Would like DropTargetDragEvent.acceptDrag(int dragOperation, File directory)

Name: js151677 Date: 07/07/2004


A DESCRIPTION OF THE REQUEST :
I have a table that is essential a file browser similar to windows explorer. With both awt DnD and swing DnD implementaions, I get notified that the dragEvent is a move unless the ctrl key is down. This is not how windows explorer works. In Windows explorer, dragging from one drive to another is a copy gesture, while dragging and dropping whithin a drive is a move. My users are complaining that my UI does not behave the same way as windows explorer and I have no way to work around the problem. I assume that the reason I am always told this action is a move is because java has no way of knowing where the file will be dropped.

I would like some way to accept a drag of a file object in my dropTarget with an optional arguement to let the dragSource know where the file will be dropped.

Can you please add a new method to accept file objects with an arguement of directory that the file will be dropped in?

JUSTIFICATION :
  To provide a consistent look and feel with windows.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
I would like drag and drop of files to behave the same as windows explorer in that some drops are copy actions even though there are no modifier keys down.
ACTUAL -
Currently dropping a file object is always a move unless there are modifier keys.

---------- BEGIN SOURCE ----------
import javax.swing.*;
import javax.swing.table.AbstractTableModel;
import javax.swing.table.TableModel;
import java.awt.dnd.*;
import java.awt.datatransfer.*;
import java.awt.*;

public class TestTableDnD extends JFrame implements DropTargetListener, DragGestureListener, DragSourceListener
{
    private JFrame fFrame;
    private JTable fTable;

    public TestTableDnD()
    {
        fFrame = new JFrame("Test DnD in Table");
        TableModel dataModel = new AbstractTableModel() {
                  public int getColumnCount() { return 10; }
                  public int getRowCount() { return 10;}
                  public Object getValueAt(int row, int col) { return new Integer(row*col); }
              };
          fTable = new JTable(dataModel);
          JScrollPane scrollpane = new JScrollPane(fTable);

        fFrame.getContentPane().add(scrollpane);

        fTable.setDragEnabled(true);
        fTable.setDropTarget(new DropTarget(this, // component
            DnDConstants.ACTION_COPY_OR_MOVE, // actions
            this)); // DropTargetListener
        fTable.setTransferHandler(new FBDefaultTransferHandler());

        fFrame.setSize(300,300);
        fFrame.setVisible(true);


    }
    public static void main(String[] args)
    {
        new TestTableDnD();
    }


    // DragGestureListener implementation begins -------------------------
    public void dragGestureRecognized(DragGestureEvent dge)
    {
       /* this doesn't matter for test */
    }

    // DragSourceListener implementation begins --------------------------
    // These methods are also part of DragSourceListener.
    // They are invoked at interesting points during the drag, and can be
    // used to perform "drag over" effects, such as changing the drag cursor
    // or drag image.
    public void dragEnter(DragSourceDragEvent dsde)
    {

        Cursor newCursor = null;
        Cursor currentCursor = dsde.getDragSourceContext().getCursor();
        switch (dsde.getUserAction())
        {
            case DnDConstants.ACTION_COPY:
                if (!currentCursor.equals(DragSource.DefaultCopyDrop))
                {
                    newCursor = DragSource.DefaultCopyDrop;
                }
                break;
            case DnDConstants.ACTION_MOVE:
                if (!currentCursor.equals(DragSource.DefaultMoveDrop))
                {
                    newCursor = DragSource.DefaultMoveDrop;
                }
                break;
            default:
                newCursor = DragSource.DefaultCopyDrop;
                break;
        }
        if (newCursor != null)
            dsde.getDragSourceContext().setCursor(newCursor);

    }

    public void dragExit(DragSourceEvent dsde)
    {
        dsde.getDragSourceContext().setCursor(DragSource.DefaultCopyNoDrop);
    }

    public void dragOver(DragSourceDragEvent dsde)
    {
        Cursor newCursor = null;
        Cursor currentCursor = dsde.getDragSourceContext().getCursor();
        switch (dsde.getUserAction())
        {
            case DnDConstants.ACTION_COPY:
                if (!currentCursor.equals(DragSource.DefaultCopyDrop))
                {
                    newCursor = DragSource.DefaultCopyDrop;
                }
                break;
            case DnDConstants.ACTION_MOVE:
                if (!currentCursor.equals(DragSource.DefaultMoveDrop))
                {
                    newCursor = DragSource.DefaultMoveDrop;
                }
                break;
            default:
                newCursor = DragSource.DefaultCopyDrop;
                break;
        }
        if (newCursor != null)
            dsde.getDragSourceContext().setCursor(newCursor);
    }

    public void dropActionChanged(DragSourceDragEvent dsde)
    {
    }

    /**
     * dragDropEnd() is invoked when the drag & drop is completed.
     **/
    public void dragDropEnd(DragSourceDropEvent e)
    {
         /* this doesn't matter for test */
    }
    // DragSourceListener implementation ends ----------------------------

    // DropTargetListener implementation begins --------------------------
    public void dragEnter(DropTargetDragEvent dtde)
    {
        if (dtde.isDataFlavorSupported(DataFlavor.javaFileListFlavor))
        {
            dtde.acceptDrag(DnDConstants.ACTION_COPY_OR_MOVE);
        }
        else
        {
            dtde.rejectDrag();
        }
    }

    public void dragExit(DropTargetEvent dte)
    {
    }

    public void dragOver(DropTargetDragEvent dtde)
    {
        if (dtde.isDataFlavorSupported(DataFlavor.javaFileListFlavor))
        {
            dtde.acceptDrag(DnDConstants.ACTION_COPY_OR_MOVE);
return; //get out.
}
        //if not a file flavor, reject.
dtde.rejectDrag();
    }

    public void drop(DropTargetDropEvent dtde)
    {
        if (dtde.isDataFlavorSupported(DataFlavor.javaFileListFlavor))
        {
            dtde.acceptDrop(DnDConstants.ACTION_COPY_OR_MOVE);

            if (dtde.getDropAction() == DnDConstants.ACTION_MOVE)
                System.out.println("drop - MOVE");
            else
                System.out.println("drop - COPY");

            //do stuff to drop. not relevant to test.
            dtde.dropComplete(true);

            return;
        }

        //If there was not a transferable object we are interested in then
        //reject the drop.
        dtde.rejectDrop();
    }

    public void dropActionChanged(DropTargetDragEvent dtde)
    {
    }

    class FBDefaultTransferHandler extends TransferHandler
    {



        public void exportToClipboard(JComponent comp, Clipboard clipboard,
                                      int action)
        {
            // Not important for test example
        }

        public void exportDone(JComponent source,
                               Transferable data,
                               int action)
        {
            cleanup(source, action == MOVE);
        }


        //If the remove argument is true, the drop has been
        //successful and it's time to remove the selected items
        //from the list. If the remove argument is false, it
        //was a Copy operation and the original list is left
        //intact.
        protected void cleanup(JComponent c, boolean remove) {

        }

        /**
         * This is called to paste. Gets data off the clipboard.
         * @param comp
         * @param t
         * @return successful import
         */
        public boolean importData(JComponent comp, Transferable t)
        {
           // Not important for test example

            return false;
        }

        private DataFlavor getFlavor(DataFlavor[] flavors)
        {

            if (flavors != null)
            {
                for (int counter = 0; counter < flavors.length; counter++)
                {
                    if (flavors[counter].equals(DataFlavor.javaFileListFlavor))
                    {
                        return flavors[counter];
                    }
                }
            }
            return null;
        }

        /**
            * Does the flavor list have a file flavor?
            */
           protected boolean hasFileFlavor(DataFlavor[] flavors) {


            for (int i = 0; i < flavors.length; i++) {
                   if (DataFlavor.javaFileListFlavor.equals(flavors[i])) {
                       return true;
                   }
               }
               return false;
           }

           /**
            * Overridden to include a check for a file flavor.
            */
           public boolean canImport(JComponent c, DataFlavor[] flavors) {
               return hasFileFlavor(flavors);
           }

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

           protected Transferable createTransferable(JComponent c) {
               // Not important for test example
               Transferable trans = new StringSelection("");
               return trans;
           }



    }


}

---------- END SOURCE ----------
(Incident Review ID: 284965)
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