java - 尝试用java创建一个移动的 Sprite ，但有残像

Question

我正在尝试用java创建一个移动的 Sprite ，我已经成功做到了，除了每次移动它时都会有一个跟随 Sprite 的残像。有没有什么方法可以轻松解决这个问题，而无需从根本上更改我的代码？

我完全不知道有什么方法可以解决这个问题。

为了获得完整的上下文，我必须发布所有三个文件。

这是第一个文件:

package gameproject;

import java.awt.Image;
import java.awt.event.KeyEvent;
import javax.swing.ImageIcon;

public class CarMovement {

private int dx;
private int dy;
private int x = 635;
private int y = 550;
private int w;
private int h;
private Image moveimage;

public CarMovement() {

    loadImage();
}

private void loadImage() {

    ImageIcon q = new ImageIcon("racecar.png");
    moveimage = q.getImage(); 

    w = moveimage.getWidth(null);
    h = moveimage.getHeight(null);
}

public void move() {

    x += dx;
    y += dy;
}

public int getX() {

    return x;
}

public int getY() {

    return y;
}

public int getWidth() {

    return w;
}

public int getHeight() {

    return h;
}    

public Image getImage() {

    return moveimage;
}

public void keyPressed(KeyEvent e) {

    int key = e.getKeyCode();

    if (key == KeyEvent.VK_A) {
        dx = -10;
    }

    if (key == KeyEvent.VK_D) {
        dx = 10;
    }

    if (key == KeyEvent.VK_W) {
        dy = -10;
    }

    if (key == KeyEvent.VK_S) {
        dy = 10;
    }
}

public void keyReleased(KeyEvent e) {

    int key = e.getKeyCode();

    if (key == KeyEvent.VK_A) {
        dx = 0;
    }

    if (key == KeyEvent.VK_D) {
        dx = 0;
    }

    if (key == KeyEvent.VK_W) {
        dy = 0;
    }

    if (key == KeyEvent.VK_S) {
        dy = 0;
    }
}
}

第二个:

 package gameproject;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import javax.swing.JPanel;
import javax.swing.Timer;

public class CarMovement2 extends JPanel implements ActionListener {

private Timer timer;
private CarMovement racecar;
private final int DELAY = 10;

public CarMovement2() {

    initBoard();
}

private void initBoard() {

    addKeyListener(new TAdapter());
    setBackground(Color.black);
setFocusable(true);

    racecar = new CarMovement();

    timer = new Timer(DELAY, this);
    timer.start();
}

@Override
public void paintComponent(Graphics g) {
    super.paintComponent(g);
    g.setColor(new Color(0, 204, 0));
    g.fillRect(0, 0, 400, 1100);
    g.fillRect(1525, 0, 400, 1100);
    g.setColor(new Color(102, 102, 102));
    g.fillRect(400, 0, 1125, 1100);
    g.setColor(new Color(255, 255, 255));
    g.fillRect(940, 25, 25, 100);
    g.fillRect(940, 325, 25, 100);
    g.fillRect(940, 475, 25, 100);
    g.fillRect(940, 625, 25, 100);
    g.fillRect(940, 775, 25, 100);
    g.fillRect(940, 925, 25, 100);
    g.setColor(new Color(255, 255, 255));
    g.fillRect(400, 175, 1125, 100);
    g.setColor(new Color(0, 0, 0));
    g.fillRect(400, 225, 50, 50);
    g.fillRect(450, 175, 50, 50);
    g.fillRect(500, 225, 50, 50);
    g.fillRect(550, 175, 50, 50);
    g.fillRect(600, 225, 50, 50);
    g.fillRect(650, 175, 50, 50);
    g.fillRect(700, 225, 50, 50);
    g.fillRect(750, 175, 50, 50);
    g.fillRect(800, 225, 50, 50);
    g.fillRect(850, 175, 50, 50);
    g.fillRect(900, 225, 50, 50);
    g.fillRect(950, 175, 50, 50);
    g.fillRect(1000, 225, 50, 50);
    g.fillRect(1050, 175, 50, 50);
    g.fillRect(1100, 225, 50, 50);
    g.fillRect(1150, 175, 50, 50);
    g.fillRect(1200, 225, 50, 50);
    g.fillRect(1250, 175, 50, 50);
    g.fillRect(1300, 225, 50, 50);
    g.fillRect(1350, 175, 50, 50);
    g.fillRect(1400, 225, 50, 50);
    g.fillRect(1450, 175, 50, 50);
    g.fillRect(1500, 225, 25, 50);
    g.setColor(new Color(255, 255, 255));
    g.fillRect(380, 0, 20, 1100);
    g.fillRect(1525, 0, 20, 1100);
    doDrawing(g);

    Toolkit.getDefaultToolkit().sync();
}

private void doDrawing(Graphics g) {

    Graphics2D g2d = (Graphics2D) g;

    g2d.drawImage(racecar.getImage(), racecar.getX(), 
        racecar.getY(), this);
}

@Override
public void actionPerformed(ActionEvent e) {

    step();
}

private void step() {

    racecar.move();

    repaint(racecar.getX()-1, racecar.getY()-1, 
            racecar.getWidth()+2, racecar.getHeight()+2);
}    

private class TAdapter extends KeyAdapter {

    @Override
    public void keyReleased(KeyEvent e) {
        racecar.keyReleased(e);
    }

    @Override
    public void keyPressed(KeyEvent e) {
        racecar.keyPressed(e);
    }
}
}

第三个:

package gameproject;


import java.awt.EventQueue;
import javax.swing.JFrame;
public final class CarMovement3 extends JFrame {

 public CarMovement3() {

    InitUI();
}

private void InitUI() {

    add(new CarMovement2());

    setTitle("Top Speed Triumph");
    setSize(1900, 1100);
    setResizable(false);

    setLocationRelativeTo(null);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}

public static void main(String[] args) {

    EventQueue.invokeLater(() -> {
        CarMovement3 ex = new CarMovement3();
        ex.setVisible(true);
    });
}


}

以及 Sprite 的链接: http://www.clker.com/clipart-red-sports-car-top-view.html

Answer 1

所以，您的问题源于使用...

repaint(racecar.getX() - 1, racecar.getY() - 1,
        racecar.getWidth() + 2, racecar.getHeight() + 2);

基本上，您没有覆盖足够的“现有”区域来完全“删除”它。

您可以简单地使用 repaint() 来代替，它将解决您的基本问题。在它真正成为问题之前，我会避免担心这种优化级别。

如果您想使用它，那么我会在移动之前拍摄护理位置的快照(即抓取其当前的 x/y 位置)并将其与新位置合并，以便覆盖这两个区域。或者调用 repaint(x, y, width, height) 两次，一次使用旧位置，一次使用新位置

private void step() {
    Rectangle old = new Rectangle(racecar.getX(), racecar.getY(), racecar.getWidth(), racecar.getHeight());

    racecar.move();

    Rectangle now = new Rectangle(racecar.getX(), racecar.getY(), racecar.getWidth(), racecar.getHeight());

    repaint(old);
    repaint(now);
}

此外，您会发现 KeyListener 不可靠，我建议使用 the key bindings API这将解决 KeyListener 遇到的问题

我还建议使用 ImageIO 而不是 ImageIcon 作为加载图像的更可靠方式，请参阅 Reading/Loading an Image了解更多详情