otype_loca.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 "otype_utilities.hpp"
#include "../utility/utility.hpp"
#include "../macros.hpp"
#include <span>
#include <cstddef>
 
hi_export_module(hikogui.font.otype_loca);
 
hi_export namespace hi { inline namespace v1 {
 
[[nodiscard]] inline std::pair<size_t, size_t> otype_loca16_get(std::span<std::byte const> bytes, hi::glyph_id glyph_id)
{
    auto const entries = implicit_cast<big_uint16_buf_t>(bytes, bytes.size() / sizeof(big_uint16_buf_t));
    auto const first = wide_cast<size_t>(*hi_check_at(entries, *glyph_id)) * 2;
    auto const last = wide_cast<size_t>(*hi_check_at(entries, *glyph_id + 1)) * 2;
    hi_check(first <= last, "'loca' table has invalid entries.");
    return {first, last};
}
 
[[nodiscard]] inline std::pair<size_t, size_t> otype_loca32_get(std::span<std::byte const> bytes, hi::glyph_id glyph_id)
{
    auto const entries = implicit_cast<big_uint32_buf_t>(bytes, bytes.size() / sizeof(big_uint32_buf_t));
    auto const first = wide_cast<size_t>(*hi_check_at(entries, *glyph_id));
    auto const last = wide_cast<size_t>(*hi_check_at(entries, *glyph_id + 1));
    hi_check(first <= last, "'loca' table has invalid entries.");
    return {first, last};
}
 
[[nodiscard]] inline std::pair<size_t, size_t>
otype_loca_get(std::span<std::byte const> loca_bytes, hi::glyph_id glyph_id, bool loca_is_offset32)
{
    if (loca_is_offset32) {
        return otype_loca32_get(loca_bytes, glyph_id);
    } else {
        return otype_loca16_get(loca_bytes, glyph_id);
    }
}
 
[[nodiscard]] inline std::span<std::byte const> otype_loca_get(
    std::span<std::byte const> loca_bytes,
    std::span<std::byte const> glyf_bytes,
    hi::glyph_id glyph_id,
    bool loca_is_offset32)
{
    auto const[first, last] = otype_loca_get(loca_bytes, glyph_id, loca_is_offset32);
    auto const size = last - first;
    return hi_check_subspan(glyf_bytes, first, size);
}
 
}} // namespace hi::v1