Java tutorial
/* * eXist Image Module Extension CropFunction * Copyright (C) 2011 Christian Wittern * * * This program 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 * of the License, or (at your option) any later version. * * This program 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 program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. * * $Id: $ */ package org.exist.xquery.modules.image; import org.apache.log4j.Logger; import org.apache.commons.io.output.ByteArrayOutputStream; import java.awt.Toolkit; import java.awt.Graphics2D; import java.awt.Image; import java.awt.image.BufferedImage; import java.awt.image.CropImageFilter; import java.awt.image.FilteredImageSource; import java.io.ByteArrayInputStream; import javax.imageio.ImageIO; import org.exist.dom.QName; import org.exist.xquery.BasicFunction; import org.exist.xquery.Cardinality; import org.exist.xquery.FunctionSignature; import org.exist.xquery.XPathException; import org.exist.xquery.XQueryContext; import org.exist.xquery.value.Base64BinaryValueType; import org.exist.xquery.value.BinaryValue; import org.exist.xquery.value.BinaryValueFromInputStream; import org.exist.xquery.value.FunctionParameterSequenceType; import org.exist.xquery.value.FunctionReturnSequenceType; import org.exist.xquery.value.IntegerValue; import org.exist.xquery.value.Sequence; import org.exist.xquery.value.SequenceType; import org.exist.xquery.value.Type; /** * eXist Image Module Extension CropFunction * * Crops an Image * * Written by Christian Wittern, based on the scale function by Adam and Loren, with help from Rafael Troilo * @author Adam Retter <adam@exist-db.org> * @author Loren Cahlander * @author Christian Wittern * @serial 2011-03-05 * @version 1.0 * * @see org.exist.xquery.BasicFunction#BasicFunction(org.exist.xquery.XQueryContext, org.exist.xquery.FunctionSignature) */ public class CropFunction extends BasicFunction { private static final Logger logger = Logger.getLogger(CropFunction.class); private final static int MAXHEIGHT = 100; private final static int MAXWIDTH = 100; public final static FunctionSignature signature = new FunctionSignature( new QName("crop", ImageModule.NAMESPACE_URI, ImageModule.PREFIX), "Crop the image $image to a specified dimension. If no dimensions are specified, then the default values are 'y1 = 0', 'x1 = 0', 'x2 = 100' and 'y2 = 100'.", new SequenceType[] { new FunctionParameterSequenceType("image", Type.BASE64_BINARY, Cardinality.EXACTLY_ONE, "The image data"), new FunctionParameterSequenceType("dimension", Type.INTEGER, Cardinality.ZERO_OR_MORE, "The maximum dimension of the cropd image. expressed in pixels (x1, y1, x2, y2). If empty, then the default values are are 'y1 = 0', 'x1 = 0', 'x2 = 100' and 'y2 = 100'."), new FunctionParameterSequenceType("mimeType", Type.STRING, Cardinality.EXACTLY_ONE, "The mime-type of the image") }, new FunctionReturnSequenceType(Type.BASE64_BINARY, Cardinality.ZERO_OR_ONE, "the cropd image or an empty sequence if $image is invalid")); /** * CropFunction Constructor * * @param context The Context of the calling XQuery */ public CropFunction(XQueryContext context) { super(context, signature); } /** * evaluate the call to the xquery crop() function, * it is really the main entry point of this class * * @param args arguments from the crop() function call * @param contextSequence the Context Sequence to operate on (not used here internally!) * @return A sequence representing the result of the crop() function call * * @see org.exist.xquery.BasicFunction#eval(org.exist.xquery.value.Sequence[], org.exist.xquery.value.Sequence) */ @Override public Sequence eval(Sequence[] args, Sequence contextSequence) throws XPathException { //was an image and a mime-type speficifed if (args[0].isEmpty() || args[2].isEmpty()) { return Sequence.EMPTY_SEQUENCE; } //get the maximum dimensions to crop to int x1 = 0; int y1 = 0; int x2 = MAXHEIGHT; int y2 = MAXWIDTH; if (!args[1].isEmpty()) { x1 = ((IntegerValue) args[1].itemAt(0)).getInt(); if (args[1].hasMany()) { y1 = ((IntegerValue) args[1].itemAt(1)).getInt(); x2 = ((IntegerValue) args[1].itemAt(2)).getInt(); y2 = ((IntegerValue) args[1].itemAt(3)).getInt(); } } //get the mime-type String mimeType = args[2].itemAt(0).getStringValue(); String formatName = mimeType.substring(mimeType.indexOf("/") + 1); //TODO currently ONLY tested for JPEG!!! Image image = null; BufferedImage bImage = null; try { //get the image data image = ImageIO.read(((BinaryValue) args[0].itemAt(0)).getInputStream()); // image = ImageModule.getImage((Base64BinaryValueType)args[0].itemAt(0)); // image = ImageIO.read(new ByteArrayInputStream(getImageData((Base64BinaryValueType)args[0].itemAt(0)))); if (image == null) { logger.error("Unable to read image data!"); return Sequence.EMPTY_SEQUENCE; } //crop the image Image cropImage = Toolkit.getDefaultToolkit() .createImage(new FilteredImageSource(image.getSource(), new CropImageFilter(x1, y1, x2, y2))); if (cropImage instanceof BufferedImage) { // just in case cropImage is allready an BufferedImage bImage = (BufferedImage) cropImage; } else { bImage = new BufferedImage(cropImage.getHeight(null), cropImage.getWidth(null), BufferedImage.TYPE_INT_RGB); Graphics2D g = bImage.createGraphics(); // Paint the image onto the buffered image g.drawImage(cropImage, 0, 0, null); g.dispose(); } ByteArrayOutputStream os = new ByteArrayOutputStream(); ImageIO.write(bImage, formatName, os); //return the new croped image data return BinaryValueFromInputStream.getInstance(context, new Base64BinaryValueType(), new ByteArrayInputStream(os.toByteArray())); } catch (Exception e) { throw new XPathException(this, e.getMessage()); } } }