nullhandle.java

来自「开源（Open Source）项目JHotDraw的文档和源程序」· Java 代码 · 共 44 行

/*
 * @(#)NullHandle.java 5.2
 *
 */

package CH.ifa.draw.standard;

import java.awt.*;
import CH.ifa.draw.framework.*;

/**
 * A handle that doesn't change the owned figure. Its only purpose is
 * to show feedback that a figure is selected.
 * <hr>
 * <b>Design Patterns</b><P>
 * <img src="images/red-ball-small.gif" width=6 height=6 alt=" o ">
 * <b>NullObject</b><br>
 * NullObject enables to treat handles that don't do
 * anything in the same way as other handles.
 *
 */
public class NullHandle extends LocatorHandle {

    /**
     * The handle's locator.
     */
    protected Locator fLocator;

    public NullHandle(Figure owner, Locator locator) {
        super(owner, locator);
    }

    /**
     * Draws the NullHandle. NullHandles are drawn as a
     * red framed rectangle.
     */
    public void draw(Graphics g) {
        Rectangle r = displayBox();

        g.setColor(Color.black);
        g.drawRect(r.x, r.y, r.width, r.height);
    }
}