Re: Alpha info from NSBitmapImageRep?
Re: Alpha info from NSBitmapImageRep?
- Subject: Re: Alpha info from NSBitmapImageRep?
- From: Andrew Platzer <email@hidden>
- Date: Thu, 27 Sep 2001 18:22:47 -0700
On Thursday, September 27, 2001, at 06:15 , j o a r wrote:
It's something, but it doesn't help me to decide which of these to use:
kCGImageAlphaNone,
kCGImageAlphaPremultipliedLast, /* For example, premultiplied RGBA *
/
kCGImageAlphaPremultipliedFirst, /* For example, premultiplied ARGB *
/
kCGImageAlphaLast, /* For example, non-premultiplied
RGBA */
kCGImageAlphaFirst, /* For example, non-premultiplied
ARGB */
kCGImageAlphaNoneSkipLast, /* Equivalent to kCGImageAlphaNone.
*/
kCGImageAlphaNoneSkipFirst
A YES from hasAlpha doesn't tell me where that alpha channel is at -
first or last, premultiplied or not. A NO is defenitely useful though,
since then I can use kCGImageAlphaNone.
AppKit bitmap images are always premultiplied RGBA so use
kCGImageAlphaPremultipliedLast.
Andrew
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