問題描述

我正在使用 TransferHandler 將數據從 JPanel 傳遞到 JTextArea 作為 JLabel(單擊左側面板中的某處以創建要拖動的 JLabel)

I am using a TransferHandler to pass data from a JPanel to a JTextArea as a JLabel (Click somewhere in the left panel to create the JLabel to drag)

數據傳輸工作正常，但我還想顯示"JLabel，因為它與鼠標指針一起被拖動.

The transfer of the data works fine, but I'd like to also "show" the JLabel as its being dragged along with the mouse pointer.

如果你注釋掉

dropLabel.setTransferHandler(new TransferHandler("text"));

dropLabel.getTransferHandler().exportAsDrag(dropLabel, e,
            TransferHandler.COPY);

你會看到我想要的樣子.(但當然數據不會被傳輸).

you will see how I want it to look. (but of course then the data won't be transferred).

如何讓傳輸工作和 JLabel 跟隨鼠標光標?

How can I get both the transfer to work and the JLabel to follow the mouse cursor?

代碼如下:

import java.awt.*;
import java.awt.datatransfer.Transferable;
import java.awt.event.*;

import javax.swing.*;
import javax.swing.border.Border;

public class DragTest extends JFrame implements MouseMotionListener,
        MouseListener {

    private JPanel leftPanel = new JPanel(null);
    private JPanel rightPanel = new JPanel(null);
    private JLabel dragLabel = new JLabel("drop");
    private final JWindow window = new JWindow();
    JLabel dropLabel;

    public DragTest() {
        this.setLayout(new GridLayout(1, 2));

        leftPanel.setBorder(BorderFactory.createLineBorder(Color.black));
        rightPanel.setBorder(BorderFactory.createLineBorder(Color.black));
        this.add(leftPanel);
        this.add(rightPanel);
        leftPanel.addMouseListener(this);
        leftPanel.addMouseMotionListener(this);

        JTextArea area = new JTextArea();

        rightPanel.setLayout(new GridLayout(1, 1));
        rightPanel.add(area);

        dragLabel.setFont(new Font("Serif", Font.BOLD, 48));
    }

    @Override
    public void mousePressed(MouseEvent e) {

        dropLabel = new JLabel("drop");

        Dimension labelSize = dropLabel.getPreferredSize();
        dropLabel.setSize(labelSize);
        int x = e.getX() - labelSize.width / 2;
        int y = e.getY() - labelSize.height / 2;
        dropLabel.setLocation(x, y);
        leftPanel.add(dropLabel);

        dropLabel.setTransferHandler(new TransferHandler("text"));

        dropLabel.getTransferHandler().exportAsDrag(dropLabel, e,
                TransferHandler.COPY);

        repaint();

    }

    @Override
    public void mouseDragged(MouseEvent me) {
        dragLabel = new JLabel("drop");
        dragLabel.setFont(new Font("Serif", Font.BOLD, 48));
        int x = me.getPoint().x;
        int y = me.getPoint().y;
        window.add(dragLabel);
        window.pack();
        Point pt = new Point(x, y);
        Component c = (Component) me.getSource();
        SwingUtilities.convertPointToScreen(pt, c);
        window.setLocation(pt);
        window.setVisible(true);
        repaint();
    }

    @Override
    public void mouseMoved(MouseEvent e) {
    }

    @Override
    public void mouseClicked(MouseEvent e) {

    }

    @Override
    public void mouseReleased(MouseEvent e) {

//      leftPanel.remove(dropLabel);

        window.remove(dragLabel);
        window.setVisible(false);

        repaint();
    }

    @Override
    public void mouseEntered(MouseEvent e) {

    }

    @Override
    public void mouseExited(MouseEvent e) {

    }

    public static void main(String[] args) {

        DragTest frame = new DragTest();
        frame.setVisible(true);
        frame.setSize(600, 400);
        frame.setResizable(false);
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
}

推薦答案

再舉一個例子:

修復閃爍的光標

import java.awt.*;
import java.awt.datatransfer.*;
import java.awt.dnd.*;
import java.awt.event.*;
import java.io.*;
import java.util.*;
import javax.activation.*;
import javax.swing.*;
import javax.swing.text.*;

public class DragTest3 {
  public JComponent makeUI() {
    DragPanel p1 = new DragPanel();
    p1.setBorder(BorderFactory.createLineBorder(Color.BLACK));
    p1.add(new JLabel(UIManager.getIcon("OptionPane.warningIcon")));
    p1.add(new JLabel(UIManager.getIcon("OptionPane.errorIcon")));
    p1.add(new JLabel("Label1"));
    p1.add(new JLabel("Label2"));
    MouseListener handler = new Handler();
    p1.addMouseListener(handler);
    LabelTransferHandler th = new LabelTransferHandler();
    p1.setTransferHandler(th);
    JPanel p = new JPanel(new GridLayout(1,2));
    p.add(p1);

    DragPanel p2 = new DragPanel();
    p2.setBorder(BorderFactory.createLineBorder(Color.BLACK));
    p2.addMouseListener(handler);
    p2.setTransferHandler(th);
    p.add(p2);

    JPanel panel = new JPanel(new GridLayout(2,1));
    panel.add(p);
    panel.add(new JScrollPane(new JTextArea()));
    return panel;
  }
  public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
      @Override public void run() {
        createAndShowGUI();
      }
    });
  }
  public static void createAndShowGUI() {
    JFrame f = new JFrame();
    f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    f.getContentPane().add(new DragTest3().makeUI());
    f.setSize(320, 240);
    f.setLocationRelativeTo(null);
    f.setVisible(true);
  }
}
class DragPanel extends JPanel {
  public DragPanel() {
    super();
  }
  public JLabel draggingLabel;
}
class Handler extends MouseAdapter {
  @Override public void mousePressed(MouseEvent e) {
    DragPanel p = (DragPanel)e.getSource();
    Component c = SwingUtilities.getDeepestComponentAt(p, e.getX(), e.getY());
    if(c!=null && c instanceof JLabel) {
      p.draggingLabel = (JLabel)c;
      p.getTransferHandler().exportAsDrag(p, e, TransferHandler.MOVE);
    }
  }
}
class LabelTransferHandler extends TransferHandler {
  private final DataFlavor localObjectFlavor;
  private final JLabel label = new JLabel() {
    @Override public boolean contains(int x, int y) {
      return false;
    }
  };
  private final JWindow window = new JWindow();
  public LabelTransferHandler() {
    System.out.println("LabelTransferHandler");
    localObjectFlavor = new ActivationDataFlavor(
      DragPanel.class, DataFlavor.javaJVMLocalObjectMimeType, "JLabel");
    window.add(label);
    window.setAlwaysOnTop(true);
    window.setBackground(new Color(0,true));
    DragSource.getDefaultDragSource().addDragSourceMotionListener(
    new DragSourceMotionListener() {
      @Override public void dragMouseMoved(DragSourceDragEvent dsde) {
        Point pt = dsde.getLocation();
        pt.translate(5, 5); // offset
        window.setLocation(pt);
      }
    });
  }
  @Override protected Transferable createTransferable(JComponent c) {
    System.out.println("createTransferable");
    DragPanel p = (DragPanel)c;
    JLabel l = p.draggingLabel;
    String text = l.getText();
    //TEST
    //if(text==null) {
    //    text = l.getIcon().toString();
    /
                
【網站聲明】本站部分內容來源于互聯網,旨在幫助大家更快的解決問題，如果有圖片或者內容侵犯了您的權益，請聯系我們刪除處理，感謝您的支持！