That's an interesting variation on the problem at hand and I'm curious about other's opinions of a function that takes two images and two pairs of coordinates, but there are pinholes in 2htdp/image -- do have a look at them and see what you think there!
Robby On Mon, Jan 31, 2011 at 1:27 PM, Stephen Bloch <sbl...@adelphi.edu> wrote: > > On Jan 31, 2011, at 7:43 AM, Robby Findler wrote: > >> How close does underlay/xy get to a function that seems useful? >> >> Also: what if I were to add overlay/align/xy and underlay/align/xy >> that accepted two images, a x-place, a y-place and a dx,dy coordinates >> that adjusted the x and y places by those amounts? Would that satisfy >> or is that getting too complex? > > Off the top of my head, that sounds too complex. And still not "fully > general": do the x-place and y-place refer to the first image, or the second? > Whichever they don't apply to, what part of that image is to be lined up > with the offset relevant part of the other one? > > Perhaps a more flexible and yet easier-to-remember solution is > "overlay/pinholes" which takes an image, two numbers, another image, and two > more numbers. We don't have to actually reintroduce pinholes, just have it > behave like > > (define (overlay/pinholes pic1 x1 y1 pic2 x2 y2) > (overlay (put-pinhole x1 y1 pic1) (put-pinhole x2 y2 pic2))) > > The real point of eliminating pinholes (as far as I'm concerned) is that an > image doesn't "know" its own pinhole. You can't have two otherwise-identical > images fail to be equal? just because they have different pinholes. When > writing a function that produces an image, you don't have to decide where to > put the pinhole. But pinholes can still be a legitimate part of an > OPERATION, not a DATA OBJECT. > > > > Stephen Bloch > sbl...@adelphi.edu > > _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
