src/java.desktop/unix/classes/sun/font/NativeStrikeDisposer.java

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
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package sun.font;

/*
 * This keeps track of data that needs to be cleaned up once a
 * strike is freed.
 * a) The native memory that is the glyph image cache.
 * b) removing the "desc" key from the strike's map.
 * This is safe to do because this disposer is invoked only when the
 * reference object has been cleared, which means the value indexed by
 * this key is just an empty reference object.
 * It is possible that a new FontStrike has been created that would
 * be referenced by the same (equals) key. If it is placed in the map
 * before this disposer is executed, then we do not want to remove that
 * object. We should only remove an object where the value is null.
 * So we first verify that the key still points to a cleared reference.
 * Updates to the map thus need to be synchronized.
 *
 * A WeakHashmap will automatically clean up, but we might maintain a
 * reference to the "desc" key in the FontStrike (value) which would
 * prevent the keys from being discarded. And since the strike is the only
 * place is likely we would maintain such a strong reference, then the map
 * entries would be removed much more promptly than we need.
 */

final class NativeStrikeDisposer extends FontStrikeDisposer {

    long pNativeScalerContext;

    public NativeStrikeDisposer(Font2D font2D, FontStrikeDesc desc,
                              long pContext, int[] images) {
        super(font2D, desc, 0L, images);
        pNativeScalerContext = pContext;
    }

    public NativeStrikeDisposer(Font2D font2D, FontStrikeDesc desc,
                              long pContext, long[] images) {
        super(font2D, desc, 0L, images);
        pNativeScalerContext = pContext;
    }

    public NativeStrikeDisposer(Font2D font2D, FontStrikeDesc desc,
                              long pContext) {
        super(font2D, desc, 0L);
        pNativeScalerContext = pContext;
    }

    public NativeStrikeDisposer(Font2D font2D, FontStrikeDesc desc) {
        super(font2D, desc);
    }

    @Override
    public synchronized void dispose() {
        if (!disposed) {
            if (pNativeScalerContext != 0L) {
                freeNativeScalerContext(pNativeScalerContext);
            }
            super.dispose();
        }
    }

    private native void freeNativeScalerContext(long pContext);
}