    001    /* ===========================================================
    002     * JFreeChart : a free chart library for the Java(tm) platform
    003     * ===========================================================
    004     *
    005     * (C) Copyright 2000-2008, by Object Refinery Limited 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     * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
    025     * in the United States and other countries.]
    026     *
    027     * ------------------
    028     * LineUtilities.java
    029     * ------------------
    030     * (C) Copyright 2008, by Object Refinery Limited and Contributors.
    031     *
    032     * Original Author:  David Gilbert (for Object Refinery Limited);
    033     * Contributor(s):   -;
    034     *
    035     * Changes
    036     * -------
    037     * 05-Nov-2008 : Version 1 (DG);
    038     *
    039     */
    040
    041    package org.jfree.chart.util;
    042
    043    import java.awt.geom.Line2D;
    044    import java.awt.geom.Rectangle2D;
    045
    046    /**
    047     * Some utility methods for {@link Line2D} objects.
    048     *
    049     * @since 1.0.12
    050     */
    051    public class LineUtilities {
    052
    053        /**
    054         * Clips the specified line to the given rectangle.
    055         *
    056         * @param line  the line (<code>null</code> not permitted).
    057         * @param rect  the clipping rectangle (<code>null</code> not permitted).
    058         *
    059         * @return <code>true</code> if the clipped line is visible, and
    060         *     <code>false</code> otherwise.
    061         */
    062        public static boolean clipLine(Line2D line, Rectangle2D rect) {
    063
    064            double x1 = line.getX1();
    065            double y1 = line.getY1();
    066            double x2 = line.getX2();
    067            double y2 = line.getY2();
    068
    069            double minX = rect.getMinX();
    070            double maxX = rect.getMaxX();
    071            double minY = rect.getMinY();
    072            double maxY = rect.getMaxY();
    073
    074            int f1 = rect.outcode(x1, y1);
    075            int f2 = rect.outcode(x2, y2);
    076
    077            while ((f1 | f2) != 0) {
    078                if ((f1 & f2) != 0) {
    079                    return false;
    080                }
    081                double dx = (x2 - x1);
    082                double dy = (y2 - y1);
    083                // update (x1, y1), (x2, y2) and f1 and f2 using intersections
    084                // then recheck
    085                if (f1 != 0) {
    086                    // first point is outside, so we update it against one of the
    087                    // four sides then continue
    088                    if ((f1 & Rectangle2D.OUT_LEFT) == Rectangle2D.OUT_LEFT
    089                            && dx != 0.0) {
    090                        y1 = y1 + (minX - x1) * dy / dx;
    091                        x1 = minX;
    092                    }
    093                    else if ((f1 & Rectangle2D.OUT_RIGHT) == Rectangle2D.OUT_RIGHT
    094                            && dx != 0.0) {
    095                        y1 = y1 + (maxX - x1) * dy / dx;
    096                        x1 = maxX;
    097                    }
    098                    else if ((f1 & Rectangle2D.OUT_BOTTOM) == Rectangle2D.OUT_BOTTOM
    099                            && dy != 0.0) {
    100                        x1 = x1 + (maxY - y1) * dx / dy;
    101                        y1 = maxY;
    102                    }
    103                    else if ((f1 & Rectangle2D.OUT_TOP) == Rectangle2D.OUT_TOP
    104                            && dy != 0.0) {
    105                        x1 = x1 + (minY - y1) * dx / dy;
    106                        y1 = minY;
    107                    }
    108                    f1 = rect.outcode(x1, y1);
    109                }
    110                else if (f2 != 0) {
    111                    // second point is outside, so we update it against one of the
    112                    // four sides then continue
    113                    if ((f2 & Rectangle2D.OUT_LEFT) == Rectangle2D.OUT_LEFT
    114                            && dx != 0.0) {
    115                        y2 = y2 + (minX - x2) * dy / dx;
    116                        x2 = minX;
    117                    }
    118                    else if ((f2 & Rectangle2D.OUT_RIGHT) == Rectangle2D.OUT_RIGHT
    119                            && dx != 0.0) {
    120                        y2 = y2 + (maxX - x2) * dy / dx;
    121                        x2 = maxX;
    122                    }
    123                    else if ((f2 & Rectangle2D.OUT_BOTTOM) == Rectangle2D.OUT_BOTTOM
    124                            && dy != 0.0) {
    125                        x2 = x2 + (maxY - y2) * dx / dy;
    126                        y2 = maxY;
    127                    }
    128                    else if ((f2 & Rectangle2D.OUT_TOP) == Rectangle2D.OUT_TOP
    129                            && dy != 0.0) {
    130                        x2 = x2 + (minY - y2) * dx / dy;
    131                        y2 = minY;
    132                    }
    133                    f2 = rect.outcode(x2, y2);
    134                }
    135            }
    136
    137            line.setLine(x1, y1, x2, y2);
    138            return true;  // the line is visible - if it wasn't, we'd have
    139                          // returned false from within the while loop above
    140
    141        }
    142    }