Add syntax highlighing feature to egui_extras (#3333)

* Add syntax highlighing feature to egui_extras

Enable "syntect" feature for great syntax highlighting of any language.

If not a simple fallback is used that works fine for C++, Rust, Python

* Check --no-default-features of egui_extras on CI

* spelling

* Fix building egui_extras without additional features

.github/workflows/rust.yml

@@ -49,19 +49,22 @@ jobs:
         run: cargo check --locked --all-features --all-targets
 
       - name: check egui_extras --all-features
-        run: cargo check --locked --all-features --all-targets -p egui_extras
+        run: cargo check --locked --all-features -p egui_extras
 
       - name: check default features
         run: cargo check --locked --all-targets
 
       - name: check --no-default-features
         run: cargo check --locked --no-default-features --lib --all-targets
 
-      - name: check epaint --no-default-features
-        run: cargo check --locked --no-default-features --lib --all-targets -p epaint
-
       - name: check eframe --no-default-features
-        run: cargo check --locked --no-default-features --features x11 --lib --all-targets -p eframe
+        run: cargo check --locked --no-default-features --features x11 --lib -p eframe
+
+      - name: check egui_extras --no-default-features
+        run: cargo check --locked --no-default-features --lib -p egui_extras
+
+      - name: check epaint --no-default-features
+        run: cargo check --locked --no-default-features --lib -p epaint
 
       - name: Test doc-tests
         run: cargo test --doc --all-features

crates/egui/src/load/bytes_loader.rs

@@ -10,11 +10,11 @@ impl DefaultBytesLoader {
         self.cache
             .lock()
             .entry(uri.into())
-            .or_insert_with_key(|uri| {
+            .or_insert_with_key(|_uri| {
                 let bytes: Bytes = bytes.into();
 
                 #[cfg(feature = "log")]
-                log::trace!("loaded {} bytes for uri {uri:?}", bytes.len());
+                log::trace!("loaded {} bytes for uri {_uri:?}", bytes.len());
 
                 bytes
             });

crates/egui_demo_app/Cargo.toml

@@ -23,7 +23,7 @@ image_viewer = ["image", "egui_extras/all-loaders", "rfd"]
 persistence = ["eframe/persistence", "egui/persistence", "serde"]
 web_screen_reader = ["eframe/web_screen_reader"]                  # experimental
 serde = ["dep:serde", "egui_demo_lib/serde", "egui/serde"]
-syntax_highlighting = ["egui_demo_lib/syntax_highlighting"]
+syntect = ["egui_demo_lib/syntect"]
 
 glow = ["eframe/glow"]
 wgpu = ["eframe/wgpu", "bytemuck"]

crates/egui_demo_app/src/apps/http_app.rs

@@ -223,25 +223,19 @@ fn selectable_text(ui: &mut egui::Ui, mut text: &str) {
 // ----------------------------------------------------------------------------
 // Syntax highlighting:
 
-#[cfg(feature = "syntect")]
 fn syntax_highlighting(
     ctx: &egui::Context,
     response: &ehttp::Response,
     text: &str,
 ) -> Option<ColoredText> {
     let extension_and_rest: Vec<&str> = response.url.rsplitn(2, '.').collect();
-    let extension = extension_and_rest.get(0)?;
-    let theme = crate::syntax_highlighting::CodeTheme::from_style(&ctx.style());
-    Some(ColoredText(crate::syntax_highlighting::highlight(
+    let extension = extension_and_rest.first()?;
+    let theme = egui_extras::syntax_highlighting::CodeTheme::from_style(&ctx.style());
+    Some(ColoredText(egui_extras::syntax_highlighting::highlight(
         ctx, &theme, text, extension,
     )))
 }
 
-#[cfg(not(feature = "syntect"))]
-fn syntax_highlighting(_ctx: &egui::Context, _: &ehttp::Response, _: &str) -> Option<ColoredText> {
-    None
-}
-
 struct ColoredText(egui::text::LayoutJob);
 
 impl ColoredText {

crates/egui_demo_lib/Cargo.toml

@@ -28,7 +28,7 @@ chrono = ["egui_extras/datepicker", "dep:chrono"]
 serde = ["egui/serde", "egui_plot/serde", "dep:serde"]
 
 ## Enable better syntax highlighting using [`syntect`](https://docs.rs/syntect).
-syntax_highlighting = ["syntect"]
+syntect = ["egui_extras/syntect"]
 
 
 [dependencies]
@@ -37,7 +37,6 @@ egui_extras = { version = "0.22.0", path = "../egui_extras", features = [
     "log",
 ] }
 egui_plot = { version = "0.22.0", path = "../egui_plot" }
-enum-map = { version = "2", features = ["serde"] }
 log = { version = "0.4", features = ["std"] }
 unicode_names2 = { version = "0.6.0", default-features = false }
 
@@ -46,9 +45,6 @@ chrono = { version = "0.4", optional = true, features = ["js-sys", "wasmbind"] }
 ## Enable this when generating docs.
 document-features = { version = "0.2", optional = true }
 serde = { version = "1", optional = true, features = ["derive"] }
-syntect = { version = "5", optional = true, default-features = false, features = [
-    "default-fancy",
-] }
 
 
 [dev-dependencies]

crates/egui_demo_lib/src/demo/about.rs

@@ -45,7 +45,6 @@ impl super::View for About {
 }
 
 fn about_immediate_mode(ui: &mut egui::Ui) {
-    use crate::syntax_highlighting::code_view_ui;
     ui.style_mut().spacing.interact_size.y = 0.0; // hack to make `horizontal_wrapped` work better with text.
 
     ui.horizontal_wrapped(|ui| {
@@ -56,7 +55,7 @@ fn about_immediate_mode(ui: &mut egui::Ui) {
         });
 
     ui.add_space(8.0);
-    code_view_ui(
+    crate::rust_view_ui(
         ui,
         r#"
   if ui.button("Save").clicked() {

crates/egui_demo_lib/src/demo/code_editor.rs

@@ -67,7 +67,7 @@ impl super::View for CodeEditor {
             });
         }
 
-        let mut theme = crate::syntax_highlighting::CodeTheme::from_memory(ui.ctx());
+        let mut theme = egui_extras::syntax_highlighting::CodeTheme::from_memory(ui.ctx());
         ui.collapsing("Theme", |ui| {
             ui.group(|ui| {
                 theme.ui(ui);
@@ -77,7 +77,7 @@ impl super::View for CodeEditor {
 
         let mut layouter = |ui: &egui::Ui, string: &str, wrap_width: f32| {
             let mut layout_job =
-                crate::syntax_highlighting::highlight(ui.ctx(), &theme, string, language);
+                egui_extras::syntax_highlighting::highlight(ui.ctx(), &theme, string, language);
             layout_job.wrap.max_width = wrap_width;
             ui.fonts(|f| f.layout_job(layout_job))
         };

crates/egui_demo_lib/src/demo/code_example.rs

@@ -81,13 +81,11 @@ impl super::Demo for CodeExample {
 
 impl super::View for CodeExample {
     fn ui(&mut self, ui: &mut egui::Ui) {
-        use crate::syntax_highlighting::code_view_ui;
-
         ui.vertical_centered(|ui| {
             ui.add(crate::egui_github_link_file!());
         });
 
-        code_view_ui(
+        crate::rust_view_ui(
             ui,
             r"
 pub struct CodeExample {
@@ -117,15 +115,15 @@ impl CodeExample {
                 });
         });
 
-        code_view_ui(ui, "    }\n}");
+        crate::rust_view_ui(ui, "    }\n}");
 
         ui.separator();
 
-        code_view_ui(ui, &format!("{self:#?}"));
+        crate::rust_view_ui(ui, &format!("{self:#?}"));
 
         ui.separator();
 
-        let mut theme = crate::syntax_highlighting::CodeTheme::from_memory(ui.ctx());
+        let mut theme = egui_extras::syntax_highlighting::CodeTheme::from_memory(ui.ctx());
         ui.collapsing("Theme", |ui| {
             theme.ui(ui);
             theme.store_in_memory(ui.ctx());
@@ -135,7 +133,7 @@ impl CodeExample {
 
 fn show_code(ui: &mut egui::Ui, code: &str) {
     let code = remove_leading_indentation(code.trim_start_matches('\n'));
-    crate::syntax_highlighting::code_view_ui(ui, &code);
+    crate::rust_view_ui(ui, &code);
 }
 
 fn remove_leading_indentation(code: &str) -> String {

crates/egui_demo_lib/src/lib.rs

@@ -15,11 +15,17 @@
 mod color_test;
 mod demo;
 pub mod easy_mark;
-pub mod syntax_highlighting;
 
 pub use color_test::ColorTest;
 pub use demo::DemoWindows;
 
+/// View some Rust code with syntax highlighting and selection.
+pub(crate) fn rust_view_ui(ui: &mut egui::Ui, code: &str) {
+    let language = "rs";
+    let theme = egui_extras::syntax_highlighting::CodeTheme::from_memory(ui.ctx());
+    egui_extras::syntax_highlighting::code_view_ui(ui, &theme, code, language);
+}
+
 // ----------------------------------------------------------------------------
 
 /// Create a [`Hyperlink`](egui::Hyperlink) to this egui source code file on github.

crates/egui_extras/Cargo.toml

@@ -49,9 +49,13 @@ puffin = ["dep:puffin", "egui/puffin"]
 ## Support loading svg images.
 svg = ["resvg", "tiny-skia", "usvg"]
 
+## Enable better syntax highlighting using [`syntect`](https://docs.rs/syntect).
+syntect = ["dep:syntect"]
+
+
 [dependencies]
 egui = { version = "0.22.0", path = "../egui", default-features = false }
-
+enum-map = { version = "2", features = ["serde"] }
 serde = { version = "1", features = ["derive"] }
 
 #! ### Optional dependencies
@@ -83,6 +87,10 @@ mime_guess = { version = "2.0.4", optional = true, default-features = false }
 
 puffin = { version = "0.16", optional = true }
 
+syntect = { version = "5", optional = true, default-features = false, features = [
+  "default-fancy",
+] }
+
 # svg feature
 resvg = { version = "0.28", optional = true, default-features = false }
 tiny-skia = { version = "0.8", optional = true, default-features = false } # must be updated in lock-step with resvg

crates/egui_extras/src/lib.rs

@@ -13,6 +13,8 @@
 #[cfg(feature = "chrono")]
 mod datepicker;
 
+pub mod syntax_highlighting;
+
 #[doc(hidden)]
 pub mod image;
 mod layout;

crates/egui_extras/src/loaders/file_loader.rs

@@ -63,21 +63,29 @@ impl BytesLoader for FileLoader {
                 .spawn({
                     let ctx = ctx.clone();
                     let cache = self.cache.clone();
-                    let uri = uri.to_owned();
+                    let _uri = uri.to_owned();
                     move || {
                         let result = match std::fs::read(&path) {
-                            Ok(bytes) => Ok(File {
-                                bytes: bytes.into(),
-                                mime: mime_guess::from_path(&path)
+                            Ok(bytes) => {
+                                #[cfg(feature = "mime_guess")]
+                                let mime = mime_guess::from_path(&path)
                                     .first_raw()
-                                    .map(|v| v.to_owned()),
-                            }),
+                                    .map(|v| v.to_owned());
+
+                                #[cfg(not(feature = "mime_guess"))]
+                                let mime = None;
+
+                                Ok(File {
+                                    bytes: bytes.into(),
+                                    mime,
+                                })
+                            }
                             Err(err) => Err(err.to_string()),
                         };
                         let prev = cache.lock().insert(path, Poll::Ready(result));
                         assert!(matches!(prev, Some(Poll::Pending)));
                         ctx.request_repaint();
-                        crate::log_trace!("finished loading {uri:?}");
+                        crate::log_trace!("finished loading {_uri:?}");
                     }
                 })
                 .expect("failed to spawn thread");

crates/egui_extras/src/sizing.rs

@@ -153,7 +153,7 @@ impl From<Vec<Size>> for Sizing {
 #[test]
 fn test_sizing() {
     let sizing: Sizing = vec![].into();
-    assert_eq!(sizing.to_lengths(50.0, 0.0), vec![]);
+    assert_eq!(sizing.to_lengths(50.0, 0.0), Vec::<f32>::new());
 
     let sizing: Sizing = vec![Size::remainder().at_least(20.0), Size::remainder()].into();
     assert_eq!(sizing.to_lengths(50.0, 0.0), vec![25.0, 25.0]);