/*
 * Copyright (c) 2004 David Flanagan.  All rights reserved.
 * This code is from the book Java Examples in a Nutshell, 3nd Edition.
 * It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied.
 * You may study, use, and modify it for any non-commercial purpose,
 * including teaching and use in open-source projects.
 * You may distribute it non-commercially as long as you retain this notice.
 * For a commercial use license, or to purchase the book, 
 * please visit http://www.davidflanagan.com/javaexamples3.
 */
package je3.datatransfer;
import javax.swing.*;
import javax.swing.border.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.datatransfer.*;
import javax.swing.Timer; // disambiguate from java.util.Timer
import java.text.DateFormat;
import java.util.Date;

/**
 * A custom Swing component that displays a simple digital clock.
 * Demonstrates how to add copy and drag support to a Swing component
 * with TransferHandler.  
 */
public class DigitalClock extends JLabel {
    DateFormat format;   // How to display the time in string form
    int updateFrequency; // How often to update the time (in milliseconds)
    Timer timer;         // Triggers repeated updates to the clock
    
    public DigitalClock() {
	// Set default values for our properties
	setFormat(DateFormat.getTimeInstance(DateFormat.MEDIUM, getLocale()));
	setUpdateFrequency(1000);  // Update once a second

	// Specify a Swing TransferHandler object to do the dirty work of
	// copy-and-paste and drag-and-drop for us.  This one will transfer
	// the value of the "time" property.  Since this property is read-only
	// it will allow drags but not drops.
	setTransferHandler(new TransferHandler("time"));

	// Since JLabel does not normally support drag-and-drop, we need an
	// event handler to detect a drag and start the transfer.
	addMouseMotionListener(new MouseMotionAdapter() {
		public void mouseDragged(MouseEvent e) {
		    getTransferHandler().exportAsDrag(DigitalClock.this, e,
						      TransferHandler.COPY);
		}
	    });

	// Before we can have a keyboard binding for a Copy command,
	// the component needs to be able to accept keyboard focus.
	setFocusable(true);
	// Request focus when we're clicked on
	addMouseListener(new MouseAdapter() {
		public void mouseClicked(MouseEvent e) { requestFocus(); }
	    });
	// Use a LineBorder to indicate when we've got the keyboard focus
	addFocusListener(new FocusListener() {
		public void focusGained(FocusEvent e) {
		    setBorder(LineBorder.createBlackLineBorder());
		}
		public void focusLost(FocusEvent e) { setBorder(null); }
	    });

	// Now bind the Ctrl-C keystroke to a "Copy" command.
	InputMap im = new InputMap();
	im.setParent(getInputMap(WHEN_FOCUSED));
	im.put(KeyStroke.getKeyStroke(KeyEvent.VK_C,InputEvent.CTRL_MASK),
	       "Copy");
	setInputMap(WHEN_FOCUSED, im);
	
	// And bind the "Copy" command to a pre-defined Action that performs
	// a copy using the TransferHandler we've installed.
	ActionMap am = new ActionMap();
	am.setParent(getActionMap());
	am.put("Copy", TransferHandler.getCopyAction());
	setActionMap(am);

	// Create a javax.swing.Timer object that will generate ActionEvents
	// to tell us when to update the displayed time.  Every updateFrequency
	// milliseconds, this timer will cause the actionPerformed() method
	// to be invoked.  (For non-GUI applications, see java.util.Timer.)
	timer = new Timer(updateFrequency, new ActionListener() {
		public void actionPerformed(ActionEvent e) {
		    setText(getTime());  // set label to current time string
		}
	    });
	timer.setInitialDelay(0); // Do the first update immediately
	timer.start();            // Start timing now!
    }

    // Return the current time as a String.
    // This is the property accessor method used by the TransferHandler.
    // Since there is a getter, but no setter, the TransferHandler will
    // reject any attempts to drop data on us.
    public String getTime() {
	// Use the DateFormat object to convert current time to a string
	return format.format(new Date());
    }

    // Here are two related property setter methods
    public void setFormat(DateFormat format) { this.format = format; }
    public void setUpdateFrequency(int ms) { this.updateFrequency = ms; }
}