how to drag my component and place it anywhere on the panel

From:
"dxuranus" <dxuranus@gmail.com>
Newsgroups:
comp.lang.java.programmer
Date:
15 Aug 2006 02:08:42 -0700
Message-ID:
<1155632922.099519.45260@m79g2000cwm.googlegroups.com>
i make a dragable component :
//class: DragAbleComponent.the father of my component
import java.awt.Graphics;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;

import javax.accessibility.Accessible;
import javax.swing.JComponent;

public abstract class DragAbleComponent extends JComponent implements
MouseListener,
FocusListener, Accessible ,MouseMotionListener{
private int X;

private int Y;

/**
*
*/
private static final long serialVersionUID = 1L;

public void mouseClicked(MouseEvent e) {
this.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) {
this.repaint();}

public void focusLost(FocusEvent e) {
this.repaint();}

protected abstract void paintComponent(Graphics graphics);

public int getX() {
return X;
}

public void setX(int x) {
X = x;
}

public int getY() {
return Y;
}

public void setY(int y) {
Y = y;
}
}

//class:DragableIcon the component

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.InputEvent;
import java.awt.event.MouseEvent;

import javax.swing.Action;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JComponent;
import javax.swing.KeyStroke;
import javax.swing.TransferHandler;

public class DragableIcon extends DragAbleComponent {

private Image image;

private MouseEvent firstMouseEvent = null;

private static boolean installKeyBordMapings = true;
/**
*
*/
private static final long serialVersionUID = 1L;

public DragableIcon(Image image) {
super();
this.image = image;
this.setFocusable(true);
this.addMouseListener(this);
this.addFocusListener(this);
this.addMouseMotionListener(this);
this.initKeyBordMaping();

}

private void initKeyBordMaping(){
if (installKeyBordMapings) {
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));
}

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());
}
@Override
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.drawImage(image, 0, 0, this);
g.dispose();

}

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 mouseMoved(MouseEvent e) {}

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 mouseReleased(MouseEvent e) {
firstMouseEvent = null;
}

public static boolean isInstallKeyBordMapings() {
return installKeyBordMapings;
}

public static void setInstallKeyBordMapings(boolean
installKeyBordMapings) {
DragableIcon.installKeyBordMapings = installKeyBordMapings;
}

public Image getImage() {
return image;
}

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

//here is my handler
import java.awt.Image;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.io.IOException;

import javax.swing.JComponent;
import javax.swing.TransferHandler;

import cn.com.ynld.bms.applet.gui.component.DragableIcon;

;

public class IconTransferHandler extends TransferHandler {

    /**
     *
     */
    private static final long serialVersionUID = 1L;

     DataFlavor pictureFlavor = DataFlavor.imageFlavor;
        DragableIcon sourceIcon;
        boolean shouldRemove;

        public boolean importData(JComponent c, Transferable t) {
         System.out.println("begin to import image----->");
            Image image;
            if (canImport(c, t.getTransferDataFlavors())) {
             DragableIcon icon = (DragableIcon)c;
                //Don't drop on myself.
                if (sourceIcon == icon) {
                    shouldRemove = false;
                    return true;
                }
                try {
                    image = (Image)t.getTransferData(pictureFlavor);
                    //Set the component to the new picture.
                    icon.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) {
            sourceIcon = (DragableIcon)c;
            shouldRemove = true;
            return new IconTransferable(sourceIcon);
        }

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

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

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

        class IconTransferable implements Transferable {
            private Image image;

            IconTransferable(DragableIcon icon) {
                image = icon.getImage();
            }

            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);
            }
        }

}

i add a handler to my DragableIcon and pane both(copy DragableIcon to
my pane);
the draging seem worked(drag icon) but place dose't (he even did't
invoke the method importData) )
what' can i do?
thanks for any help!

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