An API for loading fonts from a buffer provided by the application (#6508)

Author: jason-simmons

lib/ui/dart_ui.cc

@@ -24,6 +24,7 @@
 #include "flutter/lib/ui/painting/vertices.h"
 #include "flutter/lib/ui/semantics/semantics_update.h"
 #include "flutter/lib/ui/semantics/semantics_update_builder.h"
+#include "flutter/lib/ui/text/font_collection.h"
 #include "flutter/lib/ui/text/paragraph.h"
 #include "flutter/lib/ui/text/paragraph_builder.h"
 #include "flutter/lib/ui/window/window.h"
@@ -72,6 +73,7 @@ void DartUI::InitForGlobal() {
     Codec::RegisterNatives(g_natives);
     DartRuntimeHooks::RegisterNatives(g_natives);
     EngineLayer::RegisterNatives(g_natives);
+    FontCollection::RegisterNatives(g_natives);
     FrameInfo::RegisterNatives(g_natives);
     ImageFilter::RegisterNatives(g_natives);
     ImageShader::RegisterNatives(g_natives);

lib/ui/text.dart

@@ -1087,3 +1087,16 @@ class ParagraphBuilder extends NativeFieldWrapperClass2 {
   /// cannot be used further.
   Paragraph build() native 'ParagraphBuilder_build';
 }
+
+/// Loads a font from a buffer and makes it available for rendering text.
+///
+/// * `list`: A list of bytes containing the font file.
+/// * `fontFamily`: The family name used to identify the font in text styles.
+///  If this is not provided, then the family name will be extracted from the font file.
+Future<void> loadFontFromList(Uint8List list, {String fontFamily}) {
+  return _futurize(
+    (_Callback<void> callback) => _loadFontFromList(list, callback, fontFamily)
+  );
+}
+
+String _loadFontFromList(Uint8List list, _Callback<void> callback, String fontFamily) native 'loadFontFromList';

lib/ui/text/font_collection.cc

@@ -7,29 +7,62 @@
 #include <mutex>
 
 #include "flutter/lib/ui/text/asset_manager_font_provider.h"
+#include "flutter/lib/ui/ui_dart_state.h"
+#include "flutter/lib/ui/window/window.h"
 #include "flutter/runtime/test_font_data.h"
 #include "rapidjson/document.h"
 #include "rapidjson/rapidjson.h"
 #include "third_party/skia/include/core/SkFontMgr.h"
 #include "third_party/skia/include/core/SkGraphics.h"
 #include "third_party/skia/include/core/SkStream.h"
 #include "third_party/skia/include/core/SkTypeface.h"
+#include "third_party/tonic/dart_args.h"
+#include "third_party/tonic/dart_library_natives.h"
+#include "third_party/tonic/logging/dart_invoke.h"
+#include "third_party/tonic/typed_data/uint8_list.h"
 #include "txt/asset_font_manager.h"
 #include "txt/test_font_manager.h"
-#include "txt/typeface_font_asset_provider.h"
 
 namespace blink {
 
+namespace {
+
+void LoadFontFromList(tonic::Uint8List& font_data,
+                      Dart_Handle callback,
+                      std::string family_name) {
+  FontCollection& font_collection =
+      UIDartState::Current()->window()->client()->GetFontCollection();
+  font_collection.LoadFontFromList(font_data.data(), font_data.num_elements(),
+                                   family_name);
+  font_data.Release();
+  tonic::DartInvoke(callback, {tonic::ToDart(0)});
+}
+
+void _LoadFontFromList(Dart_NativeArguments args) {
+  tonic::DartCallStatic(LoadFontFromList, args);
+}
+
+}  // namespace
+
 FontCollection::FontCollection()
     : collection_(std::make_shared<txt::FontCollection>()) {
   collection_->SetDefaultFontManager(SkFontMgr::RefDefault());
+
+  dynamic_font_manager_ = sk_make_sp<txt::DynamicFontManager>();
+  collection_->SetDynamicFontManager(dynamic_font_manager_);
 }
 
 FontCollection::~FontCollection() {
   collection_.reset();
   SkGraphics::PurgeFontCache();
 }
 
+void FontCollection::RegisterNatives(tonic::DartLibraryNatives* natives) {
+  natives->Register({
+      {"loadFontFromList", _LoadFontFromList, 3, true},
+  });
+}
+
 std::shared_ptr<txt::FontCollection> FontCollection::GetFontCollection() const {
   return collection_;
 }
@@ -110,4 +143,20 @@ void FontCollection::RegisterTestFonts() {
   collection_->DisableFontFallback();
 }
 
+void FontCollection::LoadFontFromList(const uint8_t* font_data,
+                                      int length,
+                                      std::string family_name) {
+  std::unique_ptr<SkStreamAsset> font_stream =
+      std::make_unique<SkMemoryStream>(font_data, length, true);
+  sk_sp<SkTypeface> typeface =
+      SkTypeface::MakeFromStream(std::move(font_stream));
+  txt::TypefaceFontAssetProvider& font_provider =
+      dynamic_font_manager_->font_provider();
+  if (family_name.empty()) {
+    font_provider.RegisterTypeface(typeface);
+  } else {
+    font_provider.RegisterTypeface(typeface, family_name);
+  }
+}
+
 }  // namespace blink

lib/ui/text/font_collection.h

@@ -13,6 +13,10 @@
 #include "flutter/fml/memory/ref_ptr.h"
 #include "txt/font_collection.h"
 
+namespace tonic {
+class DartLibraryNatives;
+}  // namespace tonic
+
 namespace blink {
 
 class FontCollection {
@@ -21,14 +25,21 @@ class FontCollection {
 
   ~FontCollection();
 
+  static void RegisterNatives(tonic::DartLibraryNatives* natives);
+
   std::shared_ptr<txt::FontCollection> GetFontCollection() const;
 
   void RegisterFonts(fml::RefPtr<AssetManager> asset_manager);
 
   void RegisterTestFonts();
 
+  void LoadFontFromList(const uint8_t* font_data,
+                        int length,
+                        std::string family_name);
+
  private:
   std::shared_ptr<txt::FontCollection> collection_;
+  sk_sp<txt::DynamicFontManager> dynamic_font_manager_;
 
   FML_DISALLOW_COPY_AND_ASSIGN(FontCollection);
 };

third_party/txt/src/txt/asset_font_manager.h

@@ -22,6 +22,7 @@
 #include "third_party/skia/include/core/SkFontMgr.h"
 #include "third_party/skia/include/core/SkStream.h"
 #include "txt/font_asset_provider.h"
+#include "txt/typeface_font_asset_provider.h"
 
 namespace txt {
 
@@ -35,9 +36,9 @@ class AssetFontManager : public SkFontMgr {
   // |SkFontMgr|
   SkFontStyleSet* onMatchFamily(const char familyName[]) const override;
 
- private:
   std::unique_ptr<FontAssetProvider> font_provider_;
 
+ private:
   // |SkFontMgr|
   int onCountFamilies() const override;
 
@@ -84,6 +85,16 @@ class AssetFontManager : public SkFontMgr {
   FML_DISALLOW_COPY_AND_ASSIGN(AssetFontManager);
 };
 
+class DynamicFontManager : public AssetFontManager {
+ public:
+  DynamicFontManager()
+      : AssetFontManager(std::make_unique<TypefaceFontAssetProvider>()) {}
+
+  TypefaceFontAssetProvider& font_provider() {
+    return static_cast<TypefaceFontAssetProvider&>(*font_provider_);
+  }
+};
+
 }  // namespace txt
 
 #endif  // TXT_ASSET_FONT_MANAGER_H_

third_party/txt/src/txt/font_collection.cc

@@ -84,6 +84,10 @@ void FontCollection::SetAssetFontManager(sk_sp<SkFontMgr> font_manager) {
   asset_font_manager_ = font_manager;
 }
 
+void FontCollection::SetDynamicFontManager(sk_sp<SkFontMgr> font_manager) {
+  dynamic_font_manager_ = font_manager;
+}
+
 void FontCollection::SetTestFontManager(sk_sp<SkFontMgr> font_manager) {
   test_font_manager_ = font_manager;
 }
@@ -93,6 +97,8 @@ std::vector<sk_sp<SkFontMgr>> FontCollection::GetFontManagerOrder() const {
   std::vector<sk_sp<SkFontMgr>> order;
   if (test_font_manager_)
     order.push_back(test_font_manager_);
+  if (dynamic_font_manager_)
+    order.push_back(dynamic_font_manager_);
   if (asset_font_manager_)
     order.push_back(asset_font_manager_);
   if (default_font_manager_)

third_party/txt/src/txt/font_collection.h

@@ -42,6 +42,7 @@ class FontCollection : public std::enable_shared_from_this<FontCollection> {
 
   void SetDefaultFontManager(sk_sp<SkFontMgr> font_manager);
   void SetAssetFontManager(sk_sp<SkFontMgr> font_manager);
+  void SetDynamicFontManager(sk_sp<SkFontMgr> font_manager);
   void SetTestFontManager(sk_sp<SkFontMgr> font_manager);
 
   std::shared_ptr<minikin::FontCollection> GetMinikinFontCollectionForFamily(
@@ -73,6 +74,7 @@ class FontCollection : public std::enable_shared_from_this<FontCollection> {
 
   sk_sp<SkFontMgr> default_font_manager_;
   sk_sp<SkFontMgr> asset_font_manager_;
+  sk_sp<SkFontMgr> dynamic_font_manager_;
   sk_sp<SkFontMgr> test_font_manager_;
   std::unordered_map<FamilyKey,
                      std::shared_ptr<minikin::FontCollection>,