<div dir="ltr">Well, I didn't try to explain _that_ part of the issue here (what I called "b" in my message on the audit trail). It is much more complex and based more on conjecture, so I'm hesitant to even try especially when the existing discussion covers a more general, related problem that is likely to satisfy people. (I hope.)<div>
<br></div><div>Robby</div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Fri, Feb 22, 2013 at 3:56 PM, Sam Tobin-Hochstadt <span dir="ltr"><<a href="mailto:samth@ccs.neu.edu" target="_blank">samth@ccs.neu.edu</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Ok, that makes sense.<br>
<br>
I think you should maybe add the word "floor" in the nitty-gritty<br>
documentation. You might also link from that discussion in the docs<br>
to the Cairo docs here: <a href="http://cairographics.org/operators/" target="_blank">http://cairographics.org/operators/</a> .<br>
However, I can't find anything where they say they round down rather<br>
than to nearest. Grrr. Makes me glad for the Racket documentation<br>
(such as all the nitty-gritty sections you've written).<br>
<div class="HOEnZb"><div class="h5"><br>
On Fri, Feb 22, 2013 at 4:49 PM, Robby Findler<br>
<<a href="mailto:robby@eecs.northwestern.edu">robby@eecs.northwestern.edu</a>> wrote:<br>
> No, I don't think it does. The drawing operation is called "over" and it<br>
> takes two colors (rgb, say), and an alpha and produces a color (rgb). So you<br>
> always start with some solid color in the background and draw the shape on<br>
> top of it, resulting in another color that some other shape can be drawn on<br>
> top of.<br>
><br>
><br>
> On Fri, Feb 22, 2013 at 3:45 PM, Sam Tobin-Hochstadt <<a href="mailto:samth@ccs.neu.edu">samth@ccs.neu.edu</a>><br>
> wrote:<br>
>><br>
>> On Fri, Feb 22, 2013 at 4:40 PM, <<a href="mailto:robby@racket-lang.org">robby@racket-lang.org</a>> wrote:<br>
>> ><br>
>> > + The list of colors is obtained by drawing the image on a white<br>
>> > + background and then reading off the colors of the pixels that were<br>
>> > drawn.<br>
>><br>
>> Is there a particular reason to choose white, as opposed to clear, for<br>
>> the background in this test? Does drawing on a "clear" background<br>
>> even make any sense in this case?<br>
>><br>
>> Sam<br>
><br>
><br>
</div></div></blockquote></div><br></div>