Event target of mouse and drag-detected events

Pavel Safrata pavel.safrata at oracle.com
Mon May 27 07:25:30 PDT 2013

Hi Werner,
so you need to distinguish "your" controls from "system" controls. Can 
you mark your controls somehow? For instance by node property or style 
or perhaps even userData or id?

On 27.5.2013 15:52, Werner Lehmann wrote:
> That statement might have been too soon. Consider this FXML:
>     <ScrollPane>
>       <StackPane>
>         <Label text="foo"/>
>       </StackPane>
>     </ScrollPane>
> SceneGraph looks like this:
> ScrollPane
>  - ScrollPaneSkin
>    - StackPane
>      - StackPane
>        - Label
>          - LabelSkin
>            - LabeledText
> A drag or mouse event with target "Label" (or below) would resolve to 
> the (Skinnable) Label, following the parent chain. However, if the 
> event target is one of the stackpanes I cannot distinguish "my" 
> stackpane from the one used by the scrollpane skin. Generally 
> speaking, any skinned node accepting arbitrary children would break 
> this approach.
> Do you see an easy (centralized) way out, or would I have to register 
> event handlers on each target?
> In the latter case I'd have the extra problem of knowing when to 
> unregister the event handlers on nodes in my subtree of the scene 
> graph. This might actually require to listen on all parent properties 
> of the parent chain, probably even with some weak-listeners :-(
> Rgds
> Werner
> On 27.05.2013 14:26, Werner Lehmann wrote:
>> Thanks, Pavel. At least now I know that I am not reinventing a wheel and
>> actually have to check the parent chain of the drag target.
>> On 24.05.2013 13:32, Pavel Safrata wrote:
>>> Hi Werner,
>>> if you don't want to register handlers on the vbox children then yes,
>>> this looks like the best thing to do - the system cannot tell which 
>>> node
>>> in the target's parent chain is your desired target, you need to decide
>>> that manually.
>>> Alternatively, you can have a single handler using the event source and
>>> register it directly to the children.
>>> Regards,
>>> Pavel

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