Polylux Integration

[johannes-wolf]

This PR adds integration for the Polylux module by @andreasKroepelin.
The code currently uses private functions from Polylux logic.typ, maybe those could be made public @andreasKroepelin (see /src/lib/polylux.typ)?

To use Polylux with CeTZ, the user has to pass the Polylux module to the canvas. This allows using different Polylux versions with CeTZ, without CeTZ having a dependency on Polylux.

For an example, see the test case.
The following Polylux functions are available from cetz.polylux:

• only
• uncover

@fenjalien, to be able to modify state (counters) I've added a list of functions to ctx that get executed in the canvas function and allow returning content prior to the canvas block. Since the content returned by counter updates is not visible, this should be fine. I could not come up with a better solution.

We could also implement this binding on the Polylux side.

With #494 there is a proof-of-concept for a plug-in API either Polylux or a package like cetz-polylux could use for providing the Polylux bindings.

[andreasKroepelin]

Wow, that's cool! What Polylux functions specifically should be made public?

[johannes-wolf]

Wow, that's cool! What Polylux functions specifically should be made public?

See https://github.com/johannes-wolf/cetz/pull/492/files#diff-3d4562bd25428e8bd4aabe76e4f474ce42c427243eab52f8e09b121f1f687d4e

I had to replicate _conditional-display (which I guess is fine) and I am calling _last-required-subslide and _check-visible + using the repetitions and subslides counters.

[OrangeX4]

As a lower-level foundational graphics package, should cetz rely on higher-level slide packages like polylux and touying, especially when adding a polylux parameter to cetz's canvas? I remain skeptical. I feel that even if support for slides is to be added, it should be done by finding a way for cetz to extract a better interface. For example, adding a parameter "current subslide index" to canvas and letting polylux depend on cetz, rather than the other way around.

For example, touying now supports the use of only in cetz (thanks for the code from polylux). So I thought there might be a better way to deal with the direction of dependency.

#import "@preview/touying:0.2.0": *
#import "@preview/cetz:0.2.0"

#(s.page-args.width = auto)
#(s.page-args.height = auto)
#(s.page-args.footer = none)
#let (init, slide) = utils.methods(s)
#show: init

#slide(repeat: 3, self => [
  #let (only,) = utils.methods(self)

  Current index: #self.subslide

  #cetz.canvas({
    import cetz.draw: *

    rect((-1,-1), (1,1), fill: red)
    only(2, circle((.5,.3), fill: blue))
    only("2-3", {
      line((.2,.1), (rel: (1,1.3)), (rel: (.7, -1.8)), fill: green, close: true)
      content((0, -2), [Hello])
    })
  })
])

[OrangeX4]

Like here: #251 (comment)

[fenjalien]

Closing this as @johannes-wolf and I figured last night that CeTZ should not be the package containing the integrations/plugins from other packages. They should be in the integrating package or a separate package. We are working on making integrations easier in #494, @OrangeX4 and @andreasKroepelin please join us there to discuss.