[racket] All black images...Ahhh

From: Matthew Flatt (mflatt at cs.utah.edu)
Date: Tue Jul 20 23:26:46 EDT 2010

At Tue, 20 Jul 2010 22:20:04 -0400, Mathew Kurian wrote:
> Thanks for the update Matt....lemme know once you find a fix.... how long
> will that take? just curious.

I've pushed a repair, so the next build (i.e., a date later than July
20 03:50 EDT) that is available here should work correctly:


The problem was specific to the Windows version of Racket. Drawing a
bitmap with an alpha channel involves generating a variant of the
bitmap (with RGB values that are pre-multiplied by the alpha channel).
Generating the variant can allocate, and therefore might trigger the
little recycle icon in DrRacket during a garbage collection.
Unfortunately, drawing the recycle icon would steal a resource that was
being used to generate the variant bitmap. As a result, the generated
bitmap's RGB (not the alpha part) was all black.

Posted on the users mailing list.