Source for javax.swing.plaf.basic.BasicPanelUI

   1: /* BasicPanelUI.java
   2:    Copyright (C) 2002, 2004, 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: 
  39: package javax.swing.plaf.basic;
  40: 
  41: import javax.swing.JComponent;
  42: import javax.swing.JPanel;
  43: import javax.swing.LookAndFeel;
  44: import javax.swing.plaf.ComponentUI;
  45: import javax.swing.plaf.PanelUI;
  46: 
  47: /**
  48:  * A UI delegate for the {@link JPanel} component.
  49:  */
  50: public class BasicPanelUI extends PanelUI
  51: {
  52:   /**
  53:    * A UI delegate that can be shared by all panels (because the delegate is
  54:    * stateless).
  55:    */
  56:   static BasicPanelUI sharedUI;
  57:   
  58:   /**
  59:    * Returns a UI delegate for the specified component.
  60:    * 
  61:    * @param panel  the panel.
  62:    */
  63:   public static ComponentUI createUI(JComponent panel) 
  64:   {
  65:     if (sharedUI == null)
  66:       sharedUI = new BasicPanelUI();
  67:     return sharedUI;
  68:   }
  69: 
  70:   /**
  71:    * Installs this UI delegate in the specified component.
  72:    * 
  73:    * @param c  the component (should be a {@link JPanel}, <code>null</code> not
  74:    *     permitted).
  75:    */
  76:   public void installUI(JComponent c)
  77:   {
  78:     super.installUI(c);
  79:     if (c instanceof JPanel)
  80:       {
  81:         JPanel p = (JPanel) c;
  82:         installDefaults(p);
  83:       }
  84:   }
  85: 
  86:   /**
  87:    * Installs the defaults for this UI delegate in the specified panel.
  88:    * 
  89:    * @param p  the panel (<code>null</code> not permitted).
  90:    */
  91:   protected void installDefaults(JPanel p)
  92:   {
  93:     LookAndFeel.installColorsAndFont(p, "Panel.background", "Panel.foreground",
  94:                                      "Panel.font");
  95:     
  96:     // A test against the reference implementation shows that this method will
  97:     // install a border if one is defined in the UIDefaults table (even though
  98:     // the BasicLookAndFeel doesn't actually define a "Panel.border").  This
  99:     // test was written after discovering that a null argument to 
 100:     // uninstallDefaults throws a NullPointerException in 
 101:     // LookAndFeel.uninstallBorder()...
 102:     LookAndFeel.installBorder(p, "Panel.border");
 103:   }
 104: 
 105:   /**
 106:    * Uninstalls this UI delegate from the specified component.
 107:    *
 108:    * @param c the component (<code>null</code> not permitted).
 109:    */
 110:   public void uninstallUI(JComponent c)
 111:   {
 112:     uninstallDefaults((JPanel) c);
 113:   }
 114: 
 115:   /**
 116:    * Uninstalls the UI defaults for the specified panel.
 117:    *
 118:    * @param p  the panel (<code>null</code> not permitted).
 119:    */
 120:   protected void uninstallDefaults(JPanel p)
 121:   {
 122:     // Tests on the reference implementation showed this method:
 123:     // (1) doesn't actually remove the installed colors and font installed
 124:     //     by installDefaults(), it isn't necessary;
 125:     // (2) throws a NullPointerException in LookAndFeel.uninstallBorder() if
 126:     //     p is null.  Strangely, no border is installed by the 
 127:     //     BasicLookAndFeel - perhaps this is needed by another LAF?
 128:     
 129:     LookAndFeel.uninstallBorder(p);
 130:   }
 131:   
 132: }