What happens if you restart drracket and try the same program again? (If the double buffering appears to come back I think I know what happened.)
Robby On Thu, Sep 2, 2010 at 8:15 AM, Nadeem Abdul Hamid <nad...@acm.org> wrote: >> Why do you think it doesn't? > > (I'm assuming you mean: "What makes me think that it is not > double-buffering?") ... > > I have a list of 15 thumbnail images of people and a function that > places pairs of them side by side, using above/beside to create a 133 > x 581 image. i.e. > choose-and-show-pairs : (listof image) -> image > > Now, when I do: > (big-bang PIC-LIST > (on-draw choose-and-show-pairs)) > > I see each individual image getting laid out, one by one, rather > excrutiatingly slowly. The choose-and-show-pairs actually randomizes > the pairing up, and so if I move the mouse over the canvas, apparently > the redraw handler is called, so I see a new set of pairs getting laid > out, very slowly. > > I would have expected a double-buffered implementation to lay out the > images in memory on some bitmap buffer and then quickly transfer the > bitmap buffer to the canvas, so you don't actually witness the effect > of all the above/beside operations happening. > > >> >> >> >> >> On Sep 2, 2010, at 8:52 AM, Nadeem Abdul Hamid wrote: >> >>> Why doesn't 2htdp/universe use double-buffering? >>> >>> --- nadeem >>> _________________________________________________ >>> For list-related administrative tasks: >>> http://lists.racket-lang.org/listinfo/dev >> >> > > > > -- > Nadeem Abdul Hamid > Associate Professor, Computer Science > Berry College > PO Box 5014 > 2277 Martha Berry Hwy NW > Mount Berry, GA 30149-5014 > (706) 368-5632 > http://cs.berry.edu/~nhamid/ > _________________________________________________ > For list-related administrative tasks: > http://lists.racket-lang.org/listinfo/dev > _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/dev