add windows theme source and platform icon resolvers

crates/icons/src/segoe.rs

@@ -0,0 +1,43 @@
+//! Windows resolver: each role maps to a Segoe Fluent Icons codepoint,
+//! rendered as text in the system font (never bundled).
+
+use crate::IconRole;
+
+/// The Segoe Fluent Icons codepoint for the role.
+pub(crate) fn glyph(role: IconRole) -> Option<char> {
+    let codepoint = match role {
+        IconRole::Check => 0xE73E,        // CheckMark
+        IconRole::Close => 0xE8BB,        // ChromeClose
+        IconRole::ChevronDown => 0xE70D,  // ChevronDown
+        IconRole::ChevronLeft => 0xE76B,  // ChevronLeft
+        IconRole::ChevronRight => 0xE76C, // ChevronRight
+        IconRole::ChevronUp => 0xE70E,    // ChevronUp
+        IconRole::Plus => 0xE710,         // Add
+        IconRole::Minus => 0xE738,        // Remove
+        IconRole::Search => 0xE721,       // Search
+        IconRole::Folder => 0xE8B7,       // Folder
+        IconRole::Warning => 0xE7BA,      // Warning
+        IconRole::Info => 0xE946,         // Info
+    };
+    char::from_u32(codepoint)
+}
+
+/// The system font the codepoints resolve against (Windows 11+).
+pub(crate) const FONT_FAMILY: &str = "Segoe Fluent Icons";
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn every_role_maps_to_a_codepoint() {
+        for role in crate::IconRole::all() {
+            assert!(glyph(*role).is_some(), "missing codepoint for {role:?}");
+        }
+    }
+
+    #[test]
+    fn the_close_role_uses_the_chrome_close_glyph() {
+        assert_eq!(glyph(IconRole::Close), Some('\u{E8BB}'));
+    }
+}