shadowrenderer.java

JAVA图形特效,详细介绍SWING等的效果开发

/*
 * $Id: ShadowRenderer.java,v 1.1 2007/01/15 23:39:23 gfx Exp $
 *
 * Copyright 2006 Sun Microsystems, Inc., 4150 Network Circle,
 * Santa Clara, California 95054, U.S.A. All rights reserved.
 *
 * Licensed under LGPL.
 */

import java.awt.Color;
import java.awt.image.BufferedImage;
import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;

/**
 * <p>A shadow renderer generates a drop shadow for any given picture, respecting
 * the transparency channel if present. The resulting picture contains the
 * shadow only and to create a drop shadow effect you will need to stack the
 * original picture and the shadow generated by the renderer.</p>
 * <h2>Shadow Properties</h2>
 * <p>A shadow is defined by three properties:
 * <ul>
 *   <li><i>size</i>: The size, in pixels, of the shadow. This property also
 *   defines the fuzzyness.</li>
 *   <li><i>opacity</i>: The opacity, between 0.0 and 1.0, of the shadow.</li>
 *   <li><i>color</i>: The color of the shadow. Shadows are not meant to be
 *   black only.</li>
 * </ul>
 * You can set these properties using the provided mutaters or the appropriate
 * constructor. Here are two ways of creating a green shadow of size 10 and
 * with an opacity of 50%:
 * <pre>
 * ShadowRenderer renderer = new ShadowRenderer(10, 0.5f, Color.GREEN);
 * // ..
 * renderer = new ShadowRenderer();
 * renderer.setSize(10);
 * renderer.setOpacity(0.5f);
 * renderer.setColor(Color.GREEN);
 * </pre>
 * The default constructor provides the following default values:
 * <ul>
 *   <li><i>size</i>: 5 pixels</li>
 *   <li><i>opacity</i>: 50%</li>
 *   <li><i>color</i>: Black</li>
 * </ul></p>
 * <h2>Generating a Shadow</h2>
 * <p>A shadow is generated as a <code>BufferedImage</code> from another
 * <code>BufferedImage</code>. Once the renderer is set up, you must call
 * {@link #createShadow} to actually generate the shadow:
 * <pre>
 * ShadowRenderer renderer = new ShadowRenderer();
 * // renderer setup
 * BufferedImage shadow = renderer.createShadow(bufferedImage);
 * </pre></p>
 * <p>The generated image dimensions are computed as following:</p>
 * <pre>
 * width  = imageWidth  + 2 * shadowSize
 * height = imageHeight + 2 * shadowSize
 * </pre>
 * <h2>Properties Changes</h2>
 * <p>This renderer allows to register property change listeners with
 * {@link #addPropertyChangeListener}. Listening to properties changes is very
 * useful when you emebed the renderer in a graphical component and give the API
 * user the ability to access the renderer. By listening to properties changes,
 * you can easily repaint the component when needed.</p>
 * <h2>Threading Issues</h2>
 * <p><code>ShadowRenderer</code> is not guaranteed to be thread-safe.</p>
 * 
 * @author Romain Guy <[e-mail]>
 * @author Sebastien Petrucci
 */
public class ShadowRenderer {
    /**
     * <p>Identifies a change to the size used to render the shadow.</p>
     * <p>When the property change event is fired, the old value and the new
     * value are provided as <code>Integer</code> instances.</p>
     */
    public static final String SIZE_CHANGED_PROPERTY = "shadow_size";
    
    /**
     * <p>Identifies a change to the opacity used to render the shadow.</p>
     * <p>When the property change event is fired, the old value and the new
     * value are provided as <code>Float</code> instances.</p>
     */
    public static final String OPACITY_CHANGED_PROPERTY = "shadow_opacity";
    
    /**
     * <p>Identifies a change to the color used to render the shadow.</p>
     */
    public static final String COLOR_CHANGED_PROPERTY = "shadow_color";

    // size of the shadow in pixels (defines the fuzziness)
    private int size = 5;
    
    // opacity of the shadow
    private float opacity = 0.5f;
    
    // color of the shadow
    private Color color = Color.BLACK;
    
    // notifies listeners of properties changes
    private PropertyChangeSupport changeSupport;

    /**
     * <p>Creates a default good looking shadow generator.
     * The default shadow renderer provides the following default values:
     * <ul>
     *   <li><i>size</i>: 5 pixels</li>
     *   <li><i>opacity</i>: 50%</li>
     *   <li><i>color</i>: Black</li>
     * </ul></p>
     * <p>These properties provide a regular, good looking shadow.</p>
     */
    public ShadowRenderer() {
        this(5, 0.5f, Color.BLACK);
    }
    
    /**
     * <p>A shadow renderer needs three properties to generate shadows.
     * These properties are:</p> 
     * <ul>
     *   <li><i>size</i>: The size, in pixels, of the shadow. This property also
     *   defines the fuzzyness.</li>
     *   <li><i>opacity</i>: The opacity, between 0.0 and 1.0, of the shadow.</li>
     *   <li><i>color</i>: The color of the shadow. Shadows are not meant to be
     *   black only.</li>
     * </ul>
     * @param size the size of the shadow in pixels. Defines the fuzziness.
     * @param opacity the opacity of the shadow.
     * @param color the color of the shadow.
     */
    public ShadowRenderer(final int size, final float opacity, final Color color) {
        //noinspection ThisEscapedInObjectConstruction
        changeSupport = new PropertyChangeSupport(this);

        setSize(size);
        setOpacity(opacity);
        setColor(color);
    }

    /**
     * <p>Add a PropertyChangeListener to the listener list. The listener is
     * registered for all properties. The same listener object may be added
     * more than once, and will be called as many times as it is added. If
     * <code>listener</code> is null, no exception is thrown and no action
     * is taken.</p> 
     * @param listener the PropertyChangeListener to be added
     */
    public void addPropertyChangeListener(PropertyChangeListener listener) {
        changeSupport.addPropertyChangeListener(listener);
    }

    /**
     * <p>Remove a PropertyChangeListener from the listener list. This removes
     * a PropertyChangeListener that was registered for all properties. If
     * <code>listener</code> was added more than once to the same event source,
     * it will be notified one less time after being removed. If
     * <code>listener</code> is null, or was never added, no exception is thrown
     * and no action is taken.</p>
     * @param listener the PropertyChangeListener to be removed
     */
    public void removePropertyChangeListener(PropertyChangeListener listener) {
        changeSupport.removePropertyChangeListener(listener);
    }

    /**
     * <p>Gets the color used by the renderer to generate shadows.</p>
     * @return this renderer's shadow color
     */
    public Color getColor() {
        return color;
    }

    /**
     * <p>Sets the color used by the renderer to generate shadows.</p>
     * <p>Consecutive calls to {@link #createShadow} will all use this color
     * until it is set again.</p>
     * <p>If the color provided is null, the previous color will be retained.</p>
     * @param shadowColor the generated shadows color
     */
    public void setColor(final Color shadowColor) {
        if (shadowColor != null) {
            Color oldColor = this.color;
            this.color = shadowColor;
            changeSupport.firePropertyChange(COLOR_CHANGED_PROPERTY,
                                             oldColor,
                                             this.color);
        }
    }

    /**
     * <p>Gets the opacity used by the renderer to generate shadows.</p>
     * <p>The opacity is comprised between 0.0f and 1.0f; 0.0f being fully
     * transparent and 1.0f fully opaque.</p>
     * @return this renderer's shadow opacity
     */
    public float getOpacity() {
        return opacity;
    }

    /**
     * <p>Sets the opacity used by the renderer to generate shadows.</p>
     * <p>Consecutive calls to {@link #createShadow} will all use this opacity
     * until it is set again.</p>
     * <p>The opacity is comprised between 0.0f and 1.0f; 0.0f being fully
     * transparent and 1.0f fully opaque. If you provide a value out of these
     * boundaries, it will be restrained to the closest boundary.</p>