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    1   /*
    2    * Copyright (c) 1997, 2003, 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   package javax.swing;
   26   
   27   import java.awt;
   28   import java.awt.event;
   29   import java.io;
   30   import java.beans.PropertyChangeListener;
   31   import java.util.Locale;
   32   import java.util.Vector;
   33   
   34   import javax.accessibility;
   35   
   36   /**
   37    * This class is inserted in between cell renderers and the components that
   38    * use them.  It just exists to thwart the repaint() and invalidate() methods
   39    * which would otherwise propagate up the tree when the renderer was configured.
   40    * It's used by the implementations of JTable, JTree, and JList.  For example,
   41    * here's how CellRendererPane is used in the code the paints each row
   42    * in a JList:
   43    * <pre>
   44    *   cellRendererPane = new CellRendererPane();
   45    *   ...
   46    *   Component rendererComponent = renderer.getListCellRendererComponent();
   47    *   renderer.configureListCellRenderer(dataModel.getElementAt(row), row);
   48    *   cellRendererPane.paintComponent(g, rendererComponent, this, x, y, w, h);
   49    * </pre>
   50    * <p>
   51    * A renderer component must override isShowing() and unconditionally return
   52    * true to work correctly because the Swing paint does nothing for components
   53    * with isShowing false.
   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    * @author Hans Muller
   65    */
   66   public class CellRendererPane extends Container implements Accessible
   67   {
   68       /**
   69        * Construct a CellRendererPane object.
   70        */
   71       public CellRendererPane() {
   72           super();
   73           setLayout(null);
   74           setVisible(false);
   75       }
   76   
   77       /**
   78        * Overridden to avoid propagating a invalidate up the tree when the
   79        * cell renderer child is configured.
   80        */
   81       public void invalidate() { }
   82   
   83   
   84       /**
   85        * Shouldn't be called.
   86        */
   87       public void paint(Graphics g) { }
   88   
   89   
   90       /**
   91        * Shouldn't be called.
   92        */
   93       public void update(Graphics g) { }
   94   
   95   
   96       /**
   97        * If the specified component is already a child of this then we don't
   98        * bother doing anything - stacking order doesn't matter for cell
   99        * renderer components (CellRendererPane doesn't paint anyway).<
  100        */
  101       protected void addImpl(Component x, Object constraints, int index) {
  102           if (x.getParent() == this) {
  103               return;
  104           }
  105           else {
  106               super.addImpl(x, constraints, index);
  107           }
  108       }
  109   
  110   
  111       /**
  112        * Paint a cell renderer component c on graphics object g.  Before the component
  113        * is drawn it's reparented to this (if that's necessary), it's bounds
  114        * are set to w,h and the graphics object is (effectively) translated to x,y.
  115        * If it's a JComponent, double buffering is temporarily turned off. After
  116        * the component is painted it's bounds are reset to -w, -h, 0, 0 so that, if
  117        * it's the last renderer component painted, it will not start consuming input.
  118        * The Container p is the component we're actually drawing on, typically it's
  119        * equal to this.getParent(). If shouldValidate is true the component c will be
  120        * validated before painted.
  121        */
  122       public void paintComponent(Graphics g, Component c, Container p, int x, int y, int w, int h, boolean shouldValidate) {
  123           if (c == null) {
  124               if (p != null) {
  125                   Color oldColor = g.getColor();
  126                   g.setColor(p.getBackground());
  127                   g.fillRect(x, y, w, h);
  128                   g.setColor(oldColor);
  129               }
  130               return;
  131           }
  132   
  133           if (c.getParent() != this) {
  134               this.add(c);
  135           }
  136   
  137           c.setBounds(x, y, w, h);
  138   
  139           if(shouldValidate) {
  140               c.validate();
  141           }
  142   
  143           boolean wasDoubleBuffered = false;
  144           if ((c instanceof JComponent) && ((JComponent)c).isDoubleBuffered()) {
  145               wasDoubleBuffered = true;
  146               ((JComponent)c).setDoubleBuffered(false);
  147           }
  148   
  149           Graphics cg = g.create(x, y, w, h);
  150           try {
  151               c.paint(cg);
  152           }
  153           finally {
  154               cg.dispose();
  155           }
  156   
  157           if (wasDoubleBuffered && (c instanceof JComponent)) {
  158               ((JComponent)c).setDoubleBuffered(true);
  159           }
  160   
  161           c.setBounds(-w, -h, 0, 0);
  162       }
  163   
  164   
  165       /**
  166        * Calls this.paintComponent(g, c, p, x, y, w, h, false).
  167        */
  168       public void paintComponent(Graphics g, Component c, Container p, int x, int y, int w, int h) {
  169           paintComponent(g, c, p, x, y, w, h, false);
  170       }
  171   
  172   
  173       /**
  174        * Calls this.paintComponent() with the rectangles x,y,width,height fields.
  175        */
  176       public void paintComponent(Graphics g, Component c, Container p, Rectangle r) {
  177           paintComponent(g, c, p, r.x, r.y, r.width, r.height);
  178       }
  179   
  180   
  181       private void writeObject(ObjectOutputStream s) throws IOException {
  182           removeAll();
  183           s.defaultWriteObject();
  184       }
  185   
  186   
  187   /////////////////
  188   // Accessibility support
  189   ////////////////
  190   
  191       protected AccessibleContext accessibleContext = null;
  192   
  193       /**
  194        * Gets the AccessibleContext associated with this CellRendererPane.
  195        * For CellRendererPanes, the AccessibleContext takes the form of an
  196        * AccessibleCellRendererPane.
  197        * A new AccessibleCellRendererPane instance is created if necessary.
  198        *
  199        * @return an AccessibleCellRendererPane that serves as the
  200        *         AccessibleContext of this CellRendererPane
  201        */
  202       public AccessibleContext getAccessibleContext() {
  203           if (accessibleContext == null) {
  204               accessibleContext = new AccessibleCellRendererPane();
  205           }
  206           return accessibleContext;
  207       }
  208   
  209       /**
  210        * This class implements accessibility support for the
  211        * <code>CellRendererPane</code> class.
  212        */
  213       protected class AccessibleCellRendererPane extends AccessibleAWTContainer {
  214           // AccessibleContext methods
  215           //
  216           /**
  217            * Get the role of this object.
  218            *
  219            * @return an instance of AccessibleRole describing the role of the
  220            * object
  221            * @see AccessibleRole
  222            */
  223           public AccessibleRole getAccessibleRole() {
  224               return AccessibleRole.PANEL;
  225           }
  226       } // inner class AccessibleCellRendererPane
  227   }

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