//Title:       HopDemo
//Version:     1.2    2000/1/22
//Copyright:   Copyright (c) 2000
//Author:      David Imai
//Description: Draws a complex image using Barry Martin's
//             Hopalong algorithm.


import java.awt.*;
import java.applet.*;
//import java.awt.event.*;


public class HopDemo extends Applet
{
    boolean isStandalone = false;
    String s1 = new String();
    Panel paramPanel = new Panel();
    BorderLayout borderLayout1 = new BorderLayout();
    TextField atxt = new TextField(12);
    TextField btxt = new TextField(12);
    TextField ctxt = new TextField(12);
    Button newParamBtn = new Button();
    Panel controlPanel = new Panel();
    Label albl = new Label();
    Label blbl = new Label();
    Label clbl = new Label();
    Button zoomInBtn = new Button();
    Button newImageBtn = new Button();
    Button zoomOutBtn = new Button();
    Button changeBtn = new Button();
    Double tempD = new Double(1.0);
    HopCanvas picture = new HopCanvas(2.5, 0.5, 3.2);
    FlowLayout flowLayout1 = new FlowLayout();
    FlowLayout flowLayout2 = new FlowLayout();
    FlowLayout flowLayout3 = new FlowLayout();

//Initialize the applet

    public void init()
    {
        try
        { jbInit();  }
        catch (Exception e)
        { e.printStackTrace(); }
    }
//Component initialization

    private void jbInit() throws Exception
    {

        this.setLayout(borderLayout1);
        controlPanel.setLayout(flowLayout2);
        this.add("North", controlPanel);
//        this.add(controlPanel, BorderLayout.NORTH);//Java 1.1
        controlPanel.add(newImageBtn);
        controlPanel.add(zoomInBtn);
        controlPanel.add(zoomOutBtn);
        controlPanel.add(changeBtn);
        controlPanel.add(newParamBtn);
        zoomInBtn.setLabel("Zoom In");
        zoomOutBtn.setLabel("Zoom Out");
        changeBtn.setLabel("Change Color");
        newImageBtn.setLabel("New Image");
        newParamBtn.setLabel("Change a, b, c");

        this.add("Center", picture);
//        this.add(picture, BorderLayout.CENTER);    //Java 1.1
        this.add("South", paramPanel);
//      this.add(paramPanel, BorderLayout.SOUTH);  //Java 1.1
        paramPanel.setForeground(Color.black);
        paramPanel.setBackground(Color.white);
        paramPanel.setLayout(flowLayout3);
        paramPanel.add(albl);
        paramPanel.add(atxt);
        paramPanel.add(blbl);
        paramPanel.add(btxt);
        paramPanel.add(clbl);
        paramPanel.add(ctxt);
        albl.setBackground(Color.white);
        albl.setText(" a =");
        atxt.setBackground(Color.white);
        blbl.setBackground(Color.white);
        blbl.setText(" b =");
        btxt.setBackground(Color.white);
        clbl.setBackground(Color.white);
        clbl.setText(" c =");
        ctxt.setBackground(Color.white);
        picture.repaint();
        showParam();
    }
//Get Applet information

    public String getAppletInfo()
    {return "Applet Information"; }

//Display parameters in text boxes

    public void showParam()
    {
        Double d1;
        d1 = new Double(picture.geta());
        s1 = d1.toString();
        atxt.setText(s1);
        d1 = new Double(picture.getb());
        s1 = d1.toString();
        btxt.setText(s1);
        d1 = new Double(picture.getc());
        s1 = d1.toString();
        ctxt.setText(s1);

    }

//Check button presses

    public boolean action(Event e, Object o)
    {   if (e.target == newImageBtn) // New random image
        {   picture.setparam();
            showParam();
            picture.repaint();
            return(true);
        }
        else if (e.target == zoomInBtn)  // Zoom in
        {   picture.setdiam(picture.getdiam()/2.0d);
            picture.repaint();
            return(true);
        }
        else if (e.target == zoomOutBtn)  // Zoom out
        {   picture.setdiam(picture.getdiam()*2.0d);
            picture.repaint();
            return(true);
        }
        else if (e.target == changeBtn)  // Change background
        {   if ((picture.getbgcolor()).equals(Color.black))
            {  picture.setbgcolor(Color.white);}
            else
            {  picture.setbgcolor(Color.black); }
            picture.repaint();
            return(true);
        }
        else if (e.target == newParamBtn)  // Change a,b,c
        // redraw picture using values in text fields
        {   tempD = Double.valueOf(atxt.getText());
            picture.seta(tempD.doubleValue());
            tempD = Double.valueOf(btxt.getText());
            picture.setb(tempD.doubleValue());
            tempD = Double.valueOf(ctxt.getText());
            picture.setc(tempD.doubleValue());
            picture.repaint();

            return(true);
        }
        else
             return(false);

    }  //end action


}  //end class HopDemo

//==================================

class HopCanvas extends Canvas
{
    int scrWidth = 480;  //width of image in pixels
    double a, b, c;      //parameters that determine shape
    double diam;         //area displayed
    float hue;           //color of dot
    int numDots = 2400;   //number of dots of each color
    Color bgcolor = Color.black;  // background color
    String tempS = new String();

    //constructor
    public HopCanvas(double a0, double b0, double c0)
    {   a = a0;
        b = b0;
        c = c0;
        diam = Math.sqrt(Math.abs(a*b*c))*32;  //width of area displayed
    }


    public void setnumDots(int nd)
    {   numDots = nd;}

    public double geta()
    {   return a;}

    public void seta(double aa)
    {   a = aa;}

    public double getb()
    {   return b;}

    public void setb(double bb)
    {   b = bb;}

    public double getc()
    {   return c;}

    public void setc(double cc)
    {   c = cc;}

    public double getdiam()
    {   return diam;}

    public void setdiam(double d)
    {   diam = d;}

    public Color getbgcolor()
    {   return bgcolor;}

    public void setbgcolor(Color bc)
    {   bgcolor = bc;}

    public void setparam()
    {
        //choose values of parameters a,b,c
        a = 8*(Math.random()-0.5);
        b = 4*(Math.random()-0.5);
        c = 8*(Math.random()-0.5);
        diam = Math.sqrt(Math.abs(a*b*c))*32;  //width of area displayed
    }

    public void paint(Graphics g)
    {
        double x0, y0;       //bottom right corner coordinates
        double x,y,xx;       //for plotting points
        int u, v;            //position of dot
        double pixunit;      //pixels per unit length
        pixunit = ((double)scrWidth)/diam; //pixels per unit length
        x = 0;
        y = 0;
        x0 = -0.5 * diam;
        y0 = 0.5 * (a + diam);  //center of screen is at (0,a/2).
        u = 0;
        v = 0;
        g.setColor(bgcolor);
        g.fillRect(0,0,scrWidth,scrWidth);
        for(int colorNum=0; colorNum<32; colorNum++)
        // draw 32 different colors
        {
            hue = ((float)colorNum)/32f;
            g.setColor(Color.getHSBColor(hue,1f,1f));
            //draw numDots of this color.
            for(int i=1; i<numDots; i++)
            {
                xx = y - (this.sign(x) * Math.sqrt(Math.abs(b * x - c)));
                y = a - x;
                x = xx;
                u = (int)((x - x0)*pixunit);
                v = (int)((y0 - y)*pixunit);
                g.drawLine(u,v,u,v); //one point
            };
        };
     }   //end paint

    public double sign(double x1)
    {
        if (x1 >= 0.0) return 1.0;
        else return -1.0;
    }  // end sign

} // end class HopCanvas