Re: NSWindow not redrawing subviews
Re: NSWindow not redrawing subviews
- Subject: Re: NSWindow not redrawing subviews
- From: Tamas Nagy <email@hidden>
- Date: Sat, 07 Jan 2017 10:23:27 +0100
Makes sense, thanks Ken!
> On 2017. Jan 7., at 8:55, Ken Thomases <email@hidden> wrote:
>
> On Jan 7, 2017, at 12:59 AM, Tamas Nagy <email@hidden> wrote:
>>
>> This is a video mixer app. There are multiple windows for controlling layers, effects, etc. Rendering is done on a CVDisplayLink thread by OpenGL. Whenever I need to update something on the UI from that CVDisplayLink thread I call dispatch_async(dispatch_get_main…).
>>
>> But double-checking my code I found sometimes I call [NSSlider cell] setFloatValue:] from the CVDisplayLink thread followed by a setNeedsDisplayInRect… on the main thread, but [NSSlider cell] setFloatValue:] might be already calling setNeedsDisplay…? Than it could be the reason of the problem I guess.
>
> Yes, I would expect -setFloatValue: to call a -setNeedsDisplay… method and therefore it's not valid to call it from a background thread.
>
>> Hmm, I should double-check if drawing is always happening from the main thread. What is the common way to do that? Can Instruments helpful to debug that?
>
> I'm not aware of any comprehensive way of doing that.
>
> For calls to -setNeedsDisplay… methods, you can try overriding -setViewsNeedDisplay: in your window subclass and doing NSAssert([NSThread isMainThread], @"views marked as needing display from non-main thread") before calling through to super. Of course, make sure assertions are enabled for your build configuration.
>
> Regards,
> Ken
>
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