/*
 * [SmoothScroll.java]
 *
 * Summary: Traditional Scroll.
 *
 * Copyright: (c) 1998-2017 Roedy Green, Canadian Mind Products, http://mindprod.com
 *
 * Licence: This software may be copied and used freely for any purpose but military.
 *          http://mindprod.com/contact/nonmil.html
 *
 * Requires: JDK 1.8+
 *
 * Created with: JetBrains IntelliJ IDEA IDE http://www.jetbrains.com/idea/
 *
 * Version History:
 *  1.0 2002-06-28 original.
 */
package com.mindprod.smooth;
/**
 * Traditional Scroll.
 *
 * @author Roedy Green, Canadian Mind Products
 * @version 1.0 2002-06-28 original.
 * @since 2002-06-28
 */

import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.RenderingHints;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

public final class SmoothScroll extends JPanel
    {
    int w, h;   // width and height

    Image bigImage; // offscreen big image we pan over

    /**
     * how many pixels we have so far panned the image
     * up.
     */
    private int pixelsScrolled = 0;

    public SmoothScroll()
        {
        super( false );
        w = 800;
        h = 900;
        }

    public static void main( String[] args )
        {
        JFrame f = new JFrame();
        final SmoothScroll tp = new SmoothScroll();
        f.getContentPane().add( tp );
        f.pack();
        f.addWindowListener( new WindowAdapter()
            {
            public void windowClosing( WindowEvent we )
                {
                System.exit( 0 );
                }
            } );
        f.setVisible( true );
        }

    public void addNotify()
        {
        super.addNotify();
        // create  buffered image here
        Font f = new Font( "Arial", Font.BOLD, 48 );
        // Ideally want Image, using native video card format.
        // prepare giant image offscreen.
        bigImage = createImage( w, h );
        Graphics g = bigImage.getGraphics();
        Graphics2D g2d = null;
        if ( g instanceof Graphics2D )
            {
            g2d = ( Graphics2D ) g;
            g2d.addRenderingHints( new RenderingHints(
                    RenderingHints.KEY_ANTIALIASING,
                    RenderingHints.VALUE_ANTIALIAS_ON ) );
            }
        g.setColor( Color.RED );
        g.fillRect( 0, 0, w, 168 );
        g.setColor( Color.BLUE );
        g.fillRect( 0, 168, w, h );
        g.setColor( Color.WHITE );
        g.setFont( f );
        FontMetrics fm = g.getFontMetrics();
        int strHeight = fm.getHeight();
        g.drawString( "AQUEDUCT", ( ( w - fm.stringWidth( "AQUEDUCT" ) ) / 2 ), strHeight );
        int y = strHeight + 168;
        for ( int i = 0; i < h / strHeight; i++ )
            {
            g.drawString(
                    i + " Now is the time for all good men to come to the aid of the party.", 10, y );
            y += strHeight;
            }
        }

    public Dimension getPreferredSize()
        {
        return new Dimension( 800, 600 );
        }

    public void paintComponent( Graphics g )
        {
        // copy a small piece of the big image onto the screen
        // We are not scaling.
        g.drawImage( bigImage,
                /* dx1 */ 0, /* dy1 */ 0, /* dx2 */ w, /* dy2 */ h,
                /* sx1 */ 0, /* sy1 */ pixelsScrolled, /* sx2 */ w, /* sy2 */ h + pixelsScrolled,
                /* observer */ this );
        pixelsScrolled++;
        repaint(); // tight loop to scroll as fast as possible.
        // in real life you would control the frequency of repaints in a more sophisticated
        // manner.
        }
    }