Vendor reveal.js 5.2.1 (from 5.1.0)
Contains the upstream 5.2.x feature set, most notably the lightbox
(data-preview-image/data-preview-video opens media full-size in an
overlay), controls: "speaker-only", search API extensions and
speaker-view fixes. The package's local additions are carried over
unchanged: IDS theme (ids.css/ids.scss), extra theme fonts,
chalkboard/customcontrols/menu plugins, and the 1280x720 default
slide size (patched in js/config.js and the dist bundles).
Also fixes a pre-existing fork bug (unrelated to the upgrade): the
slidechanged Highcharts resize hook in default.html now checks that
Highcharts exists, no longer throwing in decks without highcharter.
Docs: README (Rmd + rendered md) gained a short Lightbox section,
NEWS.md notes the library bump.
Verified: examples/ids.html and examples/simple.html re-render and run
error-free through all 13/5 slides (Reveal.VERSION = 5.2.1); lightbox
opens on click and closes with Esc in a dedicated test deck.
Change-Id: I0751129dfb0c9d20b56241377905876314a26011
diff --git a/README.Rmd b/README.Rmd
index 436b961..4b4a71e 100644
--- a/README.Rmd
+++ b/README.Rmd
@@ -311,6 +311,26 @@
---
```
+## Lightbox
+
+reveal.js 5.2 added a [lightbox](https://revealjs.com/lightbox/): any element on a slide can be turned into a clickable trigger that opens an image or video full-size in a dimmed overlay, without leaving the slide. This is useful for dense figures or tables that should stay readable in the slide layout but be inspectable at full size during a presentation.
+
+Add the corresponding data attribute to an image:
+
+```markdown
+{data-preview-image}
+```
+
+or set it on knitr-generated figures via `out.extra`:
+
+````markdown
+```{r, out.extra='data-preview-image'}
+plot(cars)
+```
+````
+
+Clicking the image on the slide opens it full-size; `Esc` or another click closes the overlay.
+
## MathJax Equations
By default [MathJax](http://www.mathjax.org/) scripts are included in reveal.js presentations for rendering LaTeX and MathML equations. You can use the `mathjax` option to control how MathJax is included: