Native DnD in GWT 2.5.1

[Adolfo Rodriguez]

Hi, I am trying a theoretically easy drag and drop over a GWT 2.5.1 Grid component using the native DnD. I want to drag the id (as String) of a row and drop in different position just to change the order of rows. The process I followed is:

* Initially I tried to drag from the Grid itself as source but then I would not know how to identify the dragged row.

* So I then thought to drag from a cell/row itself, but I do not know how to attach the drag events to the cell/rows

* So finally, I decided wrapping my text content on a Label placed within the Grid cell. With this approach I managed to drag the id of the item with no problems:

final Label label = new Label("blah blah blah item");

label.getElement().setDraggable(Element.DRAGGABLE_TRUE);

label.addDragStartHandler(new DragStartHandler() {

@Override

public void onDragStart(DragStartEvent event) {

String id = "successfully calculated_id";

event.setData("item", id);

}

});

Then again the same problem for the drop target.

* Ideally I would assign the target to the Grid so I can drop in the middle of 2 rows. However no drop event looks to be fired at any time. And, even if it would be fired, again I would not know how to calculate the row/cell number receiving the drop event.

* So, again I tried assigning the drop target to the same Label instances as:

label.addDropHandler(new DropHandler() {

   @Override

   public void onDrop(DropEvent event) {

System.out.println("stop: ");

       // prevent the native text drop

       event.preventDefault();

   }

});

but no drop event looks to be fired. Finally trying to create the drop by using a DOM Handler:

label.addDomHandler(new DropHandler() {

   @Override

   public void onDrop(DropEvent event) {

System.out.println("stop: " + event.getSource());

       event.preventDefault();

       // Do something with dropLabel and dragging

System.out.println("stop: " + event.getSource());

   }

}, DropEvent.getType());

again no drop event fired.

So, at the end:

* no problem dragging the id from the source row

*  but looks impossible to trigger a event for the target item, not mater if it is a Label or the Grid itself. 

My browser is FF and my API is the Native GWT 2.5.1 DnD. Any idea/advise/experience/example?

Thanks

[Adolfo Rodriguez]

I have just came across this message in GWT 2.7 DnD API:

http://www.gwtproject.org/javadoc/latest/com/google/gwt/event/dom/client/HasDropHandlers.html#addDropHandler(com.google.gwt.event.dom.client.DropHandler)

Experimental API: This API is still under development and is subject to change.

I suspect that, if is under development in 2.7, it can not yet be working  in 2.5.1

so it looks I will need to evaluate https://code.google.com/p/gwt-dnd/

[Adolfo Rodriguez]

I solved the issue by adding

label.addDragOverHandler(new DragOverHandler() {

public void onDragOver(DragOverEvent event) {

// do nothing

}

});

even when this method does nothing.

solved, regards.