autoscroll.java

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/*
 * @(#)Autoscroll.java	1.12 03/01/23
 *
 * Copyright 2003 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package java.awt.dnd;

import java.awt.Insets;
import java.awt.Point;

/**
 * During DnD operations it is possible that a user may wish to drop the 
 * subject of the operation on a region of a scrollable GUI control that is
 * not currently visible to the user.
 * <p>
 * In such situations it is desirable that the GUI control detect this
 * and institute a scroll operation in order to make obscured region(s)
 * visible to the user. This feature is known as autoscrolling.
 * <p>
 * If a GUI control is both an active <code>DropTarget</code>
 * and is also scrollable, it
 * can receive notifications of autoscrolling gestures by the user from
 * the DnD system by implementing this interface.
 * <p>
 * An autoscrolling gesture is initiated by the user by keeping the drag
 * cursor motionless with a border region of the <code>Component</code>, 
 * referred to as
 * the "autoscrolling region", for a predefined period of time, this will
 * result in repeated scroll requests to the <code>Component</code> 
 * until the drag <code>Cursor</code> resumes its motion.
 *
 * @version 	1.12, 01/23/03
 * @since 1.2
 */

public interface Autoscroll {

    /**
     * This method returns the <code>Insets</code> describing 
     * the autoscrolling region or border relative
     * to the geometry of the implementing Component.
     * <P>
     * This value is read once by the <code>DropTarget</code> 
     * upon entry of the drag <code>Cursor</code>
     * into the associated <code>Component</code>.
     * <P>
     * @return the Insets
     */

    public Insets getAutoscrollInsets();

    /**
     * notify the <code>Component</code> to autoscroll
     * <P>
     * @param cursorLocn A <code>Point</code> indicating the 
     * location of the cursor that triggered this operation.
     */

    public void autoscroll(Point cursorLocn);

}