From 50dacbc8fc2fd386bdddef998a95d6e942bf3697 Mon Sep 17 00:00:00 2001
From: reuk <reuk@users.noreply.github.com>
Date: Tue, 25 Jan 2022 22:17:25 +0000
Subject: [PATCH] Mac Fonts:  Fix rendering of AttributedStrings with empty
 ranges

Previously, lifetime management of CTFontRefs was not implemented
correctly. For zero-length ranges, the font may not be retained when
applying it to a CFAttributedString, meaning that the reference stored
in the fontMap sometimes became invalid before
createCFAttributedString() returned.

We now retain font refs when adding them to the font map, and release
them when the map is destroyed, ensuring that the font references remain
valid throughout the lifetime of the map.
---
 .../juce_graphics/native/juce_mac_Fonts.mm    | 50 ++++++++++++++++---
 1 file changed, 42 insertions(+), 8 deletions(-)

diff --git a/modules/juce_graphics/native/juce_mac_Fonts.mm b/modules/juce_graphics/native/juce_mac_Fonts.mm
index 4802dc492c..0a9e4f6a01 100644
--- a/modules/juce_graphics/native/juce_mac_Fonts.mm
+++ b/modules/juce_graphics/native/juce_mac_Fonts.mm
@@ -208,15 +208,51 @@ namespace CoreTextTypeLayout
     }
 
     //==============================================================================
+    // A flatmap that properly retains/releases font refs
+    class FontMap
+    {
+    public:
+        void emplace (CTFontRef ctFontRef, Font value)
+        {
+            pairs.emplace (std::lower_bound (pairs.begin(), pairs.end(), ctFontRef), ctFontRef, std::move (value));
+        }
+
+        const Font* find (CTFontRef ctFontRef) const
+        {
+            const auto iter = std::lower_bound (pairs.begin(), pairs.end(), ctFontRef);
+
+            if (iter == pairs.end())
+                return nullptr;
+
+            if (iter->key.get() != ctFontRef)
+                return nullptr;
+
+            return &iter->value;
+        }
+
+    private:
+        struct Pair
+        {
+            Pair (CTFontRef ref, Font font) : key (ref), value (std::move (font)) { CFRetain (ref); }
+
+            auto operator< (CTFontRef other) const { return key.get() < other; }
+
+            CFUniquePtr<CTFontRef> key;
+            Font value;
+        };
+
+        std::vector<Pair> pairs;
+    };
+
     struct AttributedStringAndFontMap
     {
         CFUniquePtr<CFAttributedStringRef> string;
-        std::map<CTFontRef, Font> fontMap;
+        FontMap fontMap;
     };
 
     static AttributedStringAndFontMap createCFAttributedString (const AttributedString& text)
     {
-        std::map<CTFontRef, Font> fontMap;
+        FontMap fontMap;
 
         const detail::ColorSpacePtr rgbColourSpace { CGColorSpaceCreateWithName (kCGColorSpaceSRGB) };
 
@@ -300,7 +336,7 @@ namespace CoreTextTypeLayout
     struct FramesetterAndFontMap
     {
         CFUniquePtr<CTFramesetterRef> framesetter;
-        std::map<CTFontRef, Font> fontMap;
+        FontMap fontMap;
     };
 
     static FramesetterAndFontMap createCTFramesetter (const AttributedString& text)
@@ -324,7 +360,7 @@ namespace CoreTextTypeLayout
     struct FrameAndFontMap
     {
         CFUniquePtr<CTFrameRef> frame;
-        std::map<CTFontRef, Font> fontMap;
+        FontMap fontMap;
     };
 
     static FrameAndFontMap createCTFrame (const AttributedString& text, CGRect bounds)
@@ -476,10 +512,8 @@ namespace CoreTextTypeLayout
                 {
                     glyphRun->font = [&]
                     {
-                        auto it = frameAndMap.fontMap.find (ctRunFont);
-
-                        if (it != frameAndMap.fontMap.end())
-                            return it->second;
+                        if (auto* it = frameAndMap.fontMap.find (ctRunFont))
+                            return *it;
 
                         CFUniquePtr<CFStringRef> cfsFontName (CTFontCopyPostScriptName (ctRunFont));
                         CFUniquePtr<CTFontRef> ctFontRef (CTFontCreateWithName (cfsFontName.get(), referenceFontSize, nullptr));