libjava/classpath/javax/swing/JButton.java

   1 /* JButton.java --
   2    Copyright (C) 2002, 2004, 2005, 2006, 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 package javax.swing;
  39
  40 import gnu.java.lang.CPStringBuilder;
  41
  42 import javax.accessibility.Accessible;
  43 import javax.accessibility.AccessibleContext;
  44 import javax.accessibility.AccessibleRole;
  45 import javax.swing.plaf.ButtonUI;
  46
  47
  48 /**
  49  * A general purpose push button. <code>JButton</code>s can display a label,
  50  * an {@link Icon} or both.
  51  *
  52  * @author Ronald Veldema (rveldema@cs.vu.nl)
  53  */
  54 public class JButton extends AbstractButton
  55   implements Accessible
  56 {
  57
  58   /**
  59    * Accessibility support for JButtons.
  60    */
  61   protected class AccessibleJButton
  62     extends AbstractButton.AccessibleAbstractButton
  63   {
  64     /**
  65      * Returns the accessible role that this component represents.
  66      * This is {@link AccessibleRole#PUSH_BUTTON} for <code>JButton</code>s.
  67      *
  68      * @return the accessible role that this component represents
  69      */
  70     public AccessibleRole getAccessibleRole()
  71     {
  72       return AccessibleRole.PUSH_BUTTON;
  73     }
  74   }
  75
  76   private static final long serialVersionUID = -1907255238954382202L;
  77
  78   /**
  79    * Indicates if this button is capable to become the default button.
  80    */
  81   private boolean defaultCapable;
  82
  83   /**
  84    * Creates a new button with an empty string for the button text and no
  85    * icon.
  86    */
  87   public JButton()
  88   {
  89     this(null, null);
  90   }
  91
  92   /**
  93    * Creates a new button from the specified action.
  94    *
  95    * @param a  the action (<code>null</code> permitted).
  96    *
  97    * @see AbstractButton#setAction(Action)
  98    */
  99   public JButton(Action a)
 100   {
 101     this();
 102     setAction(a);
 103   }
 104
 105   /**
 106    * Creates a new button with the specified icon (and an empty string for
 107    * the button text).
 108    *
 109    * @param icon  the icon (<code>null</code> permitted).
 110    */
 111   public JButton(Icon icon)
 112   {
 113     this(null, icon);
 114   }
 115
 116   /**
 117    * Creates a new button with the specified text and no icon.
 118    *
 119    * @param text  the button text (<code>null</code> permitted, will be
 120    *     substituted by an empty string).
 121    */
 122   public JButton(String text)
 123   {
 124     this(text, null);
 125   }
 126
 127   /**
 128    * Creates a new button with the specified text and icon.
 129    *
 130    * @param text  the button text (<code>null</code> permitted, will be
 131    *     substituted by an empty string).
 132    * @param icon  the icon (<code>null</code> permitted).
 133    */
 134   public JButton(String text, Icon icon)
 135   {
 136     super();
 137     setModel(new DefaultButtonModel());
 138     init(text, icon);
 139     defaultCapable = true;
 140   }
 141
 142   protected void configurePropertiesFromAction(Action a)
 143   {
 144     super.configurePropertiesFromAction(a);
 145   }
 146
 147   /**
 148    * Returns the object that provides accessibility features for this
 149    * <code>JButton</code> component.
 150    *
 151    * @return The accessible context (an instance of {@link AccessibleJButton}).
 152    */
 153   public AccessibleContext getAccessibleContext()
 154   {
 155     if (accessibleContext == null)
 156       accessibleContext = new AccessibleJButton();
 157     return accessibleContext;
 158   }
 159
 160   /**
 161    * Returns the suffix (<code>"ButtonUI"</code> in this case) used to
 162    * determine the class name for a UI delegate that can provide the look and
 163    * feel for a <code>JButton</code>.
 164    *
 165    * @return <code>"ButtonUI"</code>.
 166    */
 167   public String getUIClassID()
 168   {
 169     // Returns a string that specifies the name of the L&F class that renders
 170     // this component.
 171     return "ButtonUI";
 172   }
 173
 174   /**
 175    * Returns <code>true</code> if this button is the default button in
 176    * its <code>JRootPane</code>. The default button gets automatically
 177    * activated when the user presses <code>ENTER</code> (or whatever
 178    * key this is bound to in the current Look and Feel).
 179    *
 180    * @return <code>true</code> if this button is the default button in
 181    *         its <code>JRootPane</code>
 182    *
 183    * @see #isDefaultCapable()
 184    * @see #setDefaultCapable(boolean)
 185    * @see JRootPane#getDefaultButton()
 186    * @see JRootPane#setDefaultButton(JButton)
 187    */
 188   public boolean isDefaultButton()
 189   {
 190     // The default button is managed by the JRootPane, so the safest way
 191     // to determine this property is to ask the root pane of this button,
 192     // if it exists.
 193     JRootPane rp = SwingUtilities.getRootPane(this);
 194     boolean isDefault = false;
 195     if (rp != null)
 196       isDefault = rp.getDefaultButton() == this;
 197     return isDefault;
 198   }
 199
 200   /**
 201    * Returns <code>true</code> if this button can act as the default button.
 202    * This is <code>true</code> by default.
 203    *
 204    * @return <code>true</code> if this button can act as the default button
 205    *
 206    * @see #setDefaultCapable(boolean)
 207    * @see #isDefaultButton()
 208    * @see JRootPane#getDefaultButton()
 209    * @see JRootPane#setDefaultButton(JButton)
 210    */
 211   public boolean isDefaultCapable()
 212   {
 213     // Returns whether or not this button is capable of being the default
 214     // button on the RootPane.
 215     return defaultCapable;
 216   }
 217
 218   /**
 219    * Returns an implementation-dependent string describing the attributes of
 220    * this <code>JButton</code>.
 221    *
 222    * @return A string describing the attributes of this <code>JButton</code>
 223    *         (never <code>null</code>).
 224    */
 225   protected String paramString()
 226   {
 227     String superParam = super.paramString();
 228
 229     // 41 is the maximum number of chars which may be needed.
 230     CPStringBuilder sb = new CPStringBuilder(41);
 231     sb.append(",defaultButton=").append(isDefaultButton());
 232     sb.append(",defaultCapable=").append(defaultCapable);
 233
 234     return superParam + sb.toString();
 235   }
 236
 237   /**
 238    * Overrides JComponent.removeNotify to check if this button is currently
 239    * set as the default button on the RootPane, and if so, sets the RootPane's
 240    * default button to null to ensure the RootPane doesn't hold onto an invalid
 241    * button reference.
 242    */
 243   public void removeNotify()
 244   {
 245     JRootPane root = SwingUtilities.getRootPane(this);
 246     if (root != null && root.getDefaultButton() == this)
 247       root.setDefaultButton(null);
 248     super.removeNotify();
 249   }
 250
 251   /**
 252    * Sets the <code>defaultCapable</code> property which indicates if
 253    * this button may become the default button in its <code>JRootPane</code>.
 254    *
 255    * @param defaultCapable <code>true</code> if this button can become the
 256    *        default button in its JRootPane, <code>false</code> otherwise
 257    *
 258    * @see #setDefaultCapable(boolean)
 259    * @see #isDefaultButton()
 260    * @see JRootPane#getDefaultButton()
 261    * @see JRootPane#setDefaultButton(JButton)
 262    */
 263   public void setDefaultCapable(boolean defaultCapable)
 264   {
 265     this.defaultCapable = defaultCapable;
 266   }
 267
 268   /**
 269    * Sets this button's UI delegate to the default (obtained from the
 270    * {@link UIManager}) for the current look and feel.
 271    */
 272   public void updateUI()
 273   {
 274     setUI((ButtonUI) UIManager.getUI(this));
 275   }
 276 }