CODEWITHSUNDEEP
javaswingjpaneljava-2dpaintcomponent
нαƒєєz
нαƒєєz

Reputation: 1249

How to draw a circle with given X and Y coordinates as the middle spot of the circle?

I have developed a telecommunication application for locating signal strengths from the towers. I have used java swing and I'm having a problem when drawing the circle around the given point of the mobile signal transmitter tower location. I have already calculated the X, Y coordinates and also the radius value.

Please find the below code which I've used to draw the circle and it is having issues.

JPanel panelBgImg = new JPanel() {
    public void paintComponent(Graphics g) {
        g.drawOval(X, Y, r, r);
    }
}

The issue is, it creates the circle but it didn't take the X and Y coordinates as the center point. It took the X and Y coordinates as the top left point of the circle.

Could anyone please help me to draw the circle by having the given X and Y coordinates as the center point of the circle.

Upvotes: 25

Views: 242646

Answers (9)

anydoby
anydoby

Reputation: 448

This draws an arc with the center in the specified rectangle. You can draw, half-circles, quarter-circles, etc.

g.drawArc(x - r, y - r, r * 2, r * 2, 0, 360)

Upvotes: 1

Udeesha Induwara
Udeesha Induwara

Reputation: 615

JPanel pnlCircle = new JPanel() {
        public void paintComponent(Graphics g) {
            int X=100;
            int Y=100;
            int d=200;
            g.drawOval(X, Y, d, d);
        }
};

you can change X,Y coordinates and radius what you want.

Upvotes: 2

Farhad
Farhad

Reputation: 57

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.Graphics;
import javax.swing.JFrame;

public class Graphiic
{   
    public Graphics GClass;
    public Graphics2D G2D;
    public  void Draw_Circle(JFrame jf,int radius , int  xLocation, int yLocation)
    {
        GClass = jf.getGraphics();
        GClass.setPaintMode();
        GClass.setColor(Color.MAGENTA);
        GClass.fillArc(xLocation, yLocation, radius, radius, 0, 360);
        GClass.drawLine(100, 100, 200, 200);    
    }

}

Upvotes: 1

Andres Mitchell
Andres Mitchell

Reputation: 31

drawCircle(int X, int Y, int Radius, ColorFill, Graphics gObj)

Upvotes: 3

Justin
Justin

Reputation: 149

So we are all doing the same home work?

Strange how the most up-voted answer is wrong. Remember, draw/fillOval take height and width as parameters, not the radius. So to correctly draw and center a circle with user-provided x, y, and radius values you would do something like this:

public static void drawCircle(Graphics g, int x, int y, int radius) {

  int diameter = radius * 2;

  //shift x and y by the radius of the circle in order to correctly center it
  g.fillOval(x - radius, y - radius, diameter, diameter); 

}

Upvotes: 14

Kordian
Kordian

Reputation: 1

The only thing that worked for me:

g.drawOval((getWidth()-200)/2,(getHeight()-200)/2, 200, 200);

Upvotes: 0

johnny
johnny

Reputation: 268

both answers are is incorrect. it should read:

x-=r;
y-=r;


drawOval(x,y,r*2,r*2);

Upvotes: 1

arynaq
arynaq

Reputation: 6870

The fillOval fits an oval inside a rectangle, with width=r, height = r you get a circle. If you want fillOval(x,y,r,r) to draw a circle with the center at (x,y) you will have to displace the rectangle by half its width and half its height.

public void drawCenteredCircle(Graphics2D g, int x, int y, int r) {
  x = x-(r/2);
  y = y-(r/2);
  g.fillOval(x,y,r,r);
}

This will draw a circle with center at x,y

Upvotes: 48

qaphla
qaphla

Reputation: 4743

Replace your draw line with

g.drawOval(X - r, Y - r, r, r)

This should make the top-left of your circle the right place to make the center be (X,Y), at least as long as the point (X - r,Y - r) has both components in range.

Upvotes: 6

Related Questions