parameterblock.java

java1.6众多例子参考

/*
 * @(#)ParameterBlock.java	1.15 05/11/17
 *
 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package java.awt.image.renderable;
import java.awt.image.RenderedImage;
import java.io.Serializable;
import java.util.Vector;

/**
 * A <code>ParameterBlock</code> encapsulates all the information about sources and
 * parameters (Objects) required by a RenderableImageOp, or other
 * classes that process images.
 *
 * <p> Although it is possible to place arbitrary objects in the
 * source Vector, users of this class may impose semantic constraints
 * such as requiring all sources to be RenderedImages or
 * RenderableImage.  <code>ParameterBlock</code> itself is merely a container and
 * performs no checking on source or parameter types.
 *
 * <p> All parameters in a <code>ParameterBlock</code> are objects; convenience
 * add and set methods are available that take arguments of base type and
 * construct the appropriate subclass of Number (such as
 * Integer or Float).  Corresponding get methods perform a
 * downward cast and have return values of base type; an exception
 * will be thrown if the stored values do not have the correct type.
 * There is no way to distinguish between the results of 
 * "short s; add(s)" and "add(new Short(s))".
 *
 * <p> Note that the get and set methods operate on references.
 * Therefore, one must be careful not to share references between
 * <code>ParameterBlock</code>s when this is inappropriate.  For example, to create
 * a new <code>ParameterBlock</code> that is equal to an old one except for an
 * added source, one might be tempted to write:
 *
 * <pre>
 * ParameterBlock addSource(ParameterBlock pb, RenderableImage im) {
 *     ParameterBlock pb1 = new ParameterBlock(pb.getSources());
 *     pb1.addSource(im);
 *     return pb1;
 * }
 * </pre>
 *
 * <p> This code will have the side effect of altering the original
 * <code>ParameterBlock</code>, since the getSources operation returned a reference
 * to its source Vector.  Both pb and pb1 share their source Vector,
 * and a change in either is visible to both.
 *
 * <p> A correct way to write the addSource function is to clone
 * the source Vector:
 *
 * <pre>
 * ParameterBlock addSource (ParameterBlock pb, RenderableImage im) {
 *     ParameterBlock pb1 = new ParameterBlock(pb.getSources().clone());
 *     pb1.addSource(im);
 *     return pb1;
 * }
 * </pre>
 *
 * <p> The clone method of <code>ParameterBlock</code> has been defined to
 * perform a clone of both the source and parameter Vectors for
 * this reason.  A standard, shallow clone is available as
 * shallowClone.
 *
 * <p> The addSource, setSource, add, and set methods are
 * defined to return 'this' after adding their argument.  This allows
 * use of syntax like:
 *
 * <pre>
 * ParameterBlock pb = new ParameterBlock();
 * op = new RenderableImageOp("operation", pb.add(arg1).add(arg2));
 * </pre>
 * */
public class ParameterBlock implements Cloneable, Serializable {
    /** A Vector of sources, stored as arbitrary Objects. */
    protected Vector<Object> sources = new Vector<Object>();
    
    /** A Vector of non-source parameters, stored as arbitrary Objects. */
    protected Vector<Object> parameters = new Vector<Object>();

    /** A dummy constructor. */
    public ParameterBlock() {}

    /** 
     * Constructs a <code>ParameterBlock</code> with a given Vector 
     * of sources. 
     * @param sources a <code>Vector</code> of source images
     */
    public ParameterBlock(Vector<Object> sources) {
        setSources(sources);
    }
    
    /**
     * Constructs a <code>ParameterBlock</code> with a given Vector of sources and
     * Vector of parameters.
     * @param sources a <code>Vector</code> of source images
     * @param parameters a <code>Vector</code> of parameters to be used in the
     *        rendering operation
     */
    public ParameterBlock(Vector<Object> sources,
			  Vector<Object> parameters)
    {
        setSources(sources);
        setParameters(parameters);
    }
    
    /**
     * Creates a shallow copy of a <code>ParameterBlock</code>.  The source and
     * parameter Vectors are copied by reference -- additions or
     * changes will be visible to both versions.
     *
     * @return an Object clone of the <code>ParameterBlock</code>.
     */
    public Object shallowClone() {
        try {
            return super.clone();
        } catch (Exception e) {
            // We can't be here since we implement Cloneable.
            return null;
        }
    }

    /**
     * Creates a copy of a <code>ParameterBlock</code>.  The source and parameter
     * Vectors are cloned, but the actual sources and parameters are
     * copied by reference.  This allows modifications to the order
     * and number of sources and parameters in the clone to be invisible
     * to the original <code>ParameterBlock</code>.  Changes to the shared sources or
     * parameters themselves will still be visible.
     *
     * @return an Object clone of the <code>ParameterBlock</code>.
     */
    public Object clone() {
        ParameterBlock theClone;

        try {
            theClone = (ParameterBlock) super.clone();
        } catch (Exception e) {
            // We can't be here since we implement Cloneable.
            return null;
        }

        if (sources != null) {
            theClone.setSources((Vector)sources.clone());
        }
        if (parameters != null) {
            theClone.setParameters((Vector)parameters.clone());
        }
        return (Object) theClone;
    }

    /**
     * Adds an image to end of the list of sources.  The image is
     * stored as an object in order to allow new node types in the
     * future.
     *
     * @param source an image object to be stored in the source list.
     * @return a new <code>ParameterBlock</code> containing the specified
     *         <code>source</code>.
     */
    public ParameterBlock addSource(Object source) {
        sources.addElement(source);
        return this;
    }
    
    /**
     * Returns a source as a general Object.  The caller must cast it into
     * an appropriate type.
     *
     * @param index the index of the source to be returned.
     * @return an <code>Object</code> that represents the source located
     *         at the specified index in the <code>sources</code>
     *         <code>Vector</code>.
     * @see #setSource(Object, int)
     */
    public Object getSource(int index) {
        return sources.elementAt(index);
    }

    /**
     * Replaces an entry in the list of source with a new source.
     * If the index lies beyond the current source list,
     * the list is extended with nulls as needed.
     * @param source the specified source image
     * @param index the index into the <code>sources</code> 
     *              <code>Vector</code> at which to
     *              insert the specified <code>source</code>
     * @return a new <code>ParameterBlock</code> that contains the
     *         specified <code>source</code> at the specified
     *         <code>index</code>.
     * @see #getSource(int)
     */
    public ParameterBlock setSource(Object source, int index) {
        int oldSize = sources.size();
        int newSize = index + 1;
        if (oldSize < newSize) {
            sources.setSize(newSize);
        }
        sources.setElementAt(source, index);
        return this;
    }
    
    /**
     * Returns a source as a <code>RenderedImage</code>.  This method is 
     * a convenience method.
     * An exception will be thrown if the source is not a RenderedImage.
     *
     * @param index the index of the source to be returned
     * @return a <code>RenderedImage</code> that represents the source
     *         image that is at the specified index in the 
     *         <code>sources</code> <code>Vector</code>.
     */
    public RenderedImage getRenderedSource(int index) {
        return (RenderedImage) sources.elementAt(index);
    }
    
    /**
     * Returns a source as a RenderableImage.  This method is a
     * convenience method.
     * An exception will be thrown if the sources is not a RenderableImage.
     *
     * @param index the index of the source to be returned
     * @return a <code>RenderableImage</code> that represents the source
     *         image that is at the specified index in the 
     *         <code>sources</code> <code>Vector</code>.
     */
    public RenderableImage getRenderableSource(int index) {
        return (RenderableImage) sources.elementAt(index);
    }

    /** 
     * Returns the number of source images. 
     * @return the number of source images in the <code>sources</code>
     *         <code>Vector</code>.
     */
    public int getNumSources() {
        return sources.size();
    }
    
    /** 
     * Returns the entire Vector of sources. 
     * @return the <code>sources</code> <code>Vector</code>.  
     * @see #setSources(Vector)  
     */
    public Vector<Object> getSources() {
        return sources;
    }
    
    /** 
     * Sets the entire Vector of sources to a given Vector. 
     * @param sources the <code>Vector</code> of source images
     * @see #getSources
     */
    public void setSources(Vector<Object> sources) {
        this.sources = sources;
    }
    
    /** Clears the list of source images. */
    public void removeSources() {
        sources = new Vector();
    }
    
    /** 
     * Returns the number of parameters (not including source images).
     * @return the number of parameters in the <code>parameters</code>
     *         <code>Vector</code>.
     */
    public int getNumParameters() {
        return parameters.size();
    }
    
    /** 
     * Returns the entire Vector of parameters. 
     * @return the <code>parameters</code> <code>Vector</code>.
     * @see #setParameters(Vector)
     */
    public Vector<Object> getParameters() {
        return parameters;
    }
    
    /** 
     * Sets the entire Vector of parameters to a given Vector. 
     * @param parameters the specified <code>Vector</code> of
     *        parameters
     * @see #getParameters
     */
    public void setParameters(Vector<Object> parameters) {
        this.parameters = parameters;
    }
    
    /** Clears the list of parameters. */
    public void removeParameters() {
        parameters = new Vector();
    }
    
    /** 
     * Adds an object to the list of parameters. 
     * @param obj the <code>Object</code> to add to the 
     *            <code>parameters</code> <code>Vector</code>
     * @return a new <code>ParameterBlock</code> containing 
     *         the specified parameter.
     */
    public ParameterBlock add(Object obj) {
        parameters.addElement(obj);
        return this;
    }

    /** 
     * Adds a Byte to the list of parameters. 
     * @param b the byte to add to the 
     *            <code>parameters</code> <code>Vector</code>
     * @return a new <code>ParameterBlock</code> containing 
     *         the specified parameter.
     */
    public ParameterBlock add(byte b) {
        return add(new Byte(b));
    }
    
    /** 
     * Adds a Character to the list of parameters. 
     * @param c the char to add to the 
     *            <code>parameters</code> <code>Vector</code>
     * @return a new <code>ParameterBlock</code> containing 
     *         the specified parameter.
     */
    public ParameterBlock add(char c) {
        return add(new Character(c));
    }
    
    /** 
     * Adds a Short to the list of parameters. 
     * @param s the short to add to the 
     *            <code>parameters</code> <code>Vector</code>
     * @return a new <code>ParameterBlock</code> containing 
     *         the specified parameter.
     */
    public ParameterBlock add(short s) {
        return add(new Short(s));
    }
    
    /** 
     * Adds a Integer to the list of parameters. 
     * @param i the int to add to the 
     *            <code>parameters</code> <code>Vector</code>
     * @return a new <code>ParameterBlock</code> containing 
     *         the specified parameter.
     */
    public ParameterBlock add(int i) {
        return add(new Integer(i));
    }