001/* ===========================================================
002 * JFreeChart : a free chart library for the Java(tm) platform
003 * ===========================================================
004 *
005 * (C) Copyright 2000-2021, 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 * [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 * LineUtils.java
029 * --------------
030 * (C) Copyright 2008-2021, by Object Refinery Limited and Contributors.
031 *
032 * Original Author:  David Gilbert (for Object Refinery Limited);
033 * Contributor(s):   -;
034 *
035 */
036
037package org.jfree.chart.util;
038
039import java.awt.geom.Line2D;
040import java.awt.geom.Rectangle2D;
041
042/**
043 * Some utility methods for {@link Line2D} objects.
044 */
045public class LineUtils {
046
047    /**
048     * Clips the specified line to the given rectangle.
049     *
050     * @param line  the line ({@code null} not permitted).
051     * @param rect  the clipping rectangle ({@code null} not permitted).
052     *
053     * @return {@code true} if the clipped line is visible, and
054     *     {@code false} otherwise.
055     */
056    public static boolean clipLine(Line2D line, Rectangle2D rect) {
057
058        double x1 = line.getX1();
059        double y1 = line.getY1();
060        double x2 = line.getX2();
061        double y2 = line.getY2();
062
063        double minX = rect.getMinX();
064        double maxX = rect.getMaxX();
065        double minY = rect.getMinY();
066        double maxY = rect.getMaxY();
067
068        int f1 = rect.outcode(x1, y1);
069        int f2 = rect.outcode(x2, y2);
070
071        while ((f1 | f2) != 0) {
072            if ((f1 & f2) != 0) {
073                return false;
074            }
075            double dx = (x2 - x1);
076            double dy = (y2 - y1);
077            // update (x1, y1), (x2, y2) and f1 and f2 using intersections
078            // then recheck
079            if (f1 != 0) {
080                // first point is outside, so we update it against one of the
081                // four sides then continue
082                if ((f1 & Rectangle2D.OUT_LEFT) == Rectangle2D.OUT_LEFT
083                        && dx != 0.0) {
084                    y1 = y1 + (minX - x1) * dy / dx;
085                    x1 = minX;
086                }
087                else if ((f1 & Rectangle2D.OUT_RIGHT) == Rectangle2D.OUT_RIGHT
088                        && dx != 0.0) {
089                    y1 = y1 + (maxX - x1) * dy / dx;
090                    x1 = maxX;
091                }
092                else if ((f1 & Rectangle2D.OUT_BOTTOM) == Rectangle2D.OUT_BOTTOM
093                        && dy != 0.0) {
094                    x1 = x1 + (maxY - y1) * dx / dy;
095                    y1 = maxY;
096                }
097                else if ((f1 & Rectangle2D.OUT_TOP) == Rectangle2D.OUT_TOP
098                        && dy != 0.0) {
099                    x1 = x1 + (minY - y1) * dx / dy;
100                    y1 = minY;
101                }
102                f1 = rect.outcode(x1, y1);
103            }
104            else if (f2 != 0) {
105                // second point is outside, so we update it against one of the
106                // four sides then continue
107                if ((f2 & Rectangle2D.OUT_LEFT) == Rectangle2D.OUT_LEFT
108                        && dx != 0.0) {
109                    y2 = y2 + (minX - x2) * dy / dx;
110                    x2 = minX;
111                }
112                else if ((f2 & Rectangle2D.OUT_RIGHT) == Rectangle2D.OUT_RIGHT
113                        && dx != 0.0) {
114                    y2 = y2 + (maxX - x2) * dy / dx;
115                    x2 = maxX;
116                }
117                else if ((f2 & Rectangle2D.OUT_BOTTOM) == Rectangle2D.OUT_BOTTOM
118                        && dy != 0.0) {
119                    x2 = x2 + (maxY - y2) * dx / dy;
120                    y2 = maxY;
121                }
122                else if ((f2 & Rectangle2D.OUT_TOP) == Rectangle2D.OUT_TOP
123                        && dy != 0.0) {
124                    x2 = x2 + (minY - y2) * dx / dy;
125                    y2 = minY;
126                }
127                f2 = rect.outcode(x2, y2);
128            }
129        }
130
131        line.setLine(x1, y1, x2, y2);
132        return true;  // the line is visible - if it wasn't, we'd have
133                      // returned false from within the while loop above
134
135    }
136    
137    /**
138     * Creates a new line by extending an existing line.
139     *
140     * @param line  the line ({@code null} not permitted).
141     * @param startPercent  the amount to extend the line at the start point
142     *                      end.
143     * @param endPercent  the amount to extend the line at the end point end.
144     *
145     * @return A new line.
146     */
147    public static Line2D extendLine(Line2D line, double startPercent,
148                              double endPercent) {
149        Args.nullNotPermitted(line, "line");
150        double x1 = line.getX1();
151        double x2 = line.getX2();
152        double deltaX = x2 - x1;
153        double y1 = line.getY1();
154        double y2 = line.getY2();
155        double deltaY = y2 - y1;
156        x1 = x1 - (startPercent * deltaX);
157        y1 = y1 - (startPercent * deltaY);
158        x2 = x2 + (endPercent * deltaX);
159        y2 = y2 + (endPercent * deltaY);
160        return new Line2D.Double(x1, y1, x2, y2);
161    }
162
163}