Creating Sketch Pad in Java

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Hello Friends Today I am going to show you how to create simple Sketch Pad in Java. This is not an advance tool or application but a simple tool, you can take idea from it and you can develop your own sketching tool in Java. Here is the code to show you the use of Frame class and some useful action listeners i.e, ActionListener, WindowListener, MouseListener, MouseMotionListener, ItemListener.

import java.awt.event.*;
import java.awt.*;
public class SketchPad extends Frame implements ActionListener, WindowListener, MouseListener, MouseMotionListener, ItemListener {

    String selectedShape = new String("Square");
    String selectedColor = new String("Blue");
    boolean Eraser = false;
    int upLX, upLY, W, H, selX1, selY1, selX2, selY2;
    String[] extrasList = {"Clear Canvas", "Eraser"};
    String[] colorList = {"Black", "Cyan", "Green", "Yellow", "Magenta", "Red", "Blue"};
    String[] shapeList = {"Line", "Rectangle", "Square", "Circle"};

	
	@Override //from WindowListener
    public void windowClosing(WindowEvent eve) {
        System.exit(0);
    }

	@Override //from WindowListener
    public void windowActivated(WindowEvent we) {
    }

	@Override //from WindowListener
    public void windowOpened(WindowEvent we) {
    }

	@Override //from WindowListener
    public void windowIconified(WindowEvent we) {
    }

	@Override //from WindowListener
    public void windowClosed(WindowEvent we) {
    }

	@Override //from WindowListener
    public void windowDeactivated(WindowEvent we) {
    }

	@Override //from WindowListener
    public void windowDeiconified(WindowEvent we) {
    }

	@Override //from MouseMotionListener
    public void mouseMoved(MouseEvent me) {
    }

	@Override //from MouseListener
    public void mouseClicked(MouseEvent me) {
    }

	@Override //from MouseListener
    public void mouseExited(MouseEvent me) {
    }

	@Override //from MouseListener
    public void mouseEntered(MouseEvent me) {
    }

	@Override //from ItemListener
    public void itemStateChanged(ItemEvent ie) {
    }

    public SketchPad(String title) {
        super(title);
        addMouseMotionListener(this);
        addWindowListener(this);
        addMouseListener(this);
        setLayout(null);
        setMenuItems();
        setBackground(Color.white);
    }

	@Override //from ActionListener
    public void actionPerformed(ActionEvent ape) {
        Graphics ga = getGraphics();
        Object s = ape.getActionCommand();
        for (int i = 0; i != colorList.length; i++) {
            if (s.equals(colorList[i])) {
                selectedColor = colorList[i];
                return;
            }
        }
        for (int i = 0; i != shapeList.length; i++) {
            if (s.equals(shapeList[i])) {
                selectedShape = shapeList[i];
                return;
            }
        }
        if (s.equals("Eraser")) {
            Eraser = true;
            return;
        } else if (s.equals("Clear Canvas")) {
            ga.clearRect(0, 0, 700, 700);
            return;
        }
    }

    void chooseColor(Graphics ga) {
        for (int i = 0; i != colorList.length; i++) {
            if (selectedColor.equals(colorList[i])) {
                switch (i) {
                    case 0:
                        ga.setColor(Color.black);
                        break;
                    case 1:
                        ga.setColor(Color.cyan);
                        break;
                    case 2:
                        ga.setColor(Color.green);
                        break;
                    case 3:
                        ga.setColor(Color.yellow);
                        break;
                    case 4:
                        ga.setColor(Color.magenta);
                        break;
                    case 5:
                        ga.setColor(Color.red);
                        break;
                    case 6:
                        ga.setColor(Color.blue);
                }
            }
        }
    }

	@Override //from MouseListener
    public void mouseReleased(MouseEvent me) {
        Graphics ga = getGraphics();
        if (Eraser) {
            Eraser = false;
            return;
        }
        chooseColor(ga);
        selX2 = me.getX();
        selY2 = me.getY();
        if (selectedShape.equals("Line")) {
            ga.drawLine(selX1, selY1, selX2, selY2);
        } else if (selectedShape.equals("Circle")) {
            drawSelectedShape(ga, "Circle");
        } else if (selectedShape.equals("Square")) {
            drawSelectedShape(ga, "Square");
        } else if (selectedShape.equals("Rectangle")) {
            drawSelectedShape(ga, "Rectangle");
        }
        ga.setColor(Color.yellow);
        ga.drawString(".", selX1, selY1);
        ga.setColor(Color.black);
    }

    void drawSelectedShape(Graphics ga, String sel_shape) {
        upLX = Math.min(selX1, selX2);
        upLY = Math.min(selY1, selY2);
        W = Math.abs(selX1 - selX2);
        H = Math.abs(selY1 - selY2);
        if (sel_shape.equals("Square")) {
            ga.fillRect(upLX, upLY, W, W);
        } else if (sel_shape.equals("Rectangle")) {
            ga.fillRect(upLX, upLY, W, H);
        } else if (sel_shape.equals("Circle")) {
            ga.fillOval(upLX, upLY, W, W);
        }
    }

	@Override //from MouseMotionListener
    public void mouseDragged(MouseEvent me) {
        Graphics ga = getGraphics();
        selX2 = me.getX();
        selY2 = me.getY();
        if (Eraser) {
            ga.setColor(Color.white);
            ga.fillRect(selX2, selY2, 10, 10);
        }
    }

	@Override //from MouseListener
    public void mousePressed(MouseEvent me) {
        if (Eraser) {
            return;
        }
        upLX = 0;
        upLY = 0;
        W = 0;
        H = 0;
        selX1 = me.getX();
        selY1 = me.getY();
        Graphics ga = getGraphics();
        ga.drawString(".", selX1, selY1);
    }

    void setMenuItems() {
        MenuBar mBar = new MenuBar();
        Menu menuShape = new Menu("Shape");
        for (int i = 0; i != shapeList.length; i++) {
            menuShape.add(shapeList[i]);
        }
        mBar.add(menuShape);
        menuShape.addActionListener(this);
        Menu menuColor = new Menu("Colors");
        for (int i = 0; i != colorList.length; i++) {
            menuColor.add(colorList[i]);
        }
        mBar.add(menuColor);
        menuColor.addActionListener(this);
        Menu menuExtras = new Menu("Extras");
        for (int i = 0; i != extrasList.length; i++) {
            menuExtras.add(extrasList[i]);
        }
        mBar.add(menuExtras);
        menuExtras.addActionListener(this);
        setMenuBar(mBar);
    }
	
	//main method menuExtrasecution starts here
	public static void main(String[] args) {
        SketchPad sp = new SketchPad("Sketchpad in Java");
        sp.setSize(700, 700);
        sp.setVisible(true);
    }
}

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import java.awt.event.*;

import java.awt.*;

public class SketchPad extends Frame implements ActionListener, WindowListener, MouseListener, MouseMotionListener, ItemListener {

String selectedShape = new String("Square");

String selectedColor = new String("Blue");

boolean Eraser = false;

int upLX, upLY, W, H, selX1, selY1, selX2, selY2;

String[] extrasList = {"Clear Canvas", "Eraser"};

String[] colorList = {"Black", "Cyan", "Green", "Yellow", "Magenta", "Red", "Blue"};

String[] shapeList = {"Line", "Rectangle", "Square", "Circle"};