Wsrtjtyk

I need help with loading an image of a map and drawing a point on the received location.
Here is the code of the server:

import java.awt.Dimension;

import java.io.IOException;

import java.net.DatagramPacket;

import java.net.DatagramSocket;

import javax.swing.JFrame;

import javax.swing.SwingUtilities;



public class Server extends JFrame{



    private  static int PACKETSIZE = 100 ;

    private static  int WIDTH = 1340;

    private static  int HEIGHT = 613;

    public DatagramSocket socket;

    public DrawPoint drawPoint;



    public Server()  {



        setDefaultCloseOperation(EXIT_ON_CLOSE);

        drawPoint = new DrawPoint();

        drawPoint.setPreferredSize(new Dimension(WIDTH, HEIGHT));

        add(drawPoint);

        pack();

        setVisible(true);

    }



    //This method converts the lat,lon coordinates to the coordinates of the pixels in the image of the map (which is 1319 by 664)



    public String GPStoCoord( double lat,  double lon){



         double latref = 30.631103;

         double lonref = -96.358981;

         double yref = 0.015128;

         double xref = 0.035589;

         int coordx = (int)((latref - lat)/yref*1319);

         int coordy = (int)((lon - lonref)/xref*664);



        return coordx + "," +coordy;

    }



    private void GPSlocdraw() {

        try {

             DatagramPacket packet_GPS1 = new DatagramPacket(new byte[PACKETSIZE], PACKETSIZE);

            socket.receive(packet_GPS1);

             String sGPS1 = new String(packet_GPS1.getData());

             String latlonGPS1 = sGPS1.split(",", 2);

             double lat1 = Double.parseDouble(latlonGPS1[0]);

             double lon1 = Double.parseDouble(latlonGPS1[1]);



            //converting the GPS data to coordinates

             String coord = GPStoCoord(lat1,lon1);

             String latlon = coord.split(",");

             int lat = Integer.parseInt(latlon[0]);

             int lon = Integer.parseInt(latlon[1]);



            drawPoint.setCoordx(lat);

            drawPoint.setCoordy(lon);

            drawPoint.repaint();

        } catch( IOException e){}

    }



    public static void main(  String args ) {



        SwingUtilities.invokeLater(() ->    new Server().GPSlocdraw());

    }

}

Here is the code to the DRawPoint class, where I am trying to draw the image loaded and draw the oval graphic on top of it by it seems that whichever is drawn last erases the other.

import java.awt.Color;

import java.awt.Graphics;

import java.awt.image.BufferedImage;

import java.io.File;

import java.io.IOException;

import javax.imageio.ImageIO;

import javax.swing.JPanel;



public class DrawPoint extends JPanel {

    private int coordx, coordy;



    @Override

    public void paintComponent( Graphics g){

        try {

            BufferedImage map = ImageIO.read(new File("CSmap.png"));



            super.paintComponent(g);

            g.setColor(Color.BLACK);

            g.fillOval(coordx,coordy,8,8);

            g.drawImage(map,0,0,this);



        } catch(IOException e){}

    }



    //use setters to change the state

    void setCoordy( int coordy) {this.coordy = coordy;}

    void setCoordx( int coordx) {this.coordx = coordx;}

}

Also, how can I draw something to permanently stay on the image for the entire run?

The following code demonstrates repeatedly drawing a point in different location on an underlying image.

It can be copy pasted into one file (Server.java) and executed:

import java.awt.Color;

import java.awt.Dimension;

import java.awt.Graphics;

import java.awt.Image;

import java.io.IOException;

import java.net.URL;

import java.util.Random;

import javax.imageio.ImageIO;

import javax.swing.JFrame;

import javax.swing.JPanel;

import javax.swing.SwingUtilities;

import javax.swing.Timer;



public class Server extends JFrame{



    private DrawPoint drawPoint;



    public Server()  {



        setDefaultCloseOperation(EXIT_ON_CLOSE);

        drawPoint = new DrawPoint();

        add(drawPoint);

        pack();

        setVisible(true);

    }



    //This conversion is not essential for the question asked. remove to make it Mcve

    //public String GPStoCoord(  double lat,   double lon){}



    private void GPSlocdraw() {

        //generate random x,y within an arbitrary range

         Random rnd = new Random();    int maxY = 350, maxX = 250;

         Timer timer = new Timer(1000, e -> { //periodically change coordinates and repaint

            drawPoint.setCoordx(rnd.nextInt(maxX));

            drawPoint.setCoordy(rnd.nextInt(maxY));

            drawPoint.repaint();

        });

        timer.start();

    }



    public static void main(     String args ) {

        SwingUtilities.invokeLater(() ->    new Server().GPSlocdraw());

    }

}



class DrawPoint extends JPanel {



    private int coordx, coordy, width, height;

    private Image map;



    public DrawPoint() {

        try {

            //to make an mcVe always use publicly available resources

            map = ImageIO.read(new URL("http://www.digitalphotoartistry.com/rose1.jpg"));

            height = map.getHeight(this);

            width = map.getWidth(this);

            setPreferredSize(new Dimension(width, height)); //fit panel to image

        } catch ( IOException ex) {ex.printStackTrace();    }

    }



    @Override

    public void paintComponent(Graphics g){

        //read from file once, not every method run BufferedImage map = ImageIO.read(new File("CSmap.png"));

        super.paintComponent(g);

        g.setColor(Color.YELLOW);

        g.drawImage(map,0,0,this);//image first 

        g.fillOval(coordx,coordy,8,8); //point on top 

    }



    //use setters to change the state

    void setCoordy( int coordy) {this.coordy = coordy;}

    void setCoordx( int coordx) {this.coordx = coordx;}

}

As for "how can I draw something to permanently stay on the image for the entire run?" : to get an idea do not change ovals x and y coordinates, and see what happens.