font_weight.hpp

// Copyright Take Vos 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 "../exception.hpp"
#include "../strings.hpp"
#include "../concepts.hpp"
#include <string>
#include <unordered_map>
#include <ostream>
#include <array>
 
namespace tt {
 
enum class font_weight {
    Thin, 
    ExtraLight, 
    Light, 
    Regular, 
    Medium, 
    SemiBold, 
    Bold, 
    ExtraBold, 
    Black, 
    ExtraBlack, 
};
 
inline ttlet font_weight_from_string_table = std::unordered_map<std::string, font_weight>{
    {"thin", font_weight::Thin},
    {"hairline", font_weight::Thin},
    {"ultra-light", font_weight::ExtraLight},
    {"ultra light", font_weight::ExtraLight},
    {"extra-light", font_weight::ExtraLight},
    {"extra light", font_weight::ExtraLight},
    {"light", font_weight::Light},
    {"normal", font_weight::Regular},
    {"regular", font_weight::Regular},
    {"medium", font_weight::Medium},
    {"semi-bold", font_weight::SemiBold},
    {"semi bold", font_weight::SemiBold},
    {"demi-bold", font_weight::SemiBold},
    {"demi bold", font_weight::SemiBold},
    {"bold", font_weight::Bold},
    {"extra-bold", font_weight::ExtraBold},
    {"extra bold", font_weight::ExtraBold},
    {"ultra-bold", font_weight::ExtraBold},
    {"ultra bold", font_weight::ExtraBold},
    {"heavy", font_weight::Black},
    {"black", font_weight::Black},
    {"extra-black", font_weight::ExtraBlack},
    {"ultra-black", font_weight::ExtraBlack},
};
 
[[nodiscard]] constexpr font_weight font_weight_from_int(numeric_integral auto rhs)
{
    if (rhs < 50 || rhs > 1000) {
        throw parse_error("Unknown font-weight {}", rhs);
    }
    return static_cast<font_weight>(((rhs + 50) / 100) - 1);
}
 
[[nodiscard]] inline font_weight font_weight_from_string(std::string_view rhs)
{
    ttlet i = font_weight_from_string_table.find(to_lower(rhs));
    if (i == font_weight_from_string_table.end()) {
        throw parse_error("Unknown font-weight {}", rhs);
    }
    return i->second;
}
 
[[nodiscard]] constexpr char const *to_const_string(font_weight const &x) noexcept
{
    switch (x) {
    case font_weight::Thin: return "Thin";
    case font_weight::ExtraLight: return "ExtraLight";
    case font_weight::Light: return "Light";
    case font_weight::Regular: return "Regular";
    case font_weight::Medium: return "Medium";
    case font_weight::SemiBold: return "SemiBold";
    case font_weight::Bold: return "Bold";
    case font_weight::ExtraBold: return "ExtraBold";
    case font_weight::Black: return "Black";
    case font_weight::ExtraBlack: return "ExtraBlack";
    default: tt_no_default();
    }
}
 
[[nodiscard]] inline std::string to_string(font_weight const &x) noexcept
{
    return to_const_string(x);
}
 
[[nodiscard]] inline char to_char(font_weight const &x) noexcept
{
    ttlet x_ = static_cast<int>(x);
    tt_axiom(x_ >= 0 && x_ <= 9);
    return static_cast<char>('0' + x_);
}
 
[[nodiscard]] constexpr int to_int(font_weight const &x) noexcept
{
    ttlet x_ = (static_cast<int>(x) + 1) * 100;
    return (x_ == 1000) ? 950 : x_;
}
 
inline std::ostream &operator<<(std::ostream &lhs, font_weight const &rhs)
{
    return lhs << to_string(rhs);
}
 
inline bool almost_equal(font_weight const &lhs, font_weight const &rhs) noexcept
{
    // Check only if it is bold or not.
    return (lhs > font_weight::Medium) == (rhs > font_weight::Medium);
}
 
[[nodiscard]] constexpr auto font_weight_alternative_table_generator() noexcept
{
    std::array<font_weight, 100> r = {font_weight::Regular};
 
    for (int w = 0; w < 10; ++w) {
        auto min_w = w;
        auto max_w = w;
        auto new_w = w;
        auto forward = false;
 
        for (int i = 0; i < 10; ++i) {
            r[w * 10 + i] = static_cast<font_weight>(new_w);
 
            // Change direction to not overflow.
            if ((forward && max_w == 9) || (!forward && min_w == 0)) {
                forward = !forward;
            }
 
            if (forward) {
                ++max_w;
                new_w = max_w;
            } else {
                --min_w;
                new_w = min_w;
            }
 
            // Change direction to zig-zag.
            forward = !forward;
        }
    }
    return r;
}
 
constexpr auto font_weight_alternative_table = font_weight_alternative_table_generator();
 
[[nodiscard]] constexpr font_weight font_weight_alterative(font_weight weight, int i) noexcept
{
    tt_axiom(i >= 0 && i < 10);
    auto w = static_cast<int>(weight);
    tt_axiom(w >= 0 && w < 10);
    return font_weight_alternative_table[(w * 10) + i];
}
 
} // namespace tt
 
namespace std {
 
template<typename CharT>
struct std::formatter<tt::font_weight, CharT> : std::formatter<char const *, CharT> {
    auto format(tt::font_weight const &t, auto &fc)
    {
        return std::formatter<char const *, CharT>::format(tt::to_const_string(t), fc);
    }
};
 
} // namespace std