Thanks for the info, Matthew. In looking at the docs again, I see now something that I should have noticed earlier, that the arguments to set-argb-pixels include a bytes?, and that should have been sufficient for me to answer my own question. Sorry for the noise.
On Thu, Sep 13, 2012 at 9:07 AM, Matthew Flatt <mfl...@cs.utah.edu> wrote: > At Mon, 10 Sep 2012 13:00:55 -0700, Danny Yoo wrote: > > Hmm. Something VERY strange is happening with the alphas being > > produced by ico->argb vs the alphas expected by the bitmap functions. > > They seem... flipped! > > The problem seems to be in `argb->bitmap' from > `mrlib/cache-image-snip'. That function creates and old style > bitmap+mask combination (insteda of a bitmap with an alpha channel), > and it uses "alpha" values as mask values (instead of inverting an > alpha value to arrive at a mask). > > Here's a version of `ico->bitmap' that uses `racket/draw' directly and > creates a bitmap with an alpha channel: > > (define (ico->bitmap ico) > (define w (ico-width ico)) > (define h (ico-height ico)) > (define bm (make-bitmap w h)) > (send bm set-argb-pixels 0 0 w h (ico->argb ico)) > bm) > > ____________________ > Racket Users list: > http://lists.racket-lang.org/users >
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