feat(pdf): embed Typst compiler with compile_pdf command

src-tauri/Cargo.toml

@@ -22,4 +22,8 @@ tauri = { version = "2", features = [] }
 tauri-plugin-opener = "2"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
+base64 = "0.22"
+typst = "0.14.2"
+typst-pdf = "0.14.2"
+typst-as-lib = "0.15.5"
 

src-tauri/src/lib.rs

@@ -1,7 +1,10 @@
+mod pdf;
+
 #[cfg_attr(mobile, tauri::mobile_entry_point)]
 pub fn run() {
     tauri::Builder::default()
         .plugin(tauri_plugin_opener::init())
+        .invoke_handler(tauri::generate_handler![pdf::compile_pdf])
         .run(tauri::generate_context!())
         .expect("error while running margin");
 }

src-tauri/src/pdf.rs

@@ -0,0 +1,67 @@
+use base64::Engine;
+use base64::engine::general_purpose::STANDARD;
+use serde::Deserialize;
+use typst::diag::{Severity, SourceDiagnostic};
+use typst::layout::PagedDocument;
+use typst_as_lib::TypstEngine;
+
+static LITERATA: &[u8] = include_bytes!("../../public/fonts/Literata-VF.ttf");
+static LITERATA_ITALIC: &[u8] = include_bytes!("../../public/fonts/Literata-Italic-VF.ttf");
+static HANKEN: &[u8] = include_bytes!("../../public/fonts/HankenGrotesk-VF.ttf");
+static HANKEN_ITALIC: &[u8] = include_bytes!("../../public/fonts/HankenGrotesk-Italic-VF.ttf");
+
+#[derive(Deserialize)]
+pub struct ImageInput {
+    path: String,
+    data: String,
+}
+
+fn compile(source: String, images: &[ImageInput]) -> Result<Vec<u8>, String> {
+    let mut binaries: Vec<(&str, Vec<u8>)> = Vec::with_capacity(images.len());
+    for image in images {
+        let bytes = STANDARD
+            .decode(image.data.as_bytes())
+            .map_err(|e| format!("failed to decode image \"{}\": {e}", image.path))?;
+        binaries.push((image.path.as_str(), bytes));
+    }
+
+    let engine = TypstEngine::builder()
+        .main_file(source)
+        .fonts([LITERATA, LITERATA_ITALIC, HANKEN, HANKEN_ITALIC])
+        .with_static_file_resolver(binaries)
+        .build();
+
+    let document: PagedDocument = engine.compile().output.map_err(|e| format_diagnostics(&e))?;
+
+    typst_pdf::pdf(&document, &Default::default()).map_err(|d| format_source_diagnostics(&d))
+}
+
+#[tauri::command]
+pub fn compile_pdf(source: String, images: Vec<ImageInput>) -> Result<tauri::ipc::Response, String> {
+    compile(source, &images).map(tauri::ipc::Response::new)
+}
+
+fn format_diagnostics(error: &typst_as_lib::TypstAsLibError) -> String {
+    match error {
+        typst_as_lib::TypstAsLibError::TypstSource(diagnostics) => format_source_diagnostics(diagnostics),
+        other => other.to_string(),
+    }
+}
+
+fn format_source_diagnostics(diagnostics: &[SourceDiagnostic]) -> String {
+    diagnostics
+        .iter()
+        .map(|diagnostic| {
+            let kind = match diagnostic.severity {
+                Severity::Error => "error",
+                Severity::Warning => "warning",
+            };
+            let mut message = format!("{kind}: {}", diagnostic.message);
+            for hint in &diagnostic.hints {
+                message.push_str(&format!("\n  hint: {hint}"));
+            }
+            message
+        })
+        .collect::<Vec<_>>()
+        .join("\n")
+}