Java example source code file (JPEGImageDecoder.java)

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Java - Java tags/keywords

argbcolormodel, awt, colormodel, directcolormodel, graycolormodel, hashtable, image, imageformatexception, indexcolormodel, inputstreamclass, ioexception, jpegimagedecoder, rgbcolormodel, util, void

The JPEGImageDecoder.java Java example source code

/*
 * Copyright (c) 1995, 2012, 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.
 */
/*-
 *      Reads JPEG images from an InputStream and reports the
 *      image data to an InputStreamImageSource object.
 *
 * The native implementation of the JPEG image decoder was adapted from
 * release 6 of the free JPEG software from the Independent JPEG Group.
 */
package sun.awt.image;

import java.util.Vector;
import java.util.Hashtable;
import java.io.InputStream;
import java.io.IOException;
import java.awt.image.*;

/**
 * JPEG Image converter
 *
 * @author Jim Graham
 */
public class JPEGImageDecoder extends ImageDecoder {
    private static ColorModel RGBcolormodel;
    private static ColorModel ARGBcolormodel;
    private static ColorModel Graycolormodel;

    private static final Class InputStreamClass = InputStream.class;
    private static native void initIDs(Class InputStreamClass);

    private ColorModel colormodel;

    static {
        java.security.AccessController.doPrivileged(
            new java.security.PrivilegedAction<Void>() {
                public Void run() {
                    System.loadLibrary("jpeg");
                    return null;
                }
            });
        initIDs(InputStreamClass);
        RGBcolormodel = new DirectColorModel(24, 0xff0000, 0xff00, 0xff);
        ARGBcolormodel = ColorModel.getRGBdefault();
        byte g[] = new byte[256];
        for (int i = 0; i < 256; i++) {
            g[i] = (byte) i;
        }
        Graycolormodel = new IndexColorModel(8, 256, g, g, g);
    }

    private native void readImage(InputStream is, byte buf[])
        throws ImageFormatException, IOException;

    Hashtable props = new Hashtable();

    public JPEGImageDecoder(InputStreamImageSource src, InputStream is) {
        super(src, is);
    }

    /**
     * An error has occurred. Throw an exception.
     */
    private static void error(String s1) throws ImageFormatException {
        throw new ImageFormatException(s1);
    }

    public boolean sendHeaderInfo(int width, int height,
                                  boolean gray, boolean hasalpha,
                                  boolean multipass)
    {
        setDimensions(width, height);

        setProperties(props);
        if (gray) {
            colormodel = Graycolormodel;
        } else {
            if (hasalpha) {
                colormodel = ARGBcolormodel;
            } else {
                colormodel = RGBcolormodel;
            }
        }

        setColorModel(colormodel);

        int flags = hintflags;
        if (!multipass) {
            flags |= ImageConsumer.SINGLEPASS;
        }
        setHints(hintflags);
        headerComplete();

        return true;
    }

    public boolean sendPixels(int pixels[], int y) {
        int count = setPixels(0, y, pixels.length, 1, colormodel,
                              pixels, 0, pixels.length);
        if (count <= 0) {
            aborted = true;
        }
        return !aborted;
    }

    public boolean sendPixels(byte pixels[], int y) {
        int count = setPixels(0, y, pixels.length, 1, colormodel,
                              pixels, 0, pixels.length);
        if (count <= 0) {
            aborted = true;
        }
        return !aborted;
    }

    /**
     * produce an image from the stream.
     */
    public void produceImage() throws IOException, ImageFormatException {
        try {
            readImage(input, new byte[1024]);
            if (!aborted) {
                imageComplete(ImageConsumer.STATICIMAGEDONE, true);
            }
        } catch (IOException e) {
            if (!aborted) {
                throw e;
            }
        } finally {
            close();
        }
    }

    /**
     * The ImageConsumer hints flag for a JPEG image.
     */
    private static final int hintflags =
        ImageConsumer.TOPDOWNLEFTRIGHT | ImageConsumer.COMPLETESCANLINES |
        ImageConsumer.SINGLEFRAME;
}