Urgent Help Needed in drawing square wave!!!

import java.awt.*;

import javax.swing.*;

public class SquareWave extends JPanel {

protected void paintComponent(Graphics g) {

super.paintComponent(g);

Graphics2D g2 = (Graphics2D)g;

g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,

RenderingHints.VALUE_ANTIALIAS_ON);

int w = getWidth();

int h = getHeight();

int pad = 15;

g2.setPaint(Color.blue);

g2.drawLine(0,h/2,w,h/2);

g2.setPaint(Color.red);

g2.drawLine(pad,h/2,pad,h-pad);

g2.drawLine(pad,h-pad,w/2,h-pad);

g2.drawLine(w/2,h-pad,w/2,pad);

g2.drawLine(w/2,pad,w-pad,pad);

g2.drawLine(w-pad,pad,w-pad,h/2);

}

public static void main(String[] args) {

JFrame f = new JFrame();

f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

f.getContentPane().add(new SquareWave());

f.setSize(400,400);

f.setLocation(200,200);

f.setVisible(true);

}

}

crwooda at 2007-7-28 15:48:26 >

> I would write a method:

> > public double squareWave(double x) {

>return Math.signum(Math.sin(x));

>

>

> then your paint method would look something like:

>

> > public void paint(Graphics g) {

>double lastX=0.0, lastY=0.0;

> for(double x=0.0; x < 10.0; x++) {

> g.drawLine((int)lastX, (int)lastY,

> (int)x,(int)squareWave(x));

>lastX = x;

> lastY = squareWave(x);

> }

>

>

>

> it's rough but it should give you an idea. You'll

> need to scale and translate the wave to see it.

>

> P.S. I don't suggest using doubles as iterators,

> floating point roundings can cause badness...

> And I havn't tested that code.

Hi Cogsy, i tried ur method but cannot work. I cannot see anything being drawn out. Please help me out. Thanks

This is my code:

import java.awt.*;

import javax.swing.*;

public class SquareWave extends JFrame {

public SquareWave(){

super("squarewave");

setSize(400,400);

setVisible(true);

}

public void paint(Graphics g) {

super.paint(g);

g.setColor(Color.RED);

double lastX=0.0, lastY=0.0;

for(double x=0.0; x < 10.0; x++) {

g.drawLine((int)lastX, (int)lastY, (int)x,(int)squareWave(x));

System.out.println("Answer is " + (int)squareWave(x));

lastX = x;

lastY = squareWave(x);

}

}

public static void main(String[] args) {

SquareWave app =new SquareWave();

app.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

}

public double squareWave(double x) {

double a = Math.sin(x);

return Math.signum(Math.sin(x));

}

}

YoZza at 2007-7-28 15:48:26 >

Hey crwood...thanks for the help....

By the way how can make as if the square wave is moving/scrolling like in real time and how do I label the pulse of the square wave for example i wanna assign the number "1" of letter "A" within the perimeter of each of the square pulse.

Thanks...anyone knows also can help me out....

Message was edited by:

YoZz

YoZza at 2007-7-28 15:48:26 >

import java.awt.*;

import java.awt.geom.*;

import javax.swing.*;

public class ScrollingSquareWave extends JPanel implements Runnable {

Shape wave = new GeneralPath();

GeneralPath waveForm;

int scrollX = 0;

Rectangle r;

protected void paintComponent(Graphics g) {

super.paintComponent(g);

Graphics2D g2 = (Graphics2D)g;

g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,

RenderingHints.VALUE_ANTIALIAS_ON);

if(waveForm == null) initWaveForm();

int w = getWidth();

int h = getHeight();

g2.setPaint(Color.blue);

g2.draw(new Line2D.Double(0,h/2,w,h/2));

g2.draw(new Line2D.Double(w/2,0,w/2,h));

g2.setPaint(Color.red);

g2.draw(wave);

drawValues(g2, w, h);

}

private void drawValues(Graphics2D g2, int w, int h) {

// Draw strings.

g2.setPaint(Color.green.darker());

// wave length/period = r.width = 904

// Draw strings at one fourth and three fourths of length.

if(r == null) return;

float sx = scrollX + r.width/8, sy;

int count = 0;

while(r.width > 0 && sx < w) {

String s;

if(count++%2 == 0) {

sy = 50;

s = "1";

} else {

sy = h-40;

s = "-1";

}

if(sx > 0)

g2.drawString(s, sx, sy);

sx += r.width/4;

}

}

private void step() {

int w = getWidth();

int h = getHeight();

int pad = 20;

r = waveForm.getBounds();

// For double period => use half of r.width.

double xScale = (w - 2*pad)/(r.getWidth()/2);

double yScale = (h - 2*pad)/r.getHeight();

double x = scrollX;

double y = h/2.0;

AffineTransform at = AffineTransform.getTranslateInstance(x, y);

at.scale(xScale, -yScale);

wave = at.createTransformedShape(waveForm);

// Set member variable for use in drawValues method.

r = wave.getBounds();

// Append another waveForm to fill out the component view.

if(scrollX + r.width < w) {

at.setToTranslation(scrollX + r.width, y);

at.scale(xScale, -yScale);

((GeneralPath)wave).append(at.createTransformedShape(waveForm), false);

}

repaint();

scrollX = (scrollX - 1 > -r.width) ? scrollX -1 : 0;

}

private void initWaveForm() {

waveForm = new GeneralPath();

// Double period for this component view.

for(int j = 0; j <= 2*360; j++) {

double theta = Math.toRadians(j%360);

double y = Math.signum(Math.sin(theta));

if(j > 0)

waveForm.lineTo(j, (float)y);

else

waveForm.moveTo(j, (float)y);

}

}

public void run() {

boolean scrollingWave = true;

while(scrollingWave) {

try {

Thread.sleep(100);

} catch(InterruptedException e) {

scrollingWave = false;

break;

}

step();

}

}

private void start() {

// Just in case...

while(wave == null) {

try {

Thread.sleep(25);

} catch(InterruptedException e) {

System.exit(1);

}

}

Thread thread = new Thread(this);

thread.setPriority(Thread.NORM_PRIORITY);

thread.start();

}

public static void main(String[] args) {

ScrollingSquareWave test = new ScrollingSquareWave();

JFrame f = new JFrame();

f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

f.getContentPane().add(test);

f.setSize(500,400);

f.setLocation(200,200);

f.setVisible(true);

test.start();

}

}

crwooda at 2007-7-28 15:48:26 >