Readme: Implement syntax highlighting via giallo

Signed-off-by: Nico Burns <nico@nicoburns.com>

Author: nicoburns

Cargo.lock

@@ -7,7 +7,7 @@ rust-version.workspace = true
 publish = false
 
 [features]
-default = ["gpu", "comrak", "floats"]
+default = ["gpu", "comrak", "syntax-highlighting-giallo", "floats"]
 
 # Renderers
 gpu = ["dep:anyrender_vello"]
@@ -23,6 +23,7 @@ cpu-base = ["dep:anyrender_vello_cpu"]
 avif = ["dep:image", "image?/avif-native"]
 comrak = ["dep:comrak"]
 pulldown_cmark = ["dep:pulldown-cmark"]
+syntax-highlighting-giallo = ["dep:giallo"]
 floats = ["blitz-dom/floats"]
 cache = ["blitz-net/cache"]
 log_frame_times = [
@@ -51,6 +52,7 @@ reqwest = { workspace = true }
 url = { workspace = true }
 winit = { workspace = true }
 comrak = { version = "0.49", default-features = false, optional = true }
+giallo = { version = "0.1", features = ["dump"], optional = true }
 pulldown-cmark = { version = "0.13", default-features = false, features = ["html"], optional = true }
 image = { workspace = true, default-features = false, optional = true }
 notify = "8.0.0"

apps/readme/Cargo.toml

@@ -28,4 +28,8 @@
   [src$="#gh-dark-mode-only"] {
     display: none !important;
   }
+}
+
+.giallo {
+  background: #f6f8fa !important;
 }

apps/readme/assets/blitz-markdown-overrides.css

@@ -90,6 +90,12 @@ fn main() {
         html = markdown_to_html(html);
         stylesheets.push(String::from(GITHUB_MD_STYLES));
         stylesheets.push(String::from(BLITZ_MD_STYLES));
+
+        #[cfg(feature = "syntax-highlighting-giallo")]
+        {
+            stylesheets.push(String::from(giallo::GIALLO_CSS))
+        }
+
         title = format!(
             "README for {}",
             base_url.rsplit("/").find(|s| !s.is_empty()).unwrap()

apps/readme/src/main.rs

@@ -1,11 +1,17 @@
-//! Render the readme.md using the gpu renderer
-
 use comrak::{Options, markdown_to_html_with_plugins, options};
 
 pub(crate) fn markdown_to_html(contents: String) -> String {
-    let plugins = options::Plugins::default();
-    // let syntax_highligher = CustomSyntectAdapter(SyntectAdapter::new(Some("InspiredGitHub")));
-    // plugins.render.codefence_syntax_highlighter = Some(&syntax_highligher as _);
+    #[allow(unused_mut)]
+    let mut plugins = options::Plugins::default();
+
+    #[cfg(feature = "syntax-highlighting-giallo")]
+    use giallo_highlighter::{GialloAdapter, ThemeVariant};
+    #[cfg(feature = "syntax-highlighting-giallo")]
+    let syntax_highligher = GialloAdapter(ThemeVariant::Single("github-light"));
+    #[cfg(feature = "syntax-highlighting-giallo")]
+    {
+        plugins.render.codefence_syntax_highlighter = Some(&syntax_highligher as _);
+    }
 
     let body_html = markdown_to_html_with_plugins(
         &contents,
@@ -50,7 +56,64 @@ pub(crate) fn markdown_to_html(contents: String) -> String {
     )
 }
 
-// #[allow(unused)]
+#[cfg(feature = "syntax-highlighting-giallo")]
+mod giallo_highlighter {
+    use comrak::adapters::SyntaxHighlighterAdapter;
+    pub(crate) use giallo::ThemeVariant;
+    use giallo::{HighlightOptions, HtmlRenderer, PLAIN_GRAMMAR_NAME, RenderOptions};
+    use std::borrow::Cow;
+    use std::collections::HashMap;
+
+    static GIALLO_REGISTRY: std::sync::LazyLock<giallo::Registry> =
+        std::sync::LazyLock::new(|| {
+            let mut registry = giallo::Registry::builtin().unwrap();
+            registry.link_grammars();
+            registry
+        });
+
+    pub(crate) struct GialloAdapter(pub(crate) ThemeVariant<&'static str>);
+
+    impl SyntaxHighlighterAdapter for GialloAdapter {
+        fn write_highlighted(
+            &self,
+            output: &mut dyn std::fmt::Write,
+            lang: Option<&str>,
+            code: &str,
+        ) -> std::fmt::Result {
+            let norm_lang = lang.map(|l| l.split_once(',').map(|(lang, _)| lang).unwrap_or(l));
+            let norm_lang = norm_lang.unwrap_or(PLAIN_GRAMMAR_NAME);
+            let options = HighlightOptions::new(&norm_lang, self.0);
+            let highlighted = GIALLO_REGISTRY.highlight(code, options).unwrap();
+            let render_options = RenderOptions {
+                show_line_numbers: false,
+                ..Default::default()
+            };
+            let html = HtmlRenderer::default().render(&highlighted, &render_options);
+            println!("{}", &html);
+            output.write_str(&html)
+        }
+
+        fn write_pre_tag(
+            &self,
+            output: &mut dyn std::fmt::Write,
+            attributes: HashMap<&'static str, Cow<'_, str>>,
+        ) -> std::fmt::Result {
+            let _ = attributes;
+            output.write_str("")
+        }
+
+        fn write_code_tag(
+            &self,
+            output: &mut dyn std::fmt::Write,
+            attributes: HashMap<&'static str, Cow<'_, str>>,
+        ) -> std::fmt::Result {
+            let _ = attributes;
+            output.write_str("")
+        }
+    }
+}
+
+// #[cfg(feature = "syntax-highlighting-syntect")]
 // mod syntax_highlighter {
 //     use comrak::adapters::SyntaxHighlighterAdapter;
 //     use comrak::plugins::syntect::SyntectAdapter;