Draw circles, select circles

[cselic]

Hi.
I have written small program.
In this program we can draw circles and select them.
I will post it here. it might be a useful for someone.

class: Circle.java

import java.awt.Graphics;
import java.awt.Point;

public class Circle {
	public Circle(Point center, Point endPoint) {
		this.center = center;
		this.radius = (int)center.distance(endPoint);
		selected = false;
	}
	
	public void drawCircle(Graphics g) {
		g.drawOval(center.x - radius, center.y - radius, 2*radius, 2*radius);
	}
	
	public boolean selectCircle(Point point) {
		int newRadius = (int)center.distance(point);
		if(Math.abs(radius - newRadius) < 4)
			return true;
		
		return false;
	}
	
	public void setSelectedCircle(boolean set) {
		selected = set;
	}
	
	public boolean getSelectedCirlce() {
		return selected;
	}
	
	private Point center;
	private int radius;
	boolean selected;
}

class: DrawCircles.java

import java.awt.Color;
import java.awt.Point;
import java.awt.Graphics;

import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.awt.event.MouseEvent;

import java.util.ArrayList;

import javax.swing.SwingUtilities;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class DrawCircles {
	public static void main(String[] args) {
		SwingUtilities.invokeLater(new Runnable() {
			
			@Override
			public void run() {
				MFrame frame = new MFrame();
				frame.showGUI();
			}
		});
	}
}

class MFrame extends JFrame {
	MPanel panel = new MPanel();
	public MFrame() {
		add(panel);
	}
	
	public void showGUI() {
		setTitle("Draw Circles, Select Circles");
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		setSize(500,500);
		setLocation(200,200);
		setVisible(true);
	}
}

class MPanel extends JPanel {
	Circle circle;
	Point startPos = null;
	Point endPos = null;
	Point relativePos = null;
	ArrayList<Circle> arrayOfCircles = new ArrayList<Circle>();
	
	public MPanel() {
		addMouseListener(new MouseListener() {

			@Override
			public void mouseClicked(MouseEvent arg0) {
				if(!arrayOfCircles.isEmpty()) {
					for(int i = 0; i < arrayOfCircles.size(); i++) {
						if(arrayOfCircles.get(i).selectCircle(arg0.getPoint()))
							arrayOfCircles.get(i).setSelectedCircle(true);
						else
							arrayOfCircles.get(i).setSelectedCircle(false);
					}
					repaint();
				}
			}

			@Override
			public void mouseEntered(MouseEvent arg0) {	
			}

			@Override
			public void mouseExited(MouseEvent arg0) {}

			@Override
			public void mousePressed(MouseEvent arg0) {
				startPos = arg0.getPoint();
			}

			@Override
			public void mouseReleased(MouseEvent arg0) {
				endPos = arg0.getPoint();
				if(startPos != null) { 
					arrayOfCircles.add(new Circle(startPos, endPos));
				}
			}
		});
		
		addMouseMotionListener(new MouseMotionListener() {

			@Override
			public void mouseDragged(MouseEvent arg0) {
				if(startPos != null) {
					relativePos = arg0.getPoint();
					circle = new Circle(startPos, relativePos);
					repaint();
				}
			}

			@Override
			public void mouseMoved(MouseEvent arg0) {
			}

		});
	}
	
	public void paint(Graphics g) {
		super.paint(g);
			if((startPos != null) && (relativePos != null)) {
				g.setColor(Color.GREEN);
			    circle.drawCircle(g);
			}
			
			for(int i = 0; i < arrayOfCircles.size(); i++) {
					if(arrayOfCircles.get(i).getSelectedCirlce())
						g.setColor(Color.RED);
					else
						g.setColor(Color.BLUE);
					
					arrayOfCircles.get(i).drawCircle(g);
			}
	}
}

[Fubarable]

The code looks great -- thanks for posting it!

A few suggestions, if you don't mind:

1) Override the JPanel's paintComponent method, not the paint method. This is safer since you have less of a chance of messing up painting of the component's children or borders.

2) Of course change the first method call in the method above from super.paint(g) to super.paintComponent(g) .

3) In the paintComponent method, get a Graphics2D object by casting the Graphics object, and use it to set the rendering hints to do anti-aliasing. This will result in smoother drawing.

Visually, I'm suggesting this:

  public void paintComponent(Graphics g) {
    super.paintComponent(g);
    
    //!! get Graphics2D object and set anti-aliasing to "on"
    Graphics2D g2 = (Graphics2D) g;
    g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, 
        RenderingHints.VALUE_ANTIALIAS_ON);
    
    //... continue with

Again, thanks and best of luck with your projects!

[cselic]

Thanks for this suggestions.

g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, 
        RenderingHints.VALUE_ANTIALIAS_ON);

This code is awesome. :cool: