Hi, having a small problem whilst trying to draw a fractal to a bitmap.

this is the code ive got it all seems fine but i get an error message every time I try to compile it.

The error being.

ArgumentNullException was unhandled

Value cannot be null
parameter name: image

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Drawing.Drawing2D; 



/* 
 * @(#)fractal.java - Fractal Program Mandelbrot Set 
 * www.eckhard-roessel.de
 * Copyright (c) Eckhard Roessel. All Rights Reserved.
 * 06/30/2000 - 03/29/2000
 */
//import java.awt.*;
//import java.applet.*;         (ARL Not Needed)
//import java.awt.event.*;
/** 
 * @version 1.1
 * @author Eckhard Roessel
 * @modified 03/29/2001
 * @modified 08/16/2006 tweaked by Duncan Mullier 8/2006
 */


//public class Fractal extends Applet implements MouseListener, MouseMotionListener (ARL Not Needed)

namespace WindowsFormsApplication3
{



    public partial class Form1 : Form
    {

        

        public Form1()
        {
            InitializeComponent();

        }




        public struct HSBColor
        {
            float h;
            float s;
            float b;
            int a;

            public HSBColor(float h, float s, float b)
            {
                this.a = 0xff;
                this.h = Math.Min(Math.Max(h, 0), 255);
                this.s = Math.Min(Math.Max(s, 0), 255);
                this.b = Math.Min(Math.Max(b, 0), 255);
            }

            public HSBColor(int a, float h, float s, float b)
            {
                this.a = a;
                this.h = Math.Min(Math.Max(h, 0), 255);
                this.s = Math.Min(Math.Max(s, 0), 255);
                this.b = Math.Min(Math.Max(b, 0), 255);
            }

            public float H
            {
                get { return h; }
            }

            public float S
            {
                get { return s; }
            }

            public float B
            {
                get { return b; }
            }

            public int A
            {
                get { return a; }
            }

            public Color Color
            {
                get
                {
                    return FromHSB(this);
                }
            }
            
            public static Color FromHSB(HSBColor hsbColor)
            {
                float r = hsbColor.b;
                float g = hsbColor.b;
                float b = hsbColor.b;
                if (hsbColor.s != 0)
                {
                    float max = hsbColor.b;
                    float dif = hsbColor.b * hsbColor.s / 255f;
                    float min = hsbColor.b - dif;

                    float h = hsbColor.h * 360f / 255f;

                    if (h < 60f)
                    {
                        r = max;
                        g = h * dif / 60f + min;
                        b = min;
                    }
                    else if (h < 120f)
                    {
                        r = -(h - 120f) * dif / 60f + min;
                        g = max;
                        b = min;
                    }
                    else if (h < 180f)
                    {
                        r = min;
                        g = max;
                        b = (h - 120f) * dif / 60f + min;
                    }
                    else if (h < 240f)
                    {
                        r = min;
                        g = -(h - 240f) * dif / 60f + min;
                        b = max;
                    }
                    else if (h < 300f)
                    {
                        r = (h - 240f) * dif / 60f + min;
                        g = min;
                        b = max;
                    }
                    else if (h <= 360f)
                    {
                        r = max;
                        g = min;
                        b = -(h - 360f) * dif / 60 + min;
                    }
                    else
                    {
                        r = 0;
                        g = 0;
                        b = 0;
                    }
                }

                return Color.FromArgb
                    (
                        hsbColor.a,
                        (int)Math.Round(Math.Min(Math.Max(r, 0), 255)),
                        (int)Math.Round(Math.Min(Math.Max(g, 0), 255)),
                        (int)Math.Round(Math.Min(Math.Max(b, 0), 255))
                        );
            }
       
        }
           





        private const int MAX = 256;      // max iterations
        private const double SX = -2.025; // start value real
        private const double SY = -1.125; // start value imaginary
        private const double EX = 0.6;    // end value real
        private const double EY = 1.125;  // end value imaginary
        private static int x1, y1, xs, ys, xe, ye;
        private static double xstart, ystart, xende, yende, xzoom, yzoom;
        private static bool action, rectangle, finished;
        private static float xy;
        // private Image picture;
        private PictureBox picture;
        private System.Drawing.Bitmap myBitmap;
        private Graphics g1;
        private Cursor c1, c2;
        private HSBColor HSBcol=new HSBColor();




        public void init() // all instances will be prepared
        {
            //HSBcolor = new HSB();
            //setSize(640, 480);
            finished = false;
            //addMouseListener(this);
            //addMouseMotionListener(this);
            //c1 = new Cursor(Cursor.WAIT_CURSOR);
            //c2 = new Cursor(Cursor.CROSSHAIR_CURSOR);
            //x1 = getSize().width;
            //y1 = getSize().height;
            xy = (float)x1 / (float)y1;
            //picture = createImage(x1, y1);
            //g1 = picture.getGraphics();

            myBitmap = new Bitmap(x1, y1);
            g1 = Graphics.FromImage(myBitmap);
            finished = true;
        }

        public void destroy() // delete all instances 
        {
            if (finished)
            {
                //removeMouseListener(this);
                //removeMouseMotionListener(this);
                picture = null;
                g1 = null;
                c1 = null;
                c2 = null;
                GC.Collect(); // garbage collection
            }
        }

        public void start()
        {
            action = false;
            rectangle = false;
            initvalues();
            xzoom = (xende - xstart) / (double)x1;
            yzoom = (yende - ystart) / (double)y1;
            mandelbrot();
        }

        public void stop()
        {
        }


        
        public void paint(Graphics g)
        {
            update(g);
        }

        
        public void update(Graphics g)
        {
            /*
            g.drawImage(picture, 0, 0, this);
            if (rectangle)
            {
                g.setColor(Color.white);
                if (xs < xe)
                {
                    if (ys < ye) g.drawRect(xs, ys, (xe - xs), (ye - ys));
                    else g.drawRect(xs, ye, (xe - xs), (ys - ye));
                }
                else
                {
                    if (ys < ye) g.drawRect(xe, ys, (xs - xe), (ye - ys));
                    else g.drawRect(xe, ye, (xs - xe), (ys - ye));
                }
            }*/
        }

        
        private void mandelbrot() // calculate all points
        {
            int x, y;
            float h, b, alt = 0.0f;

            action = false;
            //setCursor(c1);
            //showStatus("Mandelbrot-Set will be produced - please wait...");
            for (x = 0; x < x1; x += 2)
                for (y = 0; y < y1; y++)
                {
                    h = pointcolour(xstart + xzoom * (double)x, ystart + yzoom * (double)y); // color value
                    if (h != alt)
                    {
                        b = 1.0f - h * h; // brightnes
                        ///djm added
                        //HSBcolor.fromHSB(h,0.8f,b); 
                        //Color col = new Color(0,HSBcol.rChan,HSBcol.gChan,HSBcol.bChan);
                        //g1.setColor(col);
                        //djm end
                        //djm added to convert to RGB from HSB
                        Color color = HSBColor.FromHSB(new HSBColor(h * 255, 0.8f * 255, b * 255));
                        //g1.setColor(Color.getHSBColor(h, 0.8f, b));
                        //djm test
                        //Color col = Color.getHSBColor(h, 0.8f, b);
                        //int red = col.getRed();
                        //int green = col.getGreen();
                        //int blue = col.getBlue();
                        //djm 
                        alt = h;
                        Pen pen = new Pen(color);
                        g1.DrawLine(pen, x, y, x + 1, y);
                    }
                    //g1.drawLine(x, y, x + 1, y);
                }
            //showStatus("Mandelbrot-Set ready - please select zoom area with pressed mouse.");
            //setCursor(c2);
            action = true;
        }


        private void initvalues() // reset start values
        {
            xstart = SX;
            ystart = SY;
            xende = EX;
            yende = EY;
            if ((float)((xende - xstart) / (yende - ystart)) != xy)
                xstart = xende - (yende - ystart) * (double)xy;
        }


        private float pointcolour(double xwert, double ywert) // color value from 0.0 to 1.0 by iterations
        {
            double r = 0.0, i = 0.0, m = 0.0;
            int j = 0;

            while ((j < MAX) && (m < 4.0))
            {
                j++;
                m = r * r - i * i;
                i = 2.0 * r * i + ywert;
                r = m + xwert;
            }
            return (float)j / (float)MAX;
        }

        private void Form1_Load(object sender, EventArgs e)
        {

            init();
            start();

            
        }
     

        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            

            g1 = e.Graphics; // create a graphics object
            g1.DrawImage(myBitmap, 0, 0, x1, y1);
            g1.Dispose();

        }


    }
}

the error is with the line

g1.DrawImage(myBitmap, 0, 0, x1, y1);

in form1_paint

Your Form_Load event executes after the Form_Paint event so myBitmap hasn't been set yet. You need to initialize variables in the Form constructor.

Thank you for your response.

I am quite new to the c# programming language. How would I go about this?

Remove init(); from your Form_Load function and put it in the form constructor:

public Form1() {
    InitializeComponent();
    init();
}

Again thank you.

I now have come across a new error whilst compiling.

myBitmap = new Bitmap(x1, y1);

"ArgumentException was unhandled"

I am non the wiser on how to solve this problem.

I suspect that x1 and y1 have default values of zero at this point. I don't see anywhere in your code that you set them, just commented out code. The reason you don't get an error in line 205 of your code above is that the system handles zero divided by zero and sets the value to NAN (Not a Number).

Hi Moose333. I am having the same problem as you had. Did you find once you done what they suggested it worked. i have tried doing it and it just still doesnt seem to be showing the fractal. If you can give me any help i would greatly appreciate it,

Thanks

Hello

Sorry, but what was suggested did just bring up another error. Furthermore i have still been working on the code and have managed to remove these errors.

The code I have now does compile but still does not draw the fractal.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Drawing.Drawing2D;



namespace WindowsFormsApplication2
{


    public partial class Form1 : Form
    {


        public Form1()
        {
            InitializeComponent();
            start();
            init();
        }


        public struct HSBColor
        {
            float h;
            float s;
            float b;
            int a;

            public HSBColor(float h, float s, float b)
            {
                this.a = 0xff;
                this.h = Math.Min(Math.Max(h, 0), 255);
                this.s = Math.Min(Math.Max(s, 0), 255);
                this.b = Math.Min(Math.Max(b, 0), 255);
            }

            public HSBColor(int a, float h, float s, float b)
            {
                this.a = a;
                this.h = Math.Min(Math.Max(h, 0), 255);
                this.s = Math.Min(Math.Max(s, 0), 255);
                this.b = Math.Min(Math.Max(b, 0), 255);
            }

            public float H
            {
                get { return h; }
            }

            public float S
            {
                get { return s; }
            }

            public float B
            {
                get { return b; }
            }

            public int A
            {
                get { return a; }
            }

            public Color Color
            {
                get
                {
                    return FromHSB(this);
                }
            }

            public static Color FromHSB(HSBColor hsbColor)
            {
                float r = hsbColor.b;
                float g = hsbColor.b;
                float b = hsbColor.b;
                if (hsbColor.s != 0)
                {
                    float max = hsbColor.b;
                    float dif = hsbColor.b * hsbColor.s / 255f;
                    float min = hsbColor.b - dif;

                    float h = hsbColor.h * 360f / 255f;

                    if (h < 60f)
                    {
                        r = max;
                        g = h * dif / 60f + min;
                        b = min;
                    }
                    else if (h < 120f)
                    {
                        r = -(h - 120f) * dif / 60f + min;
                        g = max;
                        b = min;
                    }
                    else if (h < 180f)
                    {
                        r = min;
                        g = max;
                        b = (h - 120f) * dif / 60f + min;
                    }
                    else if (h < 240f)
                    {
                        r = min;
                        g = -(h - 240f) * dif / 60f + min;
                        b = max;
                    }
                    else if (h < 300f)
                    {
                        r = (h - 240f) * dif / 60f + min;
                        g = min;
                        b = max;
                    }
                    else if (h <= 360f)
                    {
                        r = max;
                        g = min;
                        b = -(h - 360f) * dif / 60 + min;
                    }
                    else
                    {
                        r = 0;
                        g = 0;
                        b = 0;
                    }
                }

                return Color.FromArgb
                    (
                        hsbColor.a,
                        (int)Math.Round(Math.Min(Math.Max(r, 0), 255)),
                        (int)Math.Round(Math.Min(Math.Max(g, 0), 255)),
                        (int)Math.Round(Math.Min(Math.Max(b, 0), 255))
                        );
            }




        }
        private const int MAX = 256;      // max iterations
        private const double SX = -2.025; // start value real
        private const double SY = -1.125; // start value imaginary
        private const double EX = 0.6;    // end value real
        private const double EY = 1.125;  // end value imaginary
        private static int x1, y1, xs, ys, xe, ye;
        private static double xstart, ystart, xende, yende, xzoom, yzoom;
        private static bool action, rectangle, finished;
        private static float xy;
        private Image picture;
        private Graphics g1;
        private HSBColor HSBcol=new HSBColor();
        private System.Drawing.Bitmap bitmap;




        public void init()
        {

            this.Size = new Size(640, 480);
            finished = false;
            x1 = 640;
            y1 = 480;
            xy = (float)x1 / (float)y1;

            bitmap = new Bitmap(x1, y1);
            g1 = Graphics.FromImage(bitmap);

            Pen myPen = new Pen(System.Drawing.Color.Black, 3);
            g1.DrawRectangle(myPen, 0, 0, 0, 0);

            
            if (rectangle)
            {

                
                if (xs < xe)
                {
                    if (ys < ye) g1.DrawRectangle(myPen, xs, ys, (xe - xs), (ye - ys));
                    else g1.DrawRectangle(myPen, xs, ye, (xe - xs), (ys - ye));
                }
                else
                {
                    if (ys < ye) g1.DrawRectangle(myPen, xe, ys, (xs - xe), (ye - ys));
                    else g1.DrawRectangle(myPen, xe, ye, (xs - xe), (ys - ye));
                }
            }
            
            g1.Dispose();

            finished = true;
            //mandelbrot();
        }   

        public void destroy() // delete all instances 
        {
            if (finished)
            {

                g1 = null;

                GC.Collect(); // garbage collection
            }
        }

        public void start()
        {
            action = false;
            rectangle = false;
            initvalues();
            xzoom = (xende - xstart) / (double)x1;
            yzoom = (yende - ystart) / (double)y1;
            mandelbrot();
        }

        public void stop()
        {
        }

        
        public void paint(Graphics g1) 
	    {
		    update(g1); 
	    }
    	
	    public void update(Graphics g1) 
	    {/*
		    g.drawImage(picture, 0, 0, this);
		    if (rectangle)                          
		    {
			    g.setColor(Color.white);
			    if (xs < xe)
			    {
				    if (ys < ye) g.drawRect(xs, ys, (xe - xs), (ye - ys));          
				    else g.drawRect(xs, ye, (xe - xs), (ys - ye));
			    }
			    else
			    {
				    if (ys < ye) g.drawRect(xe, ys, (xs - xe), (ye - ys));
				    else g.drawRect(xe, ye, (xs - xe), (ys - ye));
			    }
		
            }*/

        }

        private void mandelbrot() // calculate all points
        {
            int x, y;
            float h, b, alt = 0.0f;

            action = false;
            
            for (x = 0; x < x1; x += 2)
                for (y = 0; y < y1; y++)
                {
                    h = pointcolour(xstart + xzoom * (double)x, ystart + yzoom * (double)y); // color value

                    if (h != alt)
                    {
                        b = 1.0f - h * h; // brightnes
                        ///djm added
                        ///HSBcolor.fromHSB(h,0.8f,b); //convert hsb to rgb then make a Java Color
                        ///Color col = new Color(0,HSBcolor.rChan,HSBcolor.gChan,HSBcolor.bChan);
                        ///g1.setColor(col);
                        //djm end
                        //djm added to convert to RGB from HSB

                        //g1.setColor(Color.getHSBColor(h, 0.8f, b));
                        Color color = HSBColor.FromHSB(new HSBColor(h * 255, 0.8f * 255, b * 255)); 

                        //int red = col.getRed();
                        //int green = col.getGreen();
                        //int blue = col.getBlue();
                        //djm
                        
                        //Pen myPen = new Pen(System.Drawing.Color.Plum, 3);
                        alt = h;
                        Pen myPen = new Pen(color);
                        g1.DrawLine(myPen, x, y, x + 1, y);
                    }
                    //g1.drawLine(x, y, x + 1, y);
                }

            action = true;
        }

        private float pointcolour(double xwert, double ywert) // color value from 0.0 to 1.0 by iterations
        {
            double r = 0.0, i = 0.0, m = 0.0;
            int j = 0;

            while ((j < MAX) && (m < 4.0))
            {
                j++;
                m = r * r - i * i;
                i = 2.0 * r * i + ywert;
                r = m + xwert;
            }
            return (float)j / (float)MAX;
        }

        private void initvalues() // reset start values
        {
            xstart = SX;
            ystart = SY;
            xende = EX;
            yende = EY;
            if ((float)((xende - xstart) / (yende - ystart)) != xy)
                xstart = xende - (yende - ystart) * (double)xy;
        }


        private void Form1_Load(object sender, EventArgs e)
        {
            //init();
            //start();
            //mandelbrot();


        }

        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            Graphics g1 = e.Graphics;
            g1.DrawImage(bitmap, 0, 0, x1, y1);
            g1.Dispose();

        }

        

        





    }
}

I am still having problems with this so anymore help from anyone would be much appreciated.

Thank you for the links, I have however been previously using them to get to the stage I am now at. if anyone has any other ideas of how to solve this problem they would be much appreciated.

This code solves the problems I have had.

This draws the mandlebrot to a bitmap and alows zooming, i havent been able to draw a zoombox on the interface.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Drawing.Drawing2D;



/* 
 * @(#)fractal.java - Fractal Program Mandelbrot Set 
 * www.eckhard-roessel.de
 * Copyright (c) Eckhard Roessel. All Rights Reserved.
 * 06/30/2000 - 03/29/2000
 */
//import java.awt.*;
//import java.applet.*;   Not Needed
//import java.awt.event.*;
/** 
 * @version 1.1
 * @author Eckhard Roessel
 * @modified 03/29/2001
 * @modified 08/16/2006 tweaked by Duncan Mullier 8/2006
 */



namespace WindowsFormsApplication2
{

//public class Fractal extends Applet implements MouseListener, MouseMotionListener
//{  Not Needed

    public partial class Form1 : Form
    {


        public Form1()
        {
            InitializeComponent();
            init();
            start();
        }


        public struct HSBColor
        {
            float h;
            float s;
            float b;
            int a;

            public HSBColor(float h, float s, float b)
            {
                this.a = 0xff;
                this.h = Math.Min(Math.Max(h, 0), 255);
                this.s = Math.Min(Math.Max(s, 0), 255);
                this.b = Math.Min(Math.Max(b, 0), 255);
            }

            public HSBColor(int a, float h, float s, float b)
            {
                this.a = a;
                this.h = Math.Min(Math.Max(h, 0), 255);
                this.s = Math.Min(Math.Max(s, 0), 255);
                this.b = Math.Min(Math.Max(b, 0), 255);
            }

            public float H
            {
                get { return h; }
            }

            public float S
            {
                get { return s; }
            }

            public float B
            {
                get { return b; }
            }

            public int A
            {
                get { return a; }
            }

            public Color Color
            {
                get
                {
                    return FromHSB(this);
                }
            }

            public static Color FromHSB(HSBColor hsbColor)
            {
                float r = hsbColor.b;
                float g = hsbColor.b;
                float b = hsbColor.b;
                if (hsbColor.s != 0)
                {
                    float max = hsbColor.b;
                    float dif = hsbColor.b * hsbColor.s / 255f;
                    float min = hsbColor.b - dif;

                    float h = hsbColor.h * 360f / 255f;

                    if (h < 60f)
                    {
                        r = max;
                        g = h * dif / 60f + min;
                        b = min;
                    }
                    else if (h < 120f)
                    {
                        r = -(h - 120f) * dif / 60f + min;
                        g = max;
                        b = min;
                    }
                    else if (h < 180f)
                    {
                        r = min;
                        g = max;
                        b = (h - 120f) * dif / 60f + min;
                    }
                    else if (h < 240f)
                    {
                        r = min;
                        g = -(h - 240f) * dif / 60f + min;
                        b = max;
                    }
                    else if (h < 300f)
                    {
                        r = (h - 240f) * dif / 60f + min;
                        g = min;
                        b = max;
                    }
                    else if (h <= 360f)
                    {
                        r = max;
                        g = min;
                        b = -(h - 360f) * dif / 60 + min;
                    }
                    else
                    {
                        r = 0;
                        g = 0;
                        b = 0;
                    }
                }

                return Color.FromArgb
                    (
                        hsbColor.a,
                        (int)Math.Round(Math.Min(Math.Max(r, 0), 255)),
                        (int)Math.Round(Math.Min(Math.Max(g, 0), 255)),
                        (int)Math.Round(Math.Min(Math.Max(b, 0), 255))
                        );
            }




        }
        private const int MAX = 256;      // max iterations
        //private final int MAX = 256;    not needed
        private const double SX = -2.025; // start value real
        //private final double SX = -2.025; not needed
        private const double SY = -1.125; // start value imaginary
        //private final double SY = -1.125; not needed
        private const double EX = 0.6;    // end value real
        //private final double EX = 0.6;  not needed
        private const double EY = 1.125;  // end value imaginary
        //private final double EY = 1.125;  not needed
        private static int x1, y1, xs, ys, xe, ye;
        private static double xstart, ystart, xende, yende, xzoom, yzoom;
        private static bool action, rectangle, finished;
        //private static boolean action, rectangle, finished; changed to bool
        private static float xy;
        //private Image picture;
        private Graphics g1;
        private HSBColor HSBcol=new HSBColor();
        private System.Drawing.Bitmap bitmap;
        //private HSB HSBcol = new HSB(); changed to hsbcolor




        public void init() // all instances will be prepared
        {
            //HSBcol = new HSB();
            this.Size = new Size(640, 480);
            //setSize(640, 480); not needed
            finished = false;
            //addMouseListener(this); not needed
            //addMouseMotionListener(this); not needed
            //c1 = new Cursor(Cursor.WAIT_CURSOR); not needed
            //c2 = new Cursor(Cursor.CROSSHAIR_CURSOR); not needed
            //x1 = getSize().width; not needed
            //y1 = getSize().height; not needed

            //x1 = this.pictureBox1.Width; 
            //y1 = this.pictureBox1.Height;

            x1 = 640;
            y1 = 480;
            xy = (float)x1 / (float)y1;

            //picture = createImage(x1, y1); not needed
            //g1 = picture.getGraphics(); not needed

            //bitmap = new Bitmap(x1, y1, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
            bitmap = new Bitmap(x1, y1);
            g1 = Graphics.FromImage(bitmap);
            

            //Pen myPen = new Pen(System.Drawing.Color.Plum, 3);
            //g1.DrawRectangle(myPen, 0, 0, 0, 0);

            /*
            if (rectangle)
            {

                
                if (xs < xe)
                {
                    if (ys < ye) g1.DrawRectangle(myPen, xs, ys, (xe - xs), (ye - ys));
                    else g1.DrawRectangle(myPen, xs, ye, (xe - xs), (ys - ye));
                }
                else
                {
                    if (ys < ye) g1.DrawRectangle(myPen, xe, ys, (xs - xe), (ye - ys));
                    else g1.DrawRectangle(myPen, xe, ye, (xs - xe), (ys - ye));
                }
            }*/
            


            //Pen myPen = new Pen(System.Drawing.Color.Plum, 3);
            //Rectangle rectangleObj = new Rectangle(10, 10, 200, 200);
            //g1.DrawEllipse(myPen, rectangleObj);

            //g1.Dispose();

            finished = true;
        }   

        public void destroy() // delete all instances 
        {
            if (finished)
            {
                //removeMouseListener(this); not needed
                //removeMouseMotionListener(this); not needed
                //picture = null;
                bitmap = null;
                g1 = null;
                //c1 = null; not needed
                //c2 = null; not needed
                //System.gc(); // garbage collection changed
                GC.Collect(); // garbage collection
            }
        }

        public void start()
        {
            action = false;
            rectangle = false;
            initvalues();
            xzoom = (xende - xstart) / (double)x1;
            yzoom = (yende - ystart) / (double)y1;
            mandelbrot();
        }

        public void stop()
        {
        }

        
        public void paint(Graphics g1) 
	    {
		    update(g1); 
	    }
    	
	    public void update(Graphics g1) 
	    {/*
		    g.drawImage(picture, 0, 0, this);
		    if (rectangle)                          
		    {
			    g.setColor(Color.white);
			    if (xs < xe)
			    {
				    if (ys < ye) g.drawRect(xs, ys, (xe - xs), (ye - ys));          
				    else g.drawRect(xs, ye, (xe - xs), (ys - ye));
			    }
			    else
			    {
				    if (ys < ye) g.drawRect(xe, ys, (xs - xe), (ye - ys));
				    else g.drawRect(xe, ye, (xs - xe), (ys - ye));
			    }
		
            }*/

        }

        
        private void mandelbrot() // calculate all points
        {
            int x, y;
            float h, b, alt = 0.0f;

            action = false;
            //setCursor(c1); not needed
            //showStatus("Mandelbrot-Set will be produced - please wait..."); not needed
            Color color = Color.Black;
            Pen myPen = new Pen(color);

            for (x = 0; x < x1; x += 2)
                for (y = 0; y < y1; y++)
                {
                    h = pointcolour(xstart + xzoom * (double)x, ystart + yzoom * (double)y);
                    if (h != alt)
                    {
                        b = 1.0f - h * h; //brightness
                        ///djm added
                        ///HSBcolor.fromHSB(h,0.8f,b); //convert hsb to rgb then make a Java Color
                        ///Color col = new Color(0,HSBcolor.rChan,HSBcolor.gChan,HSBcolor.bChan);
                        ///g1.setColor(col);
                        //djm end
                        //djm added to convert to RGB from HSB
                        //g1.setColor(Color.getHSBColor(h, 0.8f, b));

                        color = HSBColor.FromHSB(new HSBColor(h * 255, 0.8f * 255, b * 255));

                        //djm test
                        //Color col = Color.getHSBColor(h,0.8f,b);
                        //int red = col.getRed();
                        //int green = col.getGreen();
                        //int blue = col.getBlue();
                        //djm


                        myPen = new Pen(color);
                        alt = h;
                    }
                    g1.DrawLine(myPen, x, y, x + 1, y);
                }
            //showStatus("Mandelbrot-Set ready - please select zoom area with pressed mouse.");
            //setCursor(c2);
            action = true;
        }

       

        private float pointcolour(double xwert, double ywert) // color value from 0.0 to 1.0 by iterations
        {
            double r = 0.0, i = 0.0, m = 0.0;
            int j = 0;

            while ((j < MAX) && (m < 4.0))
            {
                j++;
                m = r * r - i * i;
                i = 2.0 * r * i + ywert;
                r = m + xwert;
            }
            return (float)j / (float)MAX;
        }

        private void initvalues() // reset start values
        {
            xstart = SX;
            ystart = SY;
            xende = EX;
            yende = EY;
            if ((float)((xende - xstart) / (yende - ystart)) != xy)
                xstart = xende - (yende - ystart) * (double)xy;
        }


        private void Form1_Load(object sender, EventArgs e)
        {


        }

        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            Graphics g1 = e.Graphics;
            g1.DrawImage(bitmap, 0, 0, x1, y1);
            g1.Dispose();

        }

        

        private void Form1_MouseMove(object sender, MouseEventArgs e)
        {

            //e.consume();
            if (action)
            {
                xe = e.X;
                ye = e.Y;
                rectangle = true;
                //repaint();
            }
        }

        private void Form1_MouseDown(object sender, MouseEventArgs e)
        {

            //e.consume();
            if (action)
            {
                xs = e.X;
                ys = e.Y;
            }
        }

        private void Form1_MouseUp(object sender, MouseEventArgs e)
        {
            int z, w;

            //e.consume();
            if (action)
            {
                xe = e.X;
                ye = e.Y;
                if (xs > xe)
                {
                    z = xs;
                    xs = xe;
                    xe = z;
                }
                if (ys > ye)
                {
                    z = ys;
                    ys = ye;
                    ye = z;
                }
                w = (xe - xs);
                z = (ye - ys);
                if ((w < 2) && (z < 2)) initvalues();
                else
                {
                    if (((float)w > (float)z * xy)) ye = (int)((float)ys + (float)w / xy);
                    else xe = (int)((float)xs + (float)z * xy);
                    xende = xstart + xzoom * (double)xe;
                    yende = ystart + yzoom * (double)ye;
                    xstart += xzoom * (double)xs;
                    ystart += yzoom * (double)ys;
                }
                xzoom = (xende - xstart) / (double)x1;
                yzoom = (yende - ystart) / (double)y1;
                mandelbrot();
                rectangle = false;
                //repaint();
                Refresh();
            }
        }

        
        

        





    }
}
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