[plt-scheme] 2htdp/image questions

From: Robby Findler (robby at eecs.northwestern.edu)
Date: Sun Apr 18 16:46:15 EDT 2010

On Sun, Apr 18, 2010 at 3:33 PM, Todd O'Bryan <toddobryan at gmail.com> wrote:
> On Sun, Apr 18, 2010 at 9:07 AM, Robby Findler
> <robby at eecs.northwestern.edu> wrote:
>> As it turns out, That is a bad idea for performance reasons (computing
>> the bitmap is far more expensive than any of the other things that get
>> done to images) but image equality has to do that (in the fallback
>> slow path), so it would not be too hard to add a get-pixel function
>> that first computed the image and the returned the pixel.
> For personal curiosity's sake, do you have to compute the bitmap to
> display the image within DrScheme, or does the translation actually
> happen in the video driver or somewhere else deep in the bowels of the
> OS?

It happens on the graphics card, typically (I believe). But it depends
on various details of the platform (and I'm not sure I know them all;
2htdp/image is written at the Scheme level).


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