Aide à créer une gomme pour un programme paint en java

J'ai ajouté des commentaires où j'ai ajouté/changé le code.

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.awt.image.BufferedImage;

import javax.swing.ButtonGroup;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JColorChooser;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JRadioButton;

public class PaintProgram extends JPanel implements MouseListener, ActionListener,
/**
 * CHANGE BY S AQEEL : implement mouse motion listener
 */
MouseMotionListener
{
    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    public static int stroke, eraser = 0;
    private int xX1, yY1, xX2, yY2, choice;

    /**
     * CHANGE BY S AQEEL : Define a constant for background color, because we are using it at a lot of places
     */
    private static final Color BACKGROUND_COLOR = Color.WHITE;

    /**
     * CHANGE BY S AQEEL : Also define variables for eraser width and height. In a more usable implementation you can allow user to change eraser size
     */
    private int eraserWidth = 40;
    private int eraserHeight = 40;

    public static void main(String[] args)
    {
        new PaintProgram();
    }

    PaintProgram()
    {

        JFrame frame = new JFrame("Paint Program");
        frame.setSize(1200, 800);

        /**
         * CHANGE BY S AQEEL : Use constant instead of hardcoding
         */
        frame.setBackground(BACKGROUND_COLOR);
        frame.getContentPane().add(this);

        JMenuBar menuBar = new JMenuBar();
        frame.setJMenuBar(menuBar);
        JMenu help = new JMenu("Help");
        menuBar.add(help);
        JMenuItem about = new JMenuItem("About");
        help.add(about);
        about.addActionListener(this);

        JButton button1 = new JButton("Clear");
        button1.addActionListener(this);
        JButton color = new JButton("Color");
        color.addActionListener(this);
        JButton erase = new JButton("Erase?");
        erase.addActionListener(this);
        JButton button2 = new JButton("Empty Rect");
        button2.addActionListener(this);
        JButton button3 = new JButton("Filled oval");
        button3.addActionListener(this);
        JButton button4 = new JButton("Filled Rect");
        button4.addActionListener(this);
        JButton button5 = new JButton("Empty oval");
        button5.addActionListener(this);
        JButton button6 = new JButton("Line");
        button6.addActionListener(this);
        JRadioButton thin = new JRadioButton("Thin Line");
        thin.addActionListener(this);
        JRadioButton medium = new JRadioButton("Medium Line");
        medium.addActionListener(this);
        JRadioButton thick = new JRadioButton("Thick Line");
        thick.addActionListener(this);

        ButtonGroup lineOption = new ButtonGroup();
        lineOption.add(thin);
        lineOption.add(medium);
        lineOption.add(thick);

        this.add(button1);
        this.add(color);
        this.add(erase);
        this.add(button2);
        this.add(button3);
        this.add(button4);
        this.add(button5);
        this.add(button6);
        this.add(thin);
        this.add(medium);
        this.add(thick);
        addMouseListener(this);
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    }

    public void paintComponent(Graphics g)
    {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D) g;
        if (grid == null)
        {
            int w = this.getWidth();
            int h = this.getHeight();
            grid = (BufferedImage) (this.createImage(w, h));
            gc = grid.createGraphics();
            gc.setColor(Color.BLUE);
        }

        g2.drawImage(grid, null, 0, 0);
        check();
    }

    BufferedImage grid;
    Graphics2D gc;

    public void draw()
    {
        Graphics2D g = (Graphics2D) getGraphics();
        int w = xX2 - xX1;
        if (w < 0)
            w = w * (-1);

        int h = yY2 - yY1;
        if (h < 0)
            h = h * (-1);

        switch (choice)
        {
        case 1:
            check();
            gc.drawRect(xX1, yY1, w, h);
            repaint();
            break;

        case 2:
            check();
            gc.drawOval(xX1, yY1, w, h);
            repaint();
            break;

        case 3:
            check();
            gc.drawRect(xX1, yY1, w, h);
            gc.fillRect(xX1, yY1, w, h);
            repaint();
            break;

        case 4:
            check();
            gc.drawOval(xX1, yY1, w, h);
            gc.fillOval(xX1, yY1, w, h);
            repaint();
            break;

        case 5:

            if (stroke == 0)
                gc.setStroke(new BasicStroke(1));
            if (stroke == 1)
                gc.setStroke(new BasicStroke(3));
            if (stroke == 2)
                gc.setStroke(new BasicStroke(6));
            gc.drawLine(xX1, yY1, xX2, yY2);
            repaint();
            break;

        case 6:
            repaint();
            Color temp = gc.getColor();

            /**
             * CHANGE BY S AQEEL : Use constant instead of hardcoding
             */
            gc.setColor(BACKGROUND_COLOR);
            gc.fillRect(0, 0, getWidth(), getHeight());
            gc.setColor(temp);
            repaint();
            break;

        case 7:

            if (eraser == 1)
            {
                gc.clearRect(xX1, yY1, w, h);
            }
            else
            {

            }
            break;
        }
    }

    public void check()
    {
        if (xX1 > xX2)
        {
            int z = 0;
            z = xX1;
            xX1 = xX2;
            xX2 = z;
        }
        if (yY1 > yY2)
        {
            int z = 0;
            z = yY1;
            yY1 = yY2;
            yY2 = z;
        }
    }

    public void actionPerformed(ActionEvent e)
    {
        /**
         * CHANGE BY S AQEEL : Remove mousemotionlistener(which is added when eraser is selected) So that if another control is pressed, the user does
         * not accidentally erases
         */
        super.removeMouseMotionListener(this);

        if (e.getActionCommand().equals("Color"))
        {
            Color bgColor = JColorChooser.showDialog(this, "Choose Background Color", getBackground());
            if (bgColor != null)
                gc.setColor(bgColor);
        }

        if (e.getActionCommand().equals("About"))
        {
            System.out.println("About Has Been Pressed");
            JFrame about = new JFrame("About");
            about.setSize(300, 300);
            JButton picture = new JButton(new ImageIcon("C:/Users/TehRobot/Desktop/Logo.png"));
            about.add(picture);
            about.setVisible(true);
        }

        if (e.getActionCommand().equals("Empty Rect"))
        {
            System.out.println("Empty Rectangle Has Been Selected~");
            choice = 1;

        }

        if (e.getActionCommand().equals("Empty oval"))
        {
            System.out.println("Empty Oval Has Been Selected!");
            choice = 2;
        }

        if (e.getActionCommand().equals("Filled Rect"))
        {
            System.out.println("Filled Rectangle Has Been Selected");
            choice = 3;
        }

        if (e.getActionCommand().equals("Filled oval"))
        {
            System.out.println("Filled Oval Has Been Selected");
            choice = 4;
        }

        if (e.getActionCommand().equals("Line"))
        {
            System.out.println("Draw Line Has Been Selected");
            choice = 5;
        }

        if (e.getActionCommand().equals("Thin Line"))
        {
            stroke = 0;
        }

        if (e.getActionCommand().equals("Medium Line"))
        {
            stroke = 1;
        }

        if (e.getActionCommand().equals("Thick Line"))
        {
            stroke = 2;
        }

        if (e.getActionCommand().equals("Erase?"))
        {
            eraser = 1;
            choice = 7;

            /**
             * CHANGE BY S AQEEL : Add mousemotionlistener here.
             */
            super.addMouseMotionListener(this);
        }

        if (e.getActionCommand().equals("Clear"))
        {
            System.out.println("Clear All The Things!!!");
            choice = 6;
            draw();
        }

    }

    public void mouseExited(MouseEvent evt)
    {
    }

    public void mouseEntered(MouseEvent evt)
    {
    }

    public void mouseClicked(MouseEvent evt)
    {
    }

    public void mousePressed(MouseEvent evt)
    {

        xX1 = evt.getX();
        yY1 = evt.getY();

    }

    public void mouseReleased(MouseEvent evt)
    {
        xX2 = evt.getX();
        yY2 = evt.getY();
        draw();
        eraser = 0;
    }

    /**
     * CHANGE BY S AQEEL : MouseMotionListener functions implemented. Note this listener is only registered when eraser is selected
     */
    public void mouseDragged(MouseEvent me)
    {
        Color c = gc.getColor();
        gc.setColor(BACKGROUND_COLOR);
        gc.drawRect(me.getX(), me.getY(), eraserWidth, eraserHeight);
        gc.fillRect(me.getX(), me.getY(), eraserWidth, eraserHeight);
        gc.setColor(c);
        repaint();
    }

    public void mouseMoved(MouseEvent arg0)
    {
    }
}

Maintenant que votre problème est résolu, vous devriez essayer d'ajouter des fonctionnalités de qualité peu mais utilisables, comme: Utiliser différents curseurs pour dessiner/effacer différentes formes. Autoriser l'utilisateur à modifier la taille de la gomme. Toujours dans l'implémentation actuelle, l'utilisateur doit faire glisser la gomme pour effacer, vous devez ajouter une fonctionnalité afin que l'utilisateur puisse effacer des points en cliquant simplement (en plus de faire glisser).