/*
* $RCSfile: BoxFilterDescriptor.java,v $
*
* Copyright (c) 2005 Sun Microsystems, Inc. All rights reserved.
*
* Use is subject to license terms.
*
* $Revision: 1.1 $
* $Date: 2005/02/11 04:57:31 $
* $State: Exp $
*/
package com.lightcrafts.mediax.jai.operator;
import com.lightcrafts.media.jai.util.AreaOpPropertyGenerator;
import java.awt.RenderingHints;
import java.awt.image.RenderedImage;
import java.awt.image.renderable.ParameterBlock;
import com.lightcrafts.mediax.jai.JAI;
import com.lightcrafts.mediax.jai.OperationDescriptorImpl;
import com.lightcrafts.mediax.jai.ParameterBlockJAI;
import com.lightcrafts.mediax.jai.PropertyGenerator;
import com.lightcrafts.mediax.jai.RenderedOp;
import com.lightcrafts.mediax.jai.registry.RenderedRegistryMode;
/**
* An <code>OperationDescriptor</code> describing the "BoxFilter" operation.
*
* <p> The "BoxFilter" operation determines the intensity of a pixel
* in an image by averaging the source pixels within a rectangular
* area around the pixel. This is a special case of the convolution
* operation, in which each source pixel contributes the same weight
* to the destination pixel. The pixel values of the destination image
* are defined by the pseudocode:
*
* <pre>
* int count = width * height; // # of pixels in the box
* for (int b = 0; b < numBands; b++) {
* int total = 0;
* for (int j = -yKey; j < -yKey + height; j++) {
* for (int i = -xKey; i < -xKey + width; i++) {
* total += src[x+i][y+j][b];
* }
* }
* dst[x][y][b] = (total + count/2) / count; // round
* }
* </pre>
*
* <p> Convolution, like any neighborhood operation, leaves a band of
* pixels around the edges undefined. For example, for a 3x3 kernel
* only four kernel elements and four source pixels contribute to the
* convolution pixel at the corners of the source image. Pixels that
* do not allow the full kernel to be applied to the source are not
* included in the destination image. A "Border" operation may be used
* to add an appropriate border to the source image in order to avoid
* shrinkage of the image boundaries.
*
* <p> The kernel may not be bigger in any dimension than the image data.
*
* <p><table border=1>
* <caption>Resource List</caption>
* <tr><th>Name</th> <th>Value</th></tr>
* <tr><td>GlobalName</td> <td>BoxFilter</td></tr>
* <tr><td>LocalName</td> <td>BoxFilter</td></tr>
* <tr><td>Vendor</td> <td>com.lightcrafts.media.jai</td></tr>
* <tr><td>Description</td> <td>Performs special case convolution where each
* source pixel contributes equally to the
* intensity of the destination pixel.</td></tr>
* <tr><td>DocURL</td> <td>http://java.sun.com/products/java-media/jai/forDevelopers/jai-apidocs/javax/media/jai/operator/BoxFilterDescriptor.html</td></tr>
* <tr><td>Version</td> <td>1.0</td></tr>
* <tr><td>arg0Desc</td> <td>The width of the box.</td></tr>
* <tr><td>arg1Desc</td> <td>The height of the box.</td></tr>
* <tr><td>arg2Desc</td> <td>The X position of the key element.</td></tr>
* <tr><td>arg3Desc</td> <td>The Y position of the key element.</td></tr>
* </table></p>
*
* <p><table border=1>
* <caption>Parameter List</caption>
* <tr><th>Name</th> <th>Class Type</th>
* <th>Default Value</th></tr>
* <tr><td>width</td> <td>java.lang.Integer</td>
* <td>3</td>
* <tr><td>height</td> <td>java.lang.Integer</td>
* <td>width</td>
* <tr><td>xKey</td> <td>java.lang.Integer</td>
* <td>width/2</td>
* <tr><td>yKey</td> <td>java.lang.Integer</td>
* <td>height/2</td>
* </table></p>
*
* @see com.lightcrafts.mediax.jai.OperationDescriptor
*/
public class BoxFilterDescriptor extends OperationDescriptorImpl {
/**
* The resource strings that provide the general documentation
* and specify the parameter list for this operation.
*/
private static final String[][] resources = {
{"GlobalName", "BoxFilter"},
{"LocalName", "BoxFilter"},
{"Vendor", "com.lightcrafts.media.jai"},
{"Description", JaiI18N.getString("BoxFilterDescriptor0")},
{"DocURL", "http://java.sun.com/products/java-media/jai/forDevelopers/jai-apidocs/javax/media/jai/operator/BoxFilterDescriptor.html"},
{"Version", JaiI18N.getString("DescriptorVersion")},
{"arg0Desc", JaiI18N.getString("BoxFilterDescriptor1")},
{"arg1Desc", JaiI18N.getString("BoxFilterDescriptor2")},
{"arg2Desc", JaiI18N.getString("BoxFilterDescriptor3")},
{"arg3Desc", JaiI18N.getString("BoxFilterDescriptor4")}
};
/** The parameter class list for this operation. */
private static final Class[] paramClasses = {
java.lang.Integer.class, java.lang.Integer.class,
java.lang.Integer.class, java.lang.Integer.class
};
/** The parameter name list for this operation. */
private static final String[] paramNames = {
"width", "height", "xKey", "yKey"
};
/** The parameter default value list for this operation. */
private static final Object[] paramDefaults = {
new Integer(3), null, null, null
};
/** Constructor. */
public BoxFilterDescriptor() {
super(resources, 1, paramClasses, paramNames, paramDefaults);
}
/**
* Returns the minimum legal value of a specified numeric parameter
* for this operation.
*/
public Number getParamMinValue(int index) {
if (index == 0 || index == 1) {
return new Integer(1);
} else if (index == 2 || index == 3) {
return new Integer(Integer.MIN_VALUE);
} else {
throw new ArrayIndexOutOfBoundsException();
}
}
protected boolean validateParameters(ParameterBlock args,
StringBuffer msg) {
// The number of parameters supplied.
int argNumParams = args.getNumParameters();
if(argNumParams > 0 &&
args.getObjectParameter(0) instanceof Integer) {
Object obj;
if(argNumParams < 2) {
obj = args.getObjectParameter(0);
if(obj instanceof Integer) {
// set height to width
args.add(obj);
}
}
if(argNumParams < 3) {
obj = args.getObjectParameter(0);
if(obj instanceof Integer) {
// set xKey to width/2
args.add(((Integer)obj).intValue()/2);
}
}
if(argNumParams < 4) {
obj = args.getObjectParameter(1);
if(obj instanceof Integer) {
// set yKey to height/2
args.add(((Integer)obj).intValue()/2);
}
}
}
return super.validateParameters(args, msg);
}
/**
* Returns an array of <code>PropertyGenerators</code> implementing
* property inheritance for the "BoxFilter" operation.
*
* @return An array of property generators.
*/
public PropertyGenerator[] getPropertyGenerators() {
PropertyGenerator[] pg = new PropertyGenerator[1];
pg[0] = new AreaOpPropertyGenerator();
return pg;
}
/**
* Performs special case convolution where each source pixel contributes equally to the intensity of the destination pixel.
*
* <p>Creates a <code>ParameterBlockJAI</code> from all
* supplied arguments except <code>hints</code> and invokes
* {@link JAI#create(String,ParameterBlock,RenderingHints)}.
*
* @see JAI
* @see ParameterBlockJAI
* @see RenderedOp
*
* @param source0 <code>RenderedImage</code> source 0.
* @param width The width of the box.
* May be <code>null</code>.
* @param height The height of the box.
* May be <code>null</code>.
* @param xKey The X position of the key element.
* May be <code>null</code>.
* @param yKey The Y position of the key element.
* May be <code>null</code>.
* @param hints The <code>RenderingHints</code> to use.
* May be <code>null</code>.
* @return The <code>RenderedOp</code> destination.
* @throws IllegalArgumentException if <code>source0</code> is <code>null</code>.
*/
public static RenderedOp create(RenderedImage source0,
Integer width,
Integer height,
Integer xKey,
Integer yKey,
RenderingHints hints) {
ParameterBlockJAI pb =
new ParameterBlockJAI("BoxFilter",
RenderedRegistryMode.MODE_NAME);
pb.setSource("source0", source0);
pb.setParameter("width", width);
pb.setParameter("height", height);
pb.setParameter("xKey", xKey);
pb.setParameter("yKey", yKey);
return JAI.create("BoxFilter", pb, hints);
}
}