NullDescriptor.java

/* JAI-Ext - OpenSource Java Advanced Image Extensions Library
*    http://www.geo-solutions.it/
*    Copyright 2014 GeoSolutions


* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at

* http://www.apache.org/licenses/LICENSE-2.0

* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package it.geosolutions.jaiext.nullop;

import java.awt.Rectangle;
import java.awt.RenderingHints;
import java.awt.image.RenderedImage;
import java.awt.image.renderable.ParameterBlock;
import java.awt.image.renderable.RenderableImage;
import java.util.Vector;
import javax.media.jai.JAI;
import javax.media.jai.OperationDescriptorImpl;
import javax.media.jai.OperationNode;
import javax.media.jai.ParameterBlockJAI;
import javax.media.jai.RenderableOp;
import javax.media.jai.RenderedOp;
import javax.media.jai.registry.RenderableRegistryMode;
import javax.media.jai.registry.RenderedRegistryMode;

/**
 * An <code>OperationDescriptor</code> describing the "Null" operation.
 * 
 * <p>
 * The "Null" operation performs no processing. It merely propagates its first source along the operation chain unmodified. There may be an arbitrary
 * number of sources but only the first one is passed along so it must have the appropriate class type for the operation mode.
 * 
 * <p>
 * This operation may be useful as a placeholder in operation chains and in creating nodes to which <code>PropertyGenerator</code>s may be attached.
 * This would enable non-image data nodes to be present in chains without requiring that specific <code>OperationDescriptor</code>s be implemented for
 * these operations. The <code>PropertyGenerator</code>s required would in this case be added locally to the nodes using the
 * <code>addPropertyGenerator()</code> method of the node.
 * 
 * <p>
 * <table border=1>
 * <caption>Resource List</caption>
 * <tr>
 * <th>Name</th>
 * <th>Value</th>
 * </tr>
 * <tr>
 * <td>GlobalName</td>
 * <td>Null</td>
 * </tr>
 * <tr>
 * <td>LocalName</td>
 * <td>Null</td>
 * </tr>
 * <tr>
 * <td>Vendor</td>
 * <td>it.geosolutions.jaiext</td>
 * </tr>
 * <tr>
 * <td>Description</td>
 * <td>Operation used for wrapping other images with no processing.</td>
 * </tr>
 * <tr>
 * <td>DocURL</td>
 * <td>Not Defined</td>
 * </tr>
 * <tr>
 * <td>Version</td>
 * <td>1.0</td>
 * </tr>
 * </table>
 * </p>
 * 
 * <p>
 * No parameters are needed for this operation.
 * 
 * @see javax.media.jai.OperationDescriptor
 * 
 */
public class NullDescriptor extends OperationDescriptorImpl {

    /**
     * The resource strings that provide the general documentation and specify the parameter list for this operation.
     */
    private static final String[][] resources = { { "GlobalName", "Null" },
            { "LocalName", "Null" }, { "Vendor", "it.geosolutions.jaiext" },
            { "Description", "Operation used for wrapping other images with no processing" },
            { "DocURL", "Not Defined" }, { "Version", "1.0" }, };

    private static final String[] supportedModes = { "rendered", "renderable" };

    /** Constructor. */
    public NullDescriptor() {
        super(resources, supportedModes, 1, null, null, null, null);
    }

    /**
     * If the PB has more than one source, replace it with a new PB which has only one source equal to the first source of the input. We want to
     * support an arbitrary number of sources but only care that there is at least one of the appropriate class.
     */
    private static ParameterBlock foolSourceValidation(ParameterBlock args) {
        if (args.getNumSources() > 1) {
            Vector singleSource = new Vector();
            singleSource.add(args.getSource(0));
            args = new ParameterBlock(singleSource, args.getParameters());
        }
        return args;
    }

    /**
     * Returns <code>true</code> if there is at least one source and the first source is a <code>RenderedImage</code> or <code>RenderableImage</code>.
     * 
     * @throws IllegalArgumentException if <code>args</code> is <code>null</code>.
     * @throws IllegalArgumentException if <code>msg</code> is <code>null</code> and the validation fails.
     */
    protected boolean validateSources(String modeName, ParameterBlock args, StringBuffer msg) {

        if (args == null || msg == null) {
            throw new IllegalArgumentException("No parameterBlock or StringBuffer present");
        }

        return super.validateSources(modeName, foolSourceValidation(args), msg);
    }

    /**
     * Calculates the region over which two distinct renderings of the "Null" operation may be expected to differ.
     * 
     * <p>
     * The operation returns an empty <code>Shape</code> if the first source in each of the two <code>ParameterBlock</code>s are equal according to
     * the <code>equals()</code> method of the old source or <code>null</code> for all other cases.
     * 
     * @param modeName The name of the mode.
     * @param oldParamBlock The previous sources and parameters.
     * @param oldHints The previous hints.
     * @param newParamBlock The current sources and parameters.
     * @param newHints The current hints.
     * @param node The affected node in the processing chain (ignored).
     * 
     * @return The region over which the data of two renderings of this operation may be expected to be invalid or <code>null</code> if there is no
     *         common region of validity. A non-<code>null</code> empty region indicates that the operation would produce identical data over the
     *         bounds of the old rendering although perhaps not over the area occupied by the <i>tiles</i> of the old rendering.
     * 
     * @throws IllegalArgumentException if <code>modeName</code> is <code>null</code> or if either <code>oldParamBlock</code> or
     *         <code>newParamBlock</code> is <code>null</code>.
     * @throws IllegalArgumentException if <code>oldParamBlock</code> or <code>newParamBlock</code> does not contain at least one source.
     */
    public Object getInvalidRegion(String modeName, ParameterBlock oldParamBlock,
            RenderingHints oldHints, ParameterBlock newParamBlock, RenderingHints newHints,
            OperationNode node) {
        if (modeName == null || oldParamBlock == null || newParamBlock == null) {
            throw new IllegalArgumentException("Some parameters are not defined");
        }

        if (oldParamBlock.getNumSources() < 1 || newParamBlock.getNumSources() < 1) {

            throw new IllegalArgumentException("No sources provided");
        }

        return oldParamBlock.getSource(0).equals(newParamBlock.getSource(0)) ? new Rectangle()
                : null;
    }

    /**
     * An operation which does no processing.
     * 
     * <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 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, RenderingHints hints) {
        // Selection of the parameterBlock associated with the Null operation
        ParameterBlockJAI pb = new ParameterBlockJAI("Null", RenderedRegistryMode.MODE_NAME);
        // Setting of the source
        pb.setSource("source0", source0);
        // Creation of the RenderedOp associated with the Null operation
        return JAI.create("Null", pb, hints);
    }

    /**
     * An operation which does no processing.
     * 
     * <p>
     * Creates a <code>ParameterBlockJAI</code> from all supplied arguments except <code>hints</code> and invokes
     * {@link JAI#createRenderable(String,ParameterBlock,RenderingHints)}.
     * 
     * @see JAI
     * @see ParameterBlockJAI
     * @see RenderableOp
     * 
     * @param source0 <code>RenderableImage</code> source 0.
     * @param hints The <code>RenderingHints</code> to use. May be <code>null</code>.
     * @return The <code>RenderableOp</code> destination.
     * @throws IllegalArgumentException if <code>source0</code> is <code>null</code>.
     */
    public static RenderableOp createRenderable(RenderableImage source0, RenderingHints hints) {
        // Selection of the parameterBlock associated with the Null operation
        ParameterBlockJAI pb = new ParameterBlockJAI("Null", RenderableRegistryMode.MODE_NAME);
        // Setting of the source
        pb.setSource("source0", source0);
        // Creation of the RenderabledOp associated with the Null operation
        return JAI.createRenderable("Null", pb, hints);
    }
}