Drag/drop cursors

Pavel Safrata pavel.safrata at oracle.com
Tue May 14 06:09:25 PDT 2013

Hi Werner,
the MouseDragEvent events are delivered during the full 
press-drag-release gesture, for platform DnD you need to use entirely 
different events: DragEvent.
With regards,

On 14.5.2013 14:58, Werner Lehmann wrote:
> Pavel,
> it seems as if e.g. the IDC_NODROP cursor is somewhat undocumented in 
> Windows. I looked into the Delphi RTL source and they are using 32767 
> for the lpCursorName parameter of LoadCursor. This and a few other 
> constants are not documented on that MSDN page.
> Anyway, I'd be ok with using platform DND. Even more so since this 
> will eventually support a dragimage with FX8+. However, I am having 
> difficulties capturing the drag events on target parents.
> Consider this:
> - drag source: a label L1
> - drag target: a pane P with some children, e.g. a label L2
> I want to handle the DND on the pane level, so I add event filters on 
> DND on L1. In "L1.DRAG_DETECTED" a platform DND is started with 
> startDragAndDrop. When dragging over P or L2, the event filters are 
> not executed.
> How can I handle the DND on the pane level? The other drag gestures 
> allow event capturing here...
> Werner
> On 13.05.2013 17:08, Pavel Safrata wrote:
>> Hi Werner,
>> I'm sorry for the delay. You understand the gestures correctly. As I
>> tried to explain earlier, the DnD cursors should not be used for non-DnD
>> operation and it is not supported rather intentionally. It looks like
>> some operating systems follow this reasoning as well. For instance, look
>> at this page, it seems that on Windows we wouldn't have access to those
>> cursors even if we wanted to provide them:
>> http://msdn.microsoft.com/en-us/library/windows/desktop/ms648391%28v=vs.85%29.aspx 
>> If you have something to copy/move/link, you may consider using DnD, it
>> may not be that out of place. Note that it might fit best to pass
>> references to the intra-app gesture which is unfortunately not supported
>> yet ( https://javafx-jira.kenai.com/browse/RT-29082 ) but it can be
>> easily worked around.
>> Thanks,
>> Pavel
>> On 26.4.2013 11:29, Werner Lehmann wrote:
>>> Hi Pavel,
>>> actually I would prefer the cursors to show automatically. According
>>> to the MouseEvent JavaDoc there are 3 different drag/drop modes:
>>> 1. Simple press drag and release.
>>> 2. Full press drag and release.
>>> 3. Platform-supported drag-and-drop.
>>> I am using the 1st for node move/resize. Here I change the cursor to
>>> one of the *_SIZE cursors. Cursor mapping is incorrect on Mac but that
>>> is a known and Lombard-fixed bug - other than that it works fine.
>>> To drag a node from a toolbar into a workspace I would go with the 2nd
>>> mode (startFullDrag in onDragDetected). This one does not change the
>>> cursor automatically, and this is what I am asking about.
>>> The third mode does change the cursor but it seems a bit inappropriate
>>> for node drags within the same scene.
>>> Maybe I am missing a step? The tutorial [1] is about platform
>>> drag/drop only... Also, a drag-image would be nice but that seems to
>>> exist for platfrom drag/drop only, in Lombard only (except for a
>>> workaound like [2] which also does not solve the cursor
>>> deny/copy/move/link problem).
>>> Rgds
>>> Werner
>>> [1] http://docs.oracle.com/javafx/2/drag_drop/jfxpub-drag_drop.htm
>>> [2]
>>> http://stackoverflow.com/questions/13624491/implement-drag-and-drop-like-in-scene-builder 
>>> On 25.04.2013 17:36, Pavel Safrata wrote:
>>>> Hi Werner,
>>>> the cursors you mention should appear automatically during 
>>>> drag-and-drop
>>>> operation. I think they should not be used manually elsewhere because
>>>> they are visually informing user about an ongoing drag-and-drop
>>>> operation and using them at different times would be confusing. 
>>>> During a
>>>> drag-and-drop operation the system is in a special mode with inner 
>>>> event
>>>> loop, temporarily holding the dragged data, blocking many other
>>>> features, and the well-known cursors make this clear to the user.
>>>> If the cursors don't work for you during DnD, please file a bug. If 
>>>> you
>>>> still think you need the cursors for your mouse events (which I 
>>>> tried to
>>>> explain is a discouraged pattern), you can file feature request and 
>>>> see
>>>> if it is approved (and even technically possible on all platforms).
>>>> Thanks,
>>>> Pavel
>>>> On 25.4.2013 17:08, Werner Lehmann wrote:
>>>>> Hi,
>>>>> I am missing typical cursors during drag/drop, e.g. a deny, add, 
>>>>> move,
>>>>> link cursor. Apparently those are not supported in
>>>>> javafx.scene.Cursor. How would this be solved in a
>>>>> platform-independent way?
>>>>> Best option currently seems to be: use the default cursor, and show
>>>>> some tooltip/popup or unmanaged node below the cursor position to
>>>>> indicate the drop effect to the user. Not really optimal...
>>>>> I could also use my own drag cursors but they would not fit into all
>>>>> sets of cursors on the supported platforms. If there was at least a
>>>>> way to get an image of the default cursor - then it could be
>>>>> "enhanced" with a small overlay. But that does not seem feasible
>>>>> either.
>>>>> Werner

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