Source for javax.swing.plaf.basic.BasicComboBoxRenderer

   1: /* BasicComboBoxRenderer.java --
   2:    Copyright (C) 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 javax.swing.plaf.basic;
  40: 
  41: import java.awt.Component;
  42: import java.awt.Dimension;
  43: import java.awt.FontMetrics;
  44: import java.io.Serializable;
  45: 
  46: import javax.swing.JComboBox;
  47: import javax.swing.JLabel;
  48: import javax.swing.JList;
  49: import javax.swing.ListCellRenderer;
  50: import javax.swing.SwingConstants;
  51: import javax.swing.SwingUtilities;
  52: import javax.swing.border.Border;
  53: import javax.swing.border.EmptyBorder;
  54: 
  55: /**
  56:  * A renderer for a {@link JComboBox}. 
  57:  *
  58:  * @author Olga Rodimina
  59:  */
  60: public class BasicComboBoxRenderer 
  61:   extends JLabel 
  62:   implements ListCellRenderer, Serializable
  63: {
  64:   /**
  65:    * A shared border instance for all renderers.
  66:    */
  67:   protected static Border noFocusBorder = new EmptyBorder(0, 0, 0, 0);
  68: 
  69:   /**
  70:    * Creates a new <code>BasicComboBoxRenderer</code> object.
  71:    */
  72:   public BasicComboBoxRenderer()
  73:   {
  74:     setHorizontalAlignment(SwingConstants.LEFT);
  75:     setBorder(noFocusBorder);
  76:   }
  77: 
  78:   /**
  79:    * Returns preferredSize of the renderer
  80:    *
  81:    * @return preferredSize of the renderer
  82:    */
  83:   public Dimension getPreferredSize()
  84:   {
  85:     return super.getPreferredSize();
  86:   }
  87: 
  88:   /**
  89:    * Returns a component that has been configured to display the given
  90:    * <code>value</code>.
  91:    *
  92:    * @param list List of items for which to the background and foreground
  93:    *        colors
  94:    * @param value object that should be rendered in the cell
  95:    * @param index index of the cell in the list of items.
  96:    * @param isSelected draw cell highlighted if isSelected is true
  97:    * @param cellHasFocus draw focus rectangle around cell if the cell has
  98:    *        focus
  99:    *
 100:    * @return Component that will be used to draw the desired cell.
 101:    */
 102:   public Component getListCellRendererComponent(JList list, Object value,
 103:                                                 int index, boolean isSelected,
 104:                                                 boolean cellHasFocus)
 105:   {
 106:     String s = value.toString();
 107:     
 108:     // String maybe larger than comboBox.
 109:     FontMetrics fm = getToolkit().getFontMetrics(list.getFont());
 110:     int strWidth = SwingUtilities.computeStringWidth(fm, s);
 111:     int cbWidth = getSize().width;
 112:     if (cbWidth != 0 && strWidth > cbWidth)
 113:       {
 114:         char[] str = s.toCharArray();
 115:         int currWidth = 0;
 116:         int i = 0;
 117:         String postStr = "... ";
 118:         cbWidth -= SwingUtilities.computeStringWidth(fm, postStr);
 119:         while (i < str.length && currWidth < cbWidth)
 120:           {
 121:             ++i;
 122:             currWidth = SwingUtilities.computeStringWidth(fm, new String(str, 0, i));
 123:           }
 124:         setText(new String(str, 0, i)  + postStr);
 125:       }
 126:     else   
 127:       setText(s);
 128:     
 129:     setOpaque(true);
 130: 
 131:     if (isSelected || cellHasFocus)
 132:       {
 133:         setBackground(list.getSelectionBackground());
 134:         setForeground(list.getSelectionForeground());
 135:       }
 136:     else
 137:       {
 138:         setBackground(list.getBackground());
 139:         setForeground(list.getForeground());
 140:       }
 141: 
 142:     setEnabled(list.isEnabled());
 143:     setFont(list.getFont());
 144:     return this;
 145:   }
 146: 
 147:   /**
 148:    * A subclass of {@link BasicComboBoxRenderer} that implements the
 149:    * {@link javax.swing.plaf.UIResource} interface.
 150:    */
 151:   public static class UIResource extends BasicComboBoxRenderer
 152:     implements javax.swing.plaf.UIResource
 153:   {
 154:     /**
 155:      * Creates a new <code>UIResource</code> object.
 156:      */
 157:     public UIResource()
 158:     {
 159:       // Nothing to do here.
 160:     }
 161:   }
 162: }