old-autovect-branch/libjava/classpath/javax/swing/border/EmptyBorder.java

   1 /* EmptyBorder.java --
   2    Copyright (C) 2003 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., 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301 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
  39 package javax.swing.border;
  40
  41 import java.awt.Component;
  42 import java.awt.Graphics;
  43 import java.awt.Insets;
  44
  45
  46 /**
  47  * A border for leaving a specifiable number of pixels empty around
  48  * the enclosed component.  An EmptyBorder requires some space on each
  49  * edge, but does not perform any drawing.
  50  *
  51  * <p><img src="EmptyBorder-1.png" width="290" height="200"
  52  * alt="[An illustration of EmptyBorder]" />
  53  *
  54  * @author Sascha Brawer (brawer@dandelis.ch)
  55  */
  56 public class EmptyBorder extends AbstractBorder
  57 {
  58   /**
  59    * Determined using the <code>serialver</code> tool
  60    * of Apple/Sun JDK 1.3.1 on MacOS X 10.1.5.
  61    */
  62   static final long serialVersionUID = -8116076291731988694L;
  63
  64
  65   /**
  66    * The number of pixels required at the left edge.
  67    */
  68   protected int left;
  69
  70
  71   /**
  72    * The number of pixels required at the right edge.
  73    */
  74   protected int right;
  75
  76
  77   /**
  78    * The number of pixels required at the top edge.
  79    */
  80   protected int top;
  81
  82
  83   /**
  84    * The number of pixels required at the bottom edge.
  85    */
  86   protected int bottom;
  87
  88
  89   /**
  90    * Constructs an empty border given the number of pixels required
  91    * on each side.
  92    *
  93    * @param top the number of pixels that the border will need
  94    *        for its top edge.
  95    *
  96    * @param left the number of pixels that the border will need
  97    *        for its left edge.
  98    *
  99    * @param bottom the number of pixels that the border will need
 100    *        for its bottom edge.
 101    *
 102    * @param right the number of pixels that the border will need
 103    *        for its right edge.
 104    */
 105   public EmptyBorder(int top, int left, int bottom, int right)
 106   {
 107     this.top = top;
 108     this.left = left;
 109     this.bottom = bottom;
 110     this.right = right;
 111   }
 112
 113
 114   /**
 115    * Constructs an empty border given the number of pixels required
 116    * on each side, passed in an Insets object.
 117    *
 118    * @param borderInsets the Insets for the new border.
 119    */
 120   public EmptyBorder(Insets borderInsets)
 121   {
 122     this(borderInsets.top, borderInsets.left,
 123          borderInsets.bottom, borderInsets.right);
 124   }
 125
 126
 127   /**
 128    * Performs nothing because an EmptyBorder does not paint any
 129    * pixels. While the inherited implementation provided by
 130    * {@link AbstractBorder#paintBorder} is a no-op as well,
 131    * it is overwritten in order to match the API of the Sun
 132    * reference implementation.
 133    *
 134    * @param c the component whose border is to be painted.
 135    * @param g the graphics for painting.
 136    * @param x the horizontal position for painting the border.
 137    * @param y the vertical position for painting the border.
 138    * @param width the width of the available area for painting the border.
 139    * @param height the height of the available area for painting the border.
 140    */
 141   public void paintBorder(Component c, Graphics g,
 142                           int x, int y, int width, int height)
 143   {
 144     // Nothing to do here.
 145   }
 146
 147
 148   /**
 149    * Measures the width of this border.
 150    *
 151    * @param c the component whose border is to be measured.
 152    *
 153    * @return an Insets object whose <code>left</code>, <code>right</code>,
 154    *         <code>top</code> and <code>bottom</code> fields indicate the
 155    *         width of the border at the respective edge.
 156    *
 157    * @see #getBorderInsets(java.awt.Component, java.awt.Insets)
 158    */
 159   public Insets getBorderInsets(Component c)
 160   {
 161     return getBorderInsets(c, null);
 162   }
 163
 164
 165   /**
 166    * Measures the width of this border, storing the results into a
 167    * pre-existing Insets object.
 168    *
 169    * @param insets an Insets object for holding the result values.
 170    *        After invoking this method, the <code>left</code>,
 171    *        <code>right</code>, <code>top</code> and
 172    *        <code>bottom</code> fields indicate the width of the
 173    *        border at the respective edge.
 174    *
 175    * @return the same object that was passed for <code>insets</code>.
 176    *
 177    * @see #getBorderInsets()
 178    */
 179   public Insets getBorderInsets(Component c, Insets insets)
 180   {
 181     if (insets == null)
 182       insets = new Insets(0, 0, 0, 0);
 183
 184     insets.left = left;
 185     insets.right = right;
 186     insets.top = top;
 187     insets.bottom = bottom;
 188     return insets;
 189   }
 190
 191
 192   /**
 193    * Measures the width of this border.
 194    *
 195    * @return an Insets object whose <code>left</code>, <code>right</code>,
 196    *         <code>top</code> and <code>bottom</code> fields indicate the
 197    *         width of the border at the respective edge.
 198    *
 199    * @see #getBorderInsets(java.awt.Component, java.awt.Insets)
 200    */
 201   public Insets getBorderInsets()
 202   {
 203     return getBorderInsets(null, null);
 204   }
 205
 206
 207   /**
 208    * Determines whether this border fills every pixel in its area
 209    * when painting. Since an empty border does not paint any pixels
 210    * whatsoever, the result is <code>false</code>.
 211    *
 212    * @return <code>false</code>.
 213    */
 214   public boolean isBorderOpaque()
 215   {
 216     /* The inherited implementation of AbstractBorder.isBorderOpaque()
 217      * would also return false. It is not clear why this is overriden
 218      * in the Sun implementation, at least not from just reading the
 219      * JavaDoc.
 220      */
 221     return false;
 222   }
 223 }