자바에서 이미지 드래그 앤 드롭

Question

내가 원하는 것은 JPanel에서 다른 이미지로 드래그 앤 드롭하는 것입니다. 나는 dnd 라이브러리를 사용하여 그것을 할 수 있었다. 하지만 내가 떨어 뜨린 패널에서 이미지를 드래그 할 수 없기 때문에 (드롭 타겟에서) 나는 그걸로 붙어 있습니다. 즉 droptarget이 dragource로 작동해야 함을 의미합니다. 내가 어떻게하는거야?

Answer 1

아마도이 도움이 :

http://www.java2s.com/Code/Java/Swing-JFC/DragPictureDemo2.htm

/* From http://java.sun.com/docs/books/tutorial/index.html */ 

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/* 
* DragPictureDemo2.java is a 1.4 example that requires the following files: 
* Picture.java DTPicture.java PictureTransferHandler.java 
* TransferActionListener.java images/Maya.jpg images/Anya.jpg images/Laine.jpg 
* images/Cosmo.jpg images/Adele.jpg images/Alexi.jpg 
*/ 

import java.awt.BorderLayout; 
import java.awt.Color; 
import java.awt.Dimension; 
import java.awt.Graphics; 
import java.awt.GridLayout; 
import java.awt.Image; 
import java.awt.KeyboardFocusManager; 
import java.awt.datatransfer.DataFlavor; 
import java.awt.datatransfer.Transferable; 
import java.awt.datatransfer.UnsupportedFlavorException; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 
import java.awt.event.FocusEvent; 
import java.awt.event.FocusListener; 
import java.awt.event.InputEvent; 
import java.awt.event.KeyEvent; 
import java.awt.event.MouseEvent; 
import java.awt.event.MouseListener; 
import java.awt.event.MouseMotionListener; 
import java.beans.PropertyChangeEvent; 
import java.beans.PropertyChangeListener; 
import java.io.File; 
import java.io.IOException; 
import java.net.MalformedURLException; 

import javax.accessibility.Accessible; 
import javax.swing.Action; 
import javax.swing.ActionMap; 
import javax.swing.BorderFactory; 
import javax.swing.ImageIcon; 
import javax.swing.InputMap; 
import javax.swing.JComponent; 
import javax.swing.JFrame; 
import javax.swing.JMenu; 
import javax.swing.JMenuBar; 
import javax.swing.JMenuItem; 
import javax.swing.JPanel; 
import javax.swing.KeyStroke; 
import javax.swing.TransferHandler; 

//A version of DragPictureDemo that creates an 
//Edit menu with cut/copy/paste actions. 
//This demo adds a class called TransferActionDemo 
//that transfers the cut/copy/paste menu action 
//to the currently focused component. 
public class DragPictureDemo2 extends JPanel { 

    DTPicture pic1, pic2, pic3, pic4, pic5, pic6, pic7, pic8, pic9, pic10, 
     pic11, pic12; 

    static String mayaString = "Maya"; 

    static String anyaString = "Anya"; 

    static String laineString = "Laine"; 

    static String cosmoString = "Cosmo"; 

    static String adeleString = "Adele"; 

    static String alexiString = "Alexi"; 

    PictureTransferHandler picHandler; 

    public DragPictureDemo2() { 
    super(new BorderLayout()); 
    picHandler = new PictureTransferHandler(); 
    //Since we are using keyboard accelerators, we don't 
    //need the component to install its own input map 
    //bindings. 
    DTPicture.setInstallInputMapBindings(false); 

    JPanel mugshots = new JPanel(new GridLayout(4, 3)); 
    pic1 = new DTPicture(createImageIcon("images/" + mayaString + ".jpg", 
     mayaString).getImage()); 
    pic1.setTransferHandler(picHandler); 
    mugshots.add(pic1); 
    pic2 = new DTPicture(createImageIcon("images/" + anyaString + ".jpg", 
     anyaString).getImage()); 
    pic2.setTransferHandler(picHandler); 
    mugshots.add(pic2); 
    pic3 = new DTPicture(createImageIcon("images/" + laineString + ".jpg", 
     laineString).getImage()); 
    pic3.setTransferHandler(picHandler); 
    mugshots.add(pic3); 
    pic4 = new DTPicture(createImageIcon("images/" + cosmoString + ".jpg", 
     cosmoString).getImage()); 
    pic4.setTransferHandler(picHandler); 
    mugshots.add(pic4); 
    pic5 = new DTPicture(createImageIcon("images/" + adeleString + ".jpg", 
     adeleString).getImage()); 
    pic5.setTransferHandler(picHandler); 
    mugshots.add(pic5); 
    pic6 = new DTPicture(createImageIcon("images/" + alexiString + ".jpg", 
     alexiString).getImage()); 
    pic6.setTransferHandler(picHandler); 
    mugshots.add(pic6); 

    //These six components with no pictures provide handy 
    //drop targets. 
    pic7 = new DTPicture(null); 
    pic7.setTransferHandler(picHandler); 
    mugshots.add(pic7); 
    pic8 = new DTPicture(null); 
    pic8.setTransferHandler(picHandler); 
    mugshots.add(pic8); 
    pic9 = new DTPicture(null); 
    pic9.setTransferHandler(picHandler); 
    mugshots.add(pic9); 
    pic10 = new DTPicture(null); 
    pic10.setTransferHandler(picHandler); 
    mugshots.add(pic10); 
    pic11 = new DTPicture(null); 
    pic11.setTransferHandler(picHandler); 
    mugshots.add(pic11); 
    pic12 = new DTPicture(null); 
    pic12.setTransferHandler(picHandler); 
    mugshots.add(pic12); 

    setPreferredSize(new Dimension(450, 630)); 
    add(mugshots, BorderLayout.CENTER); 
    setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20)); 
    } 

    //Create an Edit menu to support cut/copy/paste. 
    public JMenuBar createMenuBar() { 
    JMenuItem menuItem = null; 
    JMenuBar menuBar = new JMenuBar(); 
    JMenu mainMenu = new JMenu("Edit"); 
    mainMenu.setMnemonic(KeyEvent.VK_E); 
    TransferActionListener actionListener = new TransferActionListener(); 

    menuItem = new JMenuItem("Cut"); 
    menuItem.setActionCommand((String) TransferHandler.getCutAction() 
     .getValue(Action.NAME)); 
    menuItem.addActionListener(actionListener); 
    menuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_X, 
     ActionEvent.CTRL_MASK)); 
    menuItem.setMnemonic(KeyEvent.VK_T); 
    mainMenu.add(menuItem); 
    menuItem = new JMenuItem("Copy"); 
    menuItem.setActionCommand((String) TransferHandler.getCopyAction() 
     .getValue(Action.NAME)); 
    menuItem.addActionListener(actionListener); 
    menuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_C, 
     ActionEvent.CTRL_MASK)); 
    menuItem.setMnemonic(KeyEvent.VK_C); 
    mainMenu.add(menuItem); 
    menuItem = new JMenuItem("Paste"); 
    menuItem.setActionCommand((String) TransferHandler.getPasteAction() 
     .getValue(Action.NAME)); 
    menuItem.addActionListener(actionListener); 
    menuItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_V, 
     ActionEvent.CTRL_MASK)); 
    menuItem.setMnemonic(KeyEvent.VK_P); 
    mainMenu.add(menuItem); 

    menuBar.add(mainMenu); 
    return menuBar; 
    } 

    /** Returns an ImageIcon, or null if the path was invalid. */ 
    protected static ImageIcon createImageIcon(String path, String description) { 
     try { 
      File imageURL = new File(path); 

      if (imageURL == null) { 
       System.err.println("Resource not found: " + path); 
       return null; 
      } else { 
     return new ImageIcon(imageURL.toURI().toURL(), description); 
      } 
    } catch(MalformedURLException e) { 
     e.printStackTrace(); 
    } 
    return null; 
    } 

    /** 
    * Create the GUI and show it. For thread safety, this method should be 
    * invoked from the event-dispatching thread. 
    */ 
    private static void createAndShowGUI() { 
    //Make sure we have nice window decorations. 
    JFrame.setDefaultLookAndFeelDecorated(true); 

    //Create and set up the window. 
    JFrame frame = new JFrame("DragPictureDemo2"); 
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 

    //Create and set up the menu bar and content pane. 
    DragPictureDemo2 demo = new DragPictureDemo2(); 
    frame.setJMenuBar(demo.createMenuBar()); 
    demo.setOpaque(true); //content panes must be opaque 
    frame.setContentPane(demo); 

    //Display the window. 
    frame.pack(); 
    frame.setVisible(true); 
    } 

    public static void main(String[] args) { 
    //Schedule a job for the event-dispatching thread: 
    //creating and showing this application's GUI. 
    javax.swing.SwingUtilities.invokeLater(new Runnable() { 
     public void run() { 
     createAndShowGUI(); 
     } 
    }); 
    } 
} 

/* 
* DTPicture.java is used by the 1.4 DragPictureDemo.java example. 
*/ 

//A subclass of Picture that supports Data Transfer. 

class DTPicture extends Picture implements MouseMotionListener { 
    private MouseEvent firstMouseEvent = null; 

    private static boolean installInputMapBindings = true; 

    public DTPicture(Image image) { 
    super(image); 
    addMouseMotionListener(this); 

    //Add the cut/copy/paste key bindings to the input map. 
    //Note that this step is redundant if you are installing 
    //menu accelerators that cause these actions to be invoked. 
    //DragPictureDemo does not use menu accelerators and, since 
    //the default value of installInputMapBindings is true, 
    //the bindings are installed. DragPictureDemo2 does use 
    //menu accelerators and so calls setInstallInputMapBindings 
    //with a value of false. Your program would do one or the 
    //other, but not both. 
    if (installInputMapBindings) { 
     InputMap imap = this.getInputMap(); 
     imap.put(KeyStroke.getKeyStroke("ctrl X"), TransferHandler 
      .getCutAction().getValue(Action.NAME)); 
     imap.put(KeyStroke.getKeyStroke("ctrl C"), TransferHandler 
      .getCopyAction().getValue(Action.NAME)); 
     imap.put(KeyStroke.getKeyStroke("ctrl V"), TransferHandler 
      .getPasteAction().getValue(Action.NAME)); 
    } 

    //Add the cut/copy/paste actions to the action map. 
    //This step is necessary because the menu's action listener 
    //looks for these actions to fire. 
    ActionMap map = this.getActionMap(); 
    map.put(TransferHandler.getCutAction().getValue(Action.NAME), 
     TransferHandler.getCutAction()); 
    map.put(TransferHandler.getCopyAction().getValue(Action.NAME), 
     TransferHandler.getCopyAction()); 
    map.put(TransferHandler.getPasteAction().getValue(Action.NAME), 
     TransferHandler.getPasteAction()); 
    } 

    public void setImage(Image image) { 
    this.image = image; 
    this.repaint(); 
    } 

    public void mousePressed(MouseEvent e) { 
    //Don't bother to drag if there is no image. 
    if (image == null) 
     return; 

    firstMouseEvent = e; 
    e.consume(); 
    } 

    public void mouseDragged(MouseEvent e) { 
    //Don't bother to drag if the component displays no image. 
    if (image == null) 
     return; 

    if (firstMouseEvent != null) { 
     e.consume(); 

     //If they are holding down the control key, COPY rather than MOVE 
     int ctrlMask = InputEvent.CTRL_DOWN_MASK; 
     int action = ((e.getModifiersEx() & ctrlMask) == ctrlMask) ? TransferHandler.COPY 
      : TransferHandler.MOVE; 

     int dx = Math.abs(e.getX() - firstMouseEvent.getX()); 
     int dy = Math.abs(e.getY() - firstMouseEvent.getY()); 
     //Arbitrarily define a 5-pixel shift as the 
     //official beginning of a drag. 
     if (dx > 5 || dy > 5) { 
     //This is a drag, not a click. 
     JComponent c = (JComponent) e.getSource(); 
     TransferHandler handler = c.getTransferHandler(); 
     //Tell the transfer handler to initiate the drag. 
     handler.exportAsDrag(c, firstMouseEvent, action); 
     firstMouseEvent = null; 
     } 
    } 
    } 

    public void mouseReleased(MouseEvent e) { 
    firstMouseEvent = null; 
    } 

    public void mouseMoved(MouseEvent e) { 
    } 

    //This method is necessary because DragPictureDemo and 
    //DragPictureDemo2 both use this class and DragPictureDemo 
    //needs to have the input map bindings installed for 
    //cut/copy/paste. DragPictureDemo2 uses menu accelerators 
    //and does not need to have the input map bindings installed. 
    //Your program would use one approach or the other, but not 
    //both. The default for installInputMapBindings is true. 
    public static void setInstallInputMapBindings(boolean flag) { 
    installInputMapBindings = flag; 
    } 

    public static boolean getInstallInputMapBindingds() { //for completeness 
    return installInputMapBindings; 
    } 
} 

/* 
* Picture.java is used by the 1.4 TrackFocusDemo.java and DragPictureDemo.java 
* examples. 
*/ 

class Picture extends JComponent implements MouseListener, FocusListener, 
    Accessible { 
    Image image; 

    public Picture(Image image) { 

    this.image = image; 
    setFocusable(true); 
    addMouseListener(this); 
    addFocusListener(this); 
    } 

    public void mouseClicked(MouseEvent e) { 
    //Since the user clicked on us, let's get focus! 
    requestFocusInWindow(); 
    } 

    public void mouseEntered(MouseEvent e) { 
    } 

    public void mouseExited(MouseEvent e) { 
    } 

    public void mousePressed(MouseEvent e) { 
    } 

    public void mouseReleased(MouseEvent e) { 
    } 

    public void focusGained(FocusEvent e) { 
    //Draw the component with a red border 
    //indicating that it has focus. 
    this.repaint(); 
    } 

    public void focusLost(FocusEvent e) { 
    //Draw the component with a black border 
    //indicating that it doesn't have focus. 
    this.repaint(); 
    } 

    protected void paintComponent(Graphics graphics) { 
    Graphics g = graphics.create(); 

    //Draw in our entire space, even if isOpaque is false. 
    g.setColor(Color.WHITE); 
    g.fillRect(0, 0, image == null ? 125 : image.getWidth(this), 
     image == null ? 125 : image.getHeight(this)); 

    if (image != null) { 
     //Draw image at its natural size of 125x125. 
     g.drawImage(image, 0, 0, this); 
    } 

    //Add a border, red if picture currently has focus 
    if (isFocusOwner()) { 
     g.setColor(Color.RED); 
    } else { 
     g.setColor(Color.BLACK); 
    } 
    g.drawRect(0, 0, image == null ? 125 : image.getWidth(this), 
     image == null ? 125 : image.getHeight(this)); 
    g.dispose(); 
    } 
} 

/* 
* PictureTransferHandler.java is used by the 1.4 DragPictureDemo.java example. 
*/ 

class PictureTransferHandler extends TransferHandler { 
    DataFlavor pictureFlavor = DataFlavor.imageFlavor; 

    DTPicture sourcePic; 

    boolean shouldRemove; 

    public boolean importData(JComponent c, Transferable t) { 
    Image image; 
    if (canImport(c, t.getTransferDataFlavors())) { 
     DTPicture pic = (DTPicture) c; 
     //Don't drop on myself. 
     if (sourcePic == pic) { 
     shouldRemove = false; 
     return true; 
     } 
     try { 
     image = (Image) t.getTransferData(pictureFlavor); 
     //Set the component to the new picture. 
     pic.setImage(image); 
     return true; 
     } catch (UnsupportedFlavorException ufe) { 
     System.out.println("importData: unsupported data flavor"); 
     } catch (IOException ioe) { 
     System.out.println("importData: I/O exception"); 
     } 
    } 
    return false; 
    } 

    protected Transferable createTransferable(JComponent c) { 
    sourcePic = (DTPicture) c; 
    shouldRemove = true; 
    return new PictureTransferable(sourcePic); 
    } 

    public int getSourceActions(JComponent c) { 
    return COPY_OR_MOVE; 
    } 

    protected void exportDone(JComponent c, Transferable data, int action) { 
    if (shouldRemove && (action == MOVE)) { 
     sourcePic.setImage(null); 
    } 
    sourcePic = null; 
    } 

    public boolean canImport(JComponent c, DataFlavor[] flavors) { 
    for (int i = 0; i < flavors.length; i++) { 
     if (pictureFlavor.equals(flavors[i])) { 
     return true; 
     } 
    } 
    return false; 
    } 

    class PictureTransferable implements Transferable { 
    private Image image; 

    PictureTransferable(DTPicture pic) { 
     image = pic.image; 
    } 

    public Object getTransferData(DataFlavor flavor) 
     throws UnsupportedFlavorException { 
     if (!isDataFlavorSupported(flavor)) { 
     throw new UnsupportedFlavorException(flavor); 
     } 
     return image; 
    } 

    public DataFlavor[] getTransferDataFlavors() { 
     return new DataFlavor[] { pictureFlavor }; 
    } 

    public boolean isDataFlavorSupported(DataFlavor flavor) { 
     return pictureFlavor.equals(flavor); 
    } 
    } 
} 

/* 
* TransferActionListener.java is used by the 1.4 DragPictureDemo.java example. 
*/ 

/* 
* A class that tracks the focused component. This is necessary to delegate the 
* menu cut/copy/paste commands to the right component. An instance of this 
* class is listening and when the user fires one of these commands, it calls 
* the appropriate action on the currently focused component. 
*/ 

class TransferActionListener implements ActionListener, PropertyChangeListener { 
    private JComponent focusOwner = null; 

    public TransferActionListener() { 
    KeyboardFocusManager manager = KeyboardFocusManager 
     .getCurrentKeyboardFocusManager(); 
    manager.addPropertyChangeListener("permanentFocusOwner", this); 
    } 

    public void propertyChange(PropertyChangeEvent e) { 
    Object o = e.getNewValue(); 
    if (o instanceof JComponent) { 
     focusOwner = (JComponent) o; 
    } else { 
     focusOwner = null; 
    } 
    } 

    public void actionPerformed(ActionEvent e) { 
    if (focusOwner == null) 
     return; 
    String action = (String) e.getActionCommand(); 
    Action a = focusOwner.getActionMap().get(action); 
    if (a != null) { 
     a.actionPerformed(new ActionEvent(focusOwner, 
      ActionEvent.ACTION_PERFORMED, null)); 
    } 
    } 
}