Must use the starter code

[Starter Code]

import javax.swing.*;

import java.awt.*;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.awt.event.MouseAdapter;

import java.awt.event.MouseEvent;

import java.awt.image.BufferedImage;

/*** I DON'T RECOMMEND TO CHANGE THE BELOW CODE (EVEN THOUGH YOU CAN) ***/

public class Main {

public static void main(String[] args) {

showWindow();

}

// DON'T CHANGE THE METHOD SIGNATURE OF showWindow()

public static MainWindow showWindow() {

return new MainWindow();

}

}

/*** I DON'T RECOMMEND TO CHANGE THE ABOVE CODE (EVEN THOUGH YOU CAN) ***/

class MainWindow extends JFrame {

public MainWindow() {

super("Paint Tool");

setContentPane(createContentPane());

setSize(600, 400);

setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

setVisible(true);

}

private JPanel createContentPane() {

CanvasPanel canvas = new CanvasPanel();

MouseListener listener = new MouseListener(canvas);

canvas.addMouseListener(listener);

canvas.addMouseMotionListener(listener);

JPanel contentPane = new JPanel(new BorderLayout());

contentPane.add(canvas, BorderLayout.CENTER);

/********************************/

/* You need to write code here. */

/********************************/

return contentPane;

}

}

class MouseListener extends MouseAdapter {

private final CanvasPanel canvasPanel;

// Store the most recent X and Y of `mousePressed` or `mousePressed`.

// `mousePressed` `mousePressed` XY

private int lastX;

private int lastY;

MouseListener(CanvasPanel canvas) {

canvasPanel = canvas;

}

@Override

public void mousePressed(MouseEvent e) {

/********************************/

/* You need to write code here. */

/********************************/

// Draw a line (i.e., dot) between the current mouse position and the current mouse position.

//

}

@Override

public void mouseDragged(MouseEvent e) {

/********************************/

/* You need to write code here. */

/********************************/

// Draw a line between the post-movement pixel (i.e., current mouse position) and the pre-movement pixel (i.e., (lastX, lastY)).

// (lastX, lastY)

}

}

class CanvasPanel extends JPanel {

private final BufferedImage image;

private final Graphics2D graphics;

public CanvasPanel() {

setName("canvas");

image = new BufferedImage(320, 240, BufferedImage.TYPE_INT_RGB);

graphics = image.createGraphics();

graphics.setColor(Color.WHITE);

graphics.fillRect(0, 0, image.getWidth(), image.getHeight());

graphics.setColor(Color.BLACK);

}

public void setPenSize(int size) {

/********************************/

/* You need to write code here. */

/********************************/

}

public void drawLine(int startX, int startY, int endX, int endY) {

/********************************/

/* You need to write code here. */

/********************************/

repaint();

}

@Override

public void paint(Graphics g) {

g.drawImage(image, 0, 0, this);

}

}

title of the window ( ) is following two components at least are shown immediately after the window is shown. There is a component with four choices of 1,2,3, and 5 as pen thickness (pixels) is shown. - The constructor BasicStroke(float width) of class changes the thickness of the line corresponding to the choice. - c.f. https://docs.oracle.com/javase/8/docs/api/java/awt/BasicStroke.html\#BasicStroke-float- There is a panel (_ ) with the name meeting the following requirements. - A white rectangle with a width of 320 and a height of 240 is displayed in the upper left corner of the panel. The area where the white rectangle was first displayed is called drawing area. - When the left button of the mouse is pressed in the drawing area, immediately draw a black dot with the selected thickness at the mouse pointer position by calling Graphics2D. drawLine(). - Use mousePressed(MouseEvent e) instead of mouseClicked(MouseEvent e). - When the mouse is dragged in the drawing area while the left button is pressed, draw a black line with the selected thickness between the pre-movement pixel and the post-movement pixel by calling Graphics2D. drawLine(). - Use method to detect "the mouse is dragged while the left button is pressed". Refer to the template code to understand how to use the method. - The location of the post-movement pixel is the mouse pointer position when the mouseDragged(MouseEvent e) method is fired. - The location of the pre-movement pixel is the mouse pointer position when the e) or mouseDragged(MouseEvent e) method is fired most recently except for the currently called mouseDragged(MouseEvent e) method. - Call Graphics2D.drawLine() every time mouseDragged(MouseEvent e) is fired. - You don't need to detect the end of a drag. That is, mouseReleased(MouseEvent e) is not needed. - Don't hide the image partially by putting other components (e.g. buttons) on the panel. I.e., Overlapping each other is not allowed