//
// DBApplet - An applet with an offscreen image for drawing into, and a few
//            other kooky things that turned out to be useful
//
// mdb - 12/11/96

import java.applet.Applet;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Event;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Image;

public abstract class DBApplet extends Applet implements Runnable
{
    //
    // DBApplet public member functions

    public void init ()
    {
        Dimension d = size();
        _offImage = createImage(d.width, d.height);
        _offGraphics = _offImage.getGraphics();

        // clear out the background
        _offGraphics.setColor(Color.white);
        _offGraphics.fillRect(0, 0, d.width, d.height);
        _offGraphics.setColor(Color.black);
        _offGraphics.setFont(new Font("Helvetica", Font.PLAIN, 11));

        // get some graphics stuff
        _metrics = _offGraphics.getFontMetrics();
        _height = _metrics.getHeight();
        _ascent = _metrics.getAscent();
    }

    public void start ()
    {
        _self = new Thread(this);
        _self.start();
    }

    public void stop ()
    {
        _self = null;
    }

    public boolean running ()
    {
        return _self == Thread.currentThread();
    }

    public abstract void run ();

    public void update (Graphics g)
    {
        g.drawImage(_offImage, 0, 0, null);
    }

    public void paint (Graphics g)
    {
        g.drawImage(_offImage, 0, 0, null);
    }

    public synchronized void waitForClick ()
    {
        try {
            this.wait();
            _clicked = false;
        } catch (InterruptedException e) {
        }
    }

    public synchronized boolean mouseDown (Event evt, int x, int y)
    {
        _clicked = true;
        this.notify();
        return true;
    }

    public void title (String line1, String line2)
    {
        Dimension d = size();

        int width = _metrics.stringWidth(line1);
        _offGraphics.drawString(line1, d.width-width-5, 5 + _ascent);

        width = _metrics.stringWidth(line2);
        _offGraphics.drawString(line2, d.width-width-5, 5 + _ascent + _height);
    }

    public void message (String line1, String line2)
    {
        _mwidth = Math.max(_metrics.stringWidth(line1),
                           _metrics.stringWidth(line2));
        _offGraphics.drawString(line1, 5, 5+_ascent);
        _offGraphics.setColor(Color.red);
        _offGraphics.drawString(line2, 5, 5+_ascent+_height);
        _offGraphics.setColor(Color.black);
    }

    public void clearMessage ()
    {
        _offGraphics.setColor(Color.white);
        _offGraphics.fillRect(5, 5, 5 + _mwidth, 5+_ascent+_height);
        _offGraphics.setColor(Color.black);
    }

    public void clear ()
    {
        Dimension d = size();
        _offGraphics.setColor(Color.white);
        _offGraphics.fillRect(0, 0, d.width, d.height);
        _offGraphics.setColor(Color.black);
    }

    public void sleep (long milliseconds)
    {
        try {
            Thread.sleep(milliseconds);
        } catch (InterruptedException e) {
        }
    }

    public boolean clicked ()
    {
        boolean clicked = _clicked;
        _clicked = false;
        return clicked;
    }

    //
    // DBApplet protected data members

    Thread _self;

    Image _offImage;
    Graphics _offGraphics;

    FontMetrics _metrics;
    int _height;
    int _ascent;

    int _mwidth;

    boolean _clicked;
};