Keyboard events

Artem Ananiev artem.ananiev at
Mon Oct 7 10:03:34 PDT 2013

On 10/7/2013 6:53 PM, Richard Bair wrote:
> That being said, this seems like a very common use case, and I wonder if there is something more we could do (in the longer term, short term do as Artem suggests)

One of the options is to provide API to query for keyboard state at any 
arbitrary moment, whether particular key is pressed or not. Even if we 
only support locking keys (Caps, Num, Scroll, Kana) and control keys 
(Shift, Control, Command, Alt), it will be of great value. Game 
developers will be happy to have such API for all the keys, including 
navigation and letter ones.



>> On Oct 7, 2013, at 3:56 AM, Artem Ananiev <artem.ananiev at> wrote:
>>> On 10/7/2013 2:40 AM, Pedro Duque Vieira wrote:
>>> Hi,
>>> I have the following use case:
>>> When the user presses shift and the mouse is hover the chart component the
>>> cursor must change to an open hand cursor signaling to the user that the
>>> chart is ready for a panning action.
>>> The problem is that for this to be possible I want the chart to be able to
>>> listen to keyboard events even when it doesn't have focus.
>>> I think this is not possible and I wonder why. Swing was the same, you
>>> could only listen to keyboard events if the control had focus. Is this a
>>> technical limitation? If there is no technical limitation I think it would
>>> be better to remove this restriction, I think it is limiting and the above
>>> scenario is a good use case to show that.
>> This is not a technical limitation, it's just the way how it's supposed to work. All the key events are dispatched to the component in focus, this is what input focus is.
>> Scenario you described should be easier to implement in FX than in Swing. In AWT/Swing, input events are dispatched to a single component, while FX is much more flexible. All the events are delivered to a Scene first, then dispatched to the focused component (or component under mouse, for mouse events), then bubbled up back to the Scene. What you need is to register a custom event filter for the scene and listen to all the key events.
>> See Scene.addEventFilter() and Scene.addEventHandler() for details.
>> Thanks,
>> Artem
>>> Thanks, best regards,

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