Re: CGLayer resolution on iPhone with Retina display
Re: CGLayer resolution on iPhone with Retina display
- Subject: Re: CGLayer resolution on iPhone with Retina display
- From: Ken Ferry <email@hidden>
- Date: Sun, 29 Aug 2010 14:54:12 -0700
On Sun, Aug 29, 2010 at 2:10 PM, David Duncan <email@hidden>wrote:
> On Aug 29, 2010, at 11:21 AM, Matt Neuburg wrote:
>
> > On or about 8/28/10 9:31 PM, thus spake "David Duncan"
> > <email@hidden>:
> >
> >> it is usually far more
> >> useful to use a hardware cache, which means CALayer or UIView, not
> CGLayer.
> >
> > Sorry to keep coming back to this, but the documentation implies that
> > CGLayer *is* a hardware cache - that's why I was using it. For example,
> the
> > documentation says:
>
> It is (potentially) a hardware cache on the desktop in certain situations.
> Nothing in CG is hardware accelerated on iOS however, and CGLayer is no
> exception.
>
Additionally, I don't think it's actually hardware accelerated on the
desktop either.
In practice at the moment, a CGLayer is basically a CGImage together with a
CGBitmapContext. I can think of case where something different happens, but
that case still doesn't use the GPU.
-Ken
Cocoa Frameworks
>
> >> Before you call this or any routine that uses CGLayer objects, you must
> check
> >> to make sure that the system is running Mac OS X v10.4 or later and has
> a
> >> graphics card that supports using CGLayer objects
> >
> > This suggests that CGLayer is implemented in hardware; otherwise surely
> the
> > check for a proper graphics card wouldn't be necessary? But perhaps I'm
> > misunderstanding.... m.
>
>
> If you require hardware acceleration of CGLayer objects perhaps, but to
> simply use CGLayers requires no such check. This would be a bug in the
> documentation.
>
> Much of the shared documentation between iOS and Mac OS X will contain
> information that is incorrect for one platform or another. We strive to
> point out where information applies to only one platform or another, but
> this is an ongoing effort.
> --
> David Duncan
>
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