font.hpp

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#pragma once
 
#include "lmgl/renderer/texture.hpp"
 
#include <glm/glm.hpp>
#include <memory>
#include <string>
#include <unordered_map>
 
namespace lmgl {
 
namespace ui {

struct Glyph {
    glm::vec2 tex_coord_min;

    glm::vec2 tex_coord_max;

    glm::vec2 size;

    glm::vec2 bearing;

    float advance;
};

class Font {
  public:
    Font(const std::string &filepath, unsigned int font_size = 48);

    ~Font() = default;

    const Glyph &get_glyph(char c) const;

    inline std::shared_ptr<renderer::Texture> get_atlas() const { return m_atlas; }

    inline unsigned int get_font_size() const { return m_font_size; }

    inline float get_line_height() const { return m_line_height; }

    float measure_text(const std::string &text) const;
 
  private:
    unsigned int m_font_size;

    float m_line_height;

    std::shared_ptr<renderer::Texture> m_atlas;

    std::unordered_map<char, Glyph> m_glyphs;

    void generate_atlas(const std::string &filepath);
};

class FontManager {
  public:
    static FontManager &get();

    std::shared_ptr<Font> load(const std::string &name, const std::string &filepath, unsigned int font_size = 48);

    std::shared_ptr<Font> get_font(const std::string &name);

    bool exists(const std::string &name) const;

    void clear();
 
  private:
    FontManager() = default;
    ~FontManager() = default;

    static std::unordered_map<std::string, std::shared_ptr<Font>> s_fonts;
};
 
} // namespace ui
 
} // namespace lmgl