Java小程序不会移动图像

Question

我正在尝试用 Java 制作一种 Space Invaders 游戏，首先是让 PNG 宇宙飞船在屏幕上移动。它出现在它应该去的地方，只是它拒绝移动。该程序编译得很好，eclipse没有给我任何错误/警告。谁能告诉我我做错了什么？

这是我的代码：

import java.awt.*;
import java.net.*;
import java.awt.geom.*;
import java.applet.*;
import java.awt.event.*;

public class DrawImage extends Applet implements KeyListener{
    private static final long serialVersionUID = 1L;
    private Image image;
    private int keycode;
    AffineTransform identity = new AffineTransform();
    private boolean keyleft = false;
    private boolean keyright = false;
    private URL getURL(String filename){
        URL url = null;
        try
        {
            url = this.getClass().getResource(filename);
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
        return url;
    }
    public void init()
    {
        image = getImage(getURL("spaceship.png"));
        addKeyListener(this);
    }

    public void paint(Graphics g)
    {
        Graphics2D g2d = (Graphics2D)g;
        //fill background with black
        AffineTransform trans = new AffineTransform();
        g2d.setColor(Color.GREEN);
        g2d.fillRect(0,0,getSize().width,getSize().height);
        g2d.drawImage(image,320,240,this);
        trans.setTransform(identity);
        if(keyright == true)
        {
            trans.translate(-10,0);
            keyleft = false;
        }
        else if(keyleft == true)
        {
            trans.translate(10,0);
            keyright = false;
        }
    }
    public void keyPressed(KeyEvent e)
    {
        keycode = e.getKeyCode();
        if(keycode == KeyEvent.VK_LEFT)
        {
            keyleft = true;
        }
        else if(keycode == KeyEvent.VK_RIGHT)
        {
            keyright = true;
        }
        repaint();
    }
    public void keyTyped(KeyEvent e){}
    public void keyReleased(KeyEvent e){}

}

Answer 1

您应该在您的paint() 方法中将转换设置为您的g2d：

g2d.setTransform(trans);

那么整个方法就是：

  public void paint(Graphics g)
    {
        Graphics2D g2d = (Graphics2D)g;
        //fill background with black
        AffineTransform trans = new AffineTransform();
        g2d.setColor(Color.GREEN);
        g2d.fillRect(0,0,getSize().width,getSize().height);
        trans.setTransform(identity);
        if(keyright == true)
        {
            trans.translate(-10,0);
            keyleft = false;
        }
        else if(keyleft == true)
        {
            trans.translate(10,0);
            keyright = false;
        }
        g2d.setTransform(trans);
        g2d.drawImage(image,320,240,this);
    }