[ltk-user] canvas objects

nik gaffney nik at fo.am
Sat Jan 28 15:24:48 UTC 2006


>> Ive been playing around with the canvas widget, and was wondering if there is a
>> way to find if a created object is 'selected', or at the same coordinates as
>> (ltk:event-x ltk:event-y) without having to manually keep track of each object
>> on the canvas.
> 
> It sounds as if you bound an event handler to the canvas widget and
> then tried to find a corresponding canvas item. The canvas widget is
> really powerful and provides event handlers on the items themselves,
> i.e.
> 
> (let ((item (create-line canvas (list x1 y1 x2 y2))))
>   (itembind canvas item "<Enter>" (lambda (ev)
> 				    (format t "entered item ~A~%" item)))
>   (itembind canvas item "<Leave>" (lambda (ev)
> 				    (format t "left item ~A~%" item))))
> 

Thanks. I didnt realise that items could also have event handlers, so this
simplifies things substantially.

nik





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