On Tue, May 4, 2010 at 9:30 AM, David Duncan <david.dun...@apple.com> wrote:
> On May 4, 2010, at 8:57 AM, Thomas Davie wrote: > > > After much searching about, I discovered (contrary to what the docs say), > that NSBitmapImageReps do not always premultiply their r/g/b by their alpha. > > I think you're misreading something. NSAlphaNonpremultipliedBitmapFormat exists. :-) Other than that, what David said. You should never be calling -bitmapData on an NSBitmapImageRep that you did not create explicitly yourself in a known pixel format. The 10.6 AppKit release notes<http://developer.apple.com/mac/library/releasenotes/cocoa/appkit.html>have a long discussion of such things, concerning performance and correctness. -Ken > Because of this, I've dived in, and attempted to write my own > premultiplication, but something is going very wrong. Some images are > coming out a quarter of the width they went in, others coming out completely > empty... > > > Before diving too deeply into you code, why do you want to do this > manually? Why not just create a second NSBitmapImageRep with the geometry > that you desire, then draw the first into the second? This should do the > premultiplication for you as well as cover any format that NSBitmapImageRep > supports, rather than the ones that you manually code (as well as being more > efficient since we've spent the effort to performance optimize those > conversions). > -- > David Duncan > Apple DTS Animation and Printing > > _______________________________________________ > > 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: > http://lists.apple.com/mailman/options/cocoa-dev/kenferry%40gmail.com > > This email sent to kenfe...@gmail.com > _______________________________________________ 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: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
