MouseDragged & MouseMoving 在 Java Applet 中不起作用

Question

我目前正在制作一款游戏的地图生成程序，所以我试图用鼠标修改地图上的各个贴图。我已经成功地实现了点击贴图并改变其值的能力(从4向贴图到2向贴图)，但是我在使用mousedrag时遇到了麻烦。根据Java文档，我已经将mousedrag接口正确地实现到我的MouseEventHandler中，但是当我拖动鼠标并移动鼠标时，这两个事件都不会触发并抛出我现在让它们抛出的println文本。如果有人能告诉我为什么这对我不起作用，我很乐意。谢谢!

一个侧面问题:如果有人有任何更好的方法来尝试生成这样的地图，或者任何(可能比我所做的更好)检测单个鼠标按在瓷砖上的其他方法，我很乐意听到它。这是我第一次处理这种事情，所以我很没有经验，希望你能给我一些建议。

对于代码本身:

文件1:OneQuestMapgen.java

package OneQuestMapgen;
import java.awt.Graphics;
import java.util.ArrayList;
import javax.swing.*;
import tiles.Tile;
import tiles.TileSet;
public class OneQuestMapgen extends JApplet{
    /**
     * 
     */
    public static OneQuestMapgen instance;
    ArrayList<ArrayList<Tile>> map = new ArrayList<ArrayList<Tile>>();
    TileSet tileSet = new TileSet();
    public void init(){
        this.setSize(950,600);
    }
    public void start(){
        this.addMouseListener(new MouseEventListener(this));
        int tileSize = tileSet.get("grasslands")[1].getHeight();
        for (int i = 0; i < getHeight(); i += tileSize) {
            ArrayList<Tile> temp = new ArrayList<Tile>();
            for (int j = 0; j < getWidth(); j += tileSize) {
                temp.add(new Tile(j, i, tileSize, tileSet.get("grasslands")));
            }
            map.add(temp);
        }
    }
    public void paint(Graphics g){
        for (int i = 0; i < map.size(); i++){
            for(int j = 0; j < map.get(i).size(); j++){
                map.get(i).get(j).render(g);
            }               
        }
    }
    public void stop(){
    }
    public void destroy(){
    }
    public ArrayList<ArrayList<Tile>> getMap(){
        return map;
    }
}

文件2:MouseEventListener.java

package OneQuestMapgen;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.util.ArrayList;
import tiles.Tile;
public class MouseEventListener implements MouseListener, MouseMotionListener {
    OneQuestMapgen instance;
    ArrayList<ArrayList<Tile>> map;
    public MouseEventListener(OneQuestMapgen instance) {
        this.instance = instance;
    }
    @Override
    public void mouseClicked(MouseEvent e) {
        System.out.println(e.getX() + " , " + e.getY());
        map = instance.getMap();
        for (int i = 0; i < map.size(); i++) {
            for (int j = 0; j < map.get(i).size(); j++)
                if (map.get(i).get(j).bounds(e)) {
                    map.get(i).get(j).onClicked(instance.getGraphics());
                }
        }   
    }
    @Override
    public void mouseEntered(MouseEvent e) {
        // TODO Auto-generated method stub
    }
    @Override
    public void mouseExited(MouseEvent e) {
        // TODO Auto-generated method stub
    }
    @Override
    public void mousePressed(MouseEvent e) {
        // TODO Auto-generated method stub
    }
    @Override
    public void mouseReleased(MouseEvent e) {
        // TODO Auto-generated method stub
    }
    @Override
    public void mouseDragged(MouseEvent arg0) {
        System.out.println("Mouse Dragged: " + arg0.getX() + " , " + arg0.getY());          
    }
    @Override
    public void mouseMoved(MouseEvent arg0) {
        // TODO Auto-generated method stub
        System.out.println("Mouse Moved: " + arg0.getX() + " , " + arg0.getY());
    }
}

文件3:Tile.java

package tiles;
import java.awt.Graphics;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
@SuppressWarnings("serial")
public class Tile extends Square {
    BufferedImage[] tiles;
    int tileValue = 0;
    public Tile (int x, int y, int size, BufferedImage[] tileSet){
        super(x,y,size);
        tiles = tileSet;
    }
    public void render(Graphics g) {
        g.drawImage(tiles[tileValue], getX(), getY(), getDimension(), getDimension(), null);        
    }
    public void onClicked(Graphics g) {
        tileValue++;
        System.out.println(tileValue);
        g.drawImage(tiles[tileValue], getX(), getY(), getDimension(), getDimension(), null);
    }
    public boolean bounds(MouseEvent e){
        if (e.getX() <= getX() + getDimension()  && e.getX() >= getX() && e.getY() <= getY() + getDimension() && e.getY() >= getY())
            return true;
        return false;
    }
}

文件4:TileSet.java

package tiles;
import java.awt.image.BufferedImage;
import java.net.URL;
import java.util.concurrent.ConcurrentHashMap;
import javax.imageio.ImageIO;
public final class TileSet {
    ConcurrentHashMap<String, BufferedImage[]> container = new ConcurrentHashMap<String, BufferedImage[]>(11);
    BufferedImage[] grasslands = new BufferedImage[11];
    public TileSet(){
        boolean toAdd = true;
        try {   
            grasslands[0] = ImageIO.read(new URL("http://i675.photobucket.com/albums/vv118/va023/OneQuest/GrassBlank_zpse99de845.png"));
            grasslands[1] = ImageIO.read(new URL("http://i675.photobucket.com/albums/vv118/va023/OneQuest/4WayTile_zps49ebbeea.png"));
            grasslands[2] = ImageIO.read(new URL("http://i675.photobucket.com/albums/vv118/va023/OneQuest/LineHorizontal_zpsc7bd45d5.png"));
            grasslands[3] = ImageIO.read(new URL("http://i675.photobucket.com/albums/vv118/va023/OneQuest/LineVertical_zps9719b63f.png"));
            grasslands[4] = ImageIO.read(new URL("http://i675.photobucket.com/albums/vv118/va023/OneQuest/TShapeTop_zpsa4b2aaa1.png"))          
        }
        catch (Exception e) {
            System.out.println("Unable to load resources for Grasslands");
        }
        for (int i = 0; i < grasslands.length; i++)
            if (grasslands[i].getWidth() != grasslands[i].getHeight()) {
                System.out.println("Error, tiles are not square. Grasslands has not been added.");
                toAdd = false;
            }
        if (toAdd) {
            container.put("grasslands".toLowerCase(), grasslands);
        }
    }
    public BufferedImage[] get(String s) {
        return container.get(s.toLowerCase());
    }
}

文件5:Square.java

package tiles;
import javax.swing.JLabel;
public abstract class Square extends JLabel{
    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    private int x;
    private int y;
    private int dimension;
    public Square(int x, int y, int dimension){
        this.x = x;
        this.y = y;
        this.dimension = dimension;
    }
    public int getX(){
        return x;
    }
    public int getY(){
        return y;
    }
    public int getDimension(){
        return dimension;
    }
}

注意:如果你想把它全部从github上拉下来，我在下面为这个项目添加了一个链接到我的github仓库:

的URL: https://github.com/vagrawal1/OneQuestMapgen

HTTPS: https://github.com/vagrawal1/OneQuestMapgen.git

SSH: [e-mail]: vagrawal1/OneQuestMapgen.git

Git只读:Git://github.com/vagrawal1/OneQuestMapgen.git

再次感谢您的帮助，感谢您花时间阅读这篇文章

Answer 1

您需要添加一个MouseMotionListener用于拖动工作。你只是添加了一个MouseListener。

。

public void start() {
  MouseEventListener myMouseEventListener = new MouseEventListener(this);
  addMouseListener(myMouseEventListener);
  addMouseMotionListener(myMouseEventListener);
  //this.addMouseListener(new MouseEventListener(this));

同样根据我的评论，你的getX()和getY()方法的Square类覆盖JLabel的相同的方法，如果你不小心使用这些和正确使用它们，他们可以完全搞乱你的组件在GUI中的位置。就我自己而言，我非常努力地避免重写这些方法。如果重写不是你的本意，可以考虑更改它们的名称。

此外，我倾向于mousePressed(...)而不是mouseClicked(...)方法，因为即使您在按下鼠标后移动鼠标，前者也会对按下做出响应。

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编辑:另一个bug!你几乎不应该通过在组件上调用getGraphics()来获得你的Graphics实例，因为返回的Graphics对象是暂时的，可能很快就会变为null。相反，要么在JComponent或JPanel的paintComponent(...)中显示的buffereimage上绘制，要么直接在paintComponent(...)中绘制。

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编辑2:为什么重写paint(...) ?这对我来说似乎有点危险，特别是因为你没有调用超级方法，特别是因为没有必要做这种事情。