use the pagebreak feature provided by rmarkdown 1.16 (rstudio/rmarkdo…

…wn#1626)

.travis.yml

@@ -6,6 +6,11 @@ cache: packages
 pandoc_version: 2.3.1
 addons:
   chrome: stable
+  apt:
+    sources:
+      - sourceline: 'ppa:cran/poppler'
+    packages:
+      - libpoppler-cpp-dev
 
 before_install:
   - "curl https://xran.yihui.name/.gitconfig -o ~/.gitconfig"

DESCRIPTION

@@ -19,9 +19,9 @@ Description: Use the paged media properties in CSS and the JavaScript
   pages. Each page can have its page size, page numbers, margin boxes, and
   running headers, etc. Applications of this package include books, letters,
   reports, papers, business cards, resumes, and posters.
-Imports: rmarkdown (>= 1.14), bookdown (>= 0.8), htmltools, jsonlite, later (>= 1.0.0),
+Imports: rmarkdown (>= 1.16), bookdown (>= 0.8), htmltools, jsonlite, later (>= 1.0.0),
   processx, servr (>= 0.13), httpuv, xfun, websocket
-Suggests: promises, testit, xaringan
+Suggests: promises, testit, xaringan, pdftools
 License: MIT + file LICENSE
 URL: https://github.com/rstudio/pagedown
 BugReports: https://github.com/rstudio/pagedown/issues

R/paged.R

@@ -149,6 +149,14 @@ html_format = function(
   css2 = grep('[.]css$', css, value = TRUE, invert = TRUE)
   css  = setdiff(css, css2)
   check_css(css2)
+
+  pandoc_args = c(
+    .pandoc_args,
+    pandoc_args,
+    # use the pagebreak pandoc filter provided by rmarkdown 1.15:
+    if (isTRUE(.pagedjs)) pandoc_metadata_arg('newpage_html_class', 'page-break-after')
+  )
+
   html_document2 = function(..., extra_dependencies = list()) {
     bookdown::html_document2(..., extra_dependencies = c(
       extra_dependencies, .dependencies,
@@ -157,7 +165,7 @@ html_format = function(
   }
   html_document2(
     ..., self_contained = self_contained, mathjax = mathjax, css = css,
-    template = template, pandoc_args = c(.pandoc_args, pandoc_args)
+    template = template, pandoc_args = pandoc_args
   )
 }
 

inst/examples/index.Rmd

@@ -751,6 +751,18 @@ You can modify the horizontal positioning and the font size of the lines numbers
 
 Please note that this feature is sensitive to elements which break the vertical rythm of the text like inline maths.
 
+## Page breaks
+
+There are two ways to force a page break:
+
+- with the `\newpage` $\LaTeX$ command (`\pagebreak` also works)
+
+- using one of these two CSS classes: `page-break-before` or `page-break-after`\
+For example, to force a page break before a given section, use:
+  ```markdown
+  ### New section {.page-break-before}
+  ```
+
 ## MathJax
 
 The following test comes from <http://www.cs.toronto.edu/~yujiali/test/mathjax.html>.

inst/resources/js/config.js

@@ -26,6 +26,13 @@
     insertCSS(text);
   };
 
+  const insertPageBreaksCSS = () => {
+    insertCSS(`
+    .page-break-after {break-after: page;}
+    .page-break-before {break-before: page;}
+    `);
+  };
+
   window.PagedConfig.before = async () => {
     // Front and back covers support
     let frontCover = document.querySelector('.front-cover');
@@ -34,6 +41,7 @@
     if (backCover) document.body.append(backCover);
     insertCSSForCover('front-cover');
     insertCSSForCover('back-cover');
+    insertPageBreaksCSS();
 
     if (beforePaged) await beforePaged();
   };

tests/test-travis.R

@@ -1,2 +1,12 @@
 # run tests on Travis (these tests depend on Chrome)
+
+print_pdf = function(input) {
+  chrome_print(
+    input, tempfile(),
+    # use --no-sandbox with travis
+    # https://docs.travis-ci.com/user/chrome#sandboxing
+    extra_args = c('--disable-gpu', '--no-sandbox')
+  )
+}
+
 if (!is.na(Sys.getenv('CI', NA))) testit::test_pkg('pagedown', 'test-travis')

tests/test-travis/test-chrome.R

@@ -1,14 +1,5 @@
 library(testit)
 
-print_pdf = function(input) {
-  chrome_print(
-    input, tempfile(),
-    # use --no-sandbox with travis
-    # https://docs.travis-ci.com/user/chrome#sandboxing
-    extra_args = c('--disable-gpu', '--no-sandbox')
-  )
-}
-
 is_pdf = function(file) {
   identical(readBin(file, 'raw', 5L), charToRaw('%PDF-'))
 }

tests/test-travis/test-features.R

@@ -0,0 +1,6 @@
+library(testit)
+
+assert('Page breaks work', {
+  f = print_pdf('test-page-breaks.Rmd')
+  (identical(pdftools::pdf_info(f)$pages, 5L))
+})

tests/test-travis/test-page-breaks.Rmd

@@ -0,0 +1,21 @@
+---
+title: "Test page breaks"
+output:
+  pagedown::html_paged:
+    self_contained: false
+    css: null
+---
+
+# First page
+
+\newpage
+
+# Second page
+
+\pagebreak
+
+# Third page {.page-break-after}
+
+# Fourth page
+
+# Fifth page {.page-break-before}