如何将包含JPanel的JScrollPane视口滚动到特定位置

Question

我正在尝试创建一个大型游戏板,只有部分游戏板在视口中可见,并且希望能够使用箭头键移动视口以查看整个板.现在我有一个JScrollPane包含一个JPanel,它将包含图像和文本以及其他内容,但这些都是无关紧要的.现在我有一个与JPanel相同大小的ImageIcon作为背景,我希望有一个选项,可以通过使用键移动视口,而不是有任何可见的滚动条.我试过在JPanel和JScrollPane上调用getViewPort().setViewPosition(),然后调用revalidate().但它仍然无效.我的代码如下

import javax.swing.ImageIcon;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;

import java.awt.*;
import java.awt.event.*;


public class Game extends JPanel {

    JPanel game = new JPanel();
    JScrollPane scrollPane = new JScrollPane(game);
    JLabel grass = new JLabel();

    private KeyListener keys = new KeyListener() {
        public void keyTyped(KeyEvent e) {

        }
        public void keyReleased(KeyEvent e) {
            if (e.getKeyCode() == KeyEvent.VK_DOWN) {
                System.out.println("Down");
                scrollPane.getViewport()

            } else if (e.getKeyCode() == KeyEvent.VK_UP) {
                System.out.println("up");
            }
            revalidate();
        }
        public void keyPressed(KeyEvent e) {

        }
    };

public void createGame(int turns) {

        int gameWidth = 1800;
        int gameHeight = 1600;

        int viewPortWidth = 800;
        int viewPortHeight = 600;

        //setLayout(null);
        setSize(new Dimension(viewPortWidth, viewPortHeight));

        game.setLayout(null);
        game.setSize(new Dimension(gameWidth, gameHeight));

        //add the background image
        ImageIcon background = new ImageIcon("Grass.png");
        grass.setIcon(background);
        grass.setBounds(0,0, gameWidth, gameHeight);
        game.setBackground(Color.GREEN);
        game.add(grass);
        game.setBounds(0,0, gameWidth, gameHeight);

        //key listener
        game.addKeyListener(keys);

        //add(game);
        scrollPane.setPreferredSize(new Dimension(viewPortWidth, viewPortHeight));

        add(scrollPane);

    }


}

Answer 1

这里和这里有一个例子.您应该能够根据您的使用情况进行调整.scrollRectToVisible()

顺便说一句,可以考虑使用键绑定,显示在这里,这里和这里.