Re: NSView, CALayer, setNeedsDisplay
Re: NSView, CALayer, setNeedsDisplay
- Subject: Re: NSView, CALayer, setNeedsDisplay
- From: Martin Hewitson <email@hidden>
- Date: Sat, 12 Mar 2011 19:41:07 +0100
Many thanks, Kyle. That was all the information I needed to make it work.
Martin
On 12, Mar, 2011, at 07:28 PM, Kyle Sluder wrote:
> On Sat, Mar 12, 2011 at 10:03 AM, Martin Hewitson
> <email@hidden> wrote:
>> Dear list,
>>
>> I have a layer backed view whose layer contains many sublayers. The problem is that the layer doesn't get drawn in the view when the app starts. If I resize the window, then the layer and all its sublayers draw properly. I've solved this problem before with what seemed like a magic collection of [calayer setNeedsDisplay] and [view setNeedsDisplay:YES], but this time I can't seem to get it to work. Therefore, I thought I'd ask if anyone knows the correct way to do this.
>>
>> My view subclass makes its layers like this:
>>
>> - (void) setupLayers
>> {
>> NSLog(@"Setting up layers");
>> CALayer *rootLayer = [CALayer layer];
>> rootLayer.layoutManager = [CAConstraintLayoutManager layoutManager];
>> [self setLayer:rootLayer];
>> [self setWantsLayer:YES];
>
> You don't have a layer-backed view. You have a layer-hosting view.
> This means -setNeedsDisplay: is irrelevant, because -drawRect: doesn't
> do anything.
>
>> yearLayer = [[CAYearLayer alloc] initWithDate:self.year dataSource:self.datasource];
>> [rootLayer addSublayer:yearLayer];
>> [rootLayer setNeedsDisplay];
>> [self setNeedsDisplay:YES];
>> }
>>
>> and the setupLayers is called in awakeFromNib of the view subclass.
>
> Are you sure that "wants layer" is turned OFF in the nib? IIRC, if
> that's turned on, the nib loading machinery will do a delay-perform
> that will change your view's layer *after* -awakeFromNib is called.
> Since you have a layer-hosting view, you do not want that checkbox
> checked.
>
> Rather than calling -setLayer:, you should probably be overriding
> -makeBackingLayer instead. We do that, and then call [self
> setWantsLayer:YES] from -viewDidMoveToSuperview. We also call [[self
> enclosingScrollView] setWantsLayer:YES], which is required if your
> view is contained in a scroll view.
>
> --Kyle Sluder
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Martin Hewitson
Albert-Einstein-Institut
Max-Planck-Institut fuer
Gravitationsphysik und Universitaet Hannover
Callinstr. 38, 30167 Hannover, Germany
Tel: +49-511-762-17121, Fax: +49-511-762-5861
E-Mail: email@hidden
WWW: http://www.aei.mpg.de/~hewitson
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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