pleasant projects and electronics
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I’m giving a workshop next weekend, and I had to create the slides for that. Since one of the aspirations of mmmfs is to be easily adaptable to any kind of data organization and -presentation task, that was a good opportunity to try and implement a simple slideshow system.

I started by creating a new fileder to hold the slideshow, /workshops/xy-music. In the main facet, I created a MoonScript file. Since the facet needs to access its children (the individual slides), I also used the fn -> type, that injects the current fileder into the script.

text/moonscript -> fn -> mmm/dom

import ReactiveVar, tohtml, fromhtml, text, elements from require 'mmm.component'
import article, button, div, span from elements

  index = ReactiveVar 1
  slide = index\map (index) -> @children[index]

  local view
  view = div {
    style: ... -- styling ommited here

    div {
      style: ... -- styling omitted here

      slide\map => @get 'mmm/dom'

  local left, right
  if MODE == 'CLIENT'
    left = (_, e) ->
      index\transform (a) -> math.max 1, a - 1

    right = (_, e) ->
      index\transform (a) -> math.min #@children, a + 1

  tohtml with article!
    \append div {
      button '<', onclick: left
      ' '
      span index\map (t) -> text t
      ' '
      button '>', onclick: right
    \append view

I used the mmm.component library that lets me create reactive UIs. First I declare the reactive variable index, the current slide number. Then I derive the slide reactive variable, that is defined to be the child with index index - since these are ReactiveVars, whenever index changes, slide will automatically load the current slide fileder.

Then I create the main slide view, which consists mainly of two containers and some styling. Inside, I derive another reactivevar from slide: whenever a new slide is selected, this piece of code will request the main content in mmm/dom format and replace the current view content with that.

Lastly I construct a little navigation UI, consisting of the left and right buttons. When one of them is clicked, it modifies the index variable, making sure to stay in the range of existing slides. The rest of the UI then reactively updates accordingly.

Lastly I added keyboard controls for cycling through the slides, as well as a button to enter fullscreen mode. You can find the extended code for that in the commit ca24ef1, but it is not a lot either: with the additions the file is 70 lines long.

With this done, it is just a matter of creating children-fileders and placing whichever content I want in them, they behave just like any other page of the system now.