Java example source code file (ImageFilter.java)

This example Java source code file (ImageFilter.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

cloneable, clonenotsupportedexception, colormodel, hashtable, imageconsumer, imagefilter, internalerror, object, string, util

The ImageFilter.java Java example source code

/*
 * Copyright (c) 1995, 2011, 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.
 */

package java.awt.image;

import java.util.Hashtable;

/**
 * This class implements a filter for the set of interface methods that
 * are used to deliver data from an ImageProducer to an ImageConsumer.
 * It is meant to be used in conjunction with a FilteredImageSource
 * object to produce filtered versions of existing images.  It is a
 * base class that provides the calls needed to implement a "Null filter"
 * which has no effect on the data being passed through.  Filters should
 * subclass this class and override the methods which deal with the
 * data that needs to be filtered and modify it as necessary.
 *
 * @see FilteredImageSource
 * @see ImageConsumer
 *
 * @author      Jim Graham
 */
public class ImageFilter implements ImageConsumer, Cloneable {
    /**
     * The consumer of the particular image data stream for which this
     * instance of the ImageFilter is filtering data.  It is not
     * initialized during the constructor, but rather during the
     * getFilterInstance() method call when the FilteredImageSource
     * is creating a unique instance of this object for a particular
     * image data stream.
     * @see #getFilterInstance
     * @see ImageConsumer
     */
    protected ImageConsumer consumer;

    /**
     * Returns a unique instance of an ImageFilter object which will
     * actually perform the filtering for the specified ImageConsumer.
     * The default implementation just clones this object.
     * <p>
     * Note: This method is intended to be called by the ImageProducer
     * of the Image whose pixels are being filtered.  Developers using
     * this class to filter pixels from an image should avoid calling
     * this method directly since that operation could interfere
     * with the filtering operation.
     * @param ic the specified <code>ImageConsumer
     * @return an <code>ImageFilter used to perform the
     *         filtering for the specified <code>ImageConsumer.
     */
    public ImageFilter getFilterInstance(ImageConsumer ic) {
        ImageFilter instance = (ImageFilter) clone();
        instance.consumer = ic;
        return instance;
    }

    /**
     * Filters the information provided in the setDimensions method
     * of the ImageConsumer interface.
     * <p>
     * Note: This method is intended to be called by the ImageProducer
     * of the Image whose pixels are being filtered.  Developers using
     * this class to filter pixels from an image should avoid calling
     * this method directly since that operation could interfere
     * with the filtering operation.
     * @see ImageConsumer#setDimensions
     */
    public void setDimensions(int width, int height) {
        consumer.setDimensions(width, height);
    }

    /**
     * Passes the properties from the source object along after adding a
     * property indicating the stream of filters it has been run through.
     * <p>
     * Note: This method is intended to be called by the ImageProducer
     * of the Image whose pixels are being filtered.  Developers using
     * this class to filter pixels from an image should avoid calling
     * this method directly since that operation could interfere
     * with the filtering operation.
     *
     * @param props the properties from the source object
     * @exception NullPointerException if <code>props is null
     */
    public void setProperties(Hashtable<?,?> props) {
        Hashtable<Object,Object> p = (Hashtable)props.clone();
        Object o = p.get("filters");
        if (o == null) {
            p.put("filters", toString());
        } else if (o instanceof String) {
            p.put("filters", ((String) o)+toString());
        }
        consumer.setProperties(p);
    }

    /**
     * Filter the information provided in the setColorModel method
     * of the ImageConsumer interface.
     * <p>
     * Note: This method is intended to be called by the ImageProducer
     * of the Image whose pixels are being filtered.  Developers using
     * this class to filter pixels from an image should avoid calling
     * this method directly since that operation could interfere
     * with the filtering operation.
     * @see ImageConsumer#setColorModel
     */
    public void setColorModel(ColorModel model) {
        consumer.setColorModel(model);
    }

    /**
     * Filters the information provided in the setHints method
     * of the ImageConsumer interface.
     * <p>
     * Note: This method is intended to be called by the ImageProducer
     * of the Image whose pixels are being filtered.  Developers using
     * this class to filter pixels from an image should avoid calling
     * this method directly since that operation could interfere
     * with the filtering operation.
     * @see ImageConsumer#setHints
     */
    public void setHints(int hints) {
        consumer.setHints(hints);
    }

    /**
     * Filters the information provided in the setPixels method of the
     * ImageConsumer interface which takes an array of bytes.
     * <p>
     * Note: This method is intended to be called by the ImageProducer
     * of the Image whose pixels are being filtered.  Developers using
     * this class to filter pixels from an image should avoid calling
     * this method directly since that operation could interfere
     * with the filtering operation.
     * @see ImageConsumer#setPixels
     */
    public void setPixels(int x, int y, int w, int h,
                          ColorModel model, byte pixels[], int off,
                          int scansize) {
        consumer.setPixels(x, y, w, h, model, pixels, off, scansize);
    }

    /**
     * Filters the information provided in the setPixels method of the
     * ImageConsumer interface which takes an array of integers.
     * <p>
     * Note: This method is intended to be called by the ImageProducer
     * of the Image whose pixels are being filtered.  Developers using
     * this class to filter pixels from an image should avoid calling
     * this method directly since that operation could interfere
     * with the filtering operation.
     * @see ImageConsumer#setPixels
     */
    public void setPixels(int x, int y, int w, int h,
                          ColorModel model, int pixels[], int off,
                          int scansize) {
        consumer.setPixels(x, y, w, h, model, pixels, off, scansize);
    }

    /**
     * Filters the information provided in the imageComplete method of
     * the ImageConsumer interface.
     * <p>
     * Note: This method is intended to be called by the ImageProducer
     * of the Image whose pixels are being filtered.  Developers using
     * this class to filter pixels from an image should avoid calling
     * this method directly since that operation could interfere
     * with the filtering operation.
     * @see ImageConsumer#imageComplete
     */
    public void imageComplete(int status) {
        consumer.imageComplete(status);
    }

    /**
     * Responds to a request for a TopDownLeftRight (TDLR) ordered resend
     * of the pixel data from an <code>ImageConsumer.
     * When an <code>ImageConsumer being fed
     * by an instance of this <code>ImageFilter
     * requests a resend of the data in TDLR order,
     * the <code>FilteredImageSource
     * invokes this method of the <code>ImageFilter.
     *
     * <p>
     *
     * An <code>ImageFilter subclass might override this method or not,
     * depending on if and how it can send data in TDLR order.
     * Three possibilities exist:
     *
     * <ul>
     * <li>
     * Do not override this method.
     * This makes the subclass use the default implementation,
     * which is to
     * forward the request
     * to the indicated <code>ImageProducer
     * using this filter as the requesting <code>ImageConsumer.
     * This behavior
     * is appropriate if the filter can determine
     * that it will forward the pixels
     * in TDLR order if its upstream producer object
     * sends them in TDLR order.
     *
     * <li>
     * Override the method to simply send the data.
     * This is appropriate if the filter can handle the request itself —
     * for example,
     * if the generated pixels have been saved in some sort of buffer.
     *
     * <li>
     * Override the method to do nothing.
     * This is appropriate
     * if the filter cannot produce filtered data in TDLR order.
     * </ul>
     *
     * @see ImageProducer#requestTopDownLeftRightResend
     * @param ip the ImageProducer that is feeding this instance of
     * the filter - also the ImageProducer that the request should be
     * forwarded to if necessary
     * @exception NullPointerException if <code>ip is null
     */
    public void resendTopDownLeftRight(ImageProducer ip) {
        ip.requestTopDownLeftRightResend(this);
    }

    /**
     * Clones this object.
     */
    public Object clone() {
        try {
            return super.clone();
        } catch (CloneNotSupportedException e) {
            // this shouldn't happen, since we are Cloneable
            throw new InternalError(e);
        }
    }
}