// Dy Derek Jones 2000

//-----------------------------------------------------------------------------
// Import Files
//-----------------------------------------------------------------------------

import java.awt.*;
import java.applet.Applet;

//-----------------------------------------------------------------------------
// TrivialApplet, showing buffered and non-buffered graphics
//-----------------------------------------------------------------------------

public class TrivialApplet extends Applet
{	
	//-------------------------------------------------------------------------
	// Variables
	//-------------------------------------------------------------------------
	
	// Font
	Font font = new Font("ARIAL", Font.BOLD, 20);
	
	// Buffered Graphics
	Dimension offDimension;	// Width and height of buffer
	Image offImage;		// Image to be drawn to and then drawn on the surface
	Graphics offGraphics;	// Context for drawing to the image
	
	//-------------------------------------------------------------------------
	// Program
	//-------------------------------------------------------------------------
	
	///////////////////////////////////////////////////////////
	// Name: paint()
	// Desc: paints shapes and text using buffer and without
	// using buffer, to show difference
	///////////////////////////////////////////////////////////

	public void paint(Graphics g)
	{
	        // Grab the width and height of the canvas
	        Dimension d = size();
	
	        // Create the offscreen graphics, if no good one exists
	        if (offGraphics == null || d.width != offDimension.width || d.height != offDimension.height)
	        {
	                offDimension = d;
	                offImage = createImage(d.width, d.height);
	                offGraphics = offImage.getGraphics();
	        }
	        
	        float x = 0f;
	        boolean movingRight = true;
	        
	        // Drawing Loop
	        while(true)
	        {
	        	// Update Location
			if(movingRight)
			{
				x+=0.5f;
			}
			else	
			{
				x-=0.5f;
			}
	        		
			//Clear the screen
			offGraphics.setColor(Color.white);
			offGraphics.fillRect(0,0,d.width,d.height); 
			// not clearRect() because its an offscreen image

			// Draw Items
			offGraphics.setColor(Color.black);
			offGraphics.setFont(font);
			offGraphics.drawString("GRAPHICS BUFFERS",10,25);
			offGraphics.setColor(Color.blue);
			offGraphics.fillOval((int)x,0,30,30);
	                        
			// Copy the off screen image buffer to the screen.
			g.drawImage(offImage,0,0,this);
	                
			// Bounce
			if( x >= d.width - 30f)
			{
				movingRight = false;
			}
			else  if( x <= 0f)
			{
				movingRight = true;
			}
		}
	}
}