package com.keypoint;import java.awt.Image;import java.awt.image.BufferedImage;import java.awt.image.DataBuffer;import java.awt.image.IndexColorModel;import java.awt.image.ImageObserver;import java.awt.image.PixelGrabber;import java.awt.image.WritableRaster;import java.io.ByteArrayOutputStream;import java.io.IOException;import java.util.zip.CRC32;import java.util.zip.Deflater;import java.util.zip.DeflaterOutputStream;/** * PngEncoderB takes a Java BufferedImage object and creates a byte string which can be saved as a PNG file. * The encoder will accept BufferedImages with eight-bit samples * or 4-byte ARGB samples.  *  * <p>There is also code to handle 4-byte samples returned as * one int per pixel, but that has not been tested.</p> * * <p>Thanks to Jay Denny at KeyPoint Software *    <code>http://www.keypoint.com/</code> * who let me develop this code on company time.</p> * * <p>You may contact me with (probably very-much-needed) improvements, * comments, and bug fixes at:</p> * *   <p><code>david@catcode.com</code></p> * * <p>This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version.<p> *  * <p>This library 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 * Lesser General Public License for more details.</p> *  * <p>You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA * A copy of the GNU LGPL may be found at * <code>http://www.gnu.org/copyleft/lesser.html</code></p> * * @author J. David Eisenberg * @version 1.5, 19 Oct 2003 * * CHANGES: * -------- * 19-Sep-2003 : Fix for platforms using EBCDIC (contributed by Paulo Soares); * 19-Oct-2003 : Change private fields to protected fields so that *               PngEncoderB can inherit them (JDE) *				 Fixed bug with calculation of nRows *				 Added modifications for unsigned short images *					(contributed by Christian at xpogen.com)  */public class PngEncoderB extends PngEncoder {	/** PLTE tag. */	private static final byte PLTE[] = { 80, 76, 84, 69 };    protected BufferedImage image;    protected WritableRaster wRaster;    protected int tType;    /**     * Class constructor     *     */    public PngEncoderB()    {        this( null, false, FILTER_NONE, 0 );    }    /**     * Class constructor specifying BufferedImage to encode, with no alpha channel encoding.     *     * @param image A Java BufferedImage object     */    public PngEncoderB( BufferedImage image )    {        this(image, false, FILTER_NONE, 0);    }    /**     * Class constructor specifying BufferedImage to encode, and whether to encode alpha.     *     * @param image A Java BufferedImage object     * @param encodeAlpha Encode the alpha channel? false=no; true=yes     */    public PngEncoderB( BufferedImage image, boolean encodeAlpha )    {        this( image, encodeAlpha, FILTER_NONE, 0 );    }    /**     * Class constructor specifying BufferedImage to encode, whether to encode alpha, and filter to use.     *     * @param image A Java BufferedImage object     * @param encodeAlpha Encode the alpha channel? false=no; true=yes     * @param whichFilter 0=none, 1=sub, 2=up     */    public PngEncoderB( BufferedImage image, boolean encodeAlpha,       int whichFilter )    {        this( image, encodeAlpha, whichFilter, 0 );    }    /**     * Class constructor specifying BufferedImage source to encode, whether to encode alpha, filter to use, and compression level     *     * @param image A Java BufferedImage object     * @param encodeAlpha Encode the alpha channel? false=no; true=yes     * @param whichFilter 0=none, 1=sub, 2=up     * @param compLevel 0..9     */    public PngEncoderB( BufferedImage image, boolean encodeAlpha,      int whichFilter, int compLevel )    {        this.image = image;        this.encodeAlpha = encodeAlpha;        setFilter( whichFilter );        if (compLevel >=0 && compLevel <=9)        {            this.compressionLevel = compLevel;        }    }    /**     * Set the BufferedImage to be encoded     *     * @param BufferedImage A Java BufferedImage object     */    public void setImage( BufferedImage image )    {        this.image = image;        pngBytes = null;    }    /**     * Creates an array of bytes that is the PNG equivalent of the current image, specifying whether to encode alpha or not.     *     * @param encodeAlpha boolean false=no alpha, true=encode alpha     * @return an array of bytes, or null if there was a problem     */    public byte[] pngEncode( boolean encodeAlpha )    {        byte[]  pngIdBytes = { -119, 80, 78, 71, 13, 10, 26, 10 };        int     i;        if (image == null)        {            System.err.println("pngEncode: image is null; returning null");			return null;        }        width = image.getWidth( null );        height = image.getHeight( null );        this.image = image;        if (!establishStorageInfo())        {			System.err.println("pngEncode: cannot establish storage info");            return null;        }                /*         * start with an array that is big enough to hold all the pixels         * (plus filter bytes), and an extra 200 bytes for header info         */        pngBytes = new byte[((width+1) * height * 3) + 200];        /*         * keep track of largest byte written to the array         */        maxPos = 0;        bytePos = writeBytes( pngIdBytes, 0 ); //       hdrPos = bytePos;        writeHeader();//        dataPos = bytePos;        if (writeImageData())        {            writeEnd();            pngBytes = resizeByteArray( pngBytes, maxPos );        }        else        {			System.err.println("pngEncode: writeImageData failed => null");            pngBytes = null;        }        return pngBytes;    }    /**     * Creates an array of bytes that is the PNG equivalent of the current image.     * Alpha encoding is determined by its setting in the constructor.     *     * @return an array of bytes, or null if there was a problem     */    public byte[] pngEncode()    {        return pngEncode( encodeAlpha );    }    /**     *      * Get and set variables that determine how picture is stored.     *     * Retrieves the writable raster of the buffered image,     * as well its transfer type.     *     * Sets number of output bytes per pixel, and, if only     * eight-bit bytes, turns off alpha encoding.     * @return true if 1-byte or 4-byte data, false otherwise     */    protected boolean establishStorageInfo()    {        int dataBytes;            wRaster = image.getRaster();        dataBytes = wRaster.getNumDataElements();        tType = wRaster.getTransferType();		if (((tType == DataBuffer.TYPE_BYTE  ) && (dataBytes == 4)) ||			((tType == DataBuffer.TYPE_INT   ) && (dataBytes == 1)) ||           // on Win 2k/ME, tType == 1, dataBytes == 1			((tType == DataBuffer.TYPE_USHORT) && (dataBytes == 1)) )        {            bytesPerPixel = (encodeAlpha) ? 4 : 3;        }        else if ((tType == DataBuffer.TYPE_BYTE) && (dataBytes == 1))        {            bytesPerPixel = 1;            encodeAlpha = false;    // one-byte samples        }        else		{			System.err.println("PNG encoder cannot establish storage info:");			System.err.println("  TransferType == " + tType );			System.err.println("  NumDataElements == " + dataBytes);			return false;		}        return true;    }    /**     * Write a PNG "IHDR" chunk into the pngBytes array.     */