From 03b797ef3e580e447fdc3acb548b7a8a556251a1 Mon Sep 17 00:00:00 2001
From: "David C. Norris" <david@precisionmethods.guru>
Date: Fri, 3 Nov 2023 06:58:57 -0400
Subject: [PATCH] Vignette engines for Quarto (#57)

---
 DESCRIPTION         |  3 ++-
 NAMESPACE           |  1 +
 R/zzz.R             | 24 ++++++++++++++++++++++++
 vignettes/hello.qmd | 36 ++++++++++++++++++++++++++++++++++++
 4 files changed, 63 insertions(+), 1 deletion(-)
 create mode 100644 R/zzz.R
 create mode 100644 vignettes/hello.qmd

diff --git a/DESCRIPTION b/DESCRIPTION
index 94f4f8e..26a99b1 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -22,6 +22,7 @@ Imports:
     rmarkdown,
     rstudioapi,
     utils,
+    tools,
     yaml
 Suggests: 
     curl,
@@ -31,7 +32,7 @@ Suggests:
     withr,
     xfun
 VignetteBuilder: 
-    knitr
+    knitr, quarto
 Config/testthat/edition: 3
 Encoding: UTF-8
 Roxygen: list(markdown = TRUE)
diff --git a/NAMESPACE b/NAMESPACE
index 1c1fcb6..9e9fa9f 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -26,5 +26,6 @@ importFrom(rlang,is_interactive)
 importFrom(rmarkdown,relative_to)
 importFrom(rstudioapi,isAvailable)
 importFrom(rstudioapi,viewer)
+importFrom(tools,vignetteEngine)
 importFrom(utils,browseURL)
 importFrom(yaml,write_yaml)
diff --git a/R/zzz.R b/R/zzz.R
new file mode 100644
index 0000000..ea3fc46
--- /dev/null
+++ b/R/zzz.R
@@ -0,0 +1,24 @@
+
+#' Register engines to support Quarto vignettes
+#' @importFrom tools vignetteEngine
+#' @noRd
+.onLoad <- function(libname, pkgname) { # args ignored
+  vignetteEngine(name = "pdf",
+                 package = "quarto",
+                 pattern = "[.]qmd$",
+                 weave = function(file, ..., encoding = "UTF-8") {
+                   quarto_render(file, ..., output_format = "pdf")
+                 },
+                 tangle = vignetteEngine("knitr::rmarkdown")$tangle,
+                 aspell = vignetteEngine("knitr::rmarkdown")$aspell
+                 )
+  vignetteEngine(name = "html",
+                 package = "quarto",
+                 pattern = "[.]qmd$",
+                 weave = function(file, ..., encoding = "UTF-8") {
+                   quarto_render(file, ..., output_format = "html")
+                 },
+                 tangle = vignetteEngine("knitr::rmarkdown")$tangle,
+                 aspell = vignetteEngine("knitr::rmarkdown")$aspell
+                 )
+}
diff --git a/vignettes/hello.qmd b/vignettes/hello.qmd
new file mode 100644
index 0000000..bd4a093
--- /dev/null
+++ b/vignettes/hello.qmd
@@ -0,0 +1,36 @@
+---
+title: "Quarto Vignettes"
+format:
+  pdf:
+    toc: false
+  html:
+    toc: true
+vignette: >
+  %\VignetteIndexEntry{Vignettes}
+  %\VignetteEngine{quarto::pdf}
+  %\VignetteEncoding{UTF-8}
+---
+
+## Hello Vignette World!
+
+This is an example Quarto vignette, demonstrating how the **quarto** package can let you write package vignettes in Quarto.
+
+## Two Vignette Engines
+
+The **quarto** package registers 2 vignette engines, `quarto::pdf` and `quarto::html`. Either of these may be selected in a Quarto vignette's YAML header. For example, this vignette's header reads:
+```yaml
+---
+title: "Quarto Vignettes"
+format:
+  pdf:
+    toc: false
+  html:
+    toc: true
+vignette: >
+  %\VignetteIndexEntry{Vignettes}
+  %\VignetteEngine{quarto::pdf}
+  %\VignetteEncoding{UTF-8}
+---
+```
+
+Consequently, a PDF version of this vignette is built.