libjava/javax/swing/ViewportLayout.java

   1 /* ViewportLayout.java --
   2    Copyright (C) 2002, 2004 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38 package javax.swing;
  39
  40 import java.awt.Component;
  41 import java.awt.Container;
  42 import java.awt.Dimension;
  43 import java.awt.LayoutManager;
  44 import java.awt.Point;
  45 import java.awt.Rectangle;
  46 import java.io.Serializable;
  47
  48 /**
  49  * ViewportLayout
  50  * @author      Andrew Selkirk
  51  * @author      Graydon Hoare
  52  */
  53 public class ViewportLayout implements LayoutManager, Serializable
  54 {
  55   private static final long serialVersionUID = -788225906076097229L;
  56
  57   public ViewportLayout()
  58   {
  59   }
  60   public void addLayoutComponent(String name, Component c)
  61   {
  62   }
  63   public void removeLayoutComponent(Component c)
  64   {
  65   }
  66
  67   public Dimension preferredLayoutSize(Container parent)
  68   {
  69     JViewport vp = (JViewport)parent;
  70     Component view = vp.getView();
  71     if (view != null)
  72       return view.getPreferredSize();
  73     else
  74       return new Dimension();
  75   }
  76
  77   public Dimension minimumLayoutSize(Container parent)
  78   {
  79     JViewport vp = (JViewport)parent;
  80     Component view = vp.getView();
  81     if (view != null)
  82       return view.getMinimumSize();
  83     else
  84       return new Dimension();
  85   }
  86
  87   /**
  88    * Layout the view and viewport to respect the following rules. These are
  89    * not precisely the rules described in sun's javadocs, but they are the
  90    * rules which sun's swing implementation follows, if you watch its
  91    * behavior:
  92    *
  93    * <ol>
  94    *
  95    * <li>If the port is larger than the view's minimum size, put the port
  96    * at view position <code>(0,0)</code> and make the view's size equal to
  97    * the port's.</li>
  98    *
  99    * <li>If the port is smaller than the view, leave the view at its
 100    * minimum size. also, do not move the port, <em>unless</em> the port
 101    * extends into space <em>past</em> the edge of the view. If so, move the
 102    * port up or to the left, in view space, by the amount of empty space
 103    * (keep the lower and right edges lined up)</li>
 104    *
 105    * </ol>
 106    *
 107    * @see JViewport#getViewSize
 108    * @see JViewport#setViewSize
 109    * @see JViewport#getViewPosition
 110    * @see JViewport#setViewPosition
 111    */
 112
 113   public void layoutContainer(Container parent)
 114   {
 115     // The way to interpret this function is basically to ignore the names
 116     // of methods it calls, and focus on the variable names here. getViewRect
 117     // doesn't, for example, return the view; it returns the port bounds in
 118     // view space. Likwise setViewPosition doesn't reposition the view; it
 119     // positions the port, in view coordinates.
 120
 121     JViewport port = (JViewport) parent;
 122     Component view = port.getView();
 123
 124     if (view == null)
 125       return;
 126
 127     // These dimensions and positions are in *view space*.  Do not mix
 128     // variables in here from port space (eg. parent.getBounds()). This
 129     // function should be entirely in view space, because the methods on
 130     // the viewport require inputs in view space.
 131
 132     Rectangle portBounds = port.getViewRect();
 133     Dimension viewPref = view.getPreferredSize();
 134     Dimension viewMinimum = view.getMinimumSize();
 135     Point portLowerRight = new Point(portBounds.x + portBounds.width,
 136                                      portBounds.y + portBounds.height);
 137
 138     // vertical implementation of the above rules
 139     if (portBounds.height >= viewMinimum.height)
 140       {
 141         portBounds.y = 0;
 142         viewPref.height = portBounds.height;
 143       }
 144     else
 145       {
 146         viewPref.height = viewMinimum.height;
 147         int overextension = portLowerRight.y - viewPref.height;
 148         if (overextension > 0)
 149             portBounds.y -= overextension;
 150       }
 151
 152     // horizontal implementation of the above rules
 153     if (portBounds.width >= viewMinimum.width)
 154       {
 155         portBounds.x = 0;
 156         viewPref.width = portBounds.width;
 157       }
 158     else
 159       {
 160         viewPref.width = viewMinimum.width;
 161         int overextension = portLowerRight.x - viewPref.width;
 162         if (overextension > 0)
 163             portBounds.x -= overextension;
 164       }
 165
 166     port.setViewPosition(portBounds.getLocation());
 167     port.setViewSize(viewPref);
 168   }
 169 }