Ketan's Musings

This was an interesting piece of code from a long time mentor and friend. He’s just started to learn Java some time ago, and has written this program to demonstrate how to draw an Ellipse.

He’s about 60 years of age. Has been a long time Turbo C-2.0 programmer. Mostly he develops small graphics programs to demonstrate some engineering drawing and mechanics concepts.

import java.awt.*; // Requisite files od JAVA
import java.awt.event.*;
//import java.awt.geom.*;
import javax.swing.*;
//import java.math.*;
//import java.util.*;
  //Projest name and the following class name should be same
public class leenaTrial1 extends JFrame {
        JFrame frame = new JFrame("Applet");
        JPanel drawingArea = new JPanel(); // Drawing Area is named
        JButton b1; // Defines action Button
        int mouse_i = 1;  // Counter for action

        public void run() {
                frame.setSize(1000, 500); // Frame size is defined
                final Container content = getContentPane();
                content.setBackground(Color.lightGray);
                // color of frame or container is defined
                content.setLayout(new FlowLayout());

                drawingArea.setPreferredSize(new Dimension(750, 700));
                // Size of draw area is defined & color in the next line

                drawingArea.setBackground(Color.black);
                content.add(drawingArea);
                b1 = new JButton("Next Step"); // b1 is button for the next step
                content.add(b1);

                b1.addActionListener(new ActionListener() {
                public void actionPerformed(ActionEvent event) {
                        Graphics g = drawingArea.getGraphics();
                        Font font20 =new Font("TimesRoman",Font.PLAIN,20);
                        Font f0nt14=new Font("TimesRoman",Font.PLAIN,14);
                        g.setFont(font20);
                        int r1 = 250, r2 = 150, x0 = 375, y0 = 415;
                        // r1, r2 semi-major & semi-minor axex, x0,y0 center of circles
                        double inc = 0.005; // increment 
                        int x1, y1, x2, y2; // Two ends of a line

                        // inner circle in 
                        if(mouse_i == 1) {
                                g.setColor(Color.white);
                                //g.drawOval(w, w, x, y);           // top, left, width, height
                                g.drawString("Step 1: Draw inner circle with the radius equal to semi-minor axis of the ellipse.", 20, 20);
                                ovalByPixels(x0,y0,r2,r2,1,Color.blue);
                     }

                        // outer circle
                         if(mouse_i == 2) {
                                g.setColor(Color.white);
                                g.drawString("Step 2: Draw outer circle with the radius equal to semi-major axis of the ellipse.", 20, 35);
                                ovalByPixels(x0,y0,r1,r1,1,Color.red); // Color spesified by name
                        }

                        // twelve lines
                         if(mouse_i == 3) {
                                g.setColor(Color.white);
                                g.drawString("Step 3: Divide the circles in twelve parts.", 20, 50);
                                for(int k = 0; k < 6; k++) {
                                        double cos = Math.cos(k*2*Math.PI/12);
                                        double sin = Math.sin(k*2*Math.PI/12);
                                        double f1 = 1.06 ; // numbers are printed out side of larger circle
                                        double f2 = 0.9 ; // numbers are printed in side of smaller circle
                                        x1 = x0 + (int)(r1*cos); // x1,y1 are on outer circle on one end of diameter
                                        y1 = y0 - (int)(r1*sin);
                                        x2 = x0 - (int)(r1*cos); // x2,y2 are on outer circle at other end of diameter
                                        y2 = y0 + (int)(r1*sin);
                                        lineByPixels(x1, y1, x2, y2,5,new Color(255,100,100)); // 5 is delay value
                                        // Color spesified by values of three colors
                                        g.drawString("a" + Integer.toString(k+1),  x0-10+ (int)(f1*r1*cos), y0+10 - (int)(f1*r1*sin));
                                        g.drawString("a" + Integer.toString(k+7),  x0-10 - (int)(f1*r1*cos), y0+10 + (int)(f1*r1*sin));
                                        g.drawString("b" + Integer.toString(k+1),  x0 -10+ (int)(f2*r2*cos), y0+10 - (int)(f2*r2*sin));
                                        g.drawString("b" + Integer.toString(k+7),  x0 -10- (int)(f2*r2*cos), y0+10 + (int)(f2*r2*sin));
                                        delay(500);        // call delay function         
                                }
                        }

                         if(mouse_i == 4) { // Step 4     * * * * * * * * * * *
                                g.setColor(Color.white);
                                g.drawString("Step 4: From inner circle points, draw horizontal lines and from corresponding points ", 20, 70);
                                g.drawString("         on the outer circle, draw vertical lines. Cutting points are points on Ellipse.", 20, 85);
                                Color cr = new Color(255,200,100);
                                for(int k = 0; k <= 11; k++) {
                                        //int x1,x2,y1,y2;
                                        x1 = x0 + (int)(r1*Math.cos((2*Math.PI/12)*k)); // point on outer circle
                                        y1 = y0 - (int)(r1*Math.sin((2*Math.PI/12)*k));
                                        x2 = x0 + (int)(r2*Math.cos((2*Math.PI/12)*k)); //points on inner circle
                                        y2 = y0 - (int)(r2*Math.sin((2*Math.PI/12)*k));
                                        int x1L = x0 + (int)(1.2*r1*Math.cos((2*Math.PI/12)*k)); // point on outer circle
                                        int y2L = y0 - (int)(0.9*r2*Math.sin((2*Math.PI/12)*k));
                                        g.setColor(Color.green);
                                        if(k==3 || k==9){
                                                lineByPixels(x0-20, y2, x0+20, y2,5,cr );}// 5 is delay value
                           //g.drawLine( x0-20, y2, x0+20, y2);}
                                        else{
                                                lineByPixels(x2, y2, x1L, y2,5,new Color(255,100,200));}
                                                //g.drawLine(x2, y2, x1L, y2);} // horizontal line
                                        g.setColor(Color.yellow);
                                        if(k==0 || k==6){
                                                lineByPixels(x1, y0-20, x1,  y0+20,5,new Color(100,100,200));}
                                                //g.drawLine(x1, y0-20, x1,  y0+20);}// Vertical line
                                        else {
                                                lineByPixels(x1, y1, x1, y2L,5,new Color(100,255,100));}
                                                //g.drawLine(x1, y1, x1, y2L);}// vertical line
                                        delay(500); // call delay function         
                                        g.setColor(Color.white);
                                        g.drawOval(x1-3, y2-3, 6, 6); // Box (top, left, width, height
                    delay(500);
                                }
                        }

                        if(mouse_i == 5) {
                                g.setColor(Color.white);
                                g.drawString("Step 5: Draw a smooth curve connecting the twelve cutting points.", 20, 100);
                                g.setColor(Color.RED);
                                for(double i = 0; i < 2*(3.1415926); i=i+inc) {
                                        g.drawLine((int)(x0+r1*Math.cos(i)), (int)(y0-r2*Math.sin(i)), (int)(x0+(r1+1)*Math.cos(i)), (int)(y0-(r2+1)*Math.sin(i)));
                                        delay(1); // calls delay function

                                } // Ellipse drawing is complete

                                g.drawString("Ellipse by Concentric Circles, by Dr. Vasant D. Barve", 20, 680);
                                g.drawString("DONE!", 670, 350);
                        }
                        mouse_i++;
                 }
                });

                pack();
                setVisible(true);
        }
    // This is delay procedure  
        public void delay(int dt1)
        {
                try {
                        Thread.sleep(dt1);
                }
                catch (InterruptedException e) {
                }
        } // Delay procedure ends

    // This is Oval (circle or ellipse) by pixel procedure   * * * * * * * * * * * * * * *      
        public void ovalByPixels(float x0, float y0, float r1, float r2, int dt, Color objColor)
        {   // Center of circle at x0,y0 Radius r dt delay after each pixel counterclckwise
                Graphics g = drawingArea.getGraphics();
                double rm = Math.max(r1, r2); // Greater of the two picked up
                for(double i = 0; i < 2*(3.1415926); i=i+1/rm) {
                        double x1 = x0+ r1*Math.cos(i);
                        double y1 = y0+r2*Math.sin(i);
                        double x2 = x0+(r1+1)*Math.cos(i);
                        double y2 = y0+(r2+1)*Math.sin(i);
                        g.setColor(objColor);
                        g.drawLine((int)x1, (int)y1, (int)x2, (int)y2);
                        delay(dt); // call delay function    
                }
        } // OvalByPixels procedure Ends

//       lineByPixels Procedure starts              * * * * * *  * * * * *
        public void lineByPixels(int x1, int y1, int x2, int y2, int dt,Color objCol ) {
                // Line starts at (x1,y1) & ends at (x2,y2) each point is drawn as short line of one pixel length
                Graphics g = drawingArea.getGraphics();
                //g.setColor(Color.white); 
                g.setColor(objCol);

                int L= (int) Math.sqrt(Math.pow(x2-x1,2)+Math.pow(y2-y1,2));
            // length of line is found
                double th=Math.atan2(y2-y1,x2-x1); // inclination of line with x axis
               for(int i=0; i<=L-1; i=i+1)
            { g.drawLine((int) (x1+i*Math.cos(th)), (int) (y1+i*Math.sin(th)),(int) (x1+(i+1)*Math.cos(th)), (int) (y1+(i+1)*Math.sin(th)));
          delay(dt);    //delay introduced to see line being drawn    
            }
        } // lineByPixels Procedure Ends

        // Paint graphics starts                     * * * * * * * * *
        public void paint(Graphics g) {
                super.paint(g);
        } // Paint graphics Ends

        public static void main(String[] args) {
                leenaTrial1 ecc = new leenaTrial1(); // here the function is called
                ecc.run();
        }
}

Tejas got me some Smalltalk books. It’s been worth the $120 spent on these Smalltalk books. Nirav loved the books, and I’ve lent him the honeycomb book.

I’m going through the book “Smalltalk, Objects and Design“, for now.

Having found some time off from my regular work, I’ve decided to play catchup with Ruby, more specifically the Ruby-on-rails stack.

I’ve downloaded ruby 1.8.5, and ruby gems, the package manager.

// TODO
Investigate on:

• the language
• the documentation, and the way it is organized
• some good ruby enthusiasts (read: bloggers)
• frameworks available, I found out there’s a RubyForge
• “help wanted” on open-source ruby projects

I’d been invited to take OOCS lectures at the K.K. Wagh College of Engineering. As with all hackers, I immediately took up this invitation, simply because I could enjoy doing it. Moreover, I got an opportunity to learn some real cool technologies, that were really new to me.

The course involves OO, COM, DCOM, CORBA, JAVA/RMI and XML.

About 25 students had signed up for this subject. The attendance figures, with a grand maximum attendance of 9, with some 5 students regularly attending lectures. These figures are sure to paint a different picture It’s been about three weeks that I’ve been doing these lectures.

The results were declared a week ago, and I’ve not taken any lectures since then. Today was an altogether different experience. I learnt that there were just 9 students, who have decided to continue with the subject. The rest of the folks simply choose the easier alternative. While I’ve nothing against these people. The general reason being that — the subject is too vast in its breadth, and one has to read too many books for the course.

I asked the folks who had chosen to continue with OOCS, as to why they choose the difficult alternative.

The answer, surprisingly was that I was: I’ve been doing a good job at the lectures, so far.

Thanks guys, you’ve made my day. The efforts have been worth the staying up at nights.

We at ObjectEdge had the opportunity to interact with Dave Collins. Dave Collins is one of the few remaining SmallTalkers, and author of the bestseller Designing Object-Oriented User Interfaces.

This was a 3-day basic Object-Oriented training session for begineers as well as advanced people alike.

This was a very good session that covered from basic OO concepts to Design Patterns to various techniques in persistence. It contained simple but effective exercises to better understand things.

This 3 day course was basically based on Chamond Liu’s book SmallTalk, Objects, Design

Some pictures(click to enlarge)

Amarjeet Garewal introducing Dave Collins.	Dave Collins talking on the Command Pattern	Dave Collins talking on the MVC pattern