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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</code>
* @return an <code>ImageFilter</code> used to perform the
* filtering for the specified <code>ImageConsumer</code>.
*/
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</code> is null
*/
public void setProperties(Hashtable<?,?> props) {
Hashtable<Object,Object> p = (Hashtable<Object,Object>)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</code>.
* When an <code>ImageConsumer</code> being fed
* by an instance of this <code>ImageFilter</code>
* requests a resend of the data in TDLR order,
* the <code>FilteredImageSource</code>
* invokes this method of the <code>ImageFilter</code>.
*
* <p>
*
* An <code>ImageFilter</code> 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</code>
* using this filter as the requesting <code>ImageConsumer</code>.
* 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</code> 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();
}
}
}