foldertreecellrenderer.java

一个用java写的mail.里面的代码值得我们去研究！学习。

/*
** $Id: FolderTreeCellRenderer.java,v 1.3 2001/05/07 12:37:21 kunugi Exp $
**
** Copyright (c) 2000-2001 Jeff Gay
** on behalf of ICEMail.org <http://www.icemail.org>
** Copyright (c) 1998-2000 by Timothy Gerard Endres
** 
** This program is free software.
** 
** You may redistribute it and/or modify it under the terms of the GNU
** General Public License as published by the Free Software Foundation.
** Version 2 of the license should be included with this distribution in
** the file LICENSE, as well as License.html. If the license is not
** included with this distribution, you may find a copy at the FSF web
** site at 'www.gnu.org' or 'www.fsf.org', or you may write to the
** Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139 USA.
**
** THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY OF ANY KIND,
** NOT EVEN THE IMPLIED WARRANTY OF MERCHANTABILITY. THE AUTHOR
** OF THIS SOFTWARE, ASSUMES _NO_ RESPONSIBILITY FOR ANY
** CONSEQUENCE RESULTING FROM THE USE, MODIFICATION, OR
** REDISTRIBUTION OF THIS SOFTWARE. 
*/

package org.icemail.mail;

import java.awt.Color;
import java.awt.Component;
import java.awt.Font;
import java.awt.Image;

import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JLabel;
import javax.swing.JTree;

import javax.swing.tree.TreeCellRenderer;
import javax.swing.tree.DefaultMutableTreeNode;

import org.icemail.util.AWTUtilities;
import org.icemail.util.UserProperties;


/**
 * This class renders the nodes of the various trees in the application.
 * Nodes are rendered based on the type of underlying object and state of the node.
 */
public class FolderTreeCellRenderer
  extends JLabel
  implements TreeCellRenderer
{
  static private ImageIcon  rootExpIcon;
  static private ImageIcon  rootColIcon;
  static private ImageIcon  storeExpIcon;
  static private ImageIcon  storeColIcon;
  static private ImageIcon  folderExpIcon;
  static private ImageIcon  folderColIcon;
  static private ImageIcon  mailboxExpIcon;
  static private ImageIcon  mailboxColIcon;

  static private Font       selectedFont;
  static private Font       unselectedFont;

  static private Color      selectedColor;
  static private Color      unSelectedColor;


  static {
    try {
      Image iconImg;

      iconImg = AWTUtilities.getImageResource( "/org/icemail/mail/images/rootexp.gif" );
      rootExpIcon = new ImageIcon( iconImg );
      iconImg = AWTUtilities.getImageResource( "/org/icemail/mail/images/rootcol.gif" );
      rootColIcon = new ImageIcon( iconImg );

      iconImg = AWTUtilities.getImageResource( "/org/icemail/mail/images/storexp.gif" );
      storeExpIcon = new ImageIcon( iconImg );
      iconImg = AWTUtilities.getImageResource( "/org/icemail/mail/images/storcol.gif" );
      storeColIcon = new ImageIcon( iconImg );

      iconImg = AWTUtilities.getImageResource( "/org/icemail/mail/images/foldexp.gif" );
      folderExpIcon = new ImageIcon( iconImg );
      iconImg = AWTUtilities.getImageResource( "/org/icemail/mail/images/foldcol.gif" );
      folderColIcon = new ImageIcon( iconImg );

      iconImg = AWTUtilities.getImageResource( "/org/icemail/mail/images/mboxexp.gif" );
      mailboxExpIcon = new ImageIcon( iconImg );
      iconImg = AWTUtilities.getImageResource( "/org/icemail/mail/images/mboxcol.gif" );
      mailboxColIcon = new ImageIcon( iconImg );
    } catch ( Exception ex ) {
      System.err.println( "FolderTreeCellRenderer.static: Couldn't load images: " +
                          ex.getMessage() );
    }

    selectedColor =
        UserProperties.getColor( "folderTree.colors.selected", new Color( 150, 0, 0 ) );
    unSelectedColor =
        UserProperties.getColor( "folderTree.colors.unselected", Color.black );

    selectedFont = new Font( "SansSerif", Font.BOLD, 12 );
    unselectedFont = new Font( "SansSerif", Font.BOLD, 12 );
  }

  /**
   * Default constructor.
   */
  public
  FolderTreeCellRenderer() {
    super();
  }

  /**
   * Sets the value of the current tree cell to the given value.
   * <p>
   * If selected is true, the cell will be drawn as if selected.
   * If expanded is true the node is currently expanded and
   * if leaf is true the node represets a leaf and
   * if hasFocus is true the node currently has focus.
   *
   * This is messaged from JTree whenever it needs to get the size
   * of the component or it wants to draw it.
   * This attempts to set the font based on value, which will be
   * a TreeNode.
   * <p>
   * Implementation of java.swing.tree.TreeCellRenderer.getTreeCellRendererComponent()
   *
   * @param tree the JTree the receiver is being configured for
   * @return component that the renderer uses to draw the value
   */
  public Component
  getTreeCellRendererComponent( JTree tree, Object value,
                                boolean selected, boolean expanded,
                                boolean leaf, int row, boolean hasFocus ) {
    Font  font;
    String stringValue =
      tree.convertValueToText( value, selected, expanded, leaf, row, hasFocus );

  /* Set the image. */
    if ( expanded ) {
      if ( value instanceof RootTreeNode ) {
        this.setIcon( rootExpIcon );
      } else if ( value instanceof StoreTreeNode ) {
        this.setIcon( storeExpIcon );
      } else if ( value instanceof FolderTreeNode ) {
        if ( leaf ) {
          this.setIcon( mailboxExpIcon );
        } else {
          this.setIcon( folderExpIcon );
        }
      } else {
        this.setIcon( folderColIcon );
      }
    } else {
      if ( value instanceof RootTreeNode ) {
        this.setIcon( rootColIcon );
      } else if ( value instanceof StoreTreeNode ) {
        this.setIcon( storeColIcon );
      } else if ( value instanceof FolderTreeNode) {
        if ( leaf ) {
          this.setIcon( mailboxColIcon );
        } else {
          this.setIcon( folderColIcon );
        }
      } else {
        this.setIcon( folderColIcon );
      }
    }

    if ( selected ) {
      setForeground( selectedColor );
    } else {
      setForeground( unSelectedColor );
    }

  /* Set the text. */
    this.setText( stringValue );

    return this;
  }

}