Re: Overlapping sibling views
Re: Overlapping sibling views
- Subject: Re: Overlapping sibling views
- From: Quincey Morris <email@hidden>
- Date: Tue, 30 Apr 2013 01:30:00 -0700
On Apr 30, 2013, at 00:39 , Gideon King <email@hidden> wrote:
> My scenario is a whole lot of sibling, potentially translucent, overlapping, layer backed views.
I've never seen any evidence that sibling *NSView*s draw in the wrong order since 10.5. I believe that 'drawRect:' is correctly called in the back-to-front order of the sibling arrangement in the parent view.
However, I *have* seen firsthand, in the last few weeks, that the layers of siblings under a layer-backed parent view were composited in a random order. In my case, I had two sibling views, and I observed the bottom one displaying "on top" unpredictably, about 50% of the time.
To be clear, the layers didn't get re-ordered randomly every time they were drawn. The random order was baked into the view or layer hierarchy as part of the view initialization, and didn't change subsequently as long as the view existed.
So from my own experience, I'd agree there is a problem, but I don't know where the problem lies. It may be nothing to do with layers. Perhaps there's currently a bug loading nibs that randomly re-orders sibling views. Perhaps the sibling order in the layer hierarchy doesn't match the order in the view hierarchy. Perhaps the hierarchies are correct but the layer compositing operation is wrong.
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