648 lines
19 KiB
Java
648 lines
19 KiB
Java
/*
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Copyright 2006 Rene Grothmann, modified by Eric Hakenholz
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This file is part of C.a.R. software.
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C.a.R. is a free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, version 3 of the License.
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C.a.R. is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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package rene.util;
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/**
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* PngEncoder takes a Java Image object and creates a byte string which can be saved as a PNG file.
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* The Image is presumed to use the DirectColorModel.
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*
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* Thanks to Jay Denny at KeyPoint Software
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* http://www.keypoint.com/
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* who let me develop this code on company time.
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*
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* You may contact me with (probably very-much-needed) improvements,
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* comments, and bug fixes at:
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*
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* david@catcode.com
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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* A copy of the GNU LGPL may be found at
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* http://www.gnu.org/copyleft/lesser.html,
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*
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* @author J. David Eisenberg
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* @version 1.4, 31 March 2000
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*/
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import java.awt.Image;
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import java.awt.image.ImageObserver;
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import java.awt.image.PixelGrabber;
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import java.io.ByteArrayOutputStream;
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import java.io.IOException;
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import java.util.zip.CRC32;
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import java.util.zip.Deflater;
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import java.util.zip.DeflaterOutputStream;
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public class PngEncoder extends Object {
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/** Constant specifying that alpha channel should be encoded. */
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public static final boolean ENCODE_ALPHA = true;
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/** Constant specifying that alpha channel should not be encoded. */
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public static final boolean NO_ALPHA = false;
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/** Constants for filters */
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public static final int FILTER_NONE = 0;
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public static final int FILTER_SUB = 1;
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public static final int FILTER_UP = 2;
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public static final int FILTER_LAST = 2;
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protected byte[] pngBytes;
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protected byte[] priorRow;
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protected byte[] leftBytes;
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protected Image image;
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protected int width, height;
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protected int bytePos, maxPos;
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protected int hdrPos, dataPos, endPos;
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protected CRC32 crc = new CRC32();
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protected long crcValue;
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protected boolean encodeAlpha;
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protected int filter;
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protected int bytesPerPixel;
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protected int compressionLevel;
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protected double DPI = 300;
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/**
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* Class constructor
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*
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*/
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public PngEncoder() {
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this(null, false, FILTER_NONE, 0);
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}
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/**
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* Class constructor specifying Image to encode, with no alpha channel
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* encoding.
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*
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* @param image
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* A Java Image object which uses the DirectColorModel
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* @see java.awt.Image
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*/
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public PngEncoder(final Image image) {
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this(image, false, FILTER_NONE, 0);
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}
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/**
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* Class constructor specifying Image to encode, and whether to encode
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* alpha.
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*
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* @param image
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* A Java Image object which uses the DirectColorModel
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* @param encodeAlpha
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* Encode the alpha channel? false=no; true=yes
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* @see java.awt.Image
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*/
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public PngEncoder(final Image image, final boolean encodeAlpha) {
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this(image, encodeAlpha, FILTER_NONE, 0);
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}
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/**
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* Class constructor specifying Image to encode, whether to encode alpha,
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* and filter to use.
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*
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* @param image
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* A Java Image object which uses the DirectColorModel
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* @param encodeAlpha
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* Encode the alpha channel? false=no; true=yes
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* @param whichFilter
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* 0=none, 1=sub, 2=up
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* @see java.awt.Image
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*/
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public PngEncoder(final Image image, final boolean encodeAlpha,
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final int whichFilter) {
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this(image, encodeAlpha, whichFilter, 0);
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}
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/**
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* Class constructor specifying Image source to encode, whether to encode
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* alpha, filter to use, and compression level.
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*
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* @param image
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* A Java Image object
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* @param encodeAlpha
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* Encode the alpha channel? false=no; true=yes
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* @param whichFilter
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* 0=none, 1=sub, 2=up
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* @param compLevel
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* 0..9
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* @see java.awt.Image
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*/
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public PngEncoder(final Image image, final boolean encodeAlpha,
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final int whichFilter, final int compLevel) {
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this.image = image;
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this.encodeAlpha = encodeAlpha;
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setFilter(whichFilter);
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if (compLevel >= 0 && compLevel <= 9) {
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this.compressionLevel = compLevel;
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}
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}
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/**
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* Set the image to be encoded
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*
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* @param image
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* A Java Image object which uses the DirectColorModel
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* @see java.awt.Image
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* @see java.awt.image.DirectColorModel
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*/
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public void setImage(final Image image) {
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this.image = image;
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pngBytes = null;
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}
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public void setDPI(final double dpi) {
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DPI = dpi;
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}
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/**
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* Creates an array of bytes that is the PNG equivalent of the current
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* image, specifying whether to encode alpha or not.
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*
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* @param encodeAlpha
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* boolean false=no alpha, true=encode alpha
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* @return an array of bytes, or null if there was a problem
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*/
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public byte[] pngEncode(final boolean encodeAlpha) {
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final byte[] pngIdBytes = { -119, 80, 78, 71, 13, 10, 26, 10 };
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if (image == null) {
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return null;
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}
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width = image.getWidth(null);
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height = image.getHeight(null);
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/*
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* start with an array that is big enough to hold all the pixels (plus
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* filter bytes), and an extra 200 bytes for header info
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*/
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pngBytes = new byte[((width + 1) * height * 3) + 200];
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/*
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* keep track of largest byte written to the array
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*/
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maxPos = 0;
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bytePos = writeBytes(pngIdBytes, 0);
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hdrPos = bytePos;
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writeHeader();
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writePhys();
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dataPos = bytePos;
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if (writeImageData()) {
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writeEnd();
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pngBytes = resizeByteArray(pngBytes, maxPos);
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} else {
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pngBytes = null;
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}
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return pngBytes;
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}
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/**
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* Creates an array of bytes that is the PNG equivalent of the current
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* image. Alpha encoding is determined by its setting in the constructor.
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*
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* @return an array of bytes, or null if there was a problem
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*/
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public byte[] pngEncode() {
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return pngEncode(encodeAlpha);
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}
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/**
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* Set the alpha encoding on or off.
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*
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* @param encodeAlpha
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* false=no, true=yes
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*/
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public void setEncodeAlpha(final boolean encodeAlpha) {
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this.encodeAlpha = encodeAlpha;
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}
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/**
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* Retrieve alpha encoding status.
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*
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* @return boolean false=no, true=yes
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*/
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public boolean getEncodeAlpha() {
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return encodeAlpha;
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}
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/**
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* Set the filter to use
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*
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* @param whichFilter
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* from constant list
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*/
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public void setFilter(final int whichFilter) {
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this.filter = FILTER_NONE;
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if (whichFilter <= FILTER_LAST) {
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this.filter = whichFilter;
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}
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}
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/**
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* Retrieve filtering scheme
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*
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* @return int (see constant list)
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*/
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public int getFilter() {
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return filter;
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}
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/**
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* Set the compression level to use
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*
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* @param level
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* 0 through 9
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*/
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public void setCompressionLevel(final int level) {
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if (level >= 0 && level <= 9) {
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this.compressionLevel = level;
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}
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}
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/**
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* Retrieve compression level
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*
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* @return int in range 0-9
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*/
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public int getCompressionLevel() {
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return compressionLevel;
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}
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/**
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* Increase or decrease the length of a byte array.
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*
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* @param array
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* The original array.
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* @param newLength
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* The length you wish the new array to have.
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* @return Array of newly desired length. If shorter than the original, the
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* trailing elements are truncated.
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*/
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protected byte[] resizeByteArray(final byte[] array, final int newLength) {
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final byte[] newArray = new byte[newLength];
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final int oldLength = array.length;
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System.arraycopy(array, 0, newArray, 0, Math.min(oldLength, newLength));
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return newArray;
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}
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/**
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* Write an array of bytes into the pngBytes array. Note: This routine has
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* the side effect of updating maxPos, the largest element written in the
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* array. The array is resized by 1000 bytes or the length of the data to be
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* written, whichever is larger.
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*
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* @param data
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* The data to be written into pngBytes.
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* @param offset
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* The starting point to write to.
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* @return The next place to be written to in the pngBytes array.
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*/
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protected int writeBytes(final byte[] data, final int offset) {
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maxPos = Math.max(maxPos, offset + data.length);
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if (data.length + offset > pngBytes.length) {
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pngBytes = resizeByteArray(pngBytes, pngBytes.length
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+ Math.max(1000, data.length));
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}
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System.arraycopy(data, 0, pngBytes, offset, data.length);
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return offset + data.length;
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}
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/**
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* Write an array of bytes into the pngBytes array, specifying number of
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* bytes to write. Note: This routine has the side effect of updating
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* maxPos, the largest element written in the array. The array is resized by
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* 1000 bytes or the length of the data to be written, whichever is larger.
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*
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* @param data
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* The data to be written into pngBytes.
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* @param nBytes
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* The number of bytes to be written.
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* @param offset
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* The starting point to write to.
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* @return The next place to be written to in the pngBytes array.
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*/
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protected int writeBytes(final byte[] data, final int nBytes,
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final int offset) {
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maxPos = Math.max(maxPos, offset + nBytes);
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if (nBytes + offset > pngBytes.length) {
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pngBytes = resizeByteArray(pngBytes, pngBytes.length
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+ Math.max(1000, nBytes));
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}
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System.arraycopy(data, 0, pngBytes, offset, nBytes);
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return offset + nBytes;
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}
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/**
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* Write a two-byte integer into the pngBytes array at a given position.
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*
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* @param n
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* The integer to be written into pngBytes.
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* @param offset
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* The starting point to write to.
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* @return The next place to be written to in the pngBytes array.
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*/
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protected int writeInt2(final int n, final int offset) {
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final byte[] temp = { (byte) ((n >> 8) & 0xff), (byte) (n & 0xff) };
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return writeBytes(temp, offset);
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}
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/**
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* Write a four-byte integer into the pngBytes array at a given position.
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*
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* @param n
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* The integer to be written into pngBytes.
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* @param offset
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* The starting point to write to.
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* @return The next place to be written to in the pngBytes array.
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*/
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protected int writeInt4(final int n, final int offset) {
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final byte[] temp = { (byte) ((n >> 24) & 0xff),
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(byte) ((n >> 16) & 0xff), (byte) ((n >> 8) & 0xff),
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(byte) (n & 0xff) };
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return writeBytes(temp, offset);
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}
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/**
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* Write a single byte into the pngBytes array at a given position.
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*
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* @param n
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* The integer to be written into pngBytes.
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* @param offset
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* The starting point to write to.
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* @return The next place to be written to in the pngBytes array.
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*/
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protected int writeByte(final int b, final int offset) {
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final byte[] temp = { (byte) b };
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return writeBytes(temp, offset);
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}
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/**
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* Write a string into the pngBytes array at a given position. This uses the
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* getBytes method, so the encoding used will be its default.
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*
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* @param n
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* The integer to be written into pngBytes.
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* @param offset
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* The starting point to write to.
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* @return The next place to be written to in the pngBytes array.
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* @see java.lang.String#getBytes()
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*/
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protected int writeString(final String s, final int offset) {
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return writeBytes(s.getBytes(), offset);
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}
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/**
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* Write a PNG "IHDR" chunk into the pngBytes array.
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*/
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protected void writeHeader() {
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int startPos;
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startPos = bytePos = writeInt4(13, bytePos);
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bytePos = writeString("IHDR", bytePos);
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width = image.getWidth(null);
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height = image.getHeight(null);
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bytePos = writeInt4(width, bytePos);
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bytePos = writeInt4(height, bytePos);
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bytePos = writeByte(8, bytePos); // bit depth
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bytePos = writeByte((encodeAlpha) ? 6 : 2, bytePos); // direct model
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bytePos = writeByte(0, bytePos); // compression method
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bytePos = writeByte(0, bytePos); // filter method
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bytePos = writeByte(0, bytePos); // no interlace
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crc.reset();
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crc.update(pngBytes, startPos, bytePos - startPos);
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crcValue = crc.getValue();
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bytePos = writeInt4((int) crcValue, bytePos);
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}
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/**
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* Write a PNG "pHYs" chunk into the pngBytes array.
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*/
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protected void writePhys() {
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int startPos;
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startPos = bytePos = writeInt4(9, bytePos);
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bytePos = writeString("pHYs", bytePos);
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final int dots = (int) (DPI * 39.37);
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bytePos = writeInt4(dots, bytePos);
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bytePos = writeInt4(dots, bytePos);
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bytePos = writeByte(1, bytePos); // bit depth
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crc.reset();
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crc.update(pngBytes, startPos, bytePos - startPos);
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crcValue = crc.getValue();
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bytePos = writeInt4((int) crcValue, bytePos);
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}
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/**
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* Perform "sub" filtering on the given row. Uses temporary array leftBytes
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* to store the original values of the previous pixels. The array is 16
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* bytes long, which will easily hold two-byte samples plus two-byte alpha.
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*
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* @param pixels
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* The array holding the scan lines being built
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* @param startPos
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* Starting position within pixels of bytes to be filtered.
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* @param width
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* Width of a scanline in pixels.
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*/
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protected void filterSub(final byte[] pixels, final int startPos,
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final int width) {
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int i;
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final int offset = bytesPerPixel;
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final int actualStart = startPos + offset;
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final int nBytes = width * bytesPerPixel;
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int leftInsert = offset;
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int leftExtract = 0;
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for (i = actualStart; i < startPos + nBytes; i++) {
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leftBytes[leftInsert] = pixels[i];
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pixels[i] = (byte) ((pixels[i] - leftBytes[leftExtract]) % 256);
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leftInsert = (leftInsert + 1) % 0x0f;
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leftExtract = (leftExtract + 1) % 0x0f;
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}
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}
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/**
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* Perform "up" filtering on the given row. Side effect: refills the prior
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* row with current row
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*
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* @param pixels
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* The array holding the scan lines being built
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* @param startPos
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* Starting position within pixels of bytes to be filtered.
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* @param width
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* Width of a scanline in pixels.
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*/
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protected void filterUp(final byte[] pixels, final int startPos,
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final int width) {
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int i, nBytes;
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byte current_byte;
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nBytes = width * bytesPerPixel;
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for (i = 0; i < nBytes; i++) {
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current_byte = pixels[startPos + i];
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pixels[startPos + i] = (byte) ((pixels[startPos + i] - priorRow[i]) % 256);
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priorRow[i] = current_byte;
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}
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}
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/**
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* Write the image data into the pngBytes array. This will write one or more
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* PNG "IDAT" chunks. In order to conserve memory, this method grabs as many
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* rows as will fit into 32K bytes, or the whole image; whichever is less.
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*
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*
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* @return true if no errors; false if error grabbing pixels
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*/
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protected boolean writeImageData() {
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int rowsLeft = height; // number of rows remaining to write
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int startRow = 0; // starting row to process this time through
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int nRows; // how many rows to grab at a time
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byte[] scanLines; // the scan lines to be compressed
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int scanPos; // where we are in the scan lines
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int startPos; // where this line's actual pixels start (used for
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// filtering)
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byte[] compressedLines; // the resultant compressed lines
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int nCompressed; // how big is the compressed area?
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PixelGrabber pg;
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bytesPerPixel = (encodeAlpha) ? 4 : 3;
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final Deflater scrunch = new Deflater(compressionLevel);
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final ByteArrayOutputStream outBytes = new ByteArrayOutputStream(1024);
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final DeflaterOutputStream compBytes = new DeflaterOutputStream(
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outBytes, scrunch);
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try {
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nRows = (64 * 32768 - 1) / (width * (bytesPerPixel + 1));
|
|
|
|
final int[] pixels = new int[width * nRows];
|
|
|
|
while (rowsLeft > 0) {
|
|
if (nRows >= rowsLeft)
|
|
nRows = rowsLeft;
|
|
|
|
pg = new PixelGrabber(image, 0, startRow, width, nRows, pixels,
|
|
0, width);
|
|
try {
|
|
pg.grabPixels();
|
|
} catch (final 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 (final 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);
|
|
}
|
|
}
|