On Mar 21, 2014, at 11:58 AM, Laurent <[email protected]> wrote:
> Probably a silly question: Are you drawing in a bitmap (buffer) so that each > calls to the `paint-callback` that refreshes the canvas only does a copy of a > section of the bitmap? Oh, good question! I forgot to mention that. These sounds can be as long as five or 10 minutes; at a 44.1K sample rate, that would be 10x60x44100 = 26 *million* pixels wide, at full zoom. I thought about caching the bitmap for smaller sizes, and trying to add heuristics, but I figured it would just make things more complex without solving the difficult case. > > Also, just in case, `canvas%` can be initialized with `[style > '(no-autoclear)]` to avoid being erased before each call to `paint-callback`. Ah! That’s very helpful, thanks. John ____________________ Racket Users list: http://lists.racket-lang.org/users
