DragOverEvent issue

[Thomas Lefort]

I have an issue with DragOverEvent.

At drag start I set my event data to a certain value, as follows:

panel.addDomHandler(new DragStartHandler() {

@Override

public void onDragStart(DragStartEvent event) {

event.setData("text", ResourceWidget.this.resource.getClass().getName());

event.getDataTransfer().setDragImage(panel.getElement(), 10, 10);

                                                ... some more code

}

}, DragStartEvent.getType());

On hover and on drop I test the value of the event data as follows:

campaignMap.addDomHandler(new DragOverHandler() {

@Override

public void onDragOver(DragOverEvent event) {

   event.preventDefault();

   if(event.getData("text") != null) {

                                              (1)  ... some more code

   }

}

}, DragOverEvent.getType());

campaignMap.addDomHandler(new DropHandler() {

@Override

public void onDrop(DropEvent event) {

   event.preventDefault();

   if(event.getData("text") != null) {

                                              (2)  ... some more code

   }

}

}, DropEvent.getType());

The issue is that with the hover event I get always null for my data value whilst for the drop I get the right value, ie (1) is never run and (2) runs.

In the end the drag and drop works, but I would also like to make use of the drag event to display some information based on the value of the data.

Any idea? is this a bug?

Thanks,

Thomas

[Thomas Broyer]

This is the expected behavior (a security measure): http://www.whatwg.org/specs/web-apps/current-work/multipage/dnd.html#dndevents ("protected mode" changes the behavior of getData to return early; basically you can know the type of data that's being dragged, but not the actual data).

GWT does not expose the "types" property (JsArrayString), and I don't know how well it's supported across browsers…

[Thomas Lefort]

OK, thanks for the fast answer Thomas. I guess it's not good news though. Any recommendations on how to distinguish between objects being dragged over a widget using the dragovervent?

[Thomas Broyer]

JSNI to access the "types" property of the DataTransfer object?

(along with using specific types to distinguish different types of data, rather than inferring from the content for a single type)

[Thomas Lefort]

OK, but you mentioned that it might not be supported by all browsers? I might give it a try but it sounds like I could be going into murky waters.

--
You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group.

To view this discussion on the web visit https://groups.google.com/d/msg/google-web-toolkit/-/JrFKzyv0NrAJ.

To post to this group, send email to google-we...@googlegroups.com.
To unsubscribe from this group, send email to google-web-tool...@googlegroups.com.
For more options, visit this group at http://groups.google.com/group/google-web-toolkit?hl=en.