Freehand Drawing Application with Java Swing

Here is a sample Java program which is used for freehand drawing with mouse. Features include: - Colors: You can draw in different colors. The supported colors are Black, Blue, Cyan, Gray, Green, Magenta, Orange, Pink, Red, White and Yellow. - Pointer Location: The program always shows the mouse pointer location in the title bar. The title is changed dynamically for the mouse movement. This is not a serous program – it’s a fun. You can use it for education purpose only to learn about how to draw in Java.

Output of the program

Here is the full source code:

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;

import javax.swing.BorderFactory;
import javax.swing.ButtonGroup;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.WindowConstants;

public class FreehandDrawing extends JFrame {

    private static final long serialVersionUID = 1L;

    public FreehandDrawing() {
        initComponents();
        Dimension dimension = Toolkit.getDefaultToolkit().getScreenSize();
        setSize(dimension.width, dimension.height - 30);
    }

    private void initComponents() {

        colorButtonGroup = new ButtonGroup();
        drawingPanel = new JPanel();
        colorPanel = new JPanel();
        radioButtonBlack = new JRadioButton();
        radioButtonBlue = new JRadioButton();
        radioButtonCyan = new JRadioButton();
        radioButtonGray = new JRadioButton();
        radioButtonGreen = new JRadioButton();
        radioButtonMagenta = new JRadioButton();
        radioButtonOrange = new JRadioButton();
        radioButtonPink = new JRadioButton();
        radioButtonRed = new JRadioButton();
        radioButtonWhite = new JRadioButton();
        radioButtonYellow = new JRadioButton();

        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

        drawingPanel.setBorder(BorderFactory.createEtchedBorder());
        drawingPanel.addMouseListener(new MouseAdapter() {
            public void mouseExited(MouseEvent evt) {
                drawingPanelMouseExited(evt);
            }
        });
        drawingPanel.addMouseMotionListener(new MouseMotionAdapter() {
            public void mouseDragged(MouseEvent evt) {
                drawingPanelMouseDragged(evt);
            }

            public void mouseMoved(MouseEvent evt) {
                drawingPanelMouseMoved(evt);
            }
        });

        getContentPane().add(drawingPanel, java.awt.BorderLayout.CENTER);

        colorPanel.setBorder(BorderFactory.createEtchedBorder());
        colorPanel.setLayout(new java.awt.GridLayout(1, 0));

        radioButtonBlack.setBackground(Color.BLACK);
        colorButtonGroup.add(radioButtonBlack);
        radioButtonBlack.setForeground(Color.WHITE);
        radioButtonBlack.setSelected(true);
        radioButtonBlack.setText("Black");
        radioButtonBlack.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent evt) {
                color = Color.BLACK;
            }
        });
        colorPanel.add(radioButtonBlack);

        radioButtonBlue.setBackground(Color.BLUE);
        colorButtonGroup.add(radioButtonBlue);
        radioButtonBlue.setText("Blue");
        radioButtonBlue.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent evt) {
                color = Color.BLUE;
            }
        });
        colorPanel.add(radioButtonBlue);

        radioButtonCyan.setBackground(Color.CYAN);
        colorButtonGroup.add(radioButtonCyan);
        radioButtonCyan.setText("Cyan");
        radioButtonCyan.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent evt) {
                color = Color.CYAN;
            }
        });
        colorPanel.add(radioButtonCyan);

        radioButtonGray.setBackground(Color.GRAY);
        colorButtonGroup.add(radioButtonGray);
        radioButtonGray.setText("Gray");
        radioButtonGray.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent evt) {
                color = Color.GRAY;
            }
        });
        colorPanel.add(radioButtonGray);

        radioButtonGreen.setBackground(Color.GREEN);
        colorButtonGroup.add(radioButtonGreen);
        radioButtonGreen.setText("Green");
        radioButtonGreen.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent evt) {
                color = Color.GREEN;
            }
        });
        colorPanel.add(radioButtonGreen);

        radioButtonMagenta.setBackground(Color.MAGENTA);
        colorButtonGroup.add(radioButtonMagenta);
        radioButtonMagenta.setText("Magenta");
        radioButtonMagenta.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent evt) {
                color = Color.MAGENTA;
            }
        });
        colorPanel.add(radioButtonMagenta);

        radioButtonOrange.setBackground(Color.ORANGE);
        colorButtonGroup.add(radioButtonOrange);
        radioButtonOrange.setText("Orange");
        radioButtonOrange.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent evt) {
                color = Color.ORANGE;
            }
        });
        colorPanel.add(radioButtonOrange);

        radioButtonPink.setBackground(Color.PINK);
        colorButtonGroup.add(radioButtonPink);
        radioButtonPink.setText("Pink");
        radioButtonPink.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent evt) {
                color = Color.PINK;
            }
        });
        colorPanel.add(radioButtonPink);

        radioButtonRed.setBackground(Color.RED);
        colorButtonGroup.add(radioButtonRed);
        radioButtonRed.setText("Red");
        radioButtonRed.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent evt) {
                color = Color.RED;
            }
        });
        colorPanel.add(radioButtonRed);

        radioButtonWhite.setBackground(Color.WHITE);
        colorButtonGroup.add(radioButtonWhite);
        radioButtonWhite.setText("White");
        radioButtonWhite.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent evt) {
                color = Color.WHITE;
            }
        });
        colorPanel.add(radioButtonWhite);

        radioButtonYellow.setBackground(Color.YELLOW);
        colorButtonGroup.add(radioButtonYellow);
        radioButtonYellow.setText("Yellow");
        radioButtonYellow.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent evt) {
                color = Color.YELLOW;
            }
        });
        colorPanel.add(radioButtonYellow);

        getContentPane().add(colorPanel, java.awt.BorderLayout.PAGE_START);

        pack();
    }

    private void drawingPanelMouseMoved(MouseEvent evt) {
        oldX = evt.getX();
        oldY = evt.getY();
        setTitle(oldX + "," + oldY + " - Freehand Drawing");
    }

    private void drawingPanelMouseExited(MouseEvent evt) {
        setTitle("Freehand Drawing");
    }

    private void drawingPanelMouseDragged(MouseEvent evt) {

        newX = evt.getX();
        newY = evt.getY();
        graphics = drawingPanel.getGraphics();
        graphics.setColor(color);
        graphics.drawLine(oldX, oldY, newX, newY);
        oldX = newX;
        oldY = newY;
        setTitle(oldX + "," + oldY + " - Freehand Drawing");
    }

    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new FreehandDrawing().setVisible(true);
            }
        });
    }

    private ButtonGroup colorButtonGroup;
    private JPanel colorPanel;
    private JPanel drawingPanel;
    private JRadioButton radioButtonBlack;
    private JRadioButton radioButtonBlue;
    private JRadioButton radioButtonCyan;
    private JRadioButton radioButtonGray;
    private JRadioButton radioButtonGreen;
    private JRadioButton radioButtonMagenta;
    private JRadioButton radioButtonOrange;
    private JRadioButton radioButtonPink;
    private JRadioButton radioButtonRed;
    private JRadioButton radioButtonWhite;
    private JRadioButton radioButtonYellow;
    private int oldX, oldY, newX, newY;
    private Color color = Color.BLACK;
    private Graphics graphics;
}

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