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    1   /*
    2    * Copyright (c) 1997, 2006, Oracle and/or its affiliates. All rights reserved.
    3    * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
    4    *
    5    * This code is free software; you can redistribute it and/or modify it
    6    * under the terms of the GNU General Public License version 2 only, as
    7    * published by the Free Software Foundation.  Oracle designates this
    8    * particular file as subject to the "Classpath" exception as provided
    9    * by Oracle in the LICENSE file that accompanied this code.
   10    *
   11    * This code is distributed in the hope that it will be useful, but WITHOUT
   12    * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   13    * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   14    * version 2 for more details (a copy is included in the LICENSE file that
   15    * accompanied this code).
   16    *
   17    * You should have received a copy of the GNU General Public License version
   18    * 2 along with this work; if not, write to the Free Software Foundation,
   19    * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   20    *
   21    * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   22    * or visit www.oracle.com if you need additional information or have any
   23    * questions.
   24    */
   25   
   26   
   27   package javax.swing;
   28   import javax.swing.plaf;
   29   import javax.accessibility;
   30   
   31   import java.io.ObjectOutputStream;
   32   import java.io.ObjectInputStream;
   33   import java.io.IOException;
   34   
   35   
   36   /**
   37    * Used to display a "Tip" for a Component. Typically components provide api
   38    * to automate the process of using <code>ToolTip</code>s.
   39    * For example, any Swing component can use the <code>JComponent</code>
   40    * <code>setToolTipText</code> method to specify the text
   41    * for a standard tooltip. A component that wants to create a custom
   42    * <code>ToolTip</code>
   43    * display can override <code>JComponent</code>'s <code>createToolTip</code>
   44    * method and use a subclass of this class.
   45    * <p>
   46    * See <a href="http://java.sun.com/docs/books/tutorial/uiswing/components/tooltip.html">How to Use Tool Tips</a>
   47    * in <em>The Java Tutorial</em>
   48    * for further documentation.
   49    * <p>
   50    * <strong>Warning:</strong> Swing is not thread safe. For more
   51    * information see <a
   52    * href="package-summary.html#threading">Swing's Threading
   53    * Policy</a>.
   54    * <p>
   55    * <strong>Warning:</strong>
   56    * Serialized objects of this class will not be compatible with
   57    * future Swing releases. The current serialization support is
   58    * appropriate for short term storage or RMI between applications running
   59    * the same version of Swing.  As of 1.4, support for long term storage
   60    * of all JavaBeans<sup><font size="-2">TM</font></sup>
   61    * has been added to the <code>java.beans</code> package.
   62    * Please see {@link java.beans.XMLEncoder}.
   63    *
   64    * @see JComponent#setToolTipText
   65    * @see JComponent#createToolTip
   66    * @author Dave Moore
   67    * @author Rich Shiavi
   68    */
   69   public class JToolTip extends JComponent implements Accessible {
   70       /**
   71        * @see #getUIClassID
   72        * @see #readObject
   73        */
   74       private static final String uiClassID = "ToolTipUI";
   75   
   76       String tipText;
   77       JComponent component;
   78   
   79       /** Creates a tool tip. */
   80       public JToolTip() {
   81           setOpaque(true);
   82           updateUI();
   83       }
   84   
   85       /**
   86        * Returns the L&F object that renders this component.
   87        *
   88        * @return the <code>ToolTipUI</code> object that renders this component
   89        */
   90       public ToolTipUI getUI() {
   91           return (ToolTipUI)ui;
   92       }
   93   
   94       /**
   95        * Resets the UI property to a value from the current look and feel.
   96        *
   97        * @see JComponent#updateUI
   98        */
   99       public void updateUI() {
  100           setUI((ToolTipUI)UIManager.getUI(this));
  101       }
  102   
  103   
  104       /**
  105        * Returns the name of the L&F class that renders this component.
  106        *
  107        * @return the string "ToolTipUI"
  108        * @see JComponent#getUIClassID
  109        * @see UIDefaults#getUI
  110        */
  111       public String getUIClassID() {
  112           return uiClassID;
  113       }
  114   
  115   
  116       /**
  117        * Sets the text to show when the tool tip is displayed.
  118        * The string <code>tipText</code> may be <code>null</code>.
  119        *
  120        * @param tipText the <code>String</code> to display
  121        * @beaninfo
  122        *    preferred: true
  123        *        bound: true
  124        *  description: Sets the text of the tooltip
  125        */
  126       public void setTipText(String tipText) {
  127           String oldValue = this.tipText;
  128           this.tipText = tipText;
  129           firePropertyChange("tiptext", oldValue, tipText);
  130       }
  131   
  132       /**
  133        * Returns the text that is shown when the tool tip is displayed.
  134        * The returned value may be <code>null</code>.
  135        *
  136        * @return the <code>String</code> that is displayed
  137        */
  138       public String getTipText() {
  139           return tipText;
  140       }
  141   
  142       /**
  143        * Specifies the component that the tooltip describes.
  144        * The component <code>c</code> may be <code>null</code>
  145        * and will have no effect.
  146        * <p>
  147        * This is a bound property.
  148        *
  149        * @param c the <code>JComponent</code> being described
  150        * @see JComponent#createToolTip
  151        * @beaninfo
  152        *       bound: true
  153        * description: Sets the component that the tooltip describes.
  154        */
  155       public void setComponent(JComponent c) {
  156           JComponent oldValue = this.component;
  157   
  158           component = c;
  159           firePropertyChange("component", oldValue, c);
  160       }
  161   
  162       /**
  163        * Returns the component the tooltip applies to.
  164        * The returned value may be <code>null</code>.
  165        *
  166        * @return the component that the tooltip describes
  167        *
  168        * @see JComponent#createToolTip
  169        */
  170       public JComponent getComponent() {
  171           return component;
  172       }
  173   
  174       /**
  175        * Always returns true since tooltips, by definition,
  176        * should always be on top of all other windows.
  177        */
  178       // package private
  179       boolean alwaysOnTop() {
  180           return true;
  181       }
  182   
  183   
  184       /**
  185        * See <code>readObject</code> and <code>writeObject</code>
  186        * in <code>JComponent</code> for more
  187        * information about serialization in Swing.
  188        */
  189       private void writeObject(ObjectOutputStream s) throws IOException {
  190           s.defaultWriteObject();
  191           if (getUIClassID().equals(uiClassID)) {
  192               byte count = JComponent.getWriteObjCounter(this);
  193               JComponent.setWriteObjCounter(this, --count);
  194               if (count == 0 && ui != null) {
  195                   ui.installUI(this);
  196               }
  197           }
  198       }
  199   
  200   
  201       /**
  202        * Returns a string representation of this <code>JToolTip</code>.
  203        * This method
  204        * is intended to be used only for debugging purposes, and the
  205        * content and format of the returned string may vary between
  206        * implementations. The returned string may be empty but may not
  207        * be <code>null</code>.
  208        *
  209        * @return  a string representation of this <code>JToolTip</code>
  210        */
  211       protected String paramString() {
  212           String tipTextString = (tipText != null ?
  213                                   tipText : "");
  214   
  215           return super.paramString() +
  216           ",tipText=" + tipTextString;
  217       }
  218   
  219   
  220   /////////////////
  221   // Accessibility support
  222   ////////////////
  223   
  224       /**
  225        * Gets the AccessibleContext associated with this JToolTip.
  226        * For tool tips, the AccessibleContext takes the form of an
  227        * AccessibleJToolTip.
  228        * A new AccessibleJToolTip instance is created if necessary.
  229        *
  230        * @return an AccessibleJToolTip that serves as the
  231        *         AccessibleContext of this JToolTip
  232        */
  233       public AccessibleContext getAccessibleContext() {
  234           if (accessibleContext == null) {
  235               accessibleContext = new AccessibleJToolTip();
  236           }
  237           return accessibleContext;
  238       }
  239   
  240       /**
  241        * This class implements accessibility support for the
  242        * <code>JToolTip</code> class.  It provides an implementation of the
  243        * Java Accessibility API appropriate to tool tip user-interface elements.
  244        * <p>
  245        * <strong>Warning:</strong>
  246        * Serialized objects of this class will not be compatible with
  247        * future Swing releases. The current serialization support is
  248        * appropriate for short term storage or RMI between applications running
  249        * the same version of Swing.  As of 1.4, support for long term storage
  250        * of all JavaBeans<sup><font size="-2">TM</font></sup>
  251        * has been added to the <code>java.beans</code> package.
  252        * Please see {@link java.beans.XMLEncoder}.
  253        */
  254       protected class AccessibleJToolTip extends AccessibleJComponent {
  255   
  256           /**
  257            * Get the accessible description of this object.
  258            *
  259            * @return a localized String describing this object.
  260            */
  261           public String getAccessibleDescription() {
  262               String description = accessibleDescription;
  263   
  264               // fallback to client property
  265               if (description == null) {
  266                   description = (String)getClientProperty(AccessibleContext.ACCESSIBLE_DESCRIPTION_PROPERTY);
  267               }
  268               if (description == null) {
  269                   description = getTipText();
  270               }
  271               return description;
  272           }
  273   
  274           /**
  275            * Get the role of this object.
  276            *
  277            * @return an instance of AccessibleRole describing the role of the
  278            * object
  279            */
  280           public AccessibleRole getAccessibleRole() {
  281               return AccessibleRole.TOOL_TIP;
  282           }
  283       }
  284   }

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