[racket] Slideshow: change baseline

[Laurent]

Hi,

Is it possible in slideshow to change the baseline of a pict?

I have the following code to draw a fraction:

;; Fraction
;; pict? pict? -> pict?
(define (frac a b)
  (vc-append
   a
   (hline (max (pict-width a) (pict-width b)) 20)
   b))

and I want to do some thing like:

(hbl-append (t "x=") (frac (t "1234") (t "5678")))

so that the hline is aligned with the =.

I tried the various procedures like `lift-above-baseline` and such but with no luck.

Thanks,
Laurent

[Matthew Flatt]

The `lift-above-baseline' function should be what you want, but with a
negative offset (so that it actually drops below the baseline).

#lang slideshow

;; Fraction
;; pict? pict? -> pict?
(define (frac a b)

(lift-above-baseline

(vc-append
a
(hline (max (pict-width a) (pict-width b)) 20)
b)

(- (pict-descent b) (pict-height b))))

(slide (hbl-append (t "x=") (frac (t "1234") (t "5678"))))

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[Laurent]

On Wed, May 22, 2013 at 3:47 PM, Matthew Flatt <mfl...@cs.utah.edu> wrote:

(define (frac a b)

  (lift-above-baseline

   (vc-append
    a
    (hline (max (pict-width a) (pict-width b)) 20)
    b)

   (- (pict-descent b) (pict-height b))))

(slide (hbl-append (t "x=") (frac (t "1234") (t "5678"))))

Indeed it works! I had tried with negative values but I probably had done it wrong then.

Thank you!

Laurent