Java Swing中的MouseMotionListener,将其与组件内部的组件一起使用

Question

我正在使用Swing中的Touch User界面.虽然我知道这不是最佳的,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"他们的手指,并且我制作的特殊JScrollPane的视图随之移动.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JComponents的容器.当我第一次开始研究这个时,我发现MouseMovedEvent和MouseDraggedEvent会向上传播'GUI树',直到他们遇到一个带有专门针对该事件的侦听器的Component.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,让我无法平移.

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

我想用手传播MouseEvent(将侦听器添加到每个组件然后让它们将事件发送给它们的父组件)都可以.然而,这是一个非常耗时的事业,我宁愿把时间花在其他东西的工作,我想知道如果任何人都知道任何变通针对此问题.

感谢您的阅读,并希望感谢您的回答!:)

编辑:让我的意图更清晰.我只希望panPanel捕获mousemotion事件,任何其他事件(如MouseClick,MouseRelease)应该正常处理

Answer 1

此临时方法利用了JScrollPane通常在键绑定中使用的现有操作.你必须调整N你的实现Scrollable.

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();
            }
        });
    }
}