swing/plaf/ListUI.java

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
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 *
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package javax.swing.plaf;

import javax.swing.JList;
import java.awt.Point;
import java.awt.Rectangle;


/**
 * The {@code JList} pluggable look and feel delegate.
 *
 * @author Hans Muller
 */

public abstract class ListUI extends ComponentUI
{
    /**
     * Returns the cell index in the specified {@code JList} closest to the
     * given location in the list's coordinate system. To determine if the
     * cell actually contains the specified location, compare the point against
     * the cell's bounds, as provided by {@code getCellBounds}.
     * This method returns {@code -1} if the list's model is empty.
     *
     * @param list the list
     * @param location the coordinates of the point
     * @return the cell index closest to the given location, or {@code -1}
     * @throws NullPointerException if {@code location} is null
     */
    public abstract int locationToIndex(JList list, Point location);


    /**
     * Returns the origin in the given {@code JList}, of the specified item,
     * in the list's coordinate system.
     * Returns {@code null} if the index isn't valid.
     *
     * @param list the list
     * @param index the cell index
     * @return the origin of the cell, or {@code null}
     */
    public abstract Point indexToLocation(JList list, int index);


    /**
     * Returns the bounding rectangle, in the given list's coordinate system,
     * for the range of cells specified by the two indices.
     * The indices can be supplied in any order.
     * <p>
     * If the smaller index is outside the list's range of cells, this method
     * returns {@code null}. If the smaller index is valid, but the larger
     * index is outside the list's range, the bounds of just the first index
     * is returned. Otherwise, the bounds of the valid range is returned.
     *
     * @param list the list
     * @param index1 the first index in the range
     * @param index2 the second index in the range
     * @return the bounding rectangle for the range of cells, or {@code null}
     */
    public abstract Rectangle getCellBounds(JList list, int index1, int index2);
}