On Wed, 16 Aug 2017 18:39:56 -0500, Ken Thomases said: >On Aug 16, 2017, at 6:29 PM, Sean McBride <s...@rogue-research.com> wrote: >> >> >> Right, but then I'm back where I started. :( Because there's >(apparently) no way to ensure that the NSBitmapImageRep I get is in a >particular format, and I absolutely need 8 bit per pixel & greyscale. > >It's quite old now, but the 10.6 AppKit release notes had a lot of good >information about working with images in Cocoa viz. Core Graphics. From ><https://developer.apple.com/library/content/releasenotes/AppKit/RN- >AppKitOlderNotes/#X10_6Notes>, search for "NSImage, CGImage, and >CoreGraphics impedance matching" and read from there. > >They also have advice about what you're trying to do. The advice is to >*not* try to interpret an arbitrary image rep's bitmap data. It's to >make a bitmap with the format you desired and draw the source image into >it. Then, you have bitmap data in the format you want, for sure. For >that, search for "NSBitmapImageRep: CoreGraphics impedance matching and >performance notes".
Thanks, that's quite helpful! I know I've read it before, but forgot to recheck those release notes, they sure are great, I'm glad Apple writes them! I also found 'QA1509: Getting the pixel data from a CGImage object' which is even older, but was useful too. I also found vImageBuffer_InitWithCGImage() which has been great! So my typical data is 1280x1024. With NSBitmapImageRep I can't get it into an NSData in 30 ms, whereas with CGImageCreateWithJPEGDataProvider() + vImageBuffer_InitWithCGImage() it takes only 9 ms and produces byte-for-byte identical results interestingly enough. I suspect bitmapData makes a copy somewhere. Cheers, -- ____________________________________________________________ Sean McBride, B. Eng s...@rogue-research.com Rogue Research www.rogue-research.com Mac Software Developer Montréal, Québec, Canada _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
