Question

我有以下代码在屏幕上产生两个单独的.png。这些.pngs是用鼠标移动的，一切都运行良好，除了当它们被拖动时，它们似乎在某种类型的图层下，并且在拖动超过一英寸时消失。任何建议都很受欢迎。

 import java.awt.*;
import javax.swing.*;
import java.awt.event.MouseEvent;
import java.awt.event.MouseAdapter;

public class TestMouseDrag {

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

public TestMouseDrag() {
    EventQueue.invokeLater(new Runnable() {
        @Override
        public void run() {


            JFrame frame = new JFrame();
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.setLayout(new FlowLayout());
            frame.add(new DragMyIcon("C:\\Users\\anon\\Desktop\\Hobbit.png"));
            frame.add(new DragMyIcon("C:\\Users\\anon\\Desktop\\alien.png"));

            frame.setSize(800,800);

            frame.setVisible(true);
        }
    });
}

public class DragMyIcon extends JPanel {

    public static final long serialVersionUID = 172L;
    private JLabel label;

    public DragMyIcon(String path) {


        ImageIcon icon = null;

        icon = new ImageIcon(path);

        label = new JLabel(icon);



        add(label);

        MouseHandler handler = new MouseHandler();
        label.addMouseListener(handler);
        label.addMouseMotionListener(handler);

    }

}

protected class MouseHandler extends MouseAdapter {

    private boolean active = false;
    private int xDisp;
    private int yDisp;

    @Override
    public void mousePressed(MouseEvent e) {
        active = true;
        JLabel label = (JLabel) e.getComponent();

        xDisp = e.getPoint().x - label.getLocation().x;
        yDisp = e.getPoint().y - label.getLocation().y;

        label.setCursor(Cursor.getPredefinedCursor(Cursor.MOVE_CURSOR));
    }

    @Override
    public void mouseReleased(MouseEvent e) {
        active = false;
        JLabel label = (JLabel) e.getComponent();
        label.setCursor(Cursor.getPredefinedCursor(Cursor.DEFAULT_CURSOR));
    }

    @Override
    public void mouseDragged(MouseEvent e) {
        if (active) {
            JLabel label = (JLabel) e.getComponent();
            Point point = e.getPoint();
            label.setLocation(point.x - xDisp, point.y - yDisp);
            label.invalidate();
            label.repaint();

        }
    }

    @Override
    public void mouseMoved(MouseEvent e) {
    }
}}

Answer 1

只需@Override getPreferredSize JPanel，只需pack()您的框架，而不是设置尺寸，而且效果正常。

   frame.pack();
   ...

   public class DragMyIcon extends JPanel {
       ...
       @Override
       public Dimension getPreferredSize() {
           return new Dimension(400, 600);
       }
   }

关于这一点的事情记住，这些是两个单独的面板（因为您创建了两个单独的DragMyIcon实例），因此您只能将标签移动到包含面板的范围。如果您希望能够在屏幕上移动它们，则需要将它们添加到同一个面板中。

java - FLowLayout（）中的两个图像在移动时会消失

1 个答案: