001 /* ViewportLayout.java -- 002 Copyright (C) 2002, 2004, 2006 Free Software Foundation, Inc. 003 004 This file is part of GNU Classpath. 005 006 GNU Classpath is free software; you can redistribute it and/or modify 007 it under the terms of the GNU General Public License as published by 008 the Free Software Foundation; either version 2, or (at your option) 009 any later version. 010 011 GNU Classpath is distributed in the hope that it will be useful, but 012 WITHOUT ANY WARRANTY; without even the implied warranty of 013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014 General Public License for more details. 015 016 You should have received a copy of the GNU General Public License 017 along with GNU Classpath; see the file COPYING. If not, write to the 018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 019 02110-1301 USA. 020 021 Linking this library statically or dynamically with other modules is 022 making a combined work based on this library. Thus, the terms and 023 conditions of the GNU General Public License cover the whole 024 combination. 025 026 As a special exception, the copyright holders of this library give you 027 permission to link this library with independent modules to produce an 028 executable, regardless of the license terms of these independent 029 modules, and to copy and distribute the resulting executable under 030 terms of your choice, provided that you also meet, for each linked 031 independent module, the terms and conditions of the license of that 032 module. An independent module is a module which is not derived from 033 or based on this library. If you modify this library, you may extend 034 this exception to your version of the library, but you are not 035 obligated to do so. If you do not wish to do so, delete this 036 exception statement from your version. */ 037 038 package javax.swing; 039 040 import java.awt.Component; 041 import java.awt.Container; 042 import java.awt.Dimension; 043 import java.awt.LayoutManager; 044 import java.awt.Point; 045 import java.awt.Rectangle; 046 import java.io.Serializable; 047 048 /** 049 * The default layout for {@link JViewport}. The viewport makes its view the 050 * same size as itself, but not smaller than its minimum size. 051 * 052 * If the port extends extends into space <em>past</em> the edge of the view, 053 * this layout manager moves the port up or to the left, in view space, by the 054 * amount of empty space (keep the lower and right edges lined up). 055 * 056 * @author Andrew Selkirk 057 * @author Graydon Hoare 058 * @author Audrius Meskauskas (audriusa@Bioinformatics.org) 059 */ 060 public class ViewportLayout implements LayoutManager, Serializable 061 { 062 private static final long serialVersionUID = -788225906076097229L; 063 064 public ViewportLayout() 065 { 066 // Nothing to do here. 067 } 068 069 /** 070 * The method is not used with this manager. 071 */ 072 public void addLayoutComponent(String name, Component c) 073 { 074 // Nothing to do here. 075 } 076 077 /** 078 * The method is not used with this manager. 079 */ 080 public void removeLayoutComponent(Component c) 081 { 082 // Nothing to do here. 083 } 084 085 /** 086 * Get the preferred layout size. If the view implements 087 * {@link Scrollable}, this method returns 088 * {@link Scrollable#getPreferredScrollableViewportSize}. 089 * Otherwise, it returns {@link Component#getPreferredSize()}. 090 * 091 * @return the preferred layout size, as described about. 092 */ 093 public Dimension preferredLayoutSize(Container parent) 094 { 095 JViewport vp = (JViewport)parent; 096 Component view = vp.getView(); 097 if (view != null) 098 { 099 if (view instanceof Scrollable) 100 return ((Scrollable)view).getPreferredScrollableViewportSize(); 101 return view.getPreferredSize(); 102 } 103 else 104 return new Dimension(); 105 } 106 107 /** 108 * Get the minimum layout size. Normally this method returns the value, 109 * returned by the view method {@link Component#getMinimumSize()}. 110 * 111 * If the view is not set, the zero size is returned. 112 * 113 * @param parent the viewport 114 * @return the minimum layout size. 115 */ 116 public Dimension minimumLayoutSize(Container parent) 117 { 118 // These values have been determined by the Mauve test for this method. 119 return new Dimension(4, 4); 120 } 121 122 /** 123 * Layout the view and viewport to respect the following rules. These are not 124 * precisely the rules described in sun's javadocs, but they are the rules 125 * which sun's swing implementation follows, if you watch its behavior: 126 * <ol> 127 * <li>If the port is smaller than the view, leave the view at its current 128 * size.</li> 129 * <li>If the view is smaller than the port, the view is top aligned.</li> 130 * <li>If the view tracks the port size, the view position is always zero and 131 * the size equal to the viewport size</li> 132 * <li>In {@link JViewport#setViewSize(Dimension)}, the view size is never 133 * set smaller that its minimum size.</li> 134 * </ol> 135 * 136 * @see JViewport#getViewSize 137 * @see JViewport#setViewSize 138 * @see JViewport#getViewPosition 139 * @see JViewport#setViewPosition 140 */ 141 public void layoutContainer(Container parent) 142 { 143 // The way to interpret this function is basically to ignore the names 144 // of methods it calls, and focus on the variable names here. getViewRect 145 // doesn't, for example, return the view; it returns the port bounds in 146 // view space. Likwise setViewPosition doesn't reposition the view; it 147 // positions the port, in view coordinates. 148 149 JViewport port = (JViewport) parent; 150 Component view = port.getView(); 151 152 if (view == null) 153 return; 154 155 // These dimensions and positions are in *view space*. Do not mix 156 // variables in here from port space (eg. parent.getBounds()). This 157 // function should be entirely in view space, because the methods on 158 // the viewport require inputs in view space. 159 160 Rectangle portBounds = port.getViewRect(); 161 Dimension viewPref = new Dimension(view.getPreferredSize()); 162 163 Point portLowerRight = new Point(portBounds.x + portBounds.width, 164 portBounds.y + portBounds.height); 165 166 // vertical implementation of the above rules 167 if (view instanceof Scrollable) 168 { 169 Scrollable sView = (Scrollable) view; 170 171 // If the view size matches viewport size, the port offset can 172 // only be zero. 173 if (sView.getScrollableTracksViewportWidth()) 174 { 175 viewPref.width = portBounds.width; 176 portBounds.x = 0; 177 } 178 if (sView.getScrollableTracksViewportHeight()) 179 { 180 viewPref.height = portBounds.height; 181 portBounds.y = 0; 182 } 183 } 184 185 if (viewPref.width < portBounds.width) 186 viewPref.width = portBounds.width; 187 if (viewPref.height < portBounds.height) 188 viewPref.height = portBounds.height; 189 190 // If the view is larger than the port, the port is top and right 191 // aligned. 192 if (portLowerRight.x > viewPref.width) 193 portBounds.x = 0; 194 195 if (portLowerRight.y > viewPref.height) 196 portBounds.y = 0; 197 198 port.setViewSize(viewPref); 199 port.setViewPosition(portBounds.getLocation()); 200 } 201 202 }