Java tutorial
/* =========================================================== * JFreeChart : a free chart library for the Java(tm) platform * =========================================================== * * (C) Copyright 2000-2014, by Object Refinery Limited and Contributors. * * Project Info: http://www.jfree.org/jfreechart/index.html * * This library is free software; you can redistribute it and/or modify it * under the terms of the GNU Lesser General Public License as published by * the Free Software Foundation; either version 2.1 of the License, or * (at your option) any later version. * * This library 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 Lesser General Public * License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, * USA. * * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. * Other names may be trademarks of their respective owners.] * * ------------------ * LineUtilities.java * ------------------ * (C) Copyright 2008, 2014, by Object Refinery Limited and Contributors. * * Original Author: David Gilbert (for Object Refinery Limited); * Contributor(s): -; * * Changes * ------- * 05-Nov-2008 : Version 1 (DG); * 28-Feb-2014 : Added extendLine() (DG); * */ package org.jfree.chart.util; import java.awt.geom.Line2D; import java.awt.geom.Rectangle2D; /** * Some utility methods for {@link Line2D} objects. * * @since 1.0.12 */ public class LineUtilities { /** * Clips the specified line to the given rectangle. * * @param line the line (<code>null</code> not permitted). * @param rect the clipping rectangle (<code>null</code> not permitted). * * @return <code>true</code> if the clipped line is visible, and * <code>false</code> otherwise. */ public static boolean clipLine(Line2D line, Rectangle2D rect) { double x1 = line.getX1(); double y1 = line.getY1(); double x2 = line.getX2(); double y2 = line.getY2(); double minX = rect.getMinX(); double maxX = rect.getMaxX(); double minY = rect.getMinY(); double maxY = rect.getMaxY(); int f1 = rect.outcode(x1, y1); int f2 = rect.outcode(x2, y2); while ((f1 | f2) != 0) { if ((f1 & f2) != 0) { return false; } double dx = (x2 - x1); double dy = (y2 - y1); // update (x1, y1), (x2, y2) and f1 and f2 using intersections // then recheck if (f1 != 0) { // first point is outside, so we update it against one of the // four sides then continue if ((f1 & Rectangle2D.OUT_LEFT) == Rectangle2D.OUT_LEFT && dx != 0.0) { y1 = y1 + (minX - x1) * dy / dx; x1 = minX; } else if ((f1 & Rectangle2D.OUT_RIGHT) == Rectangle2D.OUT_RIGHT && dx != 0.0) { y1 = y1 + (maxX - x1) * dy / dx; x1 = maxX; } else if ((f1 & Rectangle2D.OUT_BOTTOM) == Rectangle2D.OUT_BOTTOM && dy != 0.0) { x1 = x1 + (maxY - y1) * dx / dy; y1 = maxY; } else if ((f1 & Rectangle2D.OUT_TOP) == Rectangle2D.OUT_TOP && dy != 0.0) { x1 = x1 + (minY - y1) * dx / dy; y1 = minY; } f1 = rect.outcode(x1, y1); } else if (f2 != 0) { // second point is outside, so we update it against one of the // four sides then continue if ((f2 & Rectangle2D.OUT_LEFT) == Rectangle2D.OUT_LEFT && dx != 0.0) { y2 = y2 + (minX - x2) * dy / dx; x2 = minX; } else if ((f2 & Rectangle2D.OUT_RIGHT) == Rectangle2D.OUT_RIGHT && dx != 0.0) { y2 = y2 + (maxX - x2) * dy / dx; x2 = maxX; } else if ((f2 & Rectangle2D.OUT_BOTTOM) == Rectangle2D.OUT_BOTTOM && dy != 0.0) { x2 = x2 + (maxY - y2) * dx / dy; y2 = maxY; } else if ((f2 & Rectangle2D.OUT_TOP) == Rectangle2D.OUT_TOP && dy != 0.0) { x2 = x2 + (minY - y2) * dx / dy; y2 = minY; } f2 = rect.outcode(x2, y2); } } line.setLine(x1, y1, x2, y2); return true; // the line is visible - if it wasn't, we'd have // returned false from within the while loop above } /** * Creates a new line by extending an existing line. * * @param line the line (<code>null</code> not permitted). * @param startPercent the amount to extend the line at the start point * end. * @param endPercent the amount to extend the line at the end point end. * * @return A new line. * * @since 1.0.18 */ public static Line2D extendLine(Line2D line, double startPercent, double endPercent) { ParamChecks.nullNotPermitted(line, "line"); double x1 = line.getX1(); double x2 = line.getX2(); double deltaX = x2 - x1; double y1 = line.getY1(); double y2 = line.getY2(); double deltaY = y2 - y1; x1 = x1 - (startPercent * deltaX); y1 = y1 - (startPercent * deltaY); x2 = x2 + (endPercent * deltaX); y2 = y2 + (endPercent * deltaY); return new Line2D.Double(x1, y1, x2, y2); } }