typeface_stb.h

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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.
 
#ifndef FLUTTER_IMPELLER_TYPOGRAPHER_BACKENDS_STB_TYPEFACE_STB_H_
#define FLUTTER_IMPELLER_TYPOGRAPHER_BACKENDS_STB_TYPEFACE_STB_H_
 
#include "flutter/fml/mapping.h"
#include "flutter/third_party/stb/stb_truetype.h"
#include "impeller/base/backend_cast.h"
#include "impeller/typographer/typeface.h"
 
namespace impeller {
 
class TypefaceSTB final : public Typeface,
                          public BackendCast<TypefaceSTB, Typeface> {
 public:
  // "Typical" conversion from font Points to Pixels.
  // This assumes a constant pixels per em.
  static constexpr float kPointsToPixels = 96.0 / 72.0;
 
  explicit TypefaceSTB(std::unique_ptr<fml::Mapping> typeface_mapping);
 
  ~TypefaceSTB() override;
 
  // |Typeface|
  bool IsValid() const override;
 
  // |Comparable<Typeface>|
  std::size_t GetHash() const override;
 
  // |Comparable<Typeface>|
  bool IsEqual(const Typeface& other) const override;
 
  const uint8_t* GetTypefaceFile() const;
  const stbtt_fontinfo* GetFontInfo() const;
 
 private:
  std::unique_ptr<fml::Mapping> typeface_mapping_;
  std::unique_ptr<stbtt_fontinfo> font_info_;
  bool is_valid_ = false;
 
  TypefaceSTB(const TypefaceSTB&) = delete;
 
  TypefaceSTB& operator=(const TypefaceSTB&) = delete;
};
 
}  // namespace impeller
 
#endif  // FLUTTER_IMPELLER_TYPOGRAPHER_BACKENDS_STB_TYPEFACE_STB_H_