Fonts: review fixes on #2803 (Unix clippy, the degree sign in DOS Hebrew fonts, font-keyed caches)

- The linked-folder test (Unix only) passes a slice without a clone (clippy
  cloned_ref_to_slice_refs, which failed the Linux gate).
- In a DOS 862 Hebrew SHX font, %%d still draws from the old degree shape 127: only 128-129
  are letters there.
- The viewport highlight, drag preview and command preview caches key on the font set too,
  so text in them is drawn again when fonts change.

crates/fonts/src/shx/tests.rs

@@ -473,6 +473,9 @@ fn hebrew_letters_draw_from_their_one_byte_places() {
     // DOS 862: bet at 0x81 advances one unit.
     assert!((draws(hebrew_font(0x80..=0x9A), 'ב') - 1.0).abs() < 1e-9);
     assert_eq!(hebrew_font(0x80..=0x9A).hebrew_places(), (false, true));
+    // The old degree sign at 127 isn't a letter in DOS 862: `%%d` still draws from it
+    // (127 & 0x1F = 31 units).
+    assert!((draws(hebrew_font((0x80..=0x9A).chain([127])), '°') - 31.0).abs() < 1e-9);
     // A Cyrillic-style font (0xC0..0xFF all drawn) is not read as Hebrew: the letter comes
     // from the built-in stroke font instead of a Cyrillic shape.
     let cyr = hebrew_font(0xC0..=0xFF);

crates/fonts/src/shx/text.rs

@@ -88,9 +88,10 @@ fn candidates(c: char, font: &ShxFont) -> [Option<u16>; 4] {
         _ => None,
     };
     if let Some((s, latin, old)) = special {
-        // In a DOS 862 Hebrew font 127–129 are letters and 0xB0.. box drawing: shape 256–258 only.
+        // In a DOS 862 Hebrew font 128–129 are letters and 0xB0.. box drawing: shape 256–258,
+        // and the old degree sign 127 (not a letter there).
         if !unicode && font.kind() == ShxKind::Shapes && font.hebrew_places().1 {
-            return [Some(s), None, None, None];
+            return [Some(s), (old == 127).then_some(old), None, None];
         }
         return if unicode {
             [code(u), code(if c == '⌀' { 0x2205 } else { latin }), Some(s), Some(old)]

crates/fonts/src/ttf.rs

@@ -1324,7 +1324,7 @@ mod family_tests {
         let _ = std::os::unix::fs::symlink(&root, real.join("up"));
         let found = scan_dirs(&[root.join("link")], true);
         assert!(found.contains_key("linkedface"), "{found:?}");
-        assert_eq!(shx_dirs(&[root.clone()]).len(), 1, "the folder with the SHX file, once");
+        assert_eq!(shx_dirs(std::slice::from_ref(&root)).len(), 1, "the folder with the SHX file, once");
         let _ = std::fs::remove_dir_all(&root);
     }
 

crates/ui-egui/src/canvas/draw.rs

@@ -226,7 +226,7 @@ pub(super) fn draw_drag_gpu(
     let key = {
         use std::hash::{Hash, Hasher};
         let mut h = std::collections::hash_map::DefaultHasher::new();
-        (c.key, band, bg.0, bg.1, bg.2, &drag.handles, transparency).hash(&mut h);
+        (c.key, band, bg.0, bg.1, bg.2, &drag.handles, transparency, super::list::font_generation()).hash(&mut h);
         if drag.clipboard {
             clipboard.1.hash(&mut h);
         }

crates/ui-egui/src/canvas/list.rs

@@ -63,11 +63,16 @@ pub(super) fn rebuilt_preview<'a>(doc: &cadcraft_doc::Drawing, ents: impl IntoIt
 /// A rebuild only the view asks for (a new zoom band, a pan out of the built area) runs in the
 /// background while the current list is drawn (see [`rebuild`]); a changed drawing, or no list
 /// yet, is built at once.
+/// The font set text is drawn with: TrueType fonts (font folders, rescans) and SHX fonts
+/// (drawing folders, font folders, the search path) can each change what text looks like. Every
+/// cache of drawn geometry keys on it.
+pub(super) fn font_generation() -> u64 {
+    cadcraft_fonts::ttf::generation().wrapping_add(cadcraft_fonts::shx::generation() << 32)
+}
+
 pub(super) fn ensure_list(app: &mut CadApp, xf: &Xf, views: &[(Bounds2, f64)], ctx: &egui::Context) {
     let px = 1.0 / xf.scale;
-    // TrueType fonts (font folders, rescans) and SHX fonts (drawing folders, font folders,
-    // the search path) can each change what text looks like.
-    let fonts = cadcraft_fonts::ttf::generation().wrapping_add(cadcraft_fonts::shx::generation() << 32);
+    let fonts = font_generation();
     if app.canvas.font_generation != fonts {
         app.canvas.font_generation = fonts;
         app.canvas.list = None;
@@ -189,7 +194,8 @@ impl OnlyList {
         let key = {
             use std::hash::{Hash, Hasher};
             let mut h = std::collections::hash_map::DefaultHasher::new();
-            (st.uid, st.revision, std::sync::Arc::as_ptr(&st.doc) as usize, band, &only.handles, format!("{:?}", only.extra)).hash(&mut h);
+            (st.uid, st.revision, std::sync::Arc::as_ptr(&st.doc) as usize, band, &only.handles, format!("{:?}", only.extra), font_generation())
+                .hash(&mut h);
             outline.into_iter().flatten().for_each(|q| (q.x.to_bits(), q.y.to_bits()).hash(&mut h));
             h.finish()
         };

crates/ui-egui/src/canvas/viewport.rs

@@ -286,7 +286,8 @@ impl VpHighlight {
         let key = {
             use std::hash::{Hash, Hasher};
             let mut h = std::collections::hash_map::DefaultHasher::new();
-            (st.uid, st.revision, std::sync::Arc::as_ptr(&st.doc) as usize, tolerance.to_bits(), handles).hash(&mut h);
+            (st.uid, st.revision, std::sync::Arc::as_ptr(&st.doc) as usize, tolerance.to_bits(), handles, super::list::font_generation())
+                .hash(&mut h);
             h.finish()
         };
         if self.key != Some(key) {