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: "Clark S. Cox III" <email@hidden>
- Date: Thu, 04 Feb 2016 15:31:52 -0800
> 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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