/*

 * Copyright (c) 2007, 2014, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package sun.font;

import java.awt.geom.GeneralPath;

import java.awt.geom.Point2D;

import java.awt.geom.Rectangle2D;

import java.lang.ref.WeakReference;

import java.lang.reflect.Constructor;

import sun.java2d.Disposer;

import sun.java2d.DisposerRecord;

/* FontScaler is "internal interface" to font rasterizer library.

 *

 * Access to native rasterizers without going through this interface is

 * strongly discouraged. In particular, this is important because native

 * data could be disposed due to runtime font processing error at any time.

 *

 * FontScaler represents combination of particular rasterizer implementation

 * and particular font. It does not include rasterization attributes such as

 * transform. These attributes are part of native scalerContext object.

 * This approach allows to share same scaler for different requests related

 * to the same font file.

 *

 * Note that scaler may throw FontScalerException on any operation.

 * Generally this means that runtime error had happened and scaler is not

 * usable.  Subsequent calls to this scaler should not cause crash but will

 * likely cause exceptions to be thrown again.

 *

 * It is recommended that callee should replace its reference to the scaler

 * with something else. For instance it could be FontManager.getNullScaler().

 * Note that NullScaler is trivial and will not actually rasterize anything.

 *

 * Alternatively, callee can use more sophisticated error recovery strategies

 * and for instance try to substitute failed scaler with new scaler instance

 * using another font.

 *

 * Note that in case of error there is no need to call dispose(). Moreover,

 * dispose() generally is called by Disposer thread and explicit calls to

 * dispose might have unexpected sideeffects because scaler can be shared.

 *

 * Current disposing logic is the following:

 *   - scaler is registered in the Disposer by the FontManager (on creation)

 *   - scalers are disposed when associated Font2D object (e.g. TruetypeFont)

 *     is garbage collected. That's why this object implements DisposerRecord

 *     interface directly (as it is not used as indicator when it is safe

 *     to release native state) and that's why we have to use WeakReference

 *     to Font internally.

 *   - Majority of Font2D objects are linked from various mapping arrays

 *     (e.g. FontManager.localeFullNamesToFont). So, they are not collected.

 *     This logic only works for fonts created with Font.createFont()

 *

 *  Notes:

 *   - Eventually we may consider releasing some of the scaler resources if

 *     it was not used for a while but we do not want to be too aggressive on

 *     this (and this is probably more important for Type1 fonts).

 */

public abstract class FontScaler implements DisposerRecord {

    private static FontScaler nullScaler = null;

    private static Constructor<? extends FontScaler> scalerConstructor = null;

    //Find preferred font scaler

    //

    //NB: we can allow property based preferences

    //   (theoretically logic can be font type specific)

    static {

        Class<? extends FontScaler> scalerClass = null;

        Class<?>[] arglst = new Class<?>[] {Font2D.class, int.class,

        boolean.class, int.class};

        try {

            @SuppressWarnings("unchecked")

            Class<? extends FontScaler> tmp = (Class<? extends FontScaler>)

                 Class.forName("sun.font.FreetypeFontScaler") :

                 Class.forName("sun.font.T2KFontScaler"));

            scalerClass = tmp;

        } catch (ClassNotFoundException e) {

                scalerClass = NullFontScaler.class;

        }

        //NB: rewrite using factory? constructor is ugly way

        try {

            scalerConstructor = scalerClass.getConstructor(arglst);

        } catch (NoSuchMethodException e) {

            //should not happen

        }

    }

    /* This is the only place to instantiate new FontScaler.

     * Therefore this is very convinient place to register

     * scaler with Disposer as well as trigger deregistring bad font

     * in case when scaler reports this.

     */

    public static FontScaler getScaler(Font2D font,

                                int indexInCollection,

                                boolean supportsCJK,

                                int filesize) {

        FontScaler scaler = null;

        try {

            Object args[] = new Object[] {font, indexInCollection,

                                          supportsCJK, filesize};

            scaler = scalerConstructor.newInstance(args);

            Disposer.addObjectRecord(font, scaler);

        } catch (Throwable e) {

            scaler = nullScaler;

            //if we can not instantiate scaler assume bad font

            //NB: technically it could be also because of internal scaler

            //    error but here we are assuming scaler is ok.

            FontManager fm = FontManagerFactory.getInstance();

            fm.deRegisterBadFont(font);

        }

        return scaler;

    }

    /*

     * At the moment it is harmless to create 2 null scalers so, technically,

     * syncronized keyword is not needed.

     *

     * But it is safer to keep it to avoid subtle problems if we will be adding

     * checks like whether scaler is null scaler.

     */

    public static synchronized FontScaler getNullScaler() {

        if (nullScaler == null) {

            nullScaler = new NullFontScaler();

        }

        return nullScaler;

    }

    protected WeakReference<Font2D> font = null;

    protected long nativeScaler = 0; //used by decendants

                                     //that have native state

    protected boolean disposed = false;

    abstract StrikeMetrics getFontMetrics(long pScalerContext)

                throws FontScalerException;

    abstract float getGlyphAdvance(long pScalerContext, int glyphCode)

                throws FontScalerException;

    abstract void getGlyphMetrics(long pScalerContext, int glyphCode,

                                  Point2D.Float metrics)

                throws FontScalerException;

    /*

     *  Returns pointer to native GlyphInfo object.

     *  Callee is responsible for freeing this memory.

     *

     *  Note:

     *   currently this method has to return not 0L but pointer to valid

     *   GlyphInfo object. Because Strike and drawing releated logic does

     *   expect that.

     *   In the future we may want to rework this to allow 0L here.

     */

    abstract long getGlyphImage(long pScalerContext, int glyphCode)

                throws FontScalerException;

    abstract Rectangle2D.Float getGlyphOutlineBounds(long pContext,

                                                     int glyphCode)

                throws FontScalerException;

    abstract GeneralPath getGlyphOutline(long pScalerContext, int glyphCode,

                                         float x, float y)

                throws FontScalerException;

    abstract GeneralPath getGlyphVectorOutline(long pScalerContext, int[] glyphs,

                                               int numGlyphs, float x, float y)

                throws FontScalerException;

    /* Used by Java2D disposer to ensure native resources are released.

       Note: this method does not release any of created

             scaler context objects! */

    public void dispose() {}

    /* At the moment these 3 methods are needed for Type1 fonts only.

     * For Truetype fonts we extract required info outside of scaler

     * on java layer.

     */

    abstract int getNumGlyphs() throws FontScalerException;

    abstract int getMissingGlyphCode() throws FontScalerException;

    abstract int getGlyphCode(char charCode) throws FontScalerException;

    /* This method returns table cache used by native layout engine.

     * This cache is essentially just small collection of

     * pointers to various truetype tables. See definition of TTLayoutTableCache

     * in the fontscalerdefs.h for more details.

     *

     * Note that tables themselves have same format as defined in the truetype

     * specification, i.e. font scaler do not need to perform any preprocessing.

     *

     * Probably it is better to have API to request pointers to each table

     * separately instead of requesting pointer to some native structure.

     * (then there is not need to share its definition by different

     * implementations of scaler).

     * However, this means multiple JNI calls and potential impact on performance.

     *

     * Note: return value 0 is legal.

     *   This means tables are not available (e.g. type1 font).

     */

    abstract long getLayoutTableCache() throws FontScalerException;

    /* Used by the OpenType engine for mark positioning. */

    abstract Point2D.Float getGlyphPoint(long pScalerContext,

                                int glyphCode, int ptNumber)

        throws FontScalerException;

    abstract long getUnitsPerEm();

    /* Returns pointer to native structure describing rasterization attributes.

       Format of this structure is scaler-specific.

       Callee is responsible for freeing scaler context (using free()).

       Note:

         Context is tightly associated with strike and it is actually

        freed when corresponding strike is being released.

     */

    abstract long createScalerContext(double[] matrix,

                                      int aa, int fm,

                                      float boldness, float italic,

                                      boolean disableHinting);

    /* Marks context as invalid because native scaler is invalid.

       Notes:

         - pointer itself is still valid and has to be released

         - if pointer to native scaler was cached it

           should not be neither disposed nor used.

           it is very likely it is already disposed by this moment. */

    abstract void invalidateScalerContext(long ppScalerContext);

}