DnD with 2D scaled drop target

Question

This is more a strategy question than a code question - although code examples will be muchly appreciated.
I have a model drawing component (ModelDrawingComponent extends JInternalFrame) that contains child components ( ie. ClassNode extends JInternalFrame). I need to be able to drop information into the child component (ClassNode). My description is greatly simplified leaving out several layers such as JScrollPanes, JPanels, etc.
I have overridden the main JPanel's paintComponent() method to allow 2D drawing of lines and scale transformations of the entire model component resultant view. To provide mouse event interactions for this I use a GlassPane which transforms the mouse point to a scaled component adjusted point.
My problem is implementing a DropTarget for Drag and Drop with 2D scaling - the mouse gestures reference points that are not adjusted for the scaling. So I need to transform the point geometry to determine whether the drag is over one of the ClassNode components.
Does anyone have experience with DnD and 2D transformed targets they would like to share - ie. what is the best strategy for managing the transformation of the current drag point to the transformed / scaled point? I am assuming that the DropTarget should be the GlassPane. If so, how do you manage only showing a Drop OK Cursor when the cursor is over a child (ie. ClassNode) instead of over the GlassPane? What event listeners do I need to override to accomplish this?
Thanks in advance.

Answer 1

I don't know why your DropTarget implementation doesn't work, but an alternative, more high-level way of doing what you want is to use a TransferHandler:
        canvas.setTransferHandler(new TransferHandler() {
            @Override
            public boolean canImport(TransferSupport support) {
                if (support.isDataFlavorSupported(DataFlavor.stringFlavor)) {
                    support.setDropAction(DnDConstants.ACTION_COPY);
                    return true;
                return false;
            @Override
            public boolean importData(TransferSupport support) {
                try {
                    String text = (String) support.getTransferable().getTransferData(DataFlavor.stringFlavor);
                    System.out.println(text);
                    return true;
                catch (Exception ex) {
                    ex.printStackTrace();
                    return false;
        });