true_type_font.hpp

// Copyright Take Vos 2019-2021.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt)
 
#pragma once
 
#include "font.hpp"
#include "../graphic_path.hpp"
#include "../resource_view.hpp"
#include "../URL.hpp"
#include <memory>
 
namespace tt {
 
class true_type_font final: public font {
private:
    std::unique_ptr<resource_view> view;
 
    std::span<std::byte const> file_bytes;
 
    uint16_t OS2_xHeight = 0;
    uint16_t OS2_HHeight = 0;
 
    std::span<std::byte const> cmapTableBytes;
 
    std::span<std::byte const> cmapBytes;
 
    std::span<std::byte const> glyfTableBytes;
 
    std::span<std::byte const> headTableBytes;
    float unitsPerEm;
    float emScale;
    bool locaTableIsOffset32;
 
    std::span<std::byte const> hheaTableBytes;
    float ascender;
    float descender;
    float lineGap;
    uint16_t numberOfHMetrics;
 
    std::span<std::byte const> hmtxTableBytes;
 
    std::span<std::byte const> locaTableBytes;
 
    std::span<std::byte const> maxpTableBytes;
    int numGlyphs;
 
    std::span<std::byte const> nameTableBytes;
 
    std::span<std::byte const> postTableBytes;
 
    std::span<std::byte const> os2TableBytes;
 
    std::span<std::byte const> kernTableBytes;
 
public:
    true_type_font(std::span<std::byte const> bytes) :
        file_bytes(bytes)
    {
        parsefontDirectory();
    }
 
    true_type_font(std::unique_ptr<resource_view> view) :
        view(std::move(view))
    {
        file_bytes = this->view->bytes();
        parsefontDirectory();
    }
 
    true_type_font(URL const &url) :
        view(url.loadView())
    {
        file_bytes = this->view->bytes();
        try {
            parsefontDirectory();
 
        } catch (std::exception const &e) {
            throw parse_error("{}: Could not parse font directory.\n{}", url, e.what());
        }
    }
 
    true_type_font() = delete;
    true_type_font(true_type_font const &other) = delete;
    true_type_font &operator=(true_type_font const &other) = delete;
    true_type_font(true_type_font &&other) = delete;
    true_type_font &operator=(true_type_font &&other) = delete;
    ~true_type_font() = default;
 
    [[nodiscard]] tt::glyph_id find_glyph(char32_t c) const noexcept override;
    
    std::optional<tt::glyph_id> loadGlyph(tt::glyph_id glyph_id, graphic_path &path) const noexcept override;
 
    bool loadglyph_metrics(tt::glyph_id glyph_id, glyph_metrics &metrics, tt::glyph_id lookahead_glyph_id = tt::glyph_id{})
        const noexcept override;
 
private:
    void parsefontDirectory();
 
    void parseHeadTable(std::span<std::byte const> headTableBytes);
 
    void parseHheaTable(std::span<std::byte const> bytes);
 
    void parseNameTable(std::span<std::byte const> bytes);
 
    void parseOS2Table(std::span<std::byte const> bytes);
 
    [[nodiscard]] unicode_ranges parseCharacterMap();
 
 
    void parseMaxpTable(std::span<std::byte const> bytes);
 
    bool getGlyphBytes(tt::glyph_id glyph_id, std::span<std::byte const> &bytes) const noexcept;
 
    bool updateglyph_metrics(
        tt::glyph_id glyph_id,
        glyph_metrics &metrics,
        tt::glyph_id kern_glyph1_id = tt::glyph_id{},
        tt::glyph_id kern_glyph2_id = tt::glyph_id{}) const noexcept;
 
    bool loadSimpleGlyph(std::span<std::byte const> bytes, graphic_path &glyph) const noexcept;
 
    bool loadCompoundGlyph(std::span<std::byte const> bytes, graphic_path &glyph, tt::glyph_id &metrics_glyph_id) const noexcept;
 
    bool loadCompoundglyph_metrics(std::span<std::byte const> bytes, tt::glyph_id &metrics_glyph_id) const noexcept;
 
 
};
 
}