// This program shows the displayed values for some Unicode symbols.
// Note the command line doesn't generally support Unicode fonts.
//
// Written 3/2005 by Wayne Pollock, Tampa Florida USA.

import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;

public class UnicodeSymbols extends JApplet implements ActionListener
{
   private JTextArea ta;
   private JLabel title, currentFontLbl;
   private Font font;  // Need a font that can display Unicode!
   private ArrayList<Font> fontList;
   private JMenuBar menuBar;
   private JMenu fontMenu;

   public void init ()
   {
      ta = new JTextArea( 11, 20 );  // TextArea to display symbols
      ta.setEditable( false );

      // Find all Fonts that can display these symbols:
      fontList = new ArrayList<Font>();
      Collections.addAll( fontList,
         GraphicsEnvironment.getLocalGraphicsEnvironment().getAllFonts() );
      for (Iterator<Font> i = fontList.iterator(); i.hasNext(); )
      {
         Font f = i.next();
         if ( ! f.canDisplay( '\u25B6' ) )
            i.remove();
      }

      //Create the menu bar:
      menuBar = new JMenuBar();

      //Build the font menu:
      fontMenu = new JMenu( "Unicode Fonts" );
      fontMenu.setMnemonic( KeyEvent.VK_U );
      fontMenu.getAccessibleContext().setAccessibleDescription(
              "Menu of available Unicode fonts" );
      menuBar.add( fontMenu );

      // Populate the font menu with radio button menu items for each font:
      ButtonGroup fontGroup = new ButtonGroup();
      JRadioButtonMenuItem item;

      // If no Unicode fonts found, add something anyway (disabled):
      if ( fontList.size() == 0 )
      {
         fontList.add( new Font( "Lucida", Font.PLAIN, 18 ) );
         item = new JRadioButtonMenuItem( "Non-Unicode Font" );
         item.setEnabled( false );
         fontGroup.add( item );
         fontMenu.add( item );
      }
      else
      {  for ( Font f : fontList )
         {
            item = new JRadioButtonMenuItem( f.getName() );
            item.addActionListener( this ); // Hook up event handling.
            fontGroup.add( item );
            fontMenu.add( item );
         }
      }

      setJMenuBar( menuBar );

      // Select the first font as default:
      fontMenu.getItem( 0 ).setSelected( true );
      font = fontList.get( 0 );
      ta.setFont( font.deriveFont( Font.PLAIN, 18.0F ) );

      title = new JLabel( "Some Useful Unicode Symbols", JLabel.CENTER );
      title.setFont( new Font( "SansSeriff", Font.BOLD, 18 ) );
      title.setForeground( Color.BLUE );

      currentFontLbl = new JLabel( "(Font used: \"" + font.getName() + "\")",
        JLabel.CENTER );
      currentFontLbl.setFont( new Font( "SansSeriff", Font.BOLD, 14 ) );
      currentFontLbl.setForeground( Color.BLUE );

      // Layout and add the components:
      setContentPane( Box.createVerticalBox() );
      add( title );
      add( Box.createVerticalGlue() );
      add( currentFontLbl );
      add( Box.createVerticalGlue() );
      add( Box.createVerticalGlue() );
      add( new JScrollPane( ta ) );
      addContent( ta );
   }

   private void addContent ( JTextArea ta )
   {
      ta.append(
         "\\u2103: \u2103 (Celsius degrees)\n" +
         "\\u2109: \u2109 (Fahrenheit degrees)\n" +
         "\\u00B0: \u00B0 (Generic degree symbol)\n\n" +

         "\\u2713: \u2713 (Checkmark symbol)\n" +
         "\\u2714: \u2714 (Heavy checkmark symbol)\n" +

         "\\u00A9: \u00A9 (Copyright symbol)\n\n" +
         "\\u2192: \u2192 (Right arrow symbol)\n" +
         "\\u25B6: \u25B6 (Heirarchical menu (arrow) symbol)\n"
      );
   }

   public void actionPerformed ( ActionEvent event )
   {
      // Update Font selection:
      String fontName = event.getActionCommand();
      for ( Font f : fontList )
         if ( f.getName().equals( fontName ) )
            font = f;
      currentFontLbl.setText( "(Font used: \"" + font.getName() + "\")" );
      ta.setFont( font.deriveFont( Font.PLAIN, 18.0F ) );
   }

   public static void main ( String [] args )
   {
      JFrame frame = new JFrame( "Some Useful Unicode Symbols" );
      frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
      JApplet me = new UnicodeSymbols();
      frame.add( me, BorderLayout.CENTER );
      me.init();
      me.start();
      frame.pack();
      frame.setVisible( true );
   }
}