java - 让 JPanel 只需单击鼠标即可跟随光标

Question

这就是我想要做的，我想让一个面板在单击它后跟随光标，我最初的想法是通过拖放操作来完成它，但问题是必须按下 clic 才能让面板被拖动，我希望只需单击面板即可拖动面板，而无需按住 clic。有任何想法吗？谢谢大家:)

public class Main {
  public static void main(String[] argv) throws Exception {

    JComponent panDrag = new DraggableComponent();
    Icon newi = new ImageIcon("src/red.png");
    JLabel labelImage = new JLabel(newi);
    panDrag.add(labelImage);


    JPanel panneau = new JPanel();
    panneau.add(panDrag);

    JFrame f = new JFrame();
    f.add(panneau);
    f.setSize(300, 300);
    f.setVisible(true);
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  }



}
class DraggableComponent extends JPanel implements DragGestureListener, DragSourceListener, MouseListener {
    DragSource dragSource;

    public DraggableComponent() {
        dragSource = new DragSource();
        dragSource.createDefaultDragGestureRecognizer(this, DnDConstants.ACTION_COPY_OR_MOVE, this);
        this.setBackground(new Color(255, 0, 0));

        this.addMouseListener(this);
    }

    public void dragGestureRecognized(DragGestureEvent evt) {
        Transferable t = new StringSelection("aString");
        dragSource.startDrag(evt, DragSource.DefaultCopyDrop, t, this);
    }

    public void dragEnter(DragSourceDragEvent evt) {
        System.out.println("enters");
    }

    final JButton clickTwiceButton = new JButton();
    final JButton fireEventButton = new JButton();

    public void dragOver(DragSourceDragEvent evt) {
        System.out.println("over" + evt.getX() + "-" + evt.getY());

        this.setLocation(evt.getX() - 50, evt.getY() - 70);




    }

    public void dragExit(DragSourceEvent evt) {
        System.out.println("leaves");
    }

    public void dropActionChanged(DragSourceDragEvent evt) {
        System.out.println("changes the drag action between copy or move");
    }

    public void dragDropEnd(DragSourceDropEvent evt) {
        System.out.println("finishes or cancels the drag operation");


        // Invoking later for no reason, just to simulate your code
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                System.out.println("sdffdf");
                clickTwiceButton.dispatchEvent(new MouseEvent(
                     fireEventButton,
                     MouseEvent.MOUSE_CLICKED, 
                     1,
                     MouseEvent.BUTTON1, 
                     0, 0, 
                     1, 
                     true
                ));
            }
        });

    }


    //******************
    @Override
    public void mouseClicked(MouseEvent arg0) {
        // TODO Auto-generated method stub
        System.out.println("mouse clic");
    }

    @Override
    public void mouseEntered(MouseEvent arg0) {
        // TODO Auto-generated method stub
        System.out.println("mouse enter");

    }

    @Override
    public void mouseExited(MouseEvent arg0) {
        // TODO Auto-generated method stub
        System.out.println("mouse exit");
    }

    @Override
    public void mousePressed(MouseEvent arg0) {
        // TODO Auto-generated method stub
        System.out.println("mouse press");
    }

    @Override
    public void mouseReleased(MouseEvent e) {
        // TODO Auto-generated method stub
        System.out.println("mouse release");
        //MouseEvent press = new MouseEvent(arg0, arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8, arg9, arg10);
        //this.mousePressed(press );

    }
}

有了这个，我只能拖动面板并使其保持可见，这也是我需要的，但我仍然必须按住我不想要的 clic :(

Answer 1

我可能会更容易为您自己的拖动监听器。

您可以从 Moving Windows 中找到的 DragListener 开始博客。

您需要修改代码来处理 mouseMoved(...) 事件而不是 mouseDragged(...) 事件。您可能需要添加一个“拖动”变量，以便在生成 mousePressed(...) 事件时切换该变量。第一次单击会将拖动变量设置为“true”，第二次单击会将变量设置为“false”。那么 mouseMoved(...) 代码只会在变量为“true”时执行。