JFXPanel Dragboard setDragView

Anthony Petrov anthony.petrov at oracle.com
Tue Apr 22 18:24:56 UTC 2014

Hi Jeff,

I see what you're trying to achieve. I don't believe we've implemented 
anything specifically to support this case. No, I wouldn't expect to 
receive the OnMouseDragOver event in this case because it's only sent to 
a drop target when the mouse cursor is moving above it. In your case the 
button being dragged and the mouse cursor never move relative to each 
other, and hence the DragOver event just can't happen.

Do regular mouse events get delivered to the button? I suppose they 
don't... Well...

A hackish and extremely ineffective way to implement this would be to 
poll the current mouse pointer position using AWT APIs (MouseInfo) on a 
standalone thread and move the custom drag view accordingly. Or wait 
till RT-35812 is implemented.

best regards,

On 4/22/2014 2:39 AM, Jeff Martin wrote:
> So I'm correct that calling Node.startFullDrag() should result in the OnMouseDragOver method getting called? I wasn't sure I had that right - and I really need a OnMouseDragMoved notification anyway.
> My Sample code is below. If you think it should result in a bunch of onMouseDragOver.Handler printlns, I'll file a bug.
> jeff
> public void start(Stage aStage)
> {
>      // Create Button with DragDetected.Handler to startFullDrag/startDragAndDrop
>      final Button button = new Button("Hello World");
>      button.setOnDragDetected(new EventHandler() {
>          public void handle(Event anEvent) {
>              button.startFullDrag();
>              Dragboard db = button.startDragAndDrop(TransferMode.ANY);
>              ClipboardContent cc = new ClipboardContent(); cc.putString("Hello World");
>              db.setContent(cc); anEvent.consume();
>          }
>      });
>      // Listen to DragSource events
>      button.setOnMouseDragOver(new EventHandler<MouseDragEvent>() {
>          public void handle(MouseDragEvent e) { System.out.println(e); }
>      });
>      // Add button to pane and stage and show
>      Pane pane = new Pane(); pane.setPrefSize(400,400);
>      pane.getChildren().add(button); button.resizeRelocate(100,100,100,100);
>      aStage.setScene(new Scene(pane)); aStage.show();
> }
> On Apr 21, 2014, at 8:45 AM, Anthony Petrov <anthony.petrov at oracle.com> wrote:
>> Hi Jeff,
>> On 4/18/2014 6:43 PM, Jeff Martin wrote:
>>> I'm trying to figure out how to implement a version of Dragboard.setDragView() that works with JFXPanel (which isn't currently supported). Years ago I did this in Swing by creating a window that followed the mouse around (at an offset, so it wouldn't take all the DragOver events).
>>> I created a Popup Window and added an ImageView, but I can't figure out how to get the equivalent of DragSource events. I thought I could just call source.startFullDrag() in my DragDetected method then I would get MouseDrag events on my source, but that isn't happening. Is this a bug or am I doing something wrong?
>> Please file a new JIRA and provide a small test case that demonstrates the problem.
>>> Also, when I get my Popup moving, I'd really like it to be exactly under the mouse but have the Popup be MouseTransparent (or forward events to the window underneath).
>> You could use the TRANSPARENT style for your popup window and paint a transparent hole (alpha == 0) in its center (or wherever you need it), and keep the popup positioned so that the mouse pointer is located above the hole. Mouse events always pass through transparent pixels. This way mouse events will get delivered to a window below the popup window in the z-order, while the popup window itself can float above it following the mouse cursor.
>> --
>> best regards,
>> Anthony

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