[0.83] fix(text): resolve app-bundled font families by passing a DirectWrite font collection

change/react-native-windows-fix-app-bundled-fonts-083.json

@@ -0,0 +1 @@
+{"email":"collindanielschneide@gmail.com","comment":"Fix(text): resolve app-bundled font families by passing a DirectWrite font collection to CreateTextFormat instead of nullptr, so bundled icon fonts stop falling back to Segoe UI .notdef","dependentChangeType":"patch","type":"patch","packageName":"react-native-windows"}

vnext/Microsoft.ReactNative/Fabric/DWriteHelpers.cpp

@@ -5,6 +5,11 @@
 
 #include "DWriteHelpers.h"
 
+#include <dwrite_3.h>
+#include <windows.h>
+#include <cstdint>
+#include <string>
+
 namespace Microsoft::ReactNative {
 
 winrt::com_ptr<::IDWriteFactory> DWriteFactory() noexcept {
@@ -16,4 +21,113 @@ winrt::com_ptr<::IDWriteFactory> DWriteFactory() noexcept {
   return s_dwriteFactory;
 }
 
+namespace {
+
+// Directory that contains the running module, including the trailing separator: the
+// package root for packaged (MSIX) apps and the directory next to the .exe for
+// unpackaged apps. Bundled font assets are deployed below this directory.
+std::wstring AppDirectory() noexcept {
+  wchar_t modulePath[MAX_PATH]{};
+  const DWORD length = ::GetModuleFileNameW(nullptr, modulePath, MAX_PATH);
+  if (length == 0 || length >= MAX_PATH) {
+    return {};
+  }
+  std::wstring path(modulePath, length);
+  const auto lastSeparator = path.find_last_of(L"\\/");
+  if (lastSeparator == std::wstring::npos) {
+    return {};
+  }
+  path.resize(lastSeparator + 1);
+  return path;
+}
+
+// Adds every file matching <directory> + <pattern> to the font-set builder and returns
+// the number of files added. Per-file failures are skipped so that one bad font file
+// cannot break font resolution for the rest of the app.
+uint32_t AddFontFiles(
+    ::IDWriteFactory5 *factory,
+    ::IDWriteFontSetBuilder1 *builder,
+    const std::wstring &directory,
+    const wchar_t *pattern) noexcept {
+  uint32_t count = 0;
+  const std::wstring searchPattern = directory + pattern;
+  WIN32_FIND_DATAW findData{};
+  const HANDLE findHandle = ::FindFirstFileW(searchPattern.c_str(), &findData);
+  if (findHandle == INVALID_HANDLE_VALUE) {
+    return count;
+  }
+  do {
+    if (!(findData.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)) {
+      const std::wstring fontPath = directory + findData.cFileName;
+      winrt::com_ptr<::IDWriteFontFile> fontFile;
+      if (SUCCEEDED(factory->CreateFontFileReference(fontPath.c_str(), nullptr, fontFile.put())) &&
+          SUCCEEDED(builder->AddFontFile(fontFile.get()))) {
+        ++count;
+      }
+    }
+  } while (::FindNextFileW(findHandle, &findData));
+  ::FindClose(findHandle);
+  return count;
+}
+
+winrt::com_ptr<::IDWriteFontCollection> CreateAppFontCollection() noexcept {
+  try {
+    const std::wstring appDirectory = AppDirectory();
+    if (appDirectory.empty()) {
+      return nullptr;
+    }
+
+    const auto factory5 = DWriteFactory().as<::IDWriteFactory5>();
+
+    winrt::com_ptr<::IDWriteFontSetBuilder1> builder;
+    winrt::check_hresult(factory5->CreateFontSetBuilder(builder.put()));
+
+    // Include the system font set so that system families keep resolving when this
+    // collection is used in place of the system collection.
+    winrt::com_ptr<::IDWriteFontSet> systemFontSet;
+    winrt::check_hresult(factory5->GetSystemFontSet(systemFontSet.put()));
+    winrt::check_hresult(builder->AddFontSet(systemFontSet.get()));
+
+    uint32_t fontFileCount = 0;
+    for (const auto *subdirectory : {L"Assets\\", L"Assets\\Fonts\\"}) {
+      for (const auto *pattern : {L"*.ttf", L"*.otf"}) {
+        fontFileCount += AddFontFiles(factory5.get(), builder.get(), appDirectory + subdirectory, pattern);
+      }
+    }
+    if (fontFileCount == 0) {
+      // Nothing bundled: report "no app collection" so callers pass nullptr to DirectWrite
+      // and keep using DirectWrite's own (cached, updatable) system font collection.
+      return nullptr;
+    }
+
+    winrt::com_ptr<::IDWriteFontSet> fontSet;
+    winrt::check_hresult(builder->CreateFontSet(fontSet.put()));
+    winrt::com_ptr<::IDWriteFontCollection1> collection;
+    winrt::check_hresult(factory5->CreateFontCollectionFromFontSet(fontSet.get(), collection.put()));
+    return collection.as<::IDWriteFontCollection>();
+  } catch (...) {
+    // Fail closed: callers fall back to the system font collection (previous behavior).
+    return nullptr;
+  }
+}
+
+} // namespace
+
+::IDWriteFontCollection *DWriteAppFontCollection() noexcept {
+  // One-time initialization, thread-safe by construction: a function-local static
+  // with a dynamic initializer is initialized exactly once, and concurrent callers
+  // that arrive during that window wait for it to complete rather than racing or
+  // repeating it ([stmt.dcl]/4). So the directory enumeration and the font-file
+  // references behind CreateAppFontCollection() happen on the first call only,
+  // whichever thread gets there first - subsequent calls never touch the file
+  // system. Bundled font assets cannot change while the process runs, so the
+  // collection never needs rebuilding.
+  //
+  // Held by value for the lifetime of the process and handed out as a non-owning
+  // raw pointer: GetTextLayout() calls this on every text measure, and returning a
+  // com_ptr by value would add an AddRef/Release pair to that path for no benefit.
+  static const winrt::com_ptr<::IDWriteFontCollection> s_appFontCollection = CreateAppFontCollection();
+  return s_appFontCollection.get();
+}
+
 } // namespace Microsoft::ReactNative

vnext/Microsoft.ReactNative/Fabric/DWriteHelpers.h

@@ -10,4 +10,21 @@ namespace Microsoft::ReactNative {
 
 winrt::com_ptr<::IDWriteFactory> DWriteFactory() noexcept;
 
+// Font collection that merges the system font set with every font file bundled in the
+// application's Assets\ and Assets\Fonts\ directories (*.ttf / *.otf), so app-bundled
+// font families resolve during text layout exactly like installed fonts. Returns
+// nullptr when the app bundles no fonts or when the collection cannot be built;
+// callers should treat nullptr as "use the system font collection".
+//
+// The collection - including the directory enumeration used to find the bundled font
+// files - is built exactly once per process, on first use, and is then owned for the
+// lifetime of the process. Initialization is thread-safe: concurrent first callers
+// resolve to the same instance.
+//
+// Returns a NON-OWNING raw pointer on purpose. GetTextLayout() calls this on every
+// text measure, so handing back a com_ptr by value would put an AddRef/Release pair
+// on that path for a pointer whose lifetime is already static. Callers must not
+// release it; take a com_ptr copy if they need to extend a reference.
+::IDWriteFontCollection *DWriteAppFontCollection() noexcept;
+
 } // namespace Microsoft::ReactNative

vnext/Microsoft.ReactNative/Fabric/platform/react/renderer/textlayoutmanager/WindowsTextLayoutManager.cpp

@@ -116,7 +116,9 @@ void WindowsTextLayoutManager::GetTextLayout(
       outerFragment.textAttributes.fontFamily.empty()
           ? L"Segoe UI"
           : Microsoft::Common::Unicode::Utf8ToUtf16(outerFragment.textAttributes.fontFamily).c_str(),
-      nullptr, // Font collection (nullptr sets it to use the system font collection).
+      // Bundled app fonts merged over the system font set (nullptr when the app bundles
+      // no fonts, which selects the system font collection as before).
+      Microsoft::ReactNative::DWriteAppFontCollection(),
       static_cast<DWRITE_FONT_WEIGHT>(outerFragment.textAttributes.fontWeight.value_or(
           static_cast<facebook::react::FontWeight>(DWRITE_FONT_WEIGHT_REGULAR))),
       style,
@@ -196,12 +198,7 @@ void WindowsTextLayoutManager::GetTextLayout(
       ));
 
   // Apply max width constraint and ellipsis trimming to ensure consistency with rendering
-  DWRITE_TEXT_METRICS metrics;
-  winrt::check_hresult(spTextLayout->GetMetrics(&metrics));
-
-  if (metrics.width > size.width) {
-    spTextLayout->SetMaxWidth(size.width);
-  }
+  spTextLayout->SetMaxWidth(size.width);
 
   // Apply DWRITE_TRIMMING for ellipsizeMode
   DWRITE_TRIMMING trimming = {};
@@ -396,7 +393,7 @@ void WindowsTextLayoutManager::GetTextLayoutByAdjustingFontSizeToFit(
   }
 }
 
-// measure entire text (inluding attachments)
+// measure entire text (including attachments)
 TextMeasurement TextLayoutManager::measure(
     const AttributedStringBox &attributedStringBox,
     const ParagraphAttributes &paragraphAttributes,