Direct2D: Avoid creating multiple MemoryFontFileLoaders all referencing the same data

modules/juce_graphics/native/juce_DirectX_windows.cpp

@@ -1010,6 +1010,12 @@ public:
 
     Uuid getUuid() const { return uuid; }
 
+    Span<const std::byte> asSpan() const&& = delete;
+    Span<const std::byte> asSpan() const&
+    {
+        return { static_cast<const std::byte*> (block->getData()), block->getSize() };
+    }
+
 private:
     std::shared_ptr<const MemoryBlock> block;
     Uuid uuid;
@@ -1061,20 +1067,54 @@ DirectWriteCustomFontCollectionLoader::DirectWriteCustomFontCollectionLoader (ID
 
 DirectWriteCustomFontCollectionLoader::~DirectWriteCustomFontCollectionLoader()
 {
-    for (const auto& loader : fileLoaders)
+    for (auto& loader : loaders)
         factory.UnregisterFontFileLoader (loader);
 }
 
+auto DirectWriteCustomFontCollectionLoader::findLoaderForUuid (const Uuid& uuid) const -> ComSmartPtr<MemoryFontFileLoader>
+{
+    const auto compareUuidAndLoader = [] (ComSmartPtr<MemoryFontFileLoader> loader, const Uuid& comparisonUuid)
+    {
+        return loader->getUuid() < comparisonUuid;
+    };
+
+    const auto iter = std::lower_bound (loaders.begin(), loaders.end(), uuid, compareUuidAndLoader);
+
+    if (iter == loaders.end() || iter->get()->getUuid() != uuid)
+        return {};
+
+    return *iter;
+}
+
 Uuid DirectWriteCustomFontCollectionLoader::addRawFontData (Span<const std::byte> blob)
 {
+    const std::string_view blobAsString (reinterpret_cast<const char*> (blob.data()), blob.size());
+    const auto hashValue = std::hash<std::string_view>{} (blobAsString);
+    auto& uuids = uuidsForHash[hashValue];
+
+    for (const auto& uuid : uuids)
+    {
+        const auto matchingLoader = findLoaderForUuid (uuid);
+
+        if (matchingLoader == nullptr)
+            continue;
+
+        const auto loaderData = matchingLoader->asSpan();
+
+        if (! std::equal (blob.begin(), blob.end(), loaderData.begin(), loaderData.end()))
+            continue;
+
+        return matchingLoader->getUuid();
+    }
+
     ComSmartPtr loader { new MemoryFontFileLoader { { blob.data(), blob.size() } },
                          IncrementRef::no };
-
     factory.RegisterFontFileLoader (loader);
 
-    fileLoaders.push_back (loader);
+    const auto compareUuids = [] (const auto& a, const auto& b) { return a->getUuid() < b->getUuid(); };
-
+    OrderedContainerHelpers::insertOrAssign (loaders, loader, compareUuids);
-    return fileLoaders.back()->getUuid();
+    uuids.push_back (loader->getUuid());
+    return loader->getUuid();
 }
 
 HRESULT WINAPI DirectWriteCustomFontCollectionLoader::CreateEnumeratorFromKey (IDWriteFactory* factoryIn,
@@ -1087,16 +1127,13 @@ HRESULT WINAPI DirectWriteCustomFontCollectionLoader::CreateEnumeratorFromKey (I
 
     const Uuid requestedCollectionKey { static_cast<const uint8*> (collectionKey) };
 
-    for (const auto& loader : fileLoaders)
+    const auto matchingLoader = findLoaderForUuid (requestedCollectionKey);
-    {
-        if (loader->getUuid() != requestedCollectionKey)
-            continue;
-
-        *fontFileEnumerator = new FontFileEnumerator { *factoryIn, loader };
-        return S_OK;
-    }
 
+    if (matchingLoader == nullptr)
         return E_INVALIDARG;
+
+    *fontFileEnumerator = new FontFileEnumerator { *factoryIn, matchingLoader };
+    return S_OK;
 }
 
 //==============================================================================

modules/juce_graphics/native/juce_DirectX_windows.h

@@ -399,8 +399,15 @@ private:
     class MemoryFontFileLoader;
     class FontFileEnumerator;
 
+    ComSmartPtr<MemoryFontFileLoader> findLoaderForUuid (const Uuid&) const;
+
     IDWriteFactory& factory;
-    std::vector<ComSmartPtr<MemoryFontFileLoader>> fileLoaders;
+
+    // Allows lookup of Uuids of all loaders with data matching a particular hash
+    std::map<size_t, std::vector<Uuid>> uuidsForHash;
+
+    // Sorted by Uuid
+    std::vector<ComSmartPtr<MemoryFontFileLoader>> loaders;
 };
 
 //==============================================================================