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   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   public Dimension preferredLayoutSize(Container parent)
  67   {
  68     JViewport vp = (JViewport)parent;
  69     Component view = vp.getView();
  70       return view.getPreferredSize();
  71   }
  72   public Dimension minimumLayoutSize(Container parent)
  73   {
  74     JViewport vp = (JViewport)parent;
  75     Component view = vp.getView();
  76     return view.getMinimumSize();
  77   }
  78
  79   /**
  80    * Layout the view and viewport to respect the following rules. These are
  81    * not precisely the rules described in sun's javadocs, but they are the
  82    * rules which sun's swing implementation follows, if you watch its
  83    * behavior:
  84    *
  85    * <ol>
  86    *
  87    * <li>If the port is larger than the view's minimum size, put the port
  88    * at view position <code>(0,0)</code> and make the view's size equal to
  89    * the port's.</li>
  90    *
  91    * <li>If the port is smaller than the view, leave the view at its
  92    * minimum size. also, do not move the port, <em>unless</em> the port
  93    * extends into space <em>past</em> the edge of the view. If so, move the
  94    * port up or to the left, in view space, by the amount of empty space
  95    * (keep the lower and right edges lined up)</li>
  96    *
  97    * </ol>
  98    *
  99    * @see JViewport#getViewSize
 100    * @see JViewport#setViewSize
 101    * @see JViewport#getViewPosition
 102    * @see JViewport#setViewPosition
 103    */
 104
 105   public void layoutContainer(Container parent)
 106   {
 107     // The way to interpret this function is basically to ignore the names
 108     // of methods it calls, and focus on the variable names here. getViewRect
 109     // doesn't, for example, return the view; it returns the port bounds in
 110     // view space. Likwise setViewPosition doesn't reposition the view; it
 111     // positions the port, in view coordinates.
 112
 113     JViewport port = (JViewport) parent;
 114     Component view = port.getView();
 115
 116     // These dimensions and positions are in *view space*.  Do not mix
 117     // variables in here from port space (eg. parent.getBounds()). This
 118     // function should be entirely in view space, because the methods on
 119     // the viewport require inputs in view space.
 120
 121     Rectangle portBounds = port.getViewRect();
 122     Dimension viewPref = view.getPreferredSize();
 123     Dimension viewMinimum = view.getMinimumSize();
 124     Point portLowerRight = new Point(portBounds.x + portBounds.width,
 125                                      portBounds.y + portBounds.height);
 126
 127     // vertical implementation of the above rules
 128     if (portBounds.height >= viewMinimum.height)
 129       {
 130         portBounds.y = 0;
 131         viewPref.height = portBounds.height;
 132       }
 133     else
 134       {
 135         viewPref.height = viewMinimum.height;
 136         int overextension = portLowerRight.y - viewPref.height;
 137         if (overextension > 0)
 138             portBounds.y -= overextension;
 139       }
 140
 141     // horizontal implementation of the above rules
 142     if (portBounds.width >= viewMinimum.width)
 143       {
 144         portBounds.x = 0;
 145         viewPref.width = portBounds.width;
 146       }
 147     else
 148       {
 149         viewPref.width = viewMinimum.width;
 150         int overextension = portLowerRight.x - viewPref.width;
 151         if (overextension > 0)
 152             portBounds.x -= overextension;
 153       }
 154
 155     port.setViewPosition(portBounds.getLocation());
 156     port.setViewSize(viewPref);
 157   }
 158 }