font_metrics.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
 
namespace hi::inline v1 {

struct font_metrics {
    float ascender = 0.0f;

    float descender = 0.0f;

    float line_gap = 0.0f;

    float cap_height = 0.0f;

    float x_height = 0.0f;

    float digit_advance = 0.0f;

    float line_spacing = 1.0f;

    float paragraph_spacing = 1.5f;
 
    ~font_metrics() = default;
    constexpr font_metrics() noexcept = default;
    constexpr font_metrics(font_metrics const&) noexcept = default;
    constexpr font_metrics(font_metrics&&) noexcept = default;
    constexpr font_metrics& operator=(font_metrics const&) noexcept = default;
    constexpr font_metrics& operator=(font_metrics&&) noexcept = default;
    [[nodiscard]] constexpr friend bool operator==(font_metrics const&, font_metrics const&) noexcept = default;

    [[nodiscard]] constexpr friend font_metrics operator*(float const& lhs, font_metrics const& rhs) noexcept
    {
        font_metrics r;
        r.ascender = lhs * rhs.ascender;
        r.descender = lhs * rhs.descender;
        r.line_gap = lhs * rhs.line_gap;
        r.cap_height = lhs * rhs.cap_height;
        r.x_height = lhs * rhs.x_height;
        r.digit_advance = lhs * rhs.digit_advance;
        return r;
    }
 
    [[nodiscard]] constexpr friend font_metrics max(font_metrics const& a, font_metrics const& b) noexcept
    {
        font_metrics r;
        r.ascender = std::max(a.ascender, b.ascender);
        r.descender = std::max(a.descender, b.descender);
        r.line_gap = std::max(a.line_gap, b.line_gap);
        r.cap_height = std::max(a.cap_height, b.cap_height);
        r.x_height = std::max(a.x_height, b.x_height);
        r.digit_advance = std::max(a.digit_advance, b.digit_advance);
        return r;
    }

    [[nodiscard]] float round_scale(float size) const noexcept
    {
        return std::round(x_height * size) / x_height;
    }
};
 
} // namespace hi::inline v1