Re: NSBitmapImageRep
Re: NSBitmapImageRep
- Subject: Re: NSBitmapImageRep
- From: John Stiles <email@hidden>
- Date: Thu, 21 Jun 2007 18:17:06 -0700
On Jun 21, 2007, at 6:13 PM, Scott Stevenson wrote:
On Jun 20, 2007, at 2:58 PM, John Stiles wrote:
Is there any way to tell -initWithBitmapDataPlanes::::: that the
color channels are in reverse order? I couldn't see any option for
this in the API reference but it seems like a fairly common issue.
(OpenGL, for instance, has an incredible variety of supported
image types and is smart enough to convert from what you have to
what the card needs.)
At the end of the day I just need an NSImage, so if there is
another API better suited for the talk that's supported on 10.4.x,
I'd be interested to learn more.
I do have a simple workaround—just byteswap all the image data by
hand before calling this method. This works fine and it was only a
few lines of code, so I can use that if necessary. I'd just like
to know if there is a better way.
I don't think there's anything built in that does this
automatically, but vImage is very good for this sort of low-level
conversion, and has the benefit of using whatever special vector
units are available on the host chip architecture.
vImagePermuteChannels() could do what you want.
<http://developer.apple.com/documentation/Performance/Conceptual/
vImage/>
Interesting find, though I can't help but wonder if its performance
is any good on Intel—it looks pretty tuned for Altivec… :) Right now
it's not performance critical, so a simple byteswapping loop is doing
the trick for us.
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