Re: Scrollers on custom view appearing but not disappearing

FROM : Steve Weller
DATE : Sat Mar 01 17:57:06 2008

On Feb 29, 2008, at 10:33 PM, Quincey Morris wrote:

> A couple of small points:
>
> -- It's not quite correct to use the superview's frame to calculate 
> a view's frame, since they are in different coordinate systems. You 
> really should use [[self superview] bounds], which is in the same 
> coordinate system as [self frame].
>
> The problem is harmless in this case, because the superview is a 
> NSClipView, which happens to keep its frame coordinate system 
> synchronized with that of view it contains, but this is not 
> generally true of view-superview geometry.
>
> -- If you want to refer to the clip view, [[self 
> enclosingScrollView] contentView] is more correct than [self 
> superview]. The fact that they're the same thing is an 
> implementation detail. (But if you're going to pretend not to know 
> they're the same you really should do an explicit coordinate 
> conversion when combining their dimensions.)
>
> -- As someone suggested on this list a few weeks ago, it's perhaps 
> marginally more elegant to use [self visibleRect] instead of the 
> clip view bounds. Although the purpose of the clip view is to manage 
> the visible rect of the view it contains, using the visible rect 
> directly means you don't have to build in knowledge of that 
> implementation detail. And there's no coordinate conversion needed.



Thank you. All very helpful information. I have incorporated the 
changes, added origin offsetting to keep things central, and it works 
perfectly. The last change I made was to manually send the 
notification once the content parameters were set up. That ensured 
that the scrollers appeared when the window was first created.


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