otype_utilities.hpp

// Copyright Take Vos 2023.
// 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 "../utility/utility.hpp"
#include "../parser/parser.hpp"
#include "../macros.hpp"
#include <concepts>
 
hi_export_module(hikogui.font.otype_utilities);
 
hi_export namespace hi { inline namespace v1 {
 
struct otype_fixed15_16_buf_t {
    big_uint32_buf_t x;
 
    constexpr float operator*() const noexcept
    {
        return static_cast<float>(*x) / 65536.0f;
    }
};
 
struct otype_fixed1_14_buf_t {
    big_int16_buf_t x;
    
    constexpr float operator*() const noexcept
    {
        return static_cast<float>(*x) / 16384.0f;
    }
};
 
struct otype_fword_buf_t {
    big_int16_buf_t x;
    [[nodiscard]] constexpr float operator*(float Em_scale) const noexcept
    {
        return static_cast<float>(*x) * Em_scale;
    }
};
 
struct otype_fbyte_buf_t {
    int8_t x;
    [[nodiscard]] constexpr float operator*(float Em_scale) const noexcept
    {
        return static_cast<float>(x) * Em_scale;
    }
};
 
struct otype_fuword_buf_t {
    big_uint16_buf_t x;
    [[nodiscard]] constexpr float operator*(float Em_scale) const noexcept
    {
        return static_cast<float>(*x) * Em_scale;
    }
};
 
inline std::optional<std::string>
otype_get_string(std::span<std::byte const> bytes, uint16_t platform_id, uint16_t platform_specific_id)
{
    switch (platform_id) {
    case 2: // Deprecated, but compatible with unicode.
    case 0: // Unicode, encoded as UTF-16BE, should not be UTF-16LE, but sometimes it is.
        hi_check(bytes.size() % 2 == 0, "Length in bytes of a name must be multiple of two");
        return char_converter<"utf-16", "utf-8">{}.read(bytes.data(), bytes.size(), std::endian::big);
 
    case 1: // Macintosh
        if (platform_specific_id == 0) { // Roman script ASCII
            return char_converter<"utf-8", "utf-8">{}.read(bytes.data(), bytes.size());
        }
        break;
 
    case 3: // Windows
        if (platform_specific_id == 1 or platform_specific_id == 10) { // UTF-16BE
            hi_check(bytes.size() % 2 == 0, "Length in bytes of a name must be multiple of two");
            return char_converter<"utf-16", "utf-8">{}.read(bytes.data(), bytes.size(), std::endian::big);
        }
        break;
 
    default:
        break;
    }
    return {};
}
 
}} // namespace hi::v1