JFrame Glasspane 也在 JDialog 之上，但不应该

Question

我有一个带有 Glasspane 的 JFrame（未装饰）。 此框架打开一个 JDialog（也未装饰，也有一个 glassPane）并隐藏自身（setVisible(false)）。 Glasspanes 使用 .setGlassPane() 设置。 对话框以 Frame 作为所有者打开。

GlassPane 扩展了 JPanel 并实现了 AWTEventListener。 我用它来调整框架和对话框的大小，所以它知道它是父级（框架/对话框）——这被称为“目标”。

GlassPane 中的事件是这样处理的：

public void eventDispatched(AWTEvent event) {

  if (target instanceof JFrame) {
     e = SwingUtilities.convertMouseEvent(
     ((MouseEvent) event).getComponent(),
     (MouseEvent) event, ((JFrame) target).getGlassPane());
  } else if (target instanceof JDialog) {
     e = SwingUtilities.convertMouseEvent(
     ((MouseEvent) event).getComponent(),
     (MouseEvent) event, this);
  }


  if (e.getID() == MouseEvent.MOUSE_PRESSED) {
    this.startPos = target.getLocationOnScreen();
  }
}

在“target.getLocationOnScree”处，当 JFrame 被隐藏并单击 JDialog 时，我得到一个 IllegalComponentStateException。它说“组件必须显示在屏幕上才能确定其位置”。这是因为 JFrame 的 GlassPane 获取了事件。但是 JDialog 的 Glasspane 应该得到它。我认为，JFrame 的 Glasspane 在 JDialog 前面。但为什么呢？

感谢您的帮助！

编辑：

这是一个例子：

import java.awt.AWTEvent;
import java.awt.Frame;
import java.awt.Toolkit;
import java.awt.event.AWTEventListener;

import javax.swing.JDialog;
import javax.swing.JFrame;



public class Main {




    static JFrame frame;
static JDialog dialog;


public static void main(String[] args) {

    frame = new JFrame();
     frame.setSize(600,600);
    GlassPane frameGlas = new GlassPane(frame);
    frame.setGlassPane(frameGlas);
    frame.setVisible(true);

    frameGlas.setVisible(true);
    dialog = new JDialog(frame);

    dialog.setSize(100, 100);
    GlassPane dialogGlas = new GlassPane(dialog);

    dialog.setGlassPane(dialogGlas);
    AWTEventListener al = (AWTEventListener) frameGlas;
    Toolkit.getDefaultToolkit().addAWTEventListener(
            al,
            AWTEvent.MOUSE_MOTION_EVENT_MASK
                    | AWTEvent.MOUSE_EVENT_MASK);
    dialogGlas.setVisible(true);
    dialog.setVisible(true);
}


}


import java.awt.AWTEvent;
import java.awt.Point;
import java.awt.Window;
import java.awt.event.AWTEventListener;
import java.awt.event.MouseEvent;

import javax.swing.JDialog;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class GlassPane extends JPanel implements AWTEventListener {

    /**
     * 
     */
    private static final long serialVersionUID = 5110857185182004819L;

    private final Window target;


    public GlassPane(Window target) {
        super(null);
        this.target = target;

    }



    public void eventDispatched(AWTEvent event) {
        if (event instanceof MouseEvent) {

            MouseEvent originalEvent = (MouseEvent) event;

            MouseEvent e = originalEvent;
        if (target instanceof JDialog) {
                e = SwingUtilities.convertMouseEvent(
                        ((MouseEvent) event).getComponent(),
                        (MouseEvent) event, this);
            }


            if (e.getID() == MouseEvent.MOUSE_PRESSED) {

                Point p  = target.getLocationOnScreen();
                System.out.println(p.getX());
            }
        }

        }



}

Answer 1

查看您的源代码，您只需要将frame 的玻璃窗格注册到AWTListener。现在，从表面上看，这似乎不是一件坏事。 AWTListener 将被通知系统中的所有鼠标事件，但实际接收事件的GlassPane 实例只会知道frame...

基本上，这意味着dialogGlas 永远不会收到任何事件，因为它没有注册。

首先，您需要将frameGlas 和dialogGlas 都注册为侦听器。

其次，您不应该试图“猜测”目标。 MouseEvent（实际上所有事件）都有来源。您应该将源代码与target 进行比较，以便仅当事件发生在您感兴趣的组件上时才能对事件做出反应...

import java.awt.AWTEvent;
import java.awt.Component;
import java.awt.EventQueue;
import java.awt.Point;
import java.awt.Toolkit;
import java.awt.Window;
import java.awt.event.AWTEventListener;
import java.awt.event.MouseEvent;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Main {

    static JFrame frame;
    static JDialog dialog;

    public static void main(String[] args) {
        new Main();
    }

    public Main() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }


                frame = new JFrame();
                frame.setSize(600, 600);
                GlassPane frameGlas = new GlassPane(frame);
                frame.setGlassPane(frameGlas);
                frame.setVisible(true);

                frameGlas.setVisible(true);
                dialog = new JDialog(frame);

                dialog.setSize(100, 100);
                GlassPane dialogGlas = new GlassPane(dialog);
                dialog.setGlassPane(dialogGlas);
                dialogGlas.setVisible(true);
                dialog.setVisible(true);

                // Register a listener for the frameGlas
                Toolkit.getDefaultToolkit().addAWTEventListener(
                        frameGlas,
                        AWTEvent.MOUSE_MOTION_EVENT_MASK
                        | AWTEvent.MOUSE_EVENT_MASK);
                // Register a listener for the dialogGlas
                Toolkit.getDefaultToolkit().addAWTEventListener(
                        dialogGlas,
                        AWTEvent.MOUSE_MOTION_EVENT_MASK
                        | AWTEvent.MOUSE_EVENT_MASK);
            }
        });
    }

    public class GlassPane extends JPanel implements AWTEventListener {

        private static final long serialVersionUID = 5110857185182004819L;
        private final Window target;

        public GlassPane(Window target) {
            super(null);
            this.target = target;

        }

        @Override
        public void eventDispatched(AWTEvent event) {
            if (event instanceof MouseEvent) {

                MouseEvent originalEvent = (MouseEvent) event;

                MouseEvent e = originalEvent;
                Component source = e.getComponent();
                System.out.println("Source: " + source);
                System.out.println("Target: " + target);
                if (target != null && target.equals(source)) {
                    e = SwingUtilities.convertMouseEvent(
                            ((MouseEvent) event).getComponent(),
                            (MouseEvent) event, this);

                    if (e.getID() == MouseEvent.MOUSE_PRESSED) {

                        Point p = target.getLocationOnScreen();
                        System.out.println(p.getX());
                    }
                }
            }
        }
    }
}

现在，在我的脑海中，MouseListener 遇到的问题是它们是贪婪的，它们阻止事件级联超出它们注册的组件。