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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.
* 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.
* @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 {@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.
*
* <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.
*
* <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 {@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 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.
*
* <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 void requestTopDownLeftRightResend(ImageConsumer ic) {
if (proxies != null) {
ImageFilter imgf = proxies.get(ic);
if (imgf != null) {
imgf.resendTopDownLeftRight(src);
}
}
}
}