From 67fe8d66b29c309f316fa4ae952b0ea5b39db431 Mon Sep 17 00:00:00 2001
From: Aliaksandr Kalenik <kalenik.aliaksandr@gmail.com>
Date: Thu, 5 Sep 2024 22:33:36 +0200
Subject: [PATCH] LibWeb: Skip font if it doesn't contain needed glyph in
 FontCascadeList

Before this change, we were only checking for actual glyph containment
in a font if unicode ranges were specified. However that is not
sufficient for emoji support, where we want to continue searching for
a font until one containing emojis is found.
---
 Userland/Libraries/LibGfx/FontCascadeList.cpp   | 14 +++++++-------
 Userland/Libraries/LibGfx/FontCascadeList.h     |  7 +++++--
 Userland/Libraries/LibWeb/CSS/StyleComputer.cpp |  2 +-
 3 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/Userland/Libraries/LibGfx/FontCascadeList.cpp b/Userland/Libraries/LibGfx/FontCascadeList.cpp
index b83f6364d60..4deafb0986d 100644
--- a/Userland/Libraries/LibGfx/FontCascadeList.cpp
+++ b/Userland/Libraries/LibGfx/FontCascadeList.cpp
@@ -28,16 +28,16 @@ void FontCascadeList::extend(FontCascadeList const& other)
 Gfx::Font const& FontCascadeList::font_for_code_point(u32 code_point) const
 {
     for (auto const& entry : m_fonts) {
-        if (!entry.unicode_ranges.has_value())
+        if (entry.unicode_ranges.has_value()) {
+            for (auto const& range : *entry.unicode_ranges) {
+                if (range.contains(code_point) && entry.font->contains_glyph(code_point))
+                    return entry.font;
+            }
+        } else if (entry.font->contains_glyph(code_point)) {
             return entry.font;
-        if (!entry.font->contains_glyph(code_point))
-            continue;
-        for (auto const& range : *entry.unicode_ranges) {
-            if (range.contains(code_point))
-                return entry.font;
         }
     }
-    VERIFY_NOT_REACHED();
+    return *m_last_resort_font;
 }
 
 bool FontCascadeList::equals(FontCascadeList const& other) const
diff --git a/Userland/Libraries/LibGfx/FontCascadeList.h b/Userland/Libraries/LibGfx/FontCascadeList.h
index 999ecf97dfb..681021e82c0 100644
--- a/Userland/Libraries/LibGfx/FontCascadeList.h
+++ b/Userland/Libraries/LibGfx/FontCascadeList.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2023, Aliaksandr Kalenik <kalenik.aliaksandr@gmail.com>
+ * Copyright (c) 2023-2024, Aliaksandr Kalenik <kalenik.aliaksandr@gmail.com>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -19,7 +19,7 @@ public:
     }
 
     size_t size() const { return m_fonts.size(); }
-    bool is_empty() const { return m_fonts.is_empty(); }
+    bool is_empty() const { return m_fonts.is_empty() && !m_last_resort_font; }
     Font const& first() const { return *m_fonts.first().font; }
 
     template<typename Callback>
@@ -43,7 +43,10 @@ public:
         Optional<Vector<UnicodeRange>> unicode_ranges;
     };
 
+    void set_last_resort_font(NonnullRefPtr<Font> font) { m_last_resort_font = move(font); }
+
 private:
+    RefPtr<Font const> m_last_resort_font;
     Vector<Entry> m_fonts;
 };
 
diff --git a/Userland/Libraries/LibWeb/CSS/StyleComputer.cpp b/Userland/Libraries/LibWeb/CSS/StyleComputer.cpp
index 554eff120a0..e65a3ffed76 100644
--- a/Userland/Libraries/LibWeb/CSS/StyleComputer.cpp
+++ b/Userland/Libraries/LibWeb/CSS/StyleComputer.cpp
@@ -2326,7 +2326,7 @@ RefPtr<Gfx::FontCascadeList const> StyleComputer::compute_font_for_style_values(
     }
 
     auto found_font = StyleProperties::font_fallback(monospace, bold);
-    font_list->add(found_font->with_size(font_size_in_pt));
+    font_list->set_last_resort_font(found_font->with_size(font_size_in_pt));
 
     return font_list;
 }