Question

我有一个没有装饰的JFrame（没有标题栏，关闭按钮等），我可以使用setLocation（）和鼠标位置在屏幕上拖动。

不幸的是，在第一次移动窗口时调用mouseExited事件......

将鼠标移动到窗口并触发mouseEntered事件
点击鼠标并触发mousePressed事件。
拖动鼠标和mouseDragged事件，并调用setLocation。
即使鼠标仍在窗口中，也会触发mouseExited事件！
此时将鼠标移出窗口不会触发mouseExited。
将鼠标移出并重新进入将重置回第1步。

除了在屏幕上手动测试鼠标位置外，我该如何解决这个问题？

编辑：这是代码的提炼版本

import java.awt.*;
import javax.swing.*;
import java.awt.Event;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;

import javax.swing.JComponent;
import javax.swing.JFrame;

class DragNDropper implements MouseMotionListener, MouseListener
{
    private int x, y;
    private int dx, dy;

    private boolean clicked;

    private JFrame frame;

    public DragNDropper(JFrame frame)
    {
    dx = dy = 0;
    this.frame = frame;
    }

    public void mouseDragged(MouseEvent e)
    {
    x = e.getXOnScreen();
    y = e.getYOnScreen();

    frame.setLocation(x-dx, y-dy);
    }

    public void mouseMoved(MouseEvent e)
    {
    x = e.getXOnScreen();
    y = e.getYOnScreen();
    }

    public void mouseClicked(MouseEvent e)
    {

    }

    public void mousePressed(MouseEvent e)
    {
    clicked = true;
    dx = e.getX();
    dy = e.getY();
    }

    public void mouseReleased(MouseEvent e)
    {
    clicked = false;
    }

    public void mouseEntered(MouseEvent e)
    {
    System.out.println("Mouse entered");
    }


    public void mouseExited(MouseEvent e)
    {
    System.out.println("Mouse exited");
    }
}


public class Program
{
public static void main(String[] argv)
{
JFrame jf = new JFrame();
DragNDropper dnd = new DragNDropper(jf);

jf.setSize(new Dimension(512, 512));
jf.addMouseListener(dnd);
jf.addMouseMotionListener(dnd);

jf.show();
}
}

Answer 1

使用此代码，一切正常。请停止使用frame.show()，您可以从中了解用于显示JFrame的信息，然后使用frame.setVisible(true)。请解释一下这个问题。请看一下这段代码的修改：

import java.awt.*;
import java.awt.Event;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import javax.swing.*;

public class DragNDropper implements MouseMotionListener, MouseListener {

    private int x, y;
    private int dx, dy; 
    private boolean clicked;    
    private JFrame jf;

    public static void main(String[] argv) {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                new DragNDropper().displayGUI();
            }
        });
    }

    private void displayGUI() {
        dx = dy = 0;
        jf = new JFrame();
        jf.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        jf.setUndecorated(true);

        jf.setSize(new Dimension(512, 512));
        jf.addMouseListener(this);
        jf.addMouseMotionListener(this);

        jf.setVisible(true);
    }

    public void mouseDragged(MouseEvent e) {
        x = e.getXOnScreen();
        y = e.getYOnScreen();
        jf.setLocation(x-dx, y-dy);
    }

    public void mouseMoved(MouseEvent e) {
        x = e.getXOnScreen();
        y = e.getYOnScreen();
    }

    public void mouseClicked(MouseEvent e) {
    }

    public void mousePressed(MouseEvent e) {
        clicked = true;
        dx = e.getX();
        dy = e.getY();
    }

    public void mouseReleased(MouseEvent e) {
        clicked = false;
    }

    public void mouseEntered(MouseEvent e) {
        System.out.println("Mouse entered");
    }

    public void mouseExited(MouseEvent e) {
        System.out.println("Mouse exited");
    }
}

调用frame.setLocation（）时会触发Java mouseExited事件

1 个答案: