Re: TransferHandler exportAsDone called before exportAsDrag returns

From:
FredK <fred.l.kleinschmidt@gmail.com>
Newsgroups:
comp.lang.java.gui
Date:
Tue, 11 Jun 2013 07:44:35 -0700 (PDT)
Message-ID:
<10095392-e92c-4285-b5f8-dbde7c18cb1a@googlegroups.com>
On Monday, June 10, 2013 3:14:11 PM UTC-7, Lew wrote:

FredK wrote: > I have a subclass of JPanel for which I am trying to imple=

ment > drag-and-drop. I add a mouse listener to the component, and in > its=
 mousePressed() method I call > JComponent c = (JComponent)event.getSourc=
e(); > TransferHandler th = c.getTransferHandler(); > th.exportAsDrag( co=
mp, event, TransferHandler.COPY ); > > The problem is that the handler's ex=
portAsDone() method is > called immediately - before exportAsDrag() returns=
, and > before the mouse is moved or released. Can you provide an SSCCE? ht=
tp://sscce.org/ The problem appears to be in the part of the code you haven=
't shown us. Are you managing events on the EDT properly? -- Lew

I hadn't realized that JPanel (or I guess JComponent) had built-in DnD for =
bean properties - didn't see any mention of it in the Javadoc tutorials.
I now have it working - I had been using "text" as the argument for Transfe=
rHandler, but my component did not have a "text" property.

For example, this does work (and works for "text" when I add a "text" prope=
rty to my panel):

package boeing.geoduck.viewer.swingitems;

import java.awt.BorderLayout;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.TransferHandler;

public class DragTest {

   public static void main( String args[] ) {
      SwingUtilities.invokeLater( new Runnable() {
         public void run() {
            JFrame frame = new JFrame();
            frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
            frame.setSize( 300, 150 );

            JPanel w = new JPanel();
            frame.add( w, BorderLayout.CENTER );

            w.setTransferHandler( new TransferHandler( "background" ) );

            w.addMouseListener( new MouseAdapter() {
               @Override
               public void mousePressed( MouseEvent me ) {
                  JComponent comp = (JComponent) me.getSource();
                  TransferHandler handler = comp.getTransferHandler();
                  int actions = handler.getSourceActions( comp );
                  System.out.println( actions );
                  handler.exportAsDrag( comp, me, TransferHandler.COPY );
               }
            } );

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

--
Fred K

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