001 /* JButton.java -- 002 Copyright (C) 2002, 2004, 2005, 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 gnu.java.lang.CPStringBuilder; 041 042 import javax.accessibility.Accessible; 043 import javax.accessibility.AccessibleContext; 044 import javax.accessibility.AccessibleRole; 045 import javax.swing.plaf.ButtonUI; 046 047 048 /** 049 * A general purpose push button. <code>JButton</code>s can display a label, 050 * an {@link Icon} or both. 051 * 052 * @author Ronald Veldema (rveldema@cs.vu.nl) 053 */ 054 public class JButton extends AbstractButton 055 implements Accessible 056 { 057 058 /** 059 * Accessibility support for JButtons. 060 */ 061 protected class AccessibleJButton 062 extends AbstractButton.AccessibleAbstractButton 063 { 064 /** 065 * Returns the accessible role that this component represents. 066 * This is {@link AccessibleRole#PUSH_BUTTON} for <code>JButton</code>s. 067 * 068 * @return the accessible role that this component represents 069 */ 070 public AccessibleRole getAccessibleRole() 071 { 072 return AccessibleRole.PUSH_BUTTON; 073 } 074 } 075 076 private static final long serialVersionUID = -1907255238954382202L; 077 078 /** 079 * Indicates if this button is capable to become the default button. 080 */ 081 private boolean defaultCapable; 082 083 /** 084 * Creates a new button with an empty string for the button text and no 085 * icon. 086 */ 087 public JButton() 088 { 089 this(null, null); 090 } 091 092 /** 093 * Creates a new button from the specified action. 094 * 095 * @param a the action (<code>null</code> permitted). 096 * 097 * @see AbstractButton#setAction(Action) 098 */ 099 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 }