At Sat, 10 Sep 2016 01:10:53 -0700 (PDT), Lehi Toskin wrote: > On Friday, September 9, 2016 at 7:45:32 PM UTC-7, Matthew Flatt wrote: > > You could use 'unknown/mask, which should create a mask bitmap only if > > the source stream has an alpha channel, but at the expense of parsing > > the file an extra time. > > Running `(read-bitmap img 'unknown/mask)` produces a bitmap with a > mask, but the problem I'm seeing is that every image, no matter the > type, will return a mask. Images that have no alpha channel (I tested > several jpegs and pngs) will produce an all-black bitmap of the same > size as the image.
Ah, ok. I was going more by the docs than by memory or looking at the code (so I think the docs are misleading, and I'll adjust them). I think that means information about the source stream's alpha channel really is not available through the current interface. A pull request to add that would be welcome. -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
