typography_context.cc

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// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
 
#include "impeller/toolkit/interop/typography_context.h"
 
#include <mutex>
 
#include "flutter/fml/icu_util.h"
#include "flutter/txt/src/txt/platform.h"
#include "impeller/base/validation.h"
#include "impeller/toolkit/interop/embedded_icu_data.h"
 
namespace impeller::interop {
 
TypographyContext::TypographyContext()
    : collection_(std::make_shared<txt::FontCollection>()) {
  static std::once_flag sICUInitOnceFlag;
  std::call_once(sICUInitOnceFlag, []() {
    auto icu_data = std::make_unique<fml::NonOwnedMapping>(
        impeller_embedded_icu_data_data, impeller_embedded_icu_data_length);
    fml::icu::InitializeICUFromMapping(std::move(icu_data));
  });
  // The fallback for all fonts. Looks in platform specific locations.
  collection_->SetupDefaultFontManager(0u);
 
  // Looks for fonts in user supplied blobs.
  asset_font_manager_ = sk_make_sp<skia::textlayout::TypefaceFontProvider>();
  collection_->SetAssetFontManager(asset_font_manager_);
}
 
TypographyContext::~TypographyContext() = default;
 
bool TypographyContext::IsValid() const {
  return !!collection_;
}
 
const std::shared_ptr<txt::FontCollection>&
TypographyContext::GetFontCollection() const {
  return collection_;
}
 
static sk_sp<SkTypeface> CreateTypefaceFromFontData(
    std::unique_ptr<fml::Mapping> font_data) {
  if (!font_data) {
    VALIDATION_LOG << "Invalid font data.";
    return nullptr;
  }
  auto sk_data_context = font_data.release();
  auto sk_data = SkData::MakeWithProc(
      sk_data_context->GetMapping(),  // data ptr
      sk_data_context->GetSize(),     // data size
      [](const void*, void* context) {
        delete reinterpret_cast<decltype(sk_data_context)>(context);
      },               // release callback
      sk_data_context  // release callback context
  );
  auto sk_data_stream = SkMemoryStream::Make(sk_data);
  auto sk_typeface =
      txt::GetDefaultFontManager()->makeFromStream(std::move(sk_data_stream));
  if (!sk_typeface) {
    VALIDATION_LOG << "Could not create typeface with data.";
    return nullptr;
  }
  return sk_typeface;
}
 
bool TypographyContext::RegisterFont(std::unique_ptr<fml::Mapping> font_data,
                                     const char* family_name_alias) {
  auto typeface = CreateTypefaceFromFontData(std::move(font_data));
  if (typeface == nullptr) {
    return false;
  }
  size_t result = 0u;
  if (family_name_alias == nullptr) {
    result = asset_font_manager_->registerTypeface(std::move(typeface));
  } else {
    result = asset_font_manager_->registerTypeface(std::move(typeface),
                                                   SkString{family_name_alias});
  }
  return result != 0;
}
 
}  // namespace impeller::interop