Hi all,First off, please forgive my coding style -- that is something to clean up after the functionality is working. Also, please let me know if there's a better way to attach code or screenshots.
I was writing a bit of code to generate a diagram, and bumped into an off-by-one error. Not sure whether its in my understanding of or use of the 2htdp/image library. Testing on DrRacket 5.3.1 on 64-bit linux.
----- begin test.rkt
#lang racket
(require 2htdp/image)
(define (stack wordlist)
(let ((boxes '())
(maxwidth 0))
(for ((w wordlist))
(let* ((txt (text w 24 "black"))
(width (image-width txt)))
(set! boxes (cons txt boxes))
(when (> width maxwidth)
(set! maxwidth width))))
(let ((box (rectangle (* maxwidth 1.2)
(* (image-height (text "Gg" 24 "black")) 1.2)
"outline" "black"))
(img empty-image))
(for ((b boxes))
(set! img (above (overlay box b)
(if (equal? img empty-image)
empty-image
(line 0 15 "black"))
img)))
img)))
(stack '("hello" "world" "1" "2" "3"))
(save-image (stack '("hello" "world" "1" "2" "3")) "stack.png")
----- end test.rkt
The code runs, but there is a one-pixel white gap between each (line 0
15 "black") and the box below it. Also, the anti-aliasing is
rendering the line into the box above it. The save-image output is
attached (and matches a screenshot).
Now the questions. What is the preferred image library in Racket? Am I misusing 'above, or is there an off-by-1 error in its implementation? (e.g. in above/internal or overlay/δ in collects/2htdp/private/image-more.rkt)
Thanks, Daniel
<<attachment: stack.png>>
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