On Jun 16, 2011, at 14:57, Leonardo wrote: > I would like to reach the same effect as UIScrollView.pagingEnabled, but on > an NSScrollView. Can that be done? > > If not, which technique should I use? > I thought to deal with NSAnimationContext to move the scrollView's document > with scrollPoint: when a scrolling ends (the finger stops dragging on the > track-pad). Am I on the right way?
NSScrollView is not designed to have this behavior, so you'll have to do the work. The basic approach is to have (say) your window controller monitor the scroll view's clip view's frame- and bounds-changed notifications. When you receive these notifications, you examine the relationship between the "clip" view bounds and the "document" (i.e. enclosed) view frame, and adjust the relationship to align the two views however you want. To detect when scrolling "ends", you can use a well-known trick. When you see a notification, don't perform the scrolling adjustment immediately, but schedule it for "later" using 'performSelector: ... afterDelay: 0'. Since you don't want multiple deferred adjustments to get queued, you first cancel any pending ones with one of the 'cancelPrevious...' or 'cancelPerform...' methods, just before invoking 'performSelector:...'. That way, the last one "wins". If you want to have this adjustment animate, you should be able to use the appropriate view's animator or NSViewAnimation to move the document view frame. The only difficulty I can think of is if Lion's trackpad gesture-based scrolling itself has some animation built into it (e.g. an iOS-like "bounce"). In that case you might have some trouble trying to integrate your animation with the built-in one. However, given that all of this is not expected Mac scroll view behavior, unless you have a *very* compelling need for it, I'd recommend you don't do it. NSScrollView responds to the Page Up and Page Down keys for paging. Why limit the user to where you think the page boundaries are? _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
