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package java.awt.image;

import java.awt.Image;
import java.awt.image.ImageFilter;
import java.awt.image.ImageConsumer;
import java.awt.image.ImageProducer;
import java.util.Hashtable;
import java.awt.image.ColorModel;


This class is an implementation of the ImageProducer interface which takes an existing image and a filter object and uses them to produce image data for a new filtered version of the original image. Furthermore, FilteredImageSource is safe for use by multiple threads. Here is an example which filters an image by swapping the red and blue components: 
     Image src = getImage("doc:///demo/images/duke/T1.gif");
     ImageFilter colorfilter = new RedBlueSwapFilter();
     Image img = createImage(new FilteredImageSource(src.getSource(),
                                                     colorfilter));



Author:     Jim Graham
See Also:
/**
 * This class is an implementation of the ImageProducer interface which
 * takes an existing image and a filter object and uses them to produce
 * image data for a new filtered version of the original image. Furthermore,
 * {@code FilteredImageSource} is safe for use by multiple threads.
 * Here is an example which filters an image by swapping the red and
 * blue components:
 * <pre>
 *
 *      Image src = getImage("doc:///demo/images/duke/T1.gif");
 *      ImageFilter colorfilter = new RedBlueSwapFilter();
 *      Image img = createImage(new FilteredImageSource(src.getSource(),
 *                                                      colorfilter));
 *
 * </pre>
 *
 * @see ImageProducer
 *
 * @author      Jim Graham
 */
public class FilteredImageSource implements ImageProducer {
    ImageProducer src;
    ImageFilter filter;

    
Constructs an ImageProducer object from an existing ImageProducer
and a filter object.

Params:
  • orig – the specified ImageProducer
  • imgf – the specified ImageFilter
See Also:
/**
     * Constructs an ImageProducer object from an existing ImageProducer
     * and a filter object.
     * @param orig the specified {@code ImageProducer}
     * @param imgf the specified {@code ImageFilter}
     * @see ImageFilter
     * @see java.awt.Component#createImage
     */
    public FilteredImageSource(ImageProducer orig, ImageFilter imgf) {
        src = orig;
        filter = imgf;
    }

    private Hashtable<ImageConsumer, ImageFilter> proxies;

    
Adds the specified ImageConsumer to the list of consumers interested in data for the filtered image. An instance of the original ImageFilter is created (using the filter's getFilterInstance method) to manipulate the image data for the specified ImageConsumer. The newly created filter instance is then passed to the addConsumer method of the original ImageProducer. 
 This method is public as a side effect of this class implementing the ImageProducer interface. It should not be called from user code, and its behavior if called from user code is unspecified. 
Params:
  • ic –  the consumer for the filtered image
See Also:
/**
     * Adds the specified {@code ImageConsumer}
     * to the list of consumers interested in data for the filtered image.
     * An instance of the original {@code ImageFilter}
     * is created
     * (using the filter's {@code getFilterInstance} method)
     * to manipulate the image data
     * for the specified {@code ImageConsumer}.
     * The newly created filter instance
     * is then passed to the {@code addConsumer} method
     * of the original {@code ImageProducer}.
     *
     * <p>
     * This method is public as a side effect
     * of this class implementing
     * the {@code ImageProducer} interface.
     * It should not be called from user code,
     * and its behavior if called from user code is unspecified.
     *
     * @param ic  the consumer for the filtered image
     * @see ImageConsumer
     */
    public synchronized void addConsumer(ImageConsumer ic) {
        if (proxies == null) {
            proxies = new Hashtable<>();
        }
        if (!proxies.containsKey(ic)) {
            ImageFilter imgf = filter.getFilterInstance(ic);
            proxies.put(ic, imgf);
            src.addConsumer(imgf);
        }
    }

    
Determines whether an ImageConsumer is on the list of consumers
currently interested in data for this image.

 This method is public as a side effect of this class implementing the ImageProducer interface. It should not be called from user code, and its behavior if called from user code is unspecified. 
Params:
  • ic – the specified ImageConsumer
See Also:
Returns:true if the ImageConsumer is on the list; false otherwise
/**
     * Determines whether an ImageConsumer is on the list of consumers
     * currently interested in data for this image.
     *
     * <p>
     * This method is public as a side effect
     * of this class implementing
     * the {@code ImageProducer} interface.
     * It should not be called from user code,
     * and its behavior if called from user code is unspecified.
     *
     * @param ic the specified {@code ImageConsumer}
     * @return true if the ImageConsumer is on the list; false otherwise
     * @see ImageConsumer
     */
    public synchronized boolean isConsumer(ImageConsumer ic) {
        return (proxies != null && proxies.containsKey(ic));
    }

    
Removes an ImageConsumer from the list of consumers interested in
data for this image.

 This method is public as a side effect of this class implementing the ImageProducer interface. It should not be called from user code, and its behavior if called from user code is unspecified. 
See Also:
/**
     * Removes an ImageConsumer from the list of consumers interested in
     * data for this image.
     *
     * <p>
     * This method is public as a side effect
     * of this class implementing
     * the {@code ImageProducer} interface.
     * It should not be called from user code,
     * and its behavior if called from user code is unspecified.
     *
     * @see ImageConsumer
     */
    public synchronized void removeConsumer(ImageConsumer ic) {
        if (proxies != null) {
            ImageFilter imgf =  proxies.get(ic);
            if (imgf != null) {
                src.removeConsumer(imgf);
                proxies.remove(ic);
                if (proxies.isEmpty()) {
                    proxies = null;
                }
            }
        }
    }

    
Starts production of the filtered image. If the specified ImageConsumer isn't already a consumer of the filtered image, an instance of the original ImageFilter is created (using the filter's getFilterInstance method) to manipulate the image data for the ImageConsumer. The filter instance for the ImageConsumer is then passed to the startProduction method of the original ImageProducer. 
 This method is public as a side effect of this class implementing the ImageProducer interface. It should not be called from user code, and its behavior if called from user code is unspecified. 
Params:
  • ic –  the consumer for the filtered image
See Also:
/**
     * Starts production of the filtered image.
     * If the specified {@code ImageConsumer}
     * isn't already a consumer of the filtered image,
     * an instance of the original {@code ImageFilter}
     * is created
     * (using the filter's {@code getFilterInstance} method)
     * to manipulate the image data
     * for the {@code ImageConsumer}.
     * The filter instance for the {@code ImageConsumer}
     * is then passed to the {@code startProduction} method
     * of the original {@code ImageProducer}.
     *
     * <p>
     * This method is public as a side effect
     * of this class implementing
     * the {@code ImageProducer} interface.
     * It should not be called from user code,
     * and its behavior if called from user code is unspecified.
     *
     * @param ic  the consumer for the filtered image
     * @see ImageConsumer
     */
    public synchronized void startProduction(ImageConsumer ic) {
        if (proxies == null) {
            proxies = new Hashtable<>();
        }
        ImageFilter imgf = proxies.get(ic);
        if (imgf == null) {
            imgf = filter.getFilterInstance(ic);
            proxies.put(ic, imgf);
        }
        src.startProduction(imgf);
    }

    
Requests that a given ImageConsumer have the image data delivered
one more time in top-down, left-right order.  The request is
handed to the ImageFilter for further processing, since the
ability to preserve the pixel ordering depends on the filter.

 This method is public as a side effect of this class implementing the ImageProducer interface. It should not be called from user code, and its behavior if called from user code is unspecified. 
See Also:
/**
     * Requests that a given ImageConsumer have the image data delivered
     * one more time in top-down, left-right order.  The request is
     * handed to the ImageFilter for further processing, since the
     * ability to preserve the pixel ordering depends on the filter.
     *
     * <p>
     * This method is public as a side effect
     * of this class implementing
     * the {@code ImageProducer} interface.
     * It should not be called from user code,
     * and its behavior if called from user code is unspecified.
     *
     * @see ImageConsumer
     */
    public synchronized void requestTopDownLeftRightResend(ImageConsumer ic) {
        if (proxies != null) {
            ImageFilter imgf = proxies.get(ic);
            if (imgf != null) {
                imgf.resendTopDownLeftRight(src);
            }
        }
    }
}