001/* ===========================================================
002 * JFreeChart : a free chart library for the Java(tm) platform
003 * ===========================================================
004 *
005 * (C) Copyright 2000-present, by David Gilbert and Contributors.
006 *
007 * Project Info:  http://www.jfree.org/jfreechart/index.html
008 *
009 * This library is free software; you can redistribute it and/or modify it
010 * under the terms of the GNU Lesser General Public License as published by
011 * the Free Software Foundation; either version 2.1 of the License, or
012 * (at your option) any later version.
013 *
014 * This library is distributed in the hope that it will be useful, but
015 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
016 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
017 * License for more details.
018 *
019 * You should have received a copy of the GNU Lesser General Public
020 * License along with this library; if not, write to the Free Software
021 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
022 * USA.
023 *
024 * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. 
025 * Other names may be trademarks of their respective owners.]
026 *
027 * -----------------------------
028 * PieSectionLabelGenerator.java
029 * -----------------------------
030 * (C) Copyright 2001-present, by David Gilbert.
031 *
032 * Original Author:  David Gilbert;
033 * Contributor(s):   -;
034 *
035 */
036
037package org.jfree.chart.labels;
038
039import java.awt.Font;
040import java.awt.Paint;
041import java.awt.font.TextAttribute;
042import java.text.AttributedString;
043
044import org.jfree.data.general.PieDataset;
045
046/**
047 * Interface for a label generator for plots that use data from
048 * a {@link PieDataset}.
049 */
050public interface PieSectionLabelGenerator {
051
052    /**
053     * Generates a label for a pie section.
054     *
055     * @param dataset  the dataset ({@code null} not permitted).
056     * @param key  the section key ({@code null} not permitted).
057     *
058     * @return The label (possibly {@code null}).
059     */
060    String generateSectionLabel(PieDataset dataset, Comparable key);
061
062    /**
063     * Generates an attributed label for the specified series, or
064     * {@code null} if no attributed label is available (in which case,
065     * the string returned by
066     * {@link #generateSectionLabel(PieDataset, Comparable)} will
067     * provide the fallback).  Only certain attributes are recognised by the
068     * code that ultimately displays the labels:
069     * <ul>
070     * <li>{@link TextAttribute#FONT}: will set the font;</li>
071     * <li>{@link TextAttribute#POSTURE}: a value of
072     *     {@link TextAttribute#POSTURE_OBLIQUE} will add {@link Font#ITALIC} to
073     *     the current font;</li>
074     * <li>{@link TextAttribute#WEIGHT}: a value of
075     *     {@link TextAttribute#WEIGHT_BOLD} will add {@link Font#BOLD} to the
076     *     current font;</li>
077     * <li>{@link TextAttribute#FOREGROUND}: this will set the {@link Paint}
078     *     for the current</li>
079     * <li>{@link TextAttribute#SUPERSCRIPT}: the values
080     *     {@link TextAttribute#SUPERSCRIPT_SUB} and
081     *     {@link TextAttribute#SUPERSCRIPT_SUPER} are recognised.</li>
082     * </ul>
083     *
084     * @param dataset  the dataset.
085     * @param key  the key.
086     *
087     * @return An attributed label (possibly {@code null}).
088     */
089    AttributedString generateAttributedSectionLabel(PieDataset dataset,
090                                                    Comparable key);
091
092}