From 4573ae4a12f4b927ec6a23930a292ac8dd926447 Mon Sep 17 00:00:00 2001
From: Romain Lesur <romain.lesur@gmail.com>
Date: Wed, 27 Nov 2019 23:48:21 +0100
Subject: [PATCH] add support for PDF generation of reveal.js presentations in
 chrome_print()

---
 DESCRIPTION                         |  4 ++--
 NEWS.md                             |  2 ++
 inst/resources/js/chrome_print.js   | 30 ++++++++++++++++++++++++++---
 tests/test-travis/test-chrome.R     | 11 +++++++++++
 tests/test-travis/test-revealjs.Rmd | 29 ++++++++++++++++++++++++++++
 5 files changed, 71 insertions(+), 5 deletions(-)
 create mode 100644 tests/test-travis/test-revealjs.Rmd

diff --git a/DESCRIPTION b/DESCRIPTION
index 9888f0a6..45aff20b 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,7 +1,7 @@
 Package: pagedown
 Type: Package
 Title: Paginate the HTML Output of R Markdown with CSS for Print
-Version: 0.6.1
+Version: 0.6.2
 Authors@R: c(
   person("Yihui", "Xie", role = c("aut", "cre"), email = "xie@yihui.name", comment = c(ORCID = "0000-0003-0645-5666")),
   person("Romain", "Lesur", role = c("aut", "cph"), comment = c(ORCID = "0000-0002-0721-5595")),
@@ -21,7 +21,7 @@ Description: Use the paged media properties in CSS and the JavaScript
   reports, papers, business cards, resumes, and posters.
 Imports: rmarkdown (>= 1.16), bookdown (>= 0.8), htmltools, jsonlite, later (>= 1.0.0),
   processx, servr (>= 0.13), httpuv, xfun, websocket
-Suggests: promises, testit, xaringan, pdftools
+Suggests: promises, testit, xaringan, pdftools, revealjs
 License: MIT + file LICENSE
 URL: https://github.com/rstudio/pagedown
 BugReports: https://github.com/rstudio/pagedown/issues
diff --git a/NEWS.md b/NEWS.md
index 4ae18bbb..05a86e1f 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -4,6 +4,8 @@
 
 - Added support for pagebreaks: in output formats which use **paged.js**, a pagebreak can be forced using the LaTeX commands `\newpage` and `\pagebreak` or using the CSS classes `page-break-before` and `page-break-after`.
 
+- **reveal.js** presentations can be printed to PDF using `chrome_print()`. 
+
 # CHANGES IN pagedown VERSION 0.6
 
 ## MINOR CHANGES
diff --git a/inst/resources/js/chrome_print.js b/inst/resources/js/chrome_print.js
index e3329afa..581687b8 100644
--- a/inst/resources/js/chrome_print.js
+++ b/inst/resources/js/chrome_print.js
@@ -1,4 +1,23 @@
-(() => {
+{
+  let RevealReady = new Promise((resolve) => {
+    window.addEventListener(
+      'DOMContentLoaded',
+      () => {
+        if (window.Reveal) {
+          if (!window.location.search.match( /print-pdf/gi )) {
+            window.location.search = 'print-pdf';
+            return;
+          }
+          Reveal.addEventListener('ready', resolve);
+          if (Reveal.isReady()) resolve();
+        } else {
+          resolve();
+        }
+      },
+      {capture: true, once: true}
+    );
+  });
+
   let HTMLWidgetsReady = new Promise((resolve) => {
     window.addEventListener(
       'DOMContentLoaded',
@@ -40,5 +59,10 @@
     );
   });
 
-  window.pagedownReady = Promise.all([MathJaxReady, HTMLWidgetsReady, document.fonts.ready]);
-})();
+  window.pagedownReady = Promise.all([
+    RevealReady,
+    MathJaxReady,
+    HTMLWidgetsReady,
+    document.fonts.ready
+  ]);
+}
diff --git a/tests/test-travis/test-chrome.R b/tests/test-travis/test-chrome.R
index 18b8dfcb..a6c90905 100644
--- a/tests/test-travis/test-chrome.R
+++ b/tests/test-travis/test-chrome.R
@@ -21,3 +21,14 @@ assert('chrome_print() works with a local file path', {
 assert('chrome_print() works with html_paged format', {
   (is_pdf(print_pdf('test-chrome.Rmd')))
 })
+
+assert('chrome_print() works with reveal.js presentations', {
+  f = print_pdf('test-revealjs.Rmd')
+
+  (is_pdf(f))
+
+  (identical(pdftools::pdf_info(f)$pages, 5L))
+
+  first_page_text_content = pdftools::pdf_text('reveal.pdf')[1]
+  (identical(first_page_text_content, 'Test reveal.js'))
+})
diff --git a/tests/test-travis/test-revealjs.Rmd b/tests/test-travis/test-revealjs.Rmd
new file mode 100644
index 00000000..f78d4133
--- /dev/null
+++ b/tests/test-travis/test-revealjs.Rmd
@@ -0,0 +1,29 @@
+---
+title: "Test reveal.js"
+output: revealjs::revealjs_presentation
+---
+
+## R Markdown
+
+This is an R Markdown presentation. Markdown is a simple formatting syntax for authoring HTML, PDF, and MS Word documents. For more details on using R Markdown see <http://rmarkdown.rstudio.com>.
+
+When you click the **Knit** button a document will be generated that includes both content as well as the output of any embedded R code chunks within the document.
+
+## Slide with Bullets
+
+- Bullet 1
+- Bullet 2
+- Bullet 3
+
+## Slide with R Code and Output
+
+```{r}
+summary(cars)
+```
+
+## Slide with Plot
+
+```{r, echo=FALSE}
+plot(cars)
+```
+