From de8f0dab67a5c37e0752e89c1a9fe102ec773a75 Mon Sep 17 00:00:00 2001
From: Benjamin Abel <dev.abel@free.fr>
Date: Sun, 29 Sep 2024 08:20:57 +0200
Subject: [PATCH] Implement CeTZ diagrams (#38)

Closes: #37
---
 .github/workflows/ci.yaml       | 14 ++++++++
 Makefile                        |  2 +-
 README.md                       |  2 ++
 _extensions/diagram/diagram.lua | 37 +++++++++++++++++--
 test/expected-cetz.html         | 11 ++++++
 test/input-cetz.md              | 63 +++++++++++++++++++++++++++++++++
 test/test-cetz.yaml             |  9 +++++
 7 files changed, 135 insertions(+), 3 deletions(-)
 create mode 100644 test/expected-cetz.html
 create mode 100644 test/input-cetz.md
 create mode 100644 test/test-cetz.yaml

diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index f20e8cc..58941f3 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -153,6 +153,20 @@ jobs:
       - name: Test
         run: 'make test-tikz'
 
+  Cetz:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: true
+    container:
+      image: ghcr.io/quarto-dev/quarto:latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Render
+        run: make PANDOC=/opt/quarto/bin/tools/x86_64/pandoc test-cetz
+  
   Quarto:
     runs-on: ubuntu-latest
     strategy:
diff --git a/Makefile b/Makefile
index a1965d9..2a3604d 100644
--- a/Makefile
+++ b/Makefile
@@ -4,7 +4,7 @@ DIFF ?= diff
 
 .PHONY: test
 test: test-asymptote test-dot test-mermaid test-plantuml test-tikz \
-	test-no-alt-or-caption
+	test-no-alt-or-caption test-cetz
 
 test-%: test/test-%.yaml test/input-%.md $(FILTER_FILE)
 	@$(PANDOC) --defaults test/test-$*.yaml | \
diff --git a/README.md b/README.md
index 6af6e47..3b18348 100644
--- a/README.md
+++ b/README.md
@@ -102,6 +102,7 @@ that can be used to specify a specific executable.
 | [Mermaid]   | `mermaid`         | `mmdc`     | `MERMAID_BIN`   |
 | [PlantUML]  | `plantuml`        | `plantuml` | `PLANTUML_BIN`  |
 | [Ti*k*Z]    | `tikz`            | `pdflatex` | `PDFLATEX_BIN`  |
+| [cetz]      | `cetz`            | `typst`    | `TYPST_BIN`     |
 
 ### Other diagram engines
 
@@ -113,6 +114,7 @@ The filter can be extended with local packages; see
 [Mermaid]: https://mermaid.js.org/
 [PlantUML]: https://plantuml.com/
 [Ti*k*Z]: https://github.com/pgf-tikz/pgf
+[Cetz]: https://github.com/cetz-package/cetz
 
 Figure options
 --------------
diff --git a/_extensions/diagram/diagram.lua b/_extensions/diagram/diagram.lua
index ea3547d..46df24e 100644
--- a/_extensions/diagram/diagram.lua
+++ b/_extensions/diagram/diagram.lua
@@ -99,7 +99,8 @@ local function pipe (command, args, input)
   if pandoc.utils.type(command) == 'List' then
     command = command:map(stringify)
     cmd = command:remove(1)
-    args = command:extend(args)
+    command:extend(args)
+    args = command
   else
     cmd = stringify(command)
   end
@@ -253,12 +254,45 @@ local asymptote = {
   end,
 }
 
+--- Cetz diagram engine
+local cetz = {
+  line_comment_start = '%%',
+  mime_types = mime_types_set{'jpg', 'pdf', 'png', 'svg'},
+  mime_type = 'image/svg+xml',
+  compile = function (self, code)
+    local mime_type = self.mime_type
+    local format = extension_for_mimetype[mime_type]
+    if not format then
+      format, mime_type = 'svg', 'image/svg+xml'
+    end
+    local preamble = [[
+#import "@preview/cetz:0.2.2"
+#set page(width: auto, height: auto, margin: .5cm)
+]]
+    
+    local typst_code = preamble .. code
+
+    return with_temporary_directory("diagram", function (tmpdir)
+      return with_working_directory(tmpdir, function ()
+        local outfile = 'diagram.' .. format
+        pipe(
+          self.execpath or 'typst',
+          {"compile", "-f", format, "-", outfile},
+          typst_code
+        )
+        return read_file(outfile), mime_type
+      end)
+    end)
+  end,
+}
+
 local default_engines = {
   asymptote = asymptote,
   dot       = graphviz,
   mermaid   = mermaid,
   plantuml  = plantuml,
   tikz      = tikz,
+  cetz      = cetz,
 }
 
 --
@@ -365,7 +399,6 @@ local function configure (meta, format_name)
   }
 end
 
-
 --
 -- Format conversion
 --
diff --git a/test/expected-cetz.html b/test/expected-cetz.html
new file mode 100644
index 0000000..9d2c0a3
--- /dev/null
+++ b/test/expected-cetz.html
@@ -0,0 +1,11 @@
+<h1 id="cetz">Cetz</h1>
+<p>The image <a
+href="https://github.com/cetz-package/cetz/blob/master/gallery/karls-picture.typ">code</a>
+comes from the cetz docs licensed under <a
+href="https://github.com/cetz-package/cetz/blob/master/LICENSE">LGPLv3</a>.</p>
+<figure>
+<img src="karls.svg" style="width:90.0%"
+alt="This is an image, created with cetz" />
+<figcaption aria-hidden="true"><p>This is an image, created with
+cetz</p></figcaption>
+</figure>
diff --git a/test/input-cetz.md b/test/input-cetz.md
new file mode 100644
index 0000000..692c238
--- /dev/null
+++ b/test/input-cetz.md
@@ -0,0 +1,63 @@
+# Cetz
+
+The image
+[code](https://github.com/cetz-package/cetz/blob/master/gallery/karls-picture.typ)
+comes from the cetz docs licensed under
+[LGPLv3](https://github.com/cetz-package/cetz/blob/master/LICENSE).
+
+```{.cetz caption="This is an image, created with cetz" width=90% filename=karls}
+//| label: fig-auth
+//| class: important
+#show math.equation: block.with(fill: white, inset: 1pt)
+
+#cetz.canvas(length: 5cm, {
+  import cetz.draw: *
+
+  set-style(
+    mark: (fill: black, scale: 2),
+    stroke: (thickness: 0.4pt, cap: "round"),
+    angle: (
+      radius: 0.3,
+      label-radius: .22,
+      fill: green.lighten(80%),
+      stroke: (paint: green.darken(50%))
+    ),
+    content: (padding: 1pt)
+  )
+
+  grid((-1.5, -1.5), (1.4, 1.4), step: 0.5, stroke: gray + 0.2pt)
+
+  circle((0,0), radius: 1)
+
+  line((-1.5, 0), (1.5, 0), mark: (end: "stealth"))
+  content((), $ x $, anchor: "west")
+  line((0, -1.5), (0, 1.5), mark: (end: "stealth"))
+  content((), $ y $, anchor: "south")
+
+  for (x, ct) in ((-1, $ -1 $), (-0.5, $ -1/2 $), (1, $ 1 $)) {
+    line((x, 3pt), (x, -3pt))
+    content((), anchor: "north", ct)
+  }
+
+  for (y, ct) in ((-1, $ -1 $), (-0.5, $ -1/2 $), (0.5, $ 1/2 $), (1, $ 1 $)) {
+    line((3pt, y), (-3pt, y))
+    content((), anchor: "east", ct)
+  }
+
+  // Draw the green angle
+  cetz.angle.angle((0,0), (1,0), (1, calc.tan(30deg)),
+    label: text(green, [#sym.alpha]))
+
+  line((0,0), (1, calc.tan(30deg)))
+
+  set-style(stroke: (thickness: 1.2pt))
+
+  line((30deg, 1), ((), "|-", (0,0)), stroke: (paint: red), name: "sin")
+  content(("sin.start", 50%, "sin.end"), text(red)[$ sin alpha $])
+  line("sin.end", (0,0), stroke: (paint: blue), name: "cos")
+  content(("cos.start", 50%, "cos.end"), text(blue)[$ cos alpha $], anchor: "north")
+  line((1, 0), (1, calc.tan(30deg)), name: "tan", stroke: (paint: orange))
+  content("tan.end", $ text(#orange, tan alpha) = text(#red, sin alpha) / text(#blue, cos alpha) $, anchor: "west")
+})
+
+```
diff --git a/test/test-cetz.yaml b/test/test-cetz.yaml
new file mode 100644
index 0000000..cca62db
--- /dev/null
+++ b/test/test-cetz.yaml
@@ -0,0 +1,9 @@
+input-files: ['test/input-cetz.md']
+filters:
+  - diagram.lua
+to: html
+metadata:
+  diagram:
+    engine:
+      cetz:
+        execpath: ['quarto', 'typst']
\ No newline at end of file