[plt-scheme] changing background in slideshow

I don't know if this is the "correct" way. But here's what I do:

The parameter 'current-slide-assembler' is a function that gets to
adjust every slide before it gets displayed. You can set this for the
entirety of the slideshow of just parameterize a bit of code. Here's
something to put an icon in the upper right corner:

(define-runtime-path logo-path "PLTnolarval-small.jpg")
(define top-right-logo (bitmap logo-path))

(define (icon-assembler
         #:logo-scale [logo-scale 1])
  (let ([orig (current-slide-assembler)])
    (current-slide-assembler
     (lambda (title sep content)
       (rt-superimpose
        (size-in-pixels (scale top-right-logo logo-scale))
        (cc-superimpose (orig title sep content)
                        full-page))))))

Then just start off with:

(icon-assembler)

And the parameter is set. You could obviously load a bitmap or
rectangle of a particular color and use cc-superimpose to put it
behind everything.

Jay

On Fri, Dec 25, 2009 at 5:05 PM, Faré <fahree at gmail.com> wrote:
> Dear PLTers,
>
> I'm looking for a better tool to write my slides, and I am getting
> interested in slideshow. However, there is a feature that I need:
>
> (how) can I get slideshow to display a different background depending
> on the slide I am showing?
>
> a different color would be a start, ideally, a different vector
> graphic specified in a lispy language would be even better.
>
> (I prepared a presentation earlier this year using rst2s5, but its UI
> doesn't allow for this kind of trick that I know of, and Alan Bawden
> suggested that this particular presentation would be much better
> understood if I used color to contrast slides with the "bad" point of
> view from slides with the "good" point of view, and slides with an
> even "better" point of view.)
>
> [ François-René ÐVB Rideau | Reflection&Cybernethics | http://fare.tunes.org ]
> We [the French] will accept any master who will let us enjoy the good life,
> with good food, romance and long vacations; and we'll use that good life to
> corrupt whoever will rule us into embracing our way of life. Yet we'll
> abandon him for a stronger master the moment that his weakness is apparent.
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-- 
Jay McCarthy <jay at cs.byu.edu>
Assistant Professor / Brigham Young University
http://teammccarthy.org/jay

"The glory of God is Intelligence" - D&C 93