package myWidgets;

//======================================================================
//  PROJECT:            _programming.java_
//  FILE:               GraphicButton.java
//  PURPOSE:            Chapter 12 lablet
//  VERSION:            2.0
//  TARGET:             Java v1.1
//  UPDATE HISTORY:     2.0     12/4/98    1.1 event model
//                      1.0     8/1/97    the version in _p.j_
//======================================================================

//------------------------------- NOTES --------------------------------
/*
    Here's how to use a GraphicButton:  
   
    INITIALIZATION
        To construct a GraphicButton, supply the constructor with an array
        of two images, and an optional label.  In the array of images,
        image[0] should be the down image and image[1] the up.
        
        NOTE: While not required, it's a good idea for the images to be
        the same size. This class uses the size of the down image to
        center the label.
        
    EVENT HANDLING
        A GraphicButton object responds to MOUSE_ENTERED and MOUSE_EXITED
        events by hiliting and de-hiliting its label.  It responds to
        MOUSE_PRESSED and MOUSE_RELEASED events by redrawing the button
        in its appropriate state (down or up, respectively).
       
        We've implemented an addActionListener() method, so when a 
        GraphicButton processes a MOUSE_RELEASED event, it sends
        a new ActionEvent to all registered listeners, just like
        an ordinary AWT Button.
        
    ACCESSORS, MUTATORS
        getLabel():	Returns the label string.
        setLabel():	Sets the label string to the argument and resizes this object to fit.
*/

//------------------------------ IMPORTS -------------------------------
	
import java.awt.*;
import java.awt.event.*;
 
//======================= GraphicButton CLASS ==========================

/**
 * A GraphicButton has the same functionality as an ordinary AWT button:
 * it responds to mouse clicks by generating ActionEvents, and it keeps
 * track of all listeners that have registered themselves.
 * The primary difference is that it uses images for its up and down displays.
 */
public class GraphicButton extends Canvas implements MouseListener
{
    private final int        LABEL_INSET  = 15;
    private final Color      UP_COLOR     = Color.darkGray;
    private final Color      DOWN_COLOR   = Color.white;
    private final Color      HILITE_COLOR = Color.red;

    protected Image[]        theImage;          // 0 -> is down, 1 -> is up
    private   String         theLabel;
    private   int            thisWidth,
                             thisHeight,
                             labelBase;
    private   ActionListener listeners = null;  // all the registered listeners
    protected int            curImage = 1;
			
	//------------- Constructors and initialization utility ------------
					
    /**
     * Construct a GraphicButton with two images and a label.
     */
    public GraphicButton(Image[] imgs, String label)
    {
        theLabel = label;
        theImage = imgs;

        setFont(new Font("Helvetica", Font.BOLD, 10));
        fitLabel();
        
        addMouseListener(this);
    }
					
    /**
     *	Construct a GraphicButton with two images and no label.
     */
    public GraphicButton(Image[] imgs)
    {
        this(imgs, null);	// Call the other constructor.
    }
	
    /**
     * Size the button so that there is a LABEL_INSET pixel inset on
     * each side of the labeland the label is centered vertically
     * in the button.
     */
    private void fitLabel()
    {
        thisHeight = theImage[0].getHeight(this) - 4;

        if (theLabel != null)
        {
            FontMetrics fm = getFontMetrics(getFont());
            thisWidth = 2 * LABEL_INSET + fm.stringWidth(theLabel);
            labelBase = (thisHeight + fm.getAscent() - fm.getDescent()) / 2;
        }
        else
        {
            thisWidth = 3 * LABEL_INSET;
        }
    }
	
	//------------------------ Event handlers --------------------------
    
    /**
     * Register a new listener for action events that we'll trigger
     * from this object. The AWTEventMulticaster keeps track of all
     * the listeners that have registered with this object and will
     * broadcast any event we want to all the listeners.
     */
     public synchronized void addActionListener(ActionListener who)
     {
          // "listeners" is a chain of registered listeners.
          // This statement adds the argument to the chain.
          listeners = AWTEventMulticaster.add(listeners, who);
     }
	
    /**
     * Change the button state to down.
     */
    public void mousePressed(MouseEvent e)
    {
        curImage = 0;
        repaint();
    }
	
    /**
     * Change the button state to up and send an action event
     * to all registered listeners.
     */
    public void mouseReleased(MouseEvent e)
    {
        curImage = 1;
        repaint();

        // Make a new action event to send out,
        ActionEvent ae = new ActionEvent(this, ActionEvent.ACTION_PERFORMED, theLabel);
        
        // and let the AWTEventMulticaster tell each registered listener
        // to activate its own actionPerformed() method on the new event.
        listeners.actionPerformed(ae);
    }
    
    /**
     * Do nothing in response to a mouse click, since we
     * have already done all the necessary handling in the
     * mousePressed() and mouseReleased() methods.
     */
    public void mouseClicked(MouseEvent e)
    { }
	
    /**
     * Deal with a MOUSE_ENTERED event by hilighting the label of the button.
     */
    public void mouseEntered(MouseEvent e)
    {
        Graphics g = getGraphics();
        g.setColor(HILITE_COLOR);
        g.drawString(theLabel, LABEL_INSET, labelBase);
    }
	
    /**
     * Turn off hilighting when the mouse leaves this object.
     */
    public void mouseExited(MouseEvent e)
    {
        paintLabel(this.getGraphics());
    }
	
	//--------------------------- Graphics -----------------------------
	
    /**
     * For flicker-free animation in the AnimatedButton subclass.
     */
    public void update(Graphics g)
    {
        paint(g);
    }
	
    /**
     * Redraw the image and paint the label on top of it.
     */
    public void paint(Graphics g)
    {
        g.drawImage(theImage[curImage], 0, 0, thisWidth, thisHeight, this);
			
        if (theLabel != null)
        {
            paintLabel(g);
        }
    }
    
    /**
     * Paint the label in the appropriate color.
     * CALLED BY: mouseExited(), paint()
     */
    private void paintLabel(Graphics g)
    {
        if (curImage > 0)
        {
            g.setColor(UP_COLOR);
        }
        else
        {
            g.setColor(DOWN_COLOR);
        }
        g.drawString(theLabel, LABEL_INSET, labelBase);
    }
	
	//--------------------- Accessors, mutators ------------------------
	
    /**
     * Return a copy of the label string.
     */
    public String getLabel()
    {
        return new String(theLabel);
    }
	
    /**
     * Set the label text, center it, and update the drawing.
     */
    public void setLabel(String s)
    {
        theLabel = s;
        fitLabel();
        repaint();
    }
}