From 59ac0b824c8b6d0dd68ceae394d8f4e2ba14f2e5 Mon Sep 17 00:00:00 2001
From: Mohammad AlSaleh <CE.Mohammad.AlSaleh@gmail.com>
Date: Sun, 10 Mar 2024 21:55:24 +0300
Subject: [PATCH] Store a sorted list of monospace font ids in font system

Signed-off-by: Mohammad AlSaleh <CE.Mohammad.AlSaleh@gmail.com>
---
 src/font/fallback/mod.rs | 31 ++++++++++++++-----------------
 src/font/system.rs       | 17 +++++++++++++++++
 2 files changed, 31 insertions(+), 17 deletions(-)

diff --git a/src/font/fallback/mod.rs b/src/font/fallback/mod.rs
index 10f7d99..02d5fcb 100644
--- a/src/font/fallback/mod.rs
+++ b/src/font/fallback/mod.rs
@@ -173,24 +173,21 @@ impl<'a> Iterator for FontFallbackIter<'a> {
                 }
                 // Set a monospace fallback if Monospace family is not found
                 if is_mono {
-                    if let Some(face_info) = self.font_system.db().face(m_key.id) {
-                        // Don't use emoji fonts as Monospace
-                        if face_info.monospaced && !face_info.post_script_name.contains("Emoji") {
-                            let supported_cp_count_opt = self
-                                .font_system
-                                .get_font_supported_codepoints_in_word(m_key.id, self.word);
-                            if let Some(supported_cp_count) = supported_cp_count_opt {
-                                let codepoint_non_matches =
-                                    self.word.chars().count() - supported_cp_count;
+                    if self.font_system.is_monospace(m_key.id) {
+                        let supported_cp_count_opt = self
+                            .font_system
+                            .get_font_supported_codepoints_in_word(m_key.id, self.word);
+                        if let Some(supported_cp_count) = supported_cp_count_opt {
+                            let codepoint_non_matches =
+                                self.word.chars().count() - supported_cp_count;
 
-                                let fallback_info = MonospaceFallbackInfo {
-                                    font_weight_diff: Some(m_key.font_weight_diff),
-                                    codepoint_non_matches: Some(codepoint_non_matches),
-                                    font_weight: m_key.font_weight,
-                                    id: m_key.id,
-                                };
-                                assert!(self.monospace_fallbacks.insert(fallback_info));
-                            }
+                            let fallback_info = MonospaceFallbackInfo {
+                                font_weight_diff: Some(m_key.font_weight_diff),
+                                codepoint_non_matches: Some(codepoint_non_matches),
+                                font_weight: m_key.font_weight,
+                                id: m_key.id,
+                            };
+                            assert!(self.monospace_fallbacks.insert(fallback_info));
                         }
                     }
                 }
diff --git a/src/font/system.rs b/src/font/system.rs
index c1a3763..5cdf24a 100644
--- a/src/font/system.rs
+++ b/src/font/system.rs
@@ -86,6 +86,9 @@ pub struct FontSystem {
     /// Cache for loaded fonts from the database.
     font_cache: HashMap<fontdb::ID, Option<Arc<Font>>>,
 
+    /// Sorted unique ID's of all Monospace fonts in DB
+    monospace_font_ids: Vec<fontdb::ID>,
+
     /// Cache for font codepoint support info
     font_codepoint_support_info_cache: HashMap<fontdb::ID, FontCachedCodepointSupportInfo>,
 
@@ -141,9 +144,19 @@ impl FontSystem {
 
     /// Create a new [`FontSystem`] with a pre-specified locale and font database.
     pub fn new_with_locale_and_db(locale: String, db: fontdb::Database) -> Self {
+        let mut monospace_font_ids = db
+            .faces()
+            .filter(|face_info| {
+                face_info.monospaced && !face_info.post_script_name.contains("Emoji")
+            })
+            .map(|face_info| face_info.id)
+            .collect::<Vec<_>>();
+        monospace_font_ids.sort();
+
         Self {
             locale,
             db,
+            monospace_font_ids,
             font_cache: Default::default(),
             font_matches_cache: Default::default(),
             font_codepoint_support_info_cache: Default::default(),
@@ -202,6 +215,10 @@ impl FontSystem {
             .clone()
     }
 
+    pub fn is_monospace(&self, id: fontdb::ID) -> bool {
+        self.monospace_font_ids.binary_search(&id).is_ok()
+    }
+
     #[inline(always)]
     pub fn get_font_supported_codepoints_in_word(
         &mut self,