract long createScalerContext(double[] matrix,
 245                                       boolean fontType,
 246                                       int aa, int fm,
 247                                       float boldness, float italic,
 248                                       boolean disableHinting);
 249 
 250     /* Marks context as invalid because native scaler is invalid.
 251        Notes:
 252          - pointer itself is still valid and has to be released
 253          - if pointer to native scaler was cached it
 254            should not be neither disposed nor used.
 255            it is very likely it is already disposed by this moment. */
 256     abstract void invalidateScalerContext(long ppScalerContext);
 257 }