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1: /* Label.java -- Java label widget 2: Copyright (C) 1999, 2000, 2002, 2004, 2005 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 java.awt; 40: 41: import java.awt.peer.LabelPeer; 42: 43: import javax.accessibility.Accessible; 44: import javax.accessibility.AccessibleContext; 45: import javax.accessibility.AccessibleRole; 46: 47: /** 48: * This component is used for displaying simple text strings that cannot 49: * be edited by the user. 50: * 51: * @author Aaron M. Renn (arenn@urbanophile.com) 52: * @author Tom Tromey (tromey@cygnus.com) 53: * @author Andrew John Hughes (gnu_andrew@member.fsf.org) 54: */ 55: public class Label extends Component implements Accessible 56: { 57: 58: /* 59: * Static Variables 60: */ 61: 62: /** 63: * Alignment constant aligning the text to the left of its window. 64: */ 65: public static final int LEFT = 0; 66: 67: /** 68: * Alignment constant aligning the text in the center of its window. 69: */ 70: public static final int CENTER = 1; 71: 72: /** 73: * Alignment constant aligning the text to the right of its window. 74: */ 75: public static final int RIGHT = 2; 76: 77: // Serialization version constant: 78: private static final long serialVersionUID = 3094126758329070636L; 79: 80: /*************************************************************************/ 81: 82: /* 83: * Instance Variables 84: */ 85: 86: /** 87: * @serial Indicates the alignment of the text within this label's window. 88: * This is one of the constants in this class. The default value is 89: * <code>LEFT</code>. 90: */ 91: private int alignment; 92: 93: /** 94: * @serial The text displayed in the label 95: */ 96: private String text; 97: 98: /*************************************************************************/ 99: 100: /* 101: * Constructors 102: */ 103: 104: /** 105: * Initializes a new instance of <code>Label</code> with no text. 106: * 107: * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true. 108: */ 109: public 110: Label() 111: { 112: this("", LEFT); 113: } 114: 115: /*************************************************************************/ 116: 117: /** 118: * Initializes a new instance of <code>Label</code> with the specified 119: * text that is aligned to the left. 120: * 121: * @param text The text of the label. 122: * 123: * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true. 124: */ 125: public 126: Label(String text) 127: { 128: this(text, LEFT); 129: } 130: 131: /*************************************************************************/ 132: 133: /** 134: * Initializes a new instance of <code>Label</code> with the specified 135: * text and alignment. 136: * 137: * @param text The text of the label. 138: * @param alignment The desired alignment for the text in this label, 139: * which must be one of <code>LEFT</code>, <code>CENTER</code>, or 140: * <code>RIGHT</code>. 141: * 142: * @exception HeadlessException If GraphicsEnvironment.isHeadless() is true. 143: */ 144: public 145: Label(String text, int alignment) 146: { 147: setAlignment (alignment); 148: setText (text); 149: 150: if (GraphicsEnvironment.isHeadless()) 151: throw new HeadlessException (); 152: } 153: 154: /*************************************************************************/ 155: 156: /* 157: * Instance Variables 158: */ 159: 160: /** 161: * Returns the constant indicating the alignment of the text in this 162: * label. The value returned will be one of the alignment constants 163: * from this class. 164: * 165: * @return The alignment of the text in the label. 166: */ 167: public int 168: getAlignment() 169: { 170: return(alignment); 171: } 172: 173: /*************************************************************************/ 174: 175: /** 176: * Sets the text alignment of this label to the specified value. 177: * 178: * @param alignment The desired alignment for the text in this label, 179: * which must be one of <code>LEFT</code>, <code>CENTER</code>, or 180: * <code>RIGHT</code>. 181: */ 182: public synchronized void 183: setAlignment(int alignment) 184: { 185: if (alignment != CENTER && alignment != LEFT && alignment != RIGHT) 186: throw new IllegalArgumentException ("invalid alignment: " + alignment); 187: this.alignment = alignment; 188: if (peer != null) 189: { 190: LabelPeer lp = (LabelPeer) peer; 191: lp.setAlignment (alignment); 192: } 193: } 194: 195: /*************************************************************************/ 196: 197: /** 198: * Returns the text displayed in this label. 199: * 200: * @return The text for this label. 201: */ 202: public String 203: getText() 204: { 205: return(text); 206: } 207: 208: /*************************************************************************/ 209: 210: /** 211: * Sets the text in this label to the specified value. 212: * 213: * @param text The new text for this label. 214: */ 215: public synchronized void 216: setText(String text) 217: { 218: if ((this.text == null && text != null) 219: || (this.text != null && ! this.text.equals(text))) 220: { 221: this.text = text; 222: 223: if (peer != null) 224: { 225: LabelPeer lp = (LabelPeer) peer; 226: lp.setText (text); 227: } 228: invalidate(); 229: } 230: } 231: 232: /*************************************************************************/ 233: 234: /** 235: * Notifies this label that it has been added to a container, causing 236: * the peer to be created. This method is called internally by the AWT 237: * system. 238: */ 239: public void 240: addNotify() 241: { 242: if (peer == null) 243: peer = getToolkit ().createLabel (this); 244: super.addNotify (); 245: } 246: 247: /*************************************************************************/ 248: 249: /** 250: * Returns a parameter string useful for debugging. 251: * 252: * @return A debugging string. 253: */ 254: protected String 255: paramString() 256: { 257: return ("text=" + getText() + ",alignment=" + 258: getAlignment() + "," + super.paramString()); 259: } 260: 261: /** 262: * This class provides accessibility support for the label. 263: */ 264: protected class AccessibleAWTLabel 265: extends AccessibleAWTComponent 266: { 267: /** 268: * For compatability with Sun's JDK 1.4.2 rev. 5 269: */ 270: private static final long serialVersionUID = -3568967560160480438L; 271: 272: /** 273: * Constructor for the accessible label. 274: */ 275: public AccessibleAWTLabel() 276: { 277: } 278: 279: /** 280: * Returns the accessible name for the label. This is 281: * the text used in the label. 282: * 283: * @return a <code>String</code> containing the accessible 284: * name for this label. 285: */ 286: public String getAccessibleName() 287: { 288: return getText(); 289: } 290: 291: /** 292: * Returns the accessible role for the label. 293: * 294: * @return an instance of <code>AccessibleRole</code>, describing 295: * the role of the label. 296: */ 297: public AccessibleRole getAccessibleRole() 298: { 299: return AccessibleRole.LABEL; 300: } 301: 302: } 303: 304: /** 305: * Gets the AccessibleContext associated with this <code>Label</code>. 306: * The context is created, if necessary. 307: * 308: * @return the associated context 309: */ 310: public AccessibleContext getAccessibleContext() 311: { 312: /* Create the context if this is the first request */ 313: if (accessibleContext == null) 314: accessibleContext = new AccessibleAWTLabel(); 315: return accessibleContext; 316: } 317: 318: } // class Label
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