java - Java Swing 中的 MouseMotionListener，将其与组件内的组件一起使用等

Question

我正在 Swing 中开发触摸用户界面。虽然我知道这不是最佳选择，但我的截止日期很短，没有时间触摸屏特定的 GUI 包(如果有的话)。

我希望我的用户能够在屏幕上“滑动”手指，并且我可以用它来移动特殊的 JScrollPane View 。代码很简单 -

    public class PanScrollPane extends JScrollPane implements MouseMotionListener{  
public PanScrollPane() {
    super();        
    this.addMouseMotionListener(this);      
}
@Override
public void mouseDragged(MouseEvent arg0) {
    System.out.println("Mouse Dragged!");       
}
@Override
public void mouseMoved(MouseEvent arg0) {
    System.out.println("Mouse Moved!");     
}

我遇到的问题是 JScrollPane 是各种 JComponent 的容器。当我第一次开始研究这个问题时，我认为 MouseMovedEvent 和 MouseDraggedEvent 会沿着“GUI 树”向上传播，直到它们遇到带有专门针对该事件的监听器的组件。现在看来，我添加到 panScrollPane 的任何组件都会阻止任何这些 MouseMotion 事件，使我无法平移。

    panScrollPane.add(new JButton("This thing blocks any mouse motion events"));

我认为手动传播 MouseEvent(向每个组件添加监听器，然后让它们将事件发送给其父组件)是可行的。然而，这是一项非常耗时的工作，因为我宁愿把时间花在其他事情上，我想知道你们中是否有人知道解决这个问题的方法。

感谢您的阅读，并希望感谢您的回答! :)

编辑:为了让我的意图更清楚。我只希望 panPanel 捕获 mousemotion 事件，任何其他事件(如 MouseClick、MouseRelease)都应该正常处理

Answer 1

这种临时方法利用了现有的 JScrollPane key bindings 中通常使用的操作。您必须根据 Scrollable 的实现调整 N .

import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.Action;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JViewport;
import javax.swing.Timer;

/** @see http://stackoverflow.com/questions/7201509 */
public class ScrollAction extends JPanel {

    private static final int TILE = 64;
    private static final int DELTA = 16;

    public ScrollAction() {
        this.setOpaque(false);
        this.setFocusable(true);
        this.setPreferredSize(new Dimension(50 * TILE, 50 * TILE));
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.setColor(Color.lightGray);
        int w = this.getWidth() / TILE + 1;
        int h = this.getHeight() / TILE + 1;
        for (int row = 0; row < h; row++) {
            for (int col = 0; col < w; col++) {
                if ((row + col) % 2 == 0) {
                    g.fillRect(col * TILE, row * TILE, TILE, TILE);
                }
            }
        }
    }

    private void display() {
        JFrame f = new JFrame("ScrollAction");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        final JScrollPane scrollPane = new JScrollPane(this);
        final ScrollTimer left = new ScrollTimer(scrollPane, "scrollLeft");
        final ScrollTimer right = new ScrollTimer(scrollPane, "scrollRight");
        final ScrollTimer up = new ScrollTimer(scrollPane, "scrollUp");
        final ScrollTimer down = new ScrollTimer(scrollPane, "scrollDown");
        final JViewport viewPort = scrollPane.getViewport();
        viewPort.setPreferredSize(new Dimension(5 * TILE, 5 * TILE));
        viewPort.addMouseMotionListener(new MouseAdapter() {

            @Override
            public void mouseMoved(MouseEvent e) {
                left.stop();
                if (e.getX() < DELTA) {
                    left.start();
                }
                right.stop();
                if (e.getX() > viewPort.getWidth() - DELTA) {
                    right.start();
                }
                up.stop();
                if (e.getY() < DELTA) {
                    up.start();
                }
                down.stop();
                if (e.getY() > viewPort.getHeight() - DELTA) {
                    down.start();
                }
            }
        });
        f.add(scrollPane);
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    private static final class ScrollTimer implements ActionListener {

        private static int N = 10;
        private static int DELAY = 100;
        private String cmd;
        private Timer timer;
        private Action action;
        private JScrollPane scrollPane;
        private int count;

        public ScrollTimer(JScrollPane scrollPane, String action) {
            this.cmd = action;
            this.timer = new Timer(DELAY, this);
            this.action = scrollPane.getActionMap().get(action);
            this.scrollPane = scrollPane;
        }

        @Override
        public void actionPerformed(ActionEvent e) {
            if (count++ < N) {
                action.actionPerformed(new ActionEvent(scrollPane, 0, cmd));
            } else {
                timer.stop();
            }
        }

        public void start() {
            count = 0;
            timer.start();
        }

        public void stop() {
            timer.stop();
            count = 0;
        }
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                new ScrollAction().display();
            }
        });
    }
}