// ---------------------------------------------------------------------------
// NAME               : DoubleBox.java
// VERSION            : 1.0
// AUTHOR             : Craig Wilcox
// ---------------------------------------------------------------------------

// -----------------------
// Import java class libs.
// -----------------------
import java.io.*;   		// for Serializable
import java.awt.*;  		// for TextField
import java.awt.event.*;	// for key events
import java.beans.*; 		// for PropertyChangeSupport

// ------------------
// Define main class.
// ------------------
public class DoubleBox extends TextField implements Serializable {
	// DoubleBox's variables
	private double m_low;
	private double m_high;
	private double m_prev;
	private PropertyChangeSupport m_pcs;
	
	public DoubleBox()
	{
		super();
		enableEvents(java.awt.AWTEvent.KEY_EVENT_MASK);
		m_pcs = new PropertyChangeSupport(this);
		m_prev = 0.0;
		m_low = -Double.MAX_VALUE;
		m_high = Double.MAX_VALUE;
	
	}

	/**
	* Creates the DoubleBox text field
	* @param init an initial value,
	* @param size the size of the text field
	*/
	
	public DoubleBox(double init, int size)
	{
		super(""+init, size);
		enableEvents(java.awt.AWTEvent.KEY_EVENT_MASK);
		m_pcs = new PropertyChangeSupport(this);
		m_prev = init;
		m_low = -Double.MAX_VALUE;
		m_high = Double.MAX_VALUE;
	}
	
	/**
	* Creates the DoubleBox text field
	* @param init an initial value,
	* @param min the minimum double accepted
	* @param max the maximum double accepted
	* @param size the size of the text field
	*/

	public DoubleBox(double init, double min, double max, int size)
	{
		super("" + init, size);
		enableEvents(java.awt.AWTEvent.KEY_EVENT_MASK);
		m_pcs = new PropertyChangeSupport(this);
		m_prev = init;
		m_low = min;
		m_high = max;
	}


	public void addPropertyChangeListener(PropertyChangeListener listener) {
		m_pcs.addPropertyChangeListener(listener);
	}
	
	public void removePropertyChangeListener(PropertyChangeListener listener) {
		m_pcs.removePropertyChangeListener(listener);
	}


	/**
	* Get the double data value
	* @return the double data value
	* @remark if invalid, returns the valid prefix (or 0 if none)
	*/
   
	public double getValue() {  
		double value;  
		try {
			value = Double.valueOf(getText().trim()).doubleValue();
			if (value < m_low || value > m_high)
				throw new NumberFormatException();
		} catch (NumberFormatException e) {
			requestFocus();
			this.setText("" + m_prev);
			return m_prev;
		}
		return (double)value; 
	}

	/**
	* Set the value of this field and update its corresponding string
	* @param newVal the newValue for this field,
	* @return the double data value
	* @remark if invalid, returns the valid prefix (or 0 if none)
	*/
	void setValue(double newVal) {
		double oldVal = m_prev;
		this.setText("" + newVal);
		newVal = getValue();
		if (newVal != oldVal) {
			m_pcs.firePropertyChange("value", 
				new Double (oldVal), 
				new Double(newVal));
			m_prev = newVal;
		}
	}

	// Discard non-numeric, non-backspace characters.
	public void processKeyEvent(KeyEvent event) {
		char c = event.getKeyChar();

		// These events get default processing.
		if ((c >= '0' && c <= '9') ||
				c == KeyEvent.VK_DELETE ||
				c == KeyEvent.VK_BACK_SPACE ||
				c == '.' ||
				c == '-' ||
				c == KeyEvent.VK_LEFT ||
				c == KeyEvent.VK_RIGHT) {
					return;
		}

		// This event gets default processing, but the setValue()
		// accessor is also called.
		if ((c == KeyEvent.VK_ENTER)  || (c == KeyEvent.VK_TAB)){
			double d = getValue();
			setValue(d);
			return;
		}

		// All other characters we discard
		if (c == KeyEvent.VK_SEMICOLON)
			setValue(2.7);
			
		event.consume();
	}

}