> On Dec 29, 2015, at 2:45 PM, Ken Thomases <[email protected]> wrote:
>
> On Dec 29, 2015, at 5:44 AM, Graham Cox <[email protected]
> <mailto:[email protected]>> wrote:
>>
>> On 29 Dec 2015, at 7:44 PM, Roland King <[email protected]> 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 gives false positives if the user simply stops moving the mouse but
> doesn't release the mouse button. There's no delay you can specify that
> avoids this, since there's no upper bound to how long the user can hold the
> mouse button. (With assistive technologies, the user doesn't even have to be
> actually holding anything for the duration.)
>
> Regards,
> Ken
If you want to know when the last value is sent during mouse tracking, set the
‘actionOn’ property to mouse-up.
So, something like this:
- (void)viewDidLoad
{
[super viewDidLoad];
self.slider.action = @selector(valueChangedFinally:);
self.slider.target = self;
[self.slider sendActionOn:NSLeftMouseUpMask];
}
- (IBAction)valueChangedFinally:(id)sender
{
NSLog(@“Here is the final slider value upon mouse up:%@", [sender
stringValue]);
}
Presumably the other bindings/etc. code would still work to update your
real-time display.
Doug Hill
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