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Drawing Application In Java

Ayush Purawr December 3, 2022

Introduction

In this article, we will design and build a Drawing Application In Java. In this project, the user can set the background color, draw, erase and save his drawing as an image file to the memory. The size of the brush and eraser can be adjusted. We will try to keep this drawing application just like we have the paint application on our windows computers. This drawing application in Java will have minimal yet straightforward and easy features of the windows paint application. Let’s start with the project.

Drawing Application in Java: Project Overview

Project Name	Drawing Application in Java
Abstract	It’s a GUI-based project with the Swing module to create and save drawings.
Languages Used	Java
IDE	Eclipse IDE
Java version (Recommended)	Java SE 18.0. 2.1
Type	Desktop Application
Recommended for	Intermediates of Java

Setting up the environment

Make sure JDK is installed in your system. If not, you can install it with the help of the IDE you are using.

We are using Eclipse IDE for the project. The first step in IDE is creating a project with your preferred name. Create a package named “canvas” inside the project’s src folder. All the classes have to be created inside the package created.

Coding Paint/Drawing Application in Java

1. Main Module

Name: “Main.java“

The Main class contains the main function to start the program. Here we are just calling the function to be executed.

package canvas;

public class Main {
	public static void main(String[] args) {
		Canvas canvas = new Canvas();
		canvas.CanvasView();
	}
}

2. Project Module

Name: “Canvas.java“

The Class contains the whole project. Here we can draw, erase, save and do many other operations.

package canvas;

import java.awt.AWTException;
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.Robot;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import java.awt.image.BufferedImage;
import java.io.File;

import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class Canvas implements MouseMotionListener{
	JFrame frame = new JFrame();
	JPanel canvasPanel, toolBar;
	JButton btn;
	JTextField col, sz;
	String prev, back;
	
	Canvas() {
		canvasPanel = new JPanel();
		canvasPanel.addMouseMotionListener(this);
	}

	public void CanvasView() {
		
		//-----------CANVAS-------------
		canvasPanel.setBounds(320, 30, 850, 600);
		canvasPanel.setBackground(Color.white);
		canvasPanel.setLayout(null);
		frame.add(canvasPanel);
		canvasPanel.addMouseListener(new MouseAdapter() {
			@Override
			public void mouseClicked(MouseEvent e) {
				String cl = col.getText();
				int rad = Integer.parseInt(sz.getText());
				Graphics grap = canvasPanel.getGraphics();
				grap.setColor(Color.decode(cl));
				grap.fillRect(e.getX(), e.getY(), rad, rad);
			}
		});
		//-----------------------------
		
		//-----------TOOLBAR-------------
		toolBar = new JPanel();
		toolBar.setBounds(30, 30, 250, 600);
		toolBar.setBackground(Color.white);
		toolBar.setLayout(null);
		frame.add(toolBar);
		addButton(32, 30, "#000000");
		addButton(105, 30, "#FFFFFF");
		addButton(177, 30, "#808080");
		addButton(32, 90, "#FF0000");
		addButton(105, 90, "#00FF00");
		addButton(177, 90, "#0000FF");
		addButton(32, 150, "#FFFF00");
		addButton(105, 150, "#FFA500");
		addButton(177, 150, "#A020F0");
		addButton(32, 210, "#FFC0CB");
		addButton(105, 210, "#964B00");
		addButton(177, 210, "#C32148");
		//-----------------------------
		
		//---------CUSTOM---------------
		JLabel cllabel = new JLabel("Custom Colors : ");
		cllabel.setBounds(30, 260, 100, 50);
		toolBar.add(cllabel);
		col = new JTextField();
		col.setBounds(30, 310, 190, 30);
		col.setText("#000000");
		toolBar.add(col);
		//------------------------------
		
		//-----------BACKGROUNDCOLOUR-------------
		back = "#FFFFFF";
		JButton bc = new JButton("SET BACKGROUND");
		bc.setBounds(30, 350, 190, 30);
		toolBar.add(bc);
		bc.addActionListener(new ActionListener() {
			@Override
			public void actionPerformed(ActionEvent e) {
				back = col.getText();
				canvasPanel.setBackground(Color.decode(back));
			}
		});
		//---------------------------------

		//---------SIZE------------------
		JLabel szlabel = new JLabel("Size : ");
		szlabel.setBounds(30, 380, 100, 50);
		toolBar.add(szlabel);
		JButton sub = new JButton("-");
		sub.setBounds(30, 415, 50, 30);
		toolBar.add(sub);
		sz = new JTextField();
		sz.setBounds(100, 415, 50, 30);
		sz.setText("5");
		toolBar.add(sz);
		JButton add = new JButton("+");
		add.setBounds(170, 415, 50, 30);
		toolBar.add(add);
		sub.addActionListener(new ActionListener() {
			@Override
			public void actionPerformed(ActionEvent e) {
				sz.setText(Integer.parseInt(sz.getText())-1+"");
			}
		});
		add.addActionListener(new ActionListener() {
			@Override
			public void actionPerformed(ActionEvent e) {
				sz.setText(Integer.parseInt(sz.getText())+1+"");
			}
		});
		//-------------------------------
		
		//---------PAINT&ERASE-----------------
		JButton brush = new JButton("BRUSH");
		brush.setBounds(30, 465, 80, 30);
		toolBar.add(brush);
		JButton erase = new JButton("ERASE");
		erase.setBounds(140, 465, 80, 30);
		toolBar.add(erase);
		prev = "#000000";
		brush.addActionListener(new ActionListener() {
			@Override
			public void actionPerformed(ActionEvent e) {
				col.setText(prev);
			}
		});
		erase.addActionListener(new ActionListener() {
			@Override
			public void actionPerformed(ActionEvent e) {
				if(!col.getText().equals(back))
					prev = col.getText();
				col.setText(back);
			}
		});
		//--------------------------------
		
		//-----------CLEAN--------------
		JButton clean = new JButton("CLEAN");
		clean.setBounds(30, 515, 190, 30);
		toolBar.add(clean);
		clean.addActionListener(new ActionListener() {
			@Override
			public void actionPerformed(ActionEvent e) {
				canvasPanel.removeAll();
				canvasPanel.repaint();
			}
		});
		//-------------------------------
		
		//-----------SAVE---------------
		JButton save = new JButton("SAVE");
		save.setBounds(30, 555, 190, 30);
		toolBar.add(save);
		save.addActionListener(new ActionListener() {
			@Override
			public void actionPerformed(ActionEvent e) {
				String tm = java.time.LocalTime.now()+"";
				tm = tm.substring(0, 2) + tm.substring(3, 5) + tm.substring(6, 8) + tm.substring(9, 12) + ".png";
				try {
				BufferedImage image = getImg(canvasPanel);
				ImageIO.write(image, "png", new File(tm));
				}
				catch(Exception ex) {
					
				}
			}
		});
		//-------------------------------
		
		//------FRAME------------------
		frame.setSize(1250, 700);
		frame.setLocationRelativeTo(null);
		frame.setLayout(null);
		frame.getContentPane().setBackground(Color.decode("#001122"));
		frame.setVisible(true);
		frame.setResizable(false);
		frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
		//---------------------------------
	}
	//---------MOUSE FUNCTIONS---------------------
	@Override
	public void mouseDragged(MouseEvent e) {
		String cl = col.getText();
		int rad = Integer.parseInt(sz.getText());
		Graphics grap = canvasPanel.getGraphics();
		grap.setColor(Color.decode(cl));
		grap.fillRect(e.getX(), e.getY(), rad, rad);
	}

	@Override
	public void mouseMoved(MouseEvent e) {
		
	}
	//-------------------------------------------------

	//---------FUNCTIONS TO CREATE SIMILAR BUTTONS---------
	public void addButton(int x, int y, String clr) {
		this.btn = new JButton();
		btn.setBounds(x, y, 40, 40);
		btn.setBackground(Color.decode(clr));
		btn.addActionListener(new ActionListener() {
			@Override
			public void actionPerformed(ActionEvent e) {
				col.setText(clr);
			}
		});
		toolBar.add(btn);
	}
	//-------------------------------------------------------
	
	//----------FUNCTION TO CREATE IMAGE TO SAVE-----------------------------
	public BufferedImage getImg(Component comp) throws AWTException {
	    Point p = comp.getLocationOnScreen();
	    Dimension dim = comp.getSize();
	    BufferedImage capture = new Robot().createScreenCapture(new Rectangle(p, dim));
	    return capture;
	}
	//--------------------------------------------------------------------------
}

Output:

Image output:

output for Drawing Application In Java

Video output:

Here we can draw, erase in the canvas, set the custom brush color and size, change the background color, clean the canvas and save the drawn image. Respective buttons and text fields are given in the toolbar left of the screen.

Conclusion

In this article, we learned to create a Drawing Application In Java. This GUI-based application allows us to draw our imaginations and save them into image files. Hope you guys enjoyed it.

Thank You!

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Author: Ayush Purawr