It still behaves the same. I can literally capture a screenshot of the canvas at any point where only a portion of the pictures have been drawn on it.
On Thu, Sep 2, 2010 at 9:53 AM, Robby Findler <[email protected]> wrote: > 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 <[email protected]> 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
