package org.freehep.graphicsio.png;

//package com.keypoint;

/**
 * PngEncoder takes a Java Image object and creates a byte string which can be saved as a PNG file.
 * The Image is presumed to use the DirectColorModel.
 *
 * Thanks to Jay Denny at KeyPoint Software
 *    http://www.keypoint.com/
 * who let me develop this code on company time.
 *
 * You may contact me with (probably very-much-needed) improvements,
 * comments, and bug fixes at:
 *
 *   david@catcode.com
 *
 * 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.
 *
 * 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.
 *
 * 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
 * http://www.gnu.org/copyleft/lesser.html,
 *
 * @author J. David Eisenberg
 * @version 1.4, 31 March 2000
 */

/**
 * Added ImageObserver so that getHeight, getWidth calls work properly.
 *
 * @author M.Donszelmann
 */

import java.awt.Image;
import java.awt.Toolkit;
import java.awt.image.ImageObserver;
import java.awt.image.PixelGrabber;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.zip.CRC32;
import java.util.zip.Deflater;
import java.util.zip.DeflaterOutputStream;

public class PNGEncoder extends Object implements ImageObserver {
    /** Constant specifying that alpha channel should be encoded. */
    public static final boolean ENCODE_ALPHA = true;

    /** Constant specifying that alpha channel should not be encoded. */
    public static final boolean NO_ALPHA = false;

    /** Constants for filters */
    public static final int FILTER_NONE = 0;

    public static final int FILTER_SUB = 1;

    public static final int FILTER_UP = 2;

    public static final int FILTER_LAST = 2;

    protected byte[] pngBytes;

    protected byte[] priorRow;

    protected byte[] leftBytes;

    protected Image image;

    protected int width, height;

    protected int bytePos, maxPos;

    protected int hdrPos, dataPos, endPos;

    protected CRC32 crc = new CRC32();

    protected long crcValue;

    protected boolean encodeAlpha;

    protected int filter;

    protected int bytesPerPixel;

    protected int compressionLevel;

    protected List<String> keys = new ArrayList<String>();

    protected List<String> text = new ArrayList<String>();

    public PNGEncoder() {
        this(null, false, FILTER_NONE, 0);
    }

    /**
     * Class constructor specifying Image to encode, with no alpha channel
     * encoding.
     * 
     * @param image A Java Image object which uses the DirectColorModel
     * @see java.awt.Image
     */
    public PNGEncoder(Image image) {
        this(image, false, FILTER_NONE, 0);
    }

    /**
     * Class constructor specifying Image to encode, and whether to encode
     * alpha.
     * 
     * @param image A Java Image object which uses the DirectColorModel
     * @param encodeAlpha Encode the alpha channel? false=no; true=yes
     * @see java.awt.Image
     */
    public PNGEncoder(Image image, boolean encodeAlpha) {
        this(image, encodeAlpha, FILTER_NONE, 0);
    }

    /**
     * Class constructor specifying Image to encode, whether to encode alpha,
     * and filter to use.
     * 
     * @param image A Java Image object which uses the DirectColorModel
     * @param encodeAlpha Encode the alpha channel? false=no; true=yes
     * @param whichFilter 0=none, 1=sub, 2=up
     * @see java.awt.Image
     */
    public PNGEncoder(Image image, boolean encodeAlpha, int whichFilter) {
        this(image, encodeAlpha, whichFilter, 0);
    }

    /**
     * Class constructor specifying Image source to encode, whether to encode
     * alpha, filter to use, and compression level.
     * 
     * @param image A Java Image object
     * @param encodeAlpha Encode the alpha channel? false=no; true=yes
     * @param whichFilter 0=none, 1=sub, 2=up
     * @param compLevel 0..9
     * @see java.awt.Image
     */
    public PNGEncoder(Image image, boolean encodeAlpha, int whichFilter,
            int compLevel) {
        this.image = image;
        this.encodeAlpha = encodeAlpha;
        setFilter(whichFilter);
        if (compLevel >= 0 && compLevel <= 9) {
            this.compressionLevel = compLevel;
        }
    }

    public void addText(String key, String value) {
        if ((key == null) || (key.length() == 0))
            key = "Comment";
        keys.add(key.substring(0, Math.min(79, key.length())));
        text.add(value);
    }

    /**
     * Set the image to be encoded
     * 
     * @param image A Java Image object which uses the DirectColorModel
     * @see java.awt.Image
     */
    public void setImage(Image image) {
        this.image = image;
        pngBytes = null;
    }

    /** method to wait for image */
    private int imageStatus;

    public boolean imageUpdate(Image image, int flags, int x, int y, int width,
            int height) {
        imageStatus = flags;
        if (((flags & ALLBITS) == ALLBITS) || ((flags & (ABORT | ERROR)) != 0)) {
            return false;
        }
        return true;
    }

    /**
     * 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 };

        if (image == null) {
            return null;
        }

        imageStatus = 0;
        boolean status = Toolkit.getDefaultToolkit().prepareImage(image, -1,
                -1, this);

        if (!status) {
            while (((imageStatus & (ALLBITS)) == 0)
                    && ((imageStatus & (ABORT | ERROR)) == 0)) {
                try {
                    Thread.sleep(100);
                } catch (Exception e) {
                }
            }
            // FIXED: moved this inside the "if (!status)" area
            if ((imageStatus & (ALLBITS)) == 0) {
                return null;
            }
        }

        width = image.getWidth(null);
        height = image.getHeight(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();
        for (Iterator<String> ik = keys.iterator(), iv = text.iterator(); ik.hasNext()
                && iv.hasNext();) {
            writeText(ik.next(), iv.next());
        }
        dataPos = bytePos;
        if (writeImageData()) {
            writeEnd();
            pngBytes = resizeByteArray(pngBytes, maxPos);
        } else {
            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);
    }

    /**
     * Set the alpha encoding on or off.
     * 
     * @param encodeAlpha false=no, true=yes
     */
    public void setEncodeAlpha(boolean encodeAlpha) {
        this.encodeAlpha = encodeAlpha;
    }

    /**
     * Retrieve alpha encoding status.
     * 
     * @return boolean false=no, true=yes
     */
    public boolean getEncodeAlpha() {
        return encodeAlpha;
    }

    /**
     * Set the filter to use
     * 
     * @param whichFilter from constant list
     */
    public void setFilter(int whichFilter) {
        this.filter = FILTER_NONE;
        if (whichFilter <= FILTER_LAST) {
            this.filter = whichFilter;
        }
    }

    /**
     * Retrieve filtering scheme
     * 
     * @return int (see constant list)
     */
    public int getFilter() {
        return filter;
    }

    /**
     * Set the compression level to use
     * 
     * @param level 0 through 9
     */
    public void setCompressionLevel(int level) {
        if (level >= 0 && level <= 9) {
            this.compressionLevel = level;
        }
    }

    /**
     * Retrieve compression level
     * 
     * @return int in range 0-9
     */
    public int getCompressionLevel() {
        return compressionLevel;
    }

    /**
     * Increase or decrease the length of a byte array.
     * 
     * @param array The original array.
     * @param newLength The length you wish the new array to have.
     * @return Array of newly desired length. If shorter than the original, the
     *         trailing elements are truncated.
     */
    protected byte[] resizeByteArray(byte[] array, int newLength) {
        byte[] newArray = new byte[newLength];
        int oldLength = array.length;

        System.arraycopy(array, 0, newArray, 0, Math.min(oldLength, newLength));
        return newArray;
    }

    /**
     * Write an array of bytes into the pngBytes array. Note: This routine has
     * the side effect of updating maxPos, the largest element written in the
     * array. The array is resized by 1000 bytes or the length of the data to be
     * written, whichever is larger.
     * 
     * @param data The data to be written into pngBytes.
     * @param offset The starting point to write to.
     * @return The next place to be written to in the pngBytes array.
     */
    protected int writeBytes(byte[] data, int offset) {
        maxPos = Math.max(maxPos, offset + data.length);
        if (data.length + offset > pngBytes.length) {
            pngBytes = resizeByteArray(pngBytes, pngBytes.length
                    + Math.max(1000, data.length));
        }
        System.arraycopy(data, 0, pngBytes, offset, data.length);
        return offset + data.length;
    }

    /**
     * Write an array of bytes into the pngBytes array, specifying number of
     * bytes to write. Note: This routine has the side effect of updating
     * maxPos, the largest element written in the array. The array is resized by
     * 1000 bytes or the length of the data to be written, whichever is larger.
     * 
     * @param data The data to be written into pngBytes.
     * @param nBytes The number of bytes to be written.
     * @param offset The starting point to write to.
     * @return The next place to be written to in the pngBytes array.
     */
    protected int writeBytes(byte[] data, int nBytes, int offset) {
        maxPos = Math.max(maxPos, offset + nBytes);
        if (nBytes + offset > pngBytes.length) {
            pngBytes = resizeByteArray(pngBytes, pngBytes.length
                    + Math.max(1000, nBytes));
        }
        System.arraycopy(data, 0, pngBytes, offset, nBytes);
        return offset + nBytes;
    }

    /**
     * Write a two-byte integer into the pngBytes array at a given position.
     * 
     * @param n The integer to be written into pngBytes.
     * @param offset The starting point to write to.
     * @return The next place to be written to in the pngBytes array.
     */
    protected int writeInt2(int n, int offset) {
        byte[] temp = { (byte) ((n >> 8) & 0xff), (byte) (n & 0xff) };
        return writeBytes(temp, offset);
    }

    /**
     * Write a four-byte integer into the pngBytes array at a given position.
     * 
     * @param n The integer to be written into pngBytes.
     * @param offset The starting point to write to.
     * @return The next place to be written to in the pngBytes array.
     */
    protected int writeInt4(int n, int offset) {
        byte[] temp = { (byte) ((n >> 24) & 0xff), (byte) ((n >> 16) & 0xff),
                (byte) ((n >> 8) & 0xff), (byte) (n & 0xff) };
        return writeBytes(temp, offset);
    }

    /**
     * Write a single byte into the pngBytes array at a given position.
     * 
     * @param b The integer to be written into pngBytes.
     * @param offset The starting point to write to.
     * @return The next place to be written to in the pngBytes array.
     */
    protected int writeByte(int b, int offset) {
        byte[] temp = { (byte) b };
        return writeBytes(temp, offset);
    }

    /**
     * Write a string into the pngBytes array at a given position. This uses the
     * getBytes method, so the encoding used will be its default.
     * 
     * @param s The String to be written into pngBytes.
     * @param offset The starting point to write to.
     * @return The next place to be written to in the pngBytes array.
     * @see java.lang.String#getBytes()
     */
    protected int writeString(String s, int offset) {
        return writeBytes(s.getBytes(), offset);
    }

    /**
     * Write a PNG "IHDR" chunk into the pngBytes array.
     */
    protected void writeHeader() {
        int startPos;

        startPos = bytePos = writeInt4(13, bytePos);
        bytePos = writeString("IHDR", bytePos);
        width = image.getWidth(null);
        height = image.getHeight(null);
        bytePos = writeInt4(width, bytePos);
        bytePos = writeInt4(height, bytePos);
        bytePos = writeByte(8, bytePos); // bit depth
        bytePos = writeByte((encodeAlpha) ? 6 : 2, bytePos); // direct model
        bytePos = writeByte(0, bytePos); // compression method
        bytePos = writeByte(0, bytePos); // filter method
        bytePos = writeByte(0, bytePos); // no interlace
        crc.reset();
        crc.update(pngBytes, startPos, bytePos - startPos);
        crcValue = crc.getValue();
        bytePos = writeInt4((int) crcValue, bytePos);
    }

    protected void writeText(String key, String value) {
        int startPos;
        int len = key.length() + 1 + value.length();
        startPos = bytePos = writeInt4(len, bytePos);
        bytePos = writeString("tEXt", bytePos);
        bytePos = writeString(key, bytePos);
        bytePos = writeByte(0, bytePos);
        bytePos = writeString(value, bytePos);
        crc.reset();
        crc.update(pngBytes, startPos, bytePos - startPos);
        crcValue = crc.getValue();
        bytePos = writeInt4((int) crcValue, bytePos);
    }

    /**
     * Perform "sub" filtering on the given row. Uses temporary array leftBytes
     * to store the original values of the previous pixels. The array is 16
     * bytes long, which will easily hold two-byte samples plus two-byte alpha.
     * 
     * @param pixels The array holding the scan lines being built
     * @param startPos Starting position within pixels of bytes to be filtered.
     * @param width Width of a scanline in pixels.
     */
    protected void filterSub(byte[] pixels, int startPos, int width) {
        int i;
        int offset = bytesPerPixel;
        int actualStart = startPos + offset;
        int nBytes = width * bytesPerPixel;
        int leftInsert = offset;
        int leftExtract = 0;

        for (i = actualStart; i < startPos + nBytes; i++) {
            leftBytes[leftInsert] = pixels[i];
            pixels[i] = (byte) ((pixels[i] - leftBytes[leftExtract]) % 256);
            leftInsert = (leftInsert + 1) % 0x0f;
            leftExtract = (leftExtract + 1) % 0x0f;
        }
    }

    /**
     * Perform "up" filtering on the given row. Side effect: refills the prior
     * row with current row
     * 
     * @param pixels The array holding the scan lines being built
     * @param startPos Starting position within pixels of bytes to be filtered.
     * @param width Width of a scanline in pixels.
     */
    protected void filterUp(byte[] pixels, int startPos, int width) {
        int i, nBytes;
        byte current_byte;

        nBytes = width * bytesPerPixel;

        for (i = 0; i < nBytes; i++) {
            current_byte = pixels[startPos + i];
            pixels[startPos + i] = (byte) ((pixels[startPos + i] - priorRow[i]) % 256);
            priorRow[i] = current_byte;
        }
    }

    /**
     * Write the image data into the pngBytes array. This will write one or more
     * PNG "IDAT" chunks. In order to conserve memory, this method grabs as many
     * rows as will fit into 32K bytes, or the whole image; whichever is less.
     * 
     * 
     * @return true if no errors; false if error grabbing pixels
     */
    protected boolean writeImageData() {
        int rowsLeft = height; // number of rows remaining to write
        int startRow = 0; // starting row to process this time through
        int nRows; // how many rows to grab at a time

        byte[] scanLines; // the scan lines to be compressed
        int scanPos; // where we are in the scan lines
        int startPos; // where this line's actual pixels start (used for
                        // filtering)

        byte[] compressedLines; // the resultant compressed lines
        int nCompressed; // how big is the compressed area?

        PixelGrabber pg;

        bytesPerPixel = (encodeAlpha) ? 4 : 3;

        Deflater scrunch = new Deflater(compressionLevel);
        ByteArrayOutputStream outBytes = new ByteArrayOutputStream(1024);

        DeflaterOutputStream compBytes = new DeflaterOutputStream(outBytes,
                scrunch);
        try {
            while (rowsLeft > 0) {
                nRows = Math.min(32767 / (width * (bytesPerPixel + 1)),
                        rowsLeft);
                // nRows = rowsLeft;
                int[] pixels = new int[width * nRows];

                pg = new PixelGrabber(image, 0, startRow, width, nRows, pixels,
                        0, width);
                try {
                    pg.grabPixels();
                } catch (Exception e) {
                    System.err.println("interrupted waiting for pixels!");
                    return false;
                }
                if ((pg.getStatus() & ImageObserver.ABORT) != 0) {
                    System.err.println("image fetch aborted or errored");
                    return false;
                }

                /*
                 * Create a data chunk. scanLines adds "nRows" for the filter
                 * bytes.
                 */
                scanLines = new byte[width * nRows * bytesPerPixel + nRows];

                if (filter == FILTER_SUB) {
                    leftBytes = new byte[16];
                }
                if (filter == FILTER_UP) {
                    priorRow = new byte[width * bytesPerPixel];
                }

                scanPos = 0;
                startPos = 1;
                for (int i = 0; i < width * nRows; i++) {
                    if (i % width == 0) {
                        scanLines[scanPos++] = (byte) filter;
                        startPos = scanPos;
                    }
                    scanLines[scanPos++] = (byte) ((pixels[i] >> 16) & 0xff);
                    scanLines[scanPos++] = (byte) ((pixels[i] >> 8) & 0xff);
                    scanLines[scanPos++] = (byte) ((pixels[i]) & 0xff);
                    if (encodeAlpha) {
                        scanLines[scanPos++] = (byte) ((pixels[i] >> 24) & 0xff);
                    }
                    if ((i % width == width - 1) && (filter != FILTER_NONE)) {
                        if (filter == FILTER_SUB) {
                            filterSub(scanLines, startPos, width);
                        }
                        if (filter == FILTER_UP) {
                            filterUp(scanLines, startPos, width);
                        }
                    }
                }

                /*
                 * Write these lines to the output area
                 */
                compBytes.write(scanLines, 0, scanPos);

                startRow += nRows;
                rowsLeft -= nRows;
            }
            compBytes.close();

            /*
             * Write the compressed bytes
             */
            compressedLines = outBytes.toByteArray();
            nCompressed = compressedLines.length;

            crc.reset();
            bytePos = writeInt4(nCompressed, bytePos);
            bytePos = writeString("IDAT", bytePos);
            crc.update("IDAT".getBytes());
            bytePos = writeBytes(compressedLines, nCompressed, bytePos);
            crc.update(compressedLines, 0, nCompressed);

            crcValue = crc.getValue();
            bytePos = writeInt4((int) crcValue, bytePos);
            scrunch.finish();
            return true;
        } catch (IOException e) {
            System.err.println(e.toString());
            return false;
        }
    }

    /**
     * Write a PNG "IEND" chunk into the pngBytes array.
     */
    protected void writeEnd() {
        bytePos = writeInt4(0, bytePos);
        bytePos = writeString("IEND", bytePos);
        crc.reset();
        crc.update("IEND".getBytes());
        crcValue = crc.getValue();
        bytePos = writeInt4((int) crcValue, bytePos);
    }
}
