On Nov 15, 2012, at 17:55 , Kyle Sluder <k...@ksluder.com> wrote:
> In particular, I'm concerned about -updateTrackingAreas. This message is
> sent to the view, not the tracking area's owner, but the view itself
> doesn't know about the tracking area. If the owner doesn't happen to be
> a view in the same hierarchy, it's not guaranteed to have
> -updateTrackingAreas called.
A comment squirreled away in the Event Handling guide:
https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/EventOverview/TrackingAreaObjects/TrackingAreaObjects.html
might be relevant to your question. It says:
> "Note that the Application Kit sends updateTrackingAreas to every view
> whether it has a tracking area or not."
If that's so, there'd only be a difficulty if the owner isn't a view.
> Additionally, if the owner is a view, it doesn't receive any information
> via -mouse{Entered,Exited,Moved}: or -cursorUpdate: to differentiate its
> own mouse actions from those of the tracking area. (Yes, there's the
> userInfo property of NSTrackingArea that gets attached to the NSEvent
> argument passed to the tracking area owner—*unless* it's a mouse-moved
> event in which case it doesn't!).
If the view to which the tracking area is attached is a subview of the owner,
then I'd guess this isn't much of a problem**. In more complicated cases, the
owner is likely keeping track of the inside/outside state anyway, which means
it can tell the mouse-moved events apart if it needs to (and it can also
distinguish them with a straightforward "point in rect" test, can't it?**).
** Assuming the code is careful to convert to the right coordinate system.
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