Re: How to know if an NSView has pending draws
Re: How to know if an NSView has pending draws
- Subject: Re: How to know if an NSView has pending draws
- From: Doug Hill <email@hidden>
- Date: Thu, 04 Feb 2016 16:35:58 -0800
Jeff,
I was wondering, are you attempting to sync the drawing with the music, or is this a performance issue you’re seeing?
Doug Hill
> On Feb 4, 2016, at 3:52 PM, Jeff Evans <email@hidden> wrote:
>
> Clark, it's a music app; a piece is composed and placed on the screen; there's a lot of massaging going on as the music adjusts visually. I want the play of the example to begin once there are no more updates remaining. That is no noticeable delay in terms of human time, but makes a difference in the appearance.
>
> So I figure: the system presumably knows if it is about to send more redraw requests to that view. Is there any way I could know what it knows?
>
> Jeff
>
>
> On Feb 4, 2016, at 3:31 PM, Clark S. Cox III wrote:
>
>
>> On Feb 4, 2016, at 15:07, Jeff Evans <email@hidden> wrote:
>>
>> Suppose one wants to do a task in an NSView only once it has no drawRect calls pending. Is there any way to tell, for a particular NSView, if there are any drawing events coming up? Whether, that is, the view is up to date?
>>
>> I've tried counting my explicit uses of setNeedsDisplay and decrementing that count at drawRect, but the trouble is that one can call setNeedsDisplay many times and that will not translate into the same number of drawRects.
>>
>> One idea was to call getRectsBeingDrawn at drawRect and hope that the number of rects is equal to the number of update requests combined into that call. But the number of rects does not appear to equal the number of draw requests.
>
> Multiple invalid regions can be merged.
>
>> But there must be some place that contains a queue of upcoming draw requests. If so, is there access to it?
>
> There really isn't any such queue. There are only areas of the view that are marked as invalid.
>
>> I'm hoping this is a dumb question.
>>
>> Thanks, Jeff
>
> I hate to be "that guy", but what are you actually trying to do?
>
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