Re: Getting the final value from an NSSlider drag
Re: Getting the final value from an NSSlider drag
- Subject: Re: Getting the final value from an NSSlider drag
- From: Graham Cox <email@hidden>
- Date: Tue, 29 Dec 2015 22:44:53 +1100
> On 29 Dec 2015, at 7:44 PM, Roland King <email@hidden> wrote:
>
> I can subclass NSSlider or possibly NSSliderCell but that sounds like a whole world of pain, if I have to do that I’ll probably just put a coalescing delay into the whole thing which waits 1/2 second after an update before it actually does the update.
>
> Any good ways to do this?
In your action method, call another method that handles the final value using -performSelector:withObject:afterDelay: but just before you do that, call +[NSObject cancelPreviousPerformRequestsWithTarget:...] for the same message. This schedules a deferred message but immediately cancels it as long as the values come pouring in. On the last time, when you stop moving the slider, the final -performSelector will get to its target and do its work. The afterDelay parameter can be set to whatever value you think you’ll need to allow for a slowly moved slider NOT to fire the final message. I typically use 0.1sec.
This mechanism is available to any NSObject, and doesn’t require you to roll your own timer-based solution. Behind the scenes this is already doing that.
—Graham
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