slint-compiler: Fix fallback family handling for glyph embedding on Linux

For macOS and Windows we've had hard-coded fallbacks, but none for Linux
after the fontconfig removal. So go through the same fallback families
as when using fontique regularly, and add emoji as parley tries that
within.

This fixes picking up glyphs such as "←→↵⌫".

Author: tronical

internal/compiler/passes/embed_glyphs.rs

@@ -269,47 +269,28 @@ pub fn embed_glyphs<'a>(
 
 #[inline(never)] // workaround https://github.com/rust-lang/rust/issues/104099
 fn get_fallback_fonts(compiler_config: &CompilerConfiguration) -> Vec<Font> {
-    #[allow(unused)]
-    let mut fallback_families: Vec<String> = Vec::new();
+    let mut fallback_fonts = Vec::new();
 
-    #[cfg(target_os = "macos")]
-    {
-        fallback_families = ["Menlo", "Apple Symbols", "Apple Color Emoji"]
-            .into_iter()
-            .map(Into::into)
-            .collect::<Vec<String>>();
-    }
+    let mut collection = sharedfontique::get_collection();
+    let mut query = collection.query();
+    query.set_families(
+        sharedfontique::FALLBACK_FAMILIES.into_iter().map(fontique::QueryFamily::Generic).chain(
+            core::iter::once(fontique::QueryFamily::Generic(fontique::GenericFamily::Emoji)),
+        ),
+    );
 
-    #[cfg(target_family = "windows")]
-    {
-        fallback_families = ["Segoe UI Emoji", "Segoe UI Symbol", "Arial", "Wingdings"]
-            .into_iter()
-            .map(Into::into)
-            .collect::<Vec<String>>();
-    }
+    query.matches_with(|query_font| {
+        if let Some(font) = compiler_config
+            .load_font_by_id(&query_font)
+            .ok()
+            .map(|fontdue_font| Font { font: query_font.clone(), fontdue_font })
+        {
+            fallback_fonts.push(font);
+        }
 
-    let fallback_fonts = fallback_families
-        .iter()
-        .filter_map(|fallback_family| {
-            let mut collection = sharedfontique::get_collection();
-            let mut query = collection.query();
-            query.set_families(std::iter::once(fontique::QueryFamily::from(
-                fallback_family.as_str(),
-            )));
-            let mut font = None;
-            query.matches_with(|query_font| {
-                font = Some(query_font.clone());
-                fontique::QueryStatus::Stop
-            });
+        fontique::QueryStatus::Continue
+    });
 
-            font.and_then(|font| {
-                compiler_config
-                    .load_font_by_id(&font)
-                    .ok()
-                    .map(|fontdue_font| Font { font, fontdue_font })
-            })
-        })
-        .collect::<Vec<_>>();
     fallback_fonts
 }