From 68e43131b7fbf6cabfba540ed15798df378d9997 Mon Sep 17 00:00:00 2001
From: Shadowfacts <me@shadowfacts.net>
Date: Sun, 21 Jul 2024 19:45:03 -0700
Subject: [PATCH] Minor optimization for caching platform fonts

---
 .../HTMLStreamer/AttributedStringConverter.swift    | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/Sources/HTMLStreamer/AttributedStringConverter.swift b/Sources/HTMLStreamer/AttributedStringConverter.swift
index f58da8d..ee9221d 100644
--- a/Sources/HTMLStreamer/AttributedStringConverter.swift
+++ b/Sources/HTMLStreamer/AttributedStringConverter.swift
@@ -19,7 +19,8 @@ private typealias PlatformFont = NSFont
 
 public class AttributedStringConverter<Callbacks: HTMLConversionCallbacks> {
     private let configuration: AttributedStringConverterConfiguration
-    private var fontCache: [FontTrait: PlatformFont] = [:]
+    // There are only 8 combinations of FontTraits
+    private var fontCache: [PlatformFont?] = Array(repeating: nil, count: 8)
     
     private var tokenizer: Tokenizer<String.UnicodeScalarView.Iterator>!
     private var str: NSMutableAttributedString!
@@ -340,7 +341,7 @@ public class AttributedStringConverter<Callbacks: HTMLConversionCallbacks> {
     }
     
     private func getFont(traits: FontTrait) -> PlatformFont? {
-        if let cached = fontCache[traits] {
+        if let cached = fontCache[traits.rawValue] {
             return cached
         }
         
@@ -355,14 +356,18 @@ public class AttributedStringConverter<Callbacks: HTMLConversionCallbacks> {
         } else if traits.contains(.italic),
            let italic = descriptor.withSymbolicTraits(.traitItalic) {
             descriptor = italic
+        } else {
+            // N.B.: this does not go through the UIFontMetrics, the configuration fonts are expected to be setup for Dynamic Type already
+            fontCache[traits.rawValue] = baseFont
+            return baseFont
         }
         let font = PlatformFont(descriptor: descriptor, size: 0)
         #if os(iOS) || os(visionOS)
         let scaled = configuration.fontMetrics.scaledFont(for: font)
-        fontCache[traits] = scaled
+        fontCache[traits.rawValue] = scaled
         return scaled
         #else
-        fontCache[traits] = font
+        fontCache[traits.rawValue] = font
         return font
         #endif
     }