/*
* ScrollText.java - Scrolling text widget (super charged version)
*
* This class presents a text message that scrolls through rectangular area
* from right to left. Double buffering is used to smooth the animation.
*
* @author	Philip Meese
* @version	1.1, 3/18/96 Java Tutor, Second Column
*
* v1.101	Adds double buffering, text centering, drop shadow
*/
import java.awt.*;

public class ScrollText extends Canvas implements Runnable{
	private Thread		_thread;
	private String		_message;
	private int		_speed=50;	// medium speed default
	private Font		_font;
	private int		_msgWidth;
	private Rectangle	_rect;
	private int		_msgX, _msgY;
	private Image		_ibuffer=null;	// image buffer

	/**
	* Constructor which sets message, width and height of display area
	*
	* @arg message_	The message to be displayed
	* @arg width_		The initial width of the display area
	* @arg height_		The initial height of the display area
	*/
	public ScrollText(String message_, int width_, int height_){
	     _message=message_;
	     _font=new Font("TimesRoman", Font.BOLD, 56);
	     _rect=new Rectangle(0, 0, width_, height_);

	     reshape(0, 0, width_, height_);
	     _msgX=width_;			// offscreen, right

	     _thread=new Thread(this);
	}
	/**
	* Sets the scrolling speed
	*
	* @arg speed_ 	A value between 0 and 100 (slowest to fastest)
	*/
	public void speed(int speed_){
	     if(speed_ > 0 && speed_ < 100)
		  _speed=speed_;
	}
	/**
	* Creates the Image block of a text message.
	* Once this image is created, it is moved about within the text
	* display area, giving it the appearance of "scrolling" like a
	* stock ticker.
	*/
	private void createTextImage(){
	     Toolkit tk=Toolkit.getDefaultToolkit();
	     FontMetrics fontMetrics=tk.getFontMetrics(_font);

	     _msgWidth=fontMetrics.stringWidth(_message) + 4;

	     _ibuffer=createImage(_msgWidth, _rect.height);
	     Graphics ibg = _ibuffer.getGraphics();
	     ibg.setFont(_font);

	     _msgY=(int)((double)_rect.height/2.0 +
			 (double)fontMetrics.getAscent()/2.0 -
			 fontMetrics.getDescent());

	     ibg.setColor(Color.blue);
	     ibg.fillRect(0, 0, _msgWidth, _rect.height);
	     paintMessage(ibg, Color.yellow, 1, _msgY);
	}
	/**
	* Your standard update function: called by the AWT in response
	* to a repaint() request or when the image area has been "damaged".
	*
	* @arg g_	The Graphics object to draw on
	*/
	public void update(Graphics g_){
		Rectangle rect=bounds();
		if(_ibuffer == null || !rect.equals(_rect)){	// startup and resize
			_rect=rect;
			createTextImage();
		}
		paintBackground(g_, Color.blue);
		g_.drawImage(_ibuffer, _msgX, 0, this);
	}
	/**
	* Painter's helper: paints the message and it's drop shadow (!)
	*
	* @arg g_	The Graphics object to draw on
	* @arg c_	The color to render the font in
	* @arg x_	The X origin for font rendering
	* @arg y_	The Y origin for font rendering
	*/
	private void paintMessage(Graphics g_, Color c_, int x_, int y_){
	     g_.setColor(Color.black);
	     g_.drawString(_message, x_+2, y_+2);	// drop shadow
 	     g_.setColor(c_);
 	     g_.drawString(_message, x_, y_);
 	}
 	/**
 	* Another painter's helper
 	* Fills background area not occupied by text image. Given that the text
 	* image is shorter than the scrolling message area, there is potentially
 	* a leading area AND a trailing area. Both need to be filled with the
 	* background color.
 	*
 	* @arg g_	The Graphics object to draw on
 	* @arg c_	The Color to draw with
 	*/
 	private void paintBackground(Graphics g_, Color c_){
 	     int tail;
 	     g_.setColor(c_);
 	     if(_msgX > 0)
 		  g_.fillRect(0, 0, _msgX, _rect.height);
 	     if((tail=_msgX + _msgWidth) < _rect.width)
 		  g_.fillRect(tail, 0, _rect.width - tail, _rect.height);
 	}
 	/**
 	* The thread runner: called in response to _thread.start()
 	*/
 	public void run(){
 	     while(true){	// forever (or a very long time)
 		  try{
 		       _thread.sleep(100 - _speed);	// pause that refreshes
 		       _msgX -= 1;			// move left
 		       if(_msgX <= -1 * _msgWidth)	// message wrap
 			    _msgX = _rect.width;
 		       repaint();
 		  }
 		  catch(InterruptedException e) { break; }
 	     }
 	}
        public void start(){	_thread.start();		}
 	public void suspend(){	_thread.suspend();	}
 	public void resume(){	_thread.resume();	}
 	public void stop(){	_thread.stop();		}

 } // end class ScrollText