Notes

/*
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*/
package javaapplication5;

import java.applet.Applet;
import java.awt.Button;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.util.ArrayList;

/**
*
* @author USER PC
*/
public class LabTest extends Applet implements ActionListener,MouseListener{

Button r_clock=new Button(),
r_aclock=new Button(),
clear=new Button(),
undo=new Button(),
animation=new Button();
ArrayList<Point> elp=new ArrayList<>(),
plot_pt=new ArrayList<>();

private static final int grid_diff=1,offset=35;

@Override
public void init()
{
setSize(800,600);
setBackground(Color.pink);
addMouseListener(this);
r_clock.setLabel("Rotate Clockwise");
r_clock.addActionListener(this);
r_aclock.setLabel("Rotate Anti-Clockwise");
r_aclock.addActionListener(this);
clear.setLabel("Clear");
clear.addActionListener(this);
undo.setLabel("Undo");
undo.addActionListener(this);
animation.setLabel("Animate");
animation.addActionListener(this);

add(r_aclock);
add(r_clock);
add(clear);
add(undo);
add(animation);
}

@Override
public void paint(Graphics g)
{
for(int i=0;i<elp.size();i+=3)
{
try
{
drawLine(g, elp.get(i), elp.get(i+1));
drawLine(g, elp.get(i), elp.get(i+2));
drawMidPointCircle(g, elp.get(i), elp.get(i+2));
drawMidpointEllipse(g, elp.get(i), elp.get(i+1), elp.get(i+2));
double ang=elp.get(i).getAngle(elp.get(i+1));
plot_pt=Transform(plot_pt, elp.get(i), ang);
for(Point p : plot_pt)
drawPoint(g, p.getX(), p.getY());
}
catch(ArrayIndexOutOfBoundsException e)
{
System.out.println(e.toString());
}
plot_pt.clear();
}

}

private ArrayList<Point> Transform(ArrayList<Point> pts,Point p,double deg)
{
ArrayList<Point> fpt=new ArrayList<>();

for(Point pm : pts)
{
int x=(int) (p.getX()+(pm.getX()-p.getX())*Math.cos(deg)+(pm.getY()-p.getY())*Math.sin(deg));
int y=(int) (p.getY()-(pm.getX()-p.getX())*Math.sin(deg)+(pm.getY()-p.getY())*Math.cos(deg));
fpt.add(new Point(x,y));

}


return fpt;
}


public void drawMidpointEllipse(Graphics g, Point p, Point p2, Point p3) {
int x=(int) p.getDistance(p2);
int y=(int) p.getDistance(p3);
g.setColor(Color.BLACK);
double xsq = x * x;
double ysq = y * y;
int xplot = 0, yplot = y;
double px = 0, py = 2 * xsq * yplot;
plotElipsePoints(g, p, new Point(xplot, yplot));
double pdes = ysq - (xsq * y) + 0.25 * xsq;
while (py > px) {
xplot += grid_diff;
px += 2 * ysq;
if (pdes < 0) {
pdes = pdes + ysq + px;
} else {
yplot -= grid_diff;
py -= 2 * xsq;
pdes = pdes + ysq + px - py;
}
plotElipsePoints(g, p, new Point(xplot, yplot));
}
pdes = ysq * (xplot + 0.5) * (xplot + 0.5) + xsq * (yplot - 1) * (yplot - 1) - xsq * ysq;
while (yplot > 0) {
yplot -= grid_diff;
py = py - 2 * xsq;
if (pdes > 0) {
pdes = pdes + xsq - py;
} else {
xplot += grid_diff;
px += 2 * ysq;
pdes = pdes + xsq - py + px;
}
plotElipsePoints(g, p, new Point(xplot, yplot));
}
}

public void plotElipsePoints(Graphics g, Point p1, Point p2) {
plot_pt.add(new Point( p1.getX() + p2.getX(), p1.getY() + p2.getY()));
plot_pt.add(new Point ( p1.getX() - p2.getX(), p1.getY() + p2.getY()));
plot_pt.add(new Point ( p1.getX() + p2.getX(), p1.getY() - p2.getY()));
plot_pt.add(new Point ( p1.getX() - p2.getX(), p1.getY() - p2.getY()));
}
public void drawMidPointCircle(Graphics g,Point c,Point xrad)
{
g.setColor(Color.black);
int x=0;
int rad=(int) c.getDistance(xrad);
int y=rad;
int p=1-rad;
drawCirclepoints(g,c.getX(),c.getY(),x,y);
g.setColor(Color.black);
while(x<y){
x+=grid_diff;
if(p<0){
p+=2*x+1;
}
else{
y-=grid_diff;
p+=2*(x-y)+1;
}
drawCirclepoints(g,c.getX(),c.getY(),x,y);
}
}
public void drawCirclepoints(Graphics g,int xcenter,int ycenter,int x,int y){
drawPoint(g,xcenter+x,ycenter+y);
drawPoint(g,xcenter-x,ycenter+y);
drawPoint(g,xcenter+x,ycenter-y);
drawPoint(g,xcenter-x,ycenter-y);
drawPoint(g,xcenter+y,ycenter+x);
drawPoint(g,xcenter-y,ycenter+x);
drawPoint(g,xcenter+y,ycenter-x);
drawPoint(g,xcenter-y,ycenter-x);
}
public void drawLine(Graphics g,Point p1,Point p2)
{
int sign;
g.setColor(Color.GRAY);
double dx=p1.getX()-p2.getX();
double dy=(p1.getY()-p2.getY());
double m = (dy/dx);
double xput=p1.getX(),yput=p1.getY();
int steps=0;
if(Math.abs(p1.getX()-p2.getX())>Math.abs(p1.getY()-p2.getY()))
{
steps=Math.abs(p1.getX()-p2.getX());
sign=(int) -(dx/Math.abs(dx));
}
else
{
steps=Math.abs(p1.getY()-p2.getY());
sign=(int) -(dy/Math.abs(dy));
}
if(Math.abs(m)<=1)
{
dx=sign*grid_diff;
dy= (m*dx);
}
else
{
dy=sign*grid_diff;
dx= (1.0/m*dy);
}
for(int i=0;i<=steps;i+=grid_diff)
{
xput+=dx;
yput+=dy;
drawPoint(g, (int)Math.round(xput), (int)Math.round(yput));
}
}

void drawPoint(Graphics g,int xpos,int ypos)
{
g.fillRect(((int)Math.round(xpos*1.0f)/grid_diff)*grid_diff, ((int)(ypos-offset)/grid_diff)*grid_diff+offset, grid_diff, grid_diff);
}

@Override
public void actionPerformed(ActionEvent ae) {
if(ae.getSource()==r_aclock)
{
for(int i=0;i<elp.size();i+=3)
{
double deg=Math.toRadians(30);
int x=(int) (elp.get(i).getX()+(elp.get(i+1).getX()-elp.get(i).getX())*Math.cos(deg)+(elp.get(i+1).getY()-elp.get(i).getY())*Math.sin(deg));
int y=(int) (elp.get(i).getY()-(elp.get(i+1).getX()-elp.get(i).getX())*Math.sin(deg)+(elp.get(i+1).getY()-elp.get(i).getY())*Math.cos(deg));
Point npt1=new Point(x,y);
elp.set(i+1, npt1);

x=(int) (elp.get(i).getX()+(elp.get(i+2).getX()-elp.get(i).getX())*Math.cos(deg)+(elp.get(i+2).getY()-elp.get(i).getY())*Math.sin(deg));
y=(int) (elp.get(i).getY()-(elp.get(i+2).getX()-elp.get(i).getX())*Math.sin(deg)+(elp.get(i+2).getY()-elp.get(i).getY())*Math.cos(deg));
Point npt2=new Point(x,y);
elp.set(i+2, npt2);

}
repaint();
}
else if(ae.getSource()==r_clock)
{
for(int i=0;i<elp.size();i+=3)
{
double deg=-1*Math.toRadians(30);
int x=(int) (elp.get(i).getX()+(elp.get(i+2).getX()-elp.get(i).getX())*Math.cos(deg)+(elp.get(i+2).getY()-elp.get(i).getY())*Math.sin(deg));
int y=(int) (elp.get(i).getY()-(elp.get(i+2).getX()-elp.get(i).getX())*Math.sin(deg)+(elp.get(i+2).getY()-elp.get(i).getY())*Math.cos(deg));
Point npt1=new Point(x,y);
elp.set(i+2, npt1);

x=(int) (elp.get(i).getX()+(elp.get(i+1).getX()-elp.get(i).getX())*Math.cos(deg)+(elp.get(i+1).getY()-elp.get(i).getY())*Math.sin(deg));
y=(int) (elp.get(i).getY()-(elp.get(i+1).getX()-elp.get(i).getX())*Math.sin(deg)+(elp.get(i+1).getY()-elp.get(i).getY())*Math.cos(deg));
Point npt2=new Point(x,y);
elp.set(i+1, npt2);

}
repaint();
}
else if(ae.getSource()==clear)
{
elp.clear();
repaint();
}
else if(ae.getSource()==undo)
{
try
{
for(int i=0;i<3;i++)
elp.remove(elp.size()-1);
}
catch(ArrayIndexOutOfBoundsException e)
{
//e.printStackTrace();
System.out.println(e.toString());
}
repaint();
}
else if(ae.getSource()==animation)
{

}
}

@Override
public void mouseClicked(MouseEvent me) {
}

@Override
public void mousePressed(MouseEvent me) {
}

@Override
public void mouseReleased(MouseEvent me) {
elp.add(new Point(me.getX(),me.getY()));
repaint();
}

@Override
public void mouseEntered(MouseEvent me) {
}

@Override
public void mouseExited(MouseEvent me) {
}

}