feat(typst): extern rust functions for C ABI

6 files changed, 46 insertions, 5 deletions

diff --git a/typst/.gitignore b/typst/.gitignore
index 8afaf0c..695217d 100644
--- a/typst/.gitignore
+++ b/typst/.gitignore
@@ -9,3 +9,5 @@ target/
 
 # MSVC Windows builds of rustc generate these, which store debugging information
 *.pdb
+
+example
diff --git a/typst/Cargo.toml b/typst/Cargo.toml
index 4a01bf0..3cdc8a7 100644
--- a/typst/Cargo.toml
+++ b/typst/Cargo.toml
@@ -3,7 +3,8 @@ name = "typdown-typst"
 version = "0.1.0"
 edition = "2024"
 
-# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+[lib]
+crate-type = ["cdylib"]
 
 [dependencies]
 typst = "0.14.2"
diff --git a/typst/README.md b/typst/README.md
new file mode 100644
index 0000000..6e2530f
--- /dev/null
+++ b/typst/README.md
@@ -0,0 +1,12 @@
+# typst library
+
+This folder contains a Rust library used to compile typdown's typst components.
+We cannot write it in Zig, because there are no existing C bindings for typst.
+
+## Build example
+
+```shell
+$ cargo build
+$ gcc example.c -o example -ltypdown_typst -L./target/debug
+$ LD_LIBRARY_PATH=./target/debug ./example
+```
diff --git a/typst/example.c b/typst/example.c
new file mode 100644
index 0000000..a1df659
--- /dev/null
+++ b/typst/example.c
@@ -0,0 +1,9 @@
+#include "typst.h"
+#include <stdio.h>
+
+int main() {
+    const char* res = typst_generateSVG("Hello world");
+    printf("%s\n", res);
+    typst_freeSVG(res);
+    return 0;
+}
diff --git a/typst/src/lib.rs b/typst/src/lib.rs
index 5d9dcc4..c561c19 100644
--- a/typst/src/lib.rs
+++ b/typst/src/lib.rs
@@ -1,4 +1,6 @@
 //! Based on https://github.com/zeon256/minimal-typst-svg-renderer
+use std::ffi::{CString, CStr};
+use std::os::raw::c_char;
 
 use typst::layout::PagedDocument;
 use typst_svg::svg_frame;
@@ -7,8 +9,7 @@ use crate::world::MinimalWorld;
 
 mod world;
 
-pub fn compile() {
-    let content = include_str!("../../template.typ");
+pub fn compile(content: &str) -> String {
     let world = MinimalWorld::new(content);
 
     let res = typst::compile::<PagedDocument>(&world);
@@ -19,6 +20,20 @@ pub fn compile() {
 
     let doc = res.output.expect("Error compiling typst");
 
-    let svg = svg_frame(&doc.pages[0].frame);
-    println!("{}", svg)
+    svg_frame(&doc.pages[0].frame)
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn typst_generateSVG(source: *const c_char) ->  *const c_char {
+    unsafe {
+        let res = compile(CStr::from_ptr(source).to_str().unwrap());
+        CString::new(res).unwrap().into_raw()
+    }
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn typst_freeSVG(res: *mut c_char) {
+    unsafe {
+        drop(CString::from_raw(res));
+    }
 }
diff --git a/typst/typst.h b/typst/typst.h
new file mode 100644
index 0000000..ca6c21f
--- /dev/null
+++ b/typst/typst.h
@@ -0,0 +1,2 @@
+extern const char *typst_generateSVG(const char*);
+extern void typst_freeSVG(const char*);