JMapViewer，绘制到 OSM 并避免重复调用 MouseClick 事件

Question

假设 Map3 如下 class:

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.MouseEvent;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import javax.swing.JPanel;
import org.openstreetmap.gui.jmapviewer.Coordinate;
import org.openstreetmap.gui.jmapviewer.DefaultMapController;
import org.openstreetmap.gui.jmapviewer.JMapViewer;
import org.openstreetmap.gui.jmapviewer.MapPolygonImpl;


public class Map3 {

    private JPanel p;
    private JMapViewer map;
    private double lat, lon;

    public Map3() 
    {
            p = new JPanel();
            map = new JMapViewer();
            p.setLayout(new BorderLayout());

            new DefaultMapController(map) {
                @Override
                public void mouseClicked(MouseEvent e) {
                            Point p = e.getPoint();
                            lat = map.getPosition(p).getLat();
                            lon = map.getPosition(p).getLon();
                }
                //Where to locate the method ????
                protected void paintComponent(Graphics g){

                            Coordinate c1= new Coordinate(lat,lon),c2= new Coordinate(lat+10,lon+10);  //Draw the line

                            List<Coordinate> route = new ArrayList<Coordinate>(Arrays.asList(c1, c2, c1));
                            map.addMapPolygon(new MapPolygonImpl(route));
                        }   
            };

            p.add(map);
            p.setVisible(true);
    }


  public JPanel getJPanel() {return p;}
}

避免鼠标监听器重复调用，见题

class 不是直接派生自 JMapViewer。使用鼠标单击我得到两个坐标 [lat, lon] 将用于绘制由 P1, P2 给出的线，其中 P1=[lat, lon], P2=[lat+10, lon+10].

我不确定应该将 paintComponent() 方法放在哪里才能将一些绘图添加到 OSM 地图。

public class TEST
{
    public static void main (String [] args)
    {
            JFrame jf = new JFrame();
            jf.setSize(800, 600);
            Map3 p = new Map3();
            jf.add(p.getJPanel()); 
            jf.setVisible(true);
    }
}

当前版本运行不正常，没有调用paintComponent()...

感谢您的帮助。

Answer 1

p.add(map);

您正在将 "map" 添加到面板。因此你需要覆盖 JMapViewwer class.

的 paintComponent() 方法

无论何时重写 class 的方法，您都应该使用：

@Override
protected void paintComponent(Graphics g)
...

那么如果你不正确地覆盖了一个方法，你将得到一个编译错误。

但是，在您的情况下，您甚至不应该覆盖 paintComponent() 方法。该方法仅用于绘画。它不是用于添加新的多边形对象。也许代码应该在 mousePressed() 逻辑中？

Answer 2

已找到以下解决方案：

import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.MouseEvent;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import javax.swing.JFrame;
import org.openstreetmap.gui.jmapviewer.Coordinate;
import org.openstreetmap.gui.jmapviewer.DefaultMapController;
import org.openstreetmap.gui.jmapviewer.JMapViewer;
import org.openstreetmap.gui.jmapviewer.MapPolygonImpl;

public class Map3 extends JMapViewer{
private double lat, lon;

public Map3() 
{
   new DefaultMapController(this) {
        public void mouseClicked(MouseEvent e) {
            System.out.println(e.getPoint());
            Point  p = e.getPoint();
            lat = map.getPosition(p).getLat();
            lon = map.getPosition(p).getLon();
        }};
  }

protected void paintComponent(Graphics g){
    super.paintComponent(g);
    Coordinate c1= new Coordinate(lat,lon),c2= new Coordinate(lat+10,lon+10);
    List<Coordinate> route = new ArrayList<Coordinate>(Arrays.asList(c1, c2, c1));
    this.addMapPolygon(new MapPolygonImpl(route));
}   

public static void main (String [] args){
            JFrame jf = new JFrame();
            jf.setSize(800, 600);
            Map3 m= new Map3();
            jf.add(m);
            jf.setVisible(true);
    }
}

主要思路是替换

 addMouseListener(new DefaultMapController(this) {
        public void mouseClicked(MouseEvent e){
            System.out.println(e.getPoint());
            Point  p = e.getPoint();
            lat = map.getPosition(p).getLat();
            lon = map.getPosition(p).getLon();
        });

具有以下结构

new DefaultMapController(this) {
        public void mouseClicked(MouseEvent e) {
            System.out.println(e.getPoint());
            Point  p = e.getPoint();
            lat = map.getPosition(p).getLat();
            lon = map.getPosition(p).getLon();
        }};

在这种情况下，Map3 可能派生自 JMapViewer。希望对您有所帮助:-)

JMapViewer，绘制到 OSM 并避免重复调用 MouseClick 事件

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