canvashandler.java

GEo 地理操作源代码

/**************************************************************************************************
 **
 ** $Id: CanvasHandler.java,v 1.1 2004/03/02 03:14:41 gregreynolds Exp $
 **
 ** $Source: /cvsroot/geoapi/src/org/opengis/go/display/canvas/CanvasHandler.java,v $
 **
 ** Copyright (C) 2003 Open GIS Consortium, Inc. All Rights Reserved. http://www.opengis.org/Legal/
 **
 *************************************************************************************************/
package org.opengis.go.display.canvas;

/**
 * The <code>CanvasHandler</code> interface provides programmers with a 
 * mechanism to change <code>Canvas</code> properties.  When a handler is 
 * passed in to <code>Canvas.enableHandler(CanvasHandler)</code>, the 
 * <code>Canvas</code> will give it the active 
 * <code>CanvasController</code>.  The active controller allows the handler to
 * change the canvas, until the handler is removed.
 *
 * @author Open GIS Consortium, Inc.
 * @version $Revision: 1.1 $, $Date: 2004/03/02 03:14:41 $
 */
public interface CanvasHandler {

    /**
     * Enables this <code>CanvasHandler</code>, giving it the active 
     * <code>CanvasController<code> and thus the ability to modify the 
     * <code>Canvas</code> that enabled it.
     * @param controller the active <code>CanvasController</code>.
     */
    public void handlerEnabled(CanvasController controller);

    /**
     * Removes this <code>CanvasHandler</code>, meaning that calling methods
     * on its <code>CanvasController</code> will no longer affect the 
     * <code>Canvas</code>.  A <code>CanvasHandler</code> should 
     * <b>never</b> attempt to re-enable itself after it has been removed.
     */
    public void handlerRemoved();

}