Java tutorial
/* * Copyright (c) 1998-2002 Carnegie Mellon University. All rights * reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * THIS SOFTWARE IS PROVIDED BY CARNEGIE MELLON UNIVERSITY ``AS IS'' AND * ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY * NOR ITS EMPLOYEES BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * */ import java.awt.*; public abstract class Win { public static void center(Window window, Component ref) { position(window, ref, 0.5, 0.5); } public static void position(Window frame, Component ref, double xfrac, double yfrac) { Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize(); Dimension size = frame.getSize(); Dimension refSize = (ref != null) ? ref.getSize() : screenSize; Point origin = (ref != null) ? ref.getLocationOnScreen() : new Point(0, 0); int x = origin.x + relativePoint(xfrac, refSize.width, size.width); int y = origin.y + relativePoint(yfrac, refSize.height, size.height); // make sure frame is entirely on screen x = Math.max(0, Math.min(screenSize.width - size.width, x)); y = Math.max(0, Math.min(screenSize.height - size.height, y)); frame.setLocation(x, y); } static int relativePoint(double frac, int parentLength, int childLength) { if (frac < 0) return (int) (frac * childLength); else if (frac > 1) return (int) (parentLength + (frac - 2) * childLength); else return (int) (frac * (parentLength - childLength)); } public static Frame findFrame(Component comp) { for (; comp != null; comp = comp.getParent()) if (comp instanceof Frame) { return (Frame) comp; } return null; } public static Frame findFrameOrMakeFrame(Component parent) { return (parent != null) ? findFrame(parent) : new Frame(); } }