package learning;

import java.awt.*;
import javax.swing.*;

public class Draw4 extends JPanel {

    static int x = 0, y = 0;

    public void paint(Graphics g) {
        Graphics2D g2 = (Graphics2D) g;
        g2.fillOval(x, y, 10, 10);
    }

    public static void main(String[] args) throws InterruptedException {
        JFrame frame = new JFrame("Draw");
        Draw4 game = new Draw4();
        frame.setBackground(Color.white);
        frame.add(game);
        frame.setSize(400, 300);
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        int length = 50;
        double angle = 0.0;
        double angle_stepsize = 0.05;

        // drawing first semicircle

        while(angle > -Math.PI) {
            x = (int) Math.floor(length * Math.cos(angle))+ 50;
            y = (int) Math.floor(length * Math.sin(angle))+ 50;
            game.repaint();
            angle -= angle_stepsize;
            Thread.sleep(10);
        }

        // drawing a line using the Bresenham Algorithm

        int x2 = 100, y2 = 100;
        int w = x2 - x ;
        int h = y2 - y ;
        int dx1 = 0, dy1 = 0, dx2 = 0, dy2 = 0 ;
        if (w<0) dx1 = -1 ; else if (w>0) dx1 = 1 ;
        if (h<0) dy1 = -1 ; else if (h>0) dy1 = 1 ;
        if (w<0) dx2 = -1 ; else if (w>0) dx2 = 1 ;
        int longest = Math.abs(w) ;
        int shortest = Math.abs(h) ;
        if (!(longest>shortest)) {
            longest = Math.abs(h) ;
            shortest = Math.abs(w) ;
            if (h<0) dy2 = -1 ; else if (h>0) dy2 = 1 ;
            dx2 = 0 ;
        }
        int numerator = longest >> 1 ;
        for (int i=0;i<=longest;i++) {
            game.repaint();
            Thread.sleep(10);
            numerator += shortest ;
            if (!(numerator<longest)) {
                numerator -= longest ;
                x += dx1 ;
                y += dy1 ;
            } else {
                x += dx2 ;
                y += dy2 ;
            }
        }

        //drawing second circle

        angle = 0.0;
        while(angle < Math.PI) {
            x = (int) Math.floor(length * Math.cos(angle))+ 50;
            y = (int) Math.floor(length * Math.sin(angle))+ 100;
            game.repaint();
            angle += angle_stepsize;
            Thread.sleep(10);
        }
    }
}