Build PDF through tinytex::latexmk() (#1222)

* use tinytex::latexmk() if available

* always use latexmk() to create PDF and never use Pandoc to create the PDF directly

this will make it faster to build PDF with keep_tex, because Pandoc does not need to convert Markdown to LaTeX twice (once for .tex, and once for .pdf)

* load quietly

* tinytex is on CRAN now, so no longer need to load it from the dark

* a news item for the PR #1222

* remove version requirement of tinytex

* always assume the output file is PDF unless it has the extension .tex

* see if _R_CHECK_TESTS_NLINES_ works (I want to seem more lines of output when the check fails)

* preinstall the LaTeX package units

* tweak comments

.travis.yml

@@ -5,8 +5,12 @@ cache:
 pandoc_version: 1.19.2.1
 
 env:
-  - PANDOC_VERSION=default
-  - PANDOC_VERSION=latest PATH=$HOME/bin:$PATH
+  global:
+    - _R_CHECK_TESTS_NLINES_=0
+  matrix:
+    - PANDOC_VERSION=default
+    - PANDOC_VERSION=latest PATH=$HOME/bin:$PATH
 
 before_install:
   - "[[ ${PANDOC_VERSION} = latest ]] && ./tools/install-pandoc.sh || true"
+  - tlmgr install units

DESCRIPTION

@@ -74,6 +74,7 @@ Imports:
     methods,
     stringr (>= 1.2.0)
 Suggests:
+    tinytex,
     shiny (>= 0.11),
     tufte,
     testthat,

R/render.R

@@ -647,25 +647,23 @@ render <- function(input,
       status
     }
     texfile <- file_with_ext(output_file, "tex")
-    # compile Rmd to tex when we need to generate bibliography with natbib/biblatex
-    if (need_bibtex) {
-      convert(texfile)
-      # manually compile tex if PDF output is expected
-      if (grepl('[.]pdf$', output_file)) {
+    # determine whether we need to run citeproc (based on whether we have
+    # references in the input)
+    run_citeproc <- citeproc_required(yaml_front_matter, input_lines)
+    # if the output format is LaTeX, first convert .md to .tex, and then convert
+    # .tex to .pdf via latexmk() if PDF output is requested (in rmarkdown <=
+    # v1.8, we used to call Pandoc to convert .md to .tex and .pdf separately)
+    if (output_format$pandoc$keep_tex || knitr:::is_latex_output()) {
+      # do not use pandoc-citeproc if needs to build bibliography
+      convert(texfile, run_citeproc && !need_bibtex)
+      # unless the output file has the extension .tex, we assume it is PDF
+      if (!grepl('[.]tex$', output_file)) {
         latexmk(texfile, output_format$pandoc$latex_engine, '--biblatex' %in% output_format$pandoc$args)
         file.rename(file_with_ext(texfile, "pdf"), output_file)
+        # clean up the tex file if necessary
+        if (!output_format$pandoc$keep_tex) on.exit(unlink(texfile), add = TRUE)
       }
-      # clean up the tex file if necessary
-      if ((texfile != output_file) && !output_format$pandoc$keep_tex)
-        on.exit(unlink(texfile), add = TRUE)
     } else {
-      # determine whether we need to run citeproc (based on whether we
-      # have references in the input)
-      run_citeproc <- citeproc_required(yaml_front_matter, input_lines)
-      # generate .tex if we want to keep the tex source
-      if (texfile != output_file && output_format$pandoc$keep_tex)
-        convert(texfile, run_citeproc)
-      # run the main conversion if the output file is not .tex
       convert(output_file, run_citeproc)
     }
 

R/util.R

@@ -314,6 +314,10 @@ escape_regex_metas <- function(in_str) {
 
 # call latexmk to compile tex to PDF; if not available, use a simple emulation
 latexmk <- function(file, engine, biblatex = FALSE) {
+  if (requireNamespace('tinytex', quietly = TRUE)) {
+    return(tinytex::latexmk(file, engine, if (biblatex) 'biber' else 'bibtex'))
+  }
+  warning('You are recommended to install the tinytex package to build PDF.', call. = FALSE)
   if (!grepl('[.]tex$', file))
     stop("The input file '", file, "' does not appear to be a LaTeX document")
   engine <- find_latex_engine(engine)

inst/NEWS

@@ -1,6 +1,10 @@
 rmarkdown 1.9 (unreleased)
 --------------------------------------------------------------------------------
 
+## MAJOR CHANGES
+
+* If the **tinytex** package is installed, PDF output is built through `tinytex::latexmk()`, otherwise it is generated by `rmarkdown:::latexmk()`, which has been factored out and improved in the **tinytex** package, so it is recommended that you install the **tinytex** package (#1222).
+
 ## BUG FIXES
 
 * Temporary files created in `render()` may be cleaned up prematurely, which can cause problems with Shiny R Markdown documents (#1184).