Hi Kevin,
On May 2, 2009, at 6:42 AM, Kevin McGuinness wrote:
Hi,
I'm wondering if it is possible to use the userData field of NSEvent
in
MacRuby. I want to add tracking rectangles to a NSView subclass, and
store
the object that is mouse has entered in the userData field.
Something along
the lines of:
addTrackingRect(rect, owner:self, userData:obj, assumeInside:false)
...
def mouseEntered(event)
obj = event.userData[0]
end
However this produces the runtime error:
can't convert C/Objective-C value `0x800418240' of type `ƿ_\377'
to Ruby
object (ArgumentError)
Is it possible to set the NSEvent userData field at all in MacRuby?
I can
work around if not, but the userData field would be more efficient.
Thanks,
Kevin.
This is a recurrent question on the list, and I unfortunately don't
think it may work. You could allocate a Pointer object, set it to your
object, and pass it to the
addTrackingRect:owner:userData:assumeInside: method (making sure both
the pointer and the object inside the pointer are retained, otherwise
the GC might collect it), then later, call userData and retrieve the
object inside the pointer. The problem is that userData returns ^v and
there is currently no way to "cast" a Pointer object. I will add this
later (RubyCocoa does it IIRC).
I would recommend an alternative solution, because dealing with this
can be cumbersome (and cause GC crashes if you're not careful).
Laurent
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