New “base has width” check

profile-universal/src/checks/base_has_width.rs

@@ -0,0 +1,68 @@
+use std::collections::HashMap;
+
+use fontspector_checkapi::{constants::GlyphClass, prelude::*, testfont, FileTypeConvert};
+use read_fonts::TableProvider;
+use skrifa::{GlyphId, MetadataProvider};
+use unicode_properties::{GeneralCategory, UnicodeGeneralCategory};
+
+fn is_space(c: char) -> bool {
+    matches!(
+        c.general_category(),
+        GeneralCategory::SpaceSeparator
+            | GeneralCategory::LineSeparator
+            | GeneralCategory::ParagraphSeparator
+            | GeneralCategory::Format
+            | GeneralCategory::NonspacingMark
+            | GeneralCategory::Control
+    )
+}
+
+#[check(
+    id = "base_has_width",
+    rationale = "Base characters should have non-zero advance width.",
+    proposal = "Rod on chat",
+    title = "Check base characters have non-zero advance width."
+)]
+fn base_has_width(f: &Testable, context: &Context) -> CheckFnResult {
+    let font = testfont!(f);
+    let hmtx = font.font().hmtx()?;
+    let mut problems = vec![];
+    let reverse_charmap: HashMap<_, _> = font
+        .font()
+        .charmap()
+        .mappings()
+        .map(|(c, g)| (g, c))
+        .collect();
+    for (gid, metric) in hmtx.h_metrics().iter().enumerate() {
+        let gid = GlyphId::new(gid as u16);
+        if metric.advance() == 0 && font.gdef_class(gid) != Some(GlyphClass::Mark) {
+            let codepoint = reverse_charmap.get(&gid);
+            if codepoint == Some(&0) || codepoint.is_none() {
+                continue;
+            }
+            if codepoint
+                .and_then(|c| char::from_u32(*c))
+                .map_or(false, is_space)
+            {
+                continue;
+            }
+            #[allow(clippy::unwrap_used)]
+            let name = font.glyph_name_for_id(gid, true).unwrap();
+            if name == "NULL" {
+                continue;
+            }
+            problems.push(format!("{} ({:?})", name, codepoint));
+        }
+    }
+    if problems.is_empty() {
+        Ok(Status::just_one_pass())
+    } else {
+        Ok(Status::just_one_fail(
+            "zero-width-bases",
+            &format!(
+                "The following glyphs had zero advance width:\n{}",
+                bullet_list(context, problems),
+            ),
+        ))
+    }
+}

profile-universal/src/lib.rs

@@ -7,6 +7,7 @@ pub struct Universal;
 impl fontspector_checkapi::Plugin for Universal {
     fn register(&self, cr: &mut Registry) -> Result<(), String> {
         cr.register_check(checks::arabic_spacing_symbols::arabic_spacing_symbols);
+        cr.register_check(checks::base_has_width::base_has_width);
         cr.register_check(checks::case_mapping::case_mapping);
         cr.register_check(checks::cmap_format_12::cmap_format_12);
         cr.register_check(checks::colorfont_tables::colorfont_tables);