text_shaper_char.hpp

// Copyright Take Vos 2022.
// 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 "text_style_set.hpp"
#include "text_style.hpp"
#include "../font/font.hpp"
#include "../unicode/unicode.hpp"
#include "../geometry/geometry.hpp"
#include "../units/units.hpp"
#include "../macros.hpp"
 
hi_export_module(hikogui.text.text_shaper_char);
 
hi_export namespace hi::inline v1 {
 
class text_shaper_char {
public:
    hi::grapheme grapheme;

    hi::text_style style;

    unit::pixel_density pixel_density;

    hi::font_glyph_ids glyphs;

    hi::glyph_metrics metrics;

    size_t line_nr;

    size_t column_nr;

    point2 position;

    aarectangle rectangle;

    unicode_general_category general_category;

    unicode_bidi_class direction;

    iso_15924 script;

    au::Quantity<unit::PixelsPerEm, float> font_size;

    float width = 0.0f;

    bool is_trailing_white_space = false;

    bool glyph_is_initial = false;
 
    [[nodiscard]] text_shaper_char(hi::grapheme const& grapheme, text_style_set const& style, unit::pixel_density pixel_density) noexcept :
        grapheme(grapheme),
        style(style[grapheme.attributes()]),
        pixel_density(pixel_density),
        line_nr(std::numeric_limits<size_t>::max()),
        column_nr(std::numeric_limits<size_t>::max()),
        general_category(ucd_get_general_category(grapheme.starter()))
    {
    }

    void initialize_glyph(hi::font_id font) noexcept
    {
        if (not glyph_is_initial) {
            set_glyph(find_glyph(font, grapheme));
 
            width = metrics.advance;
            glyph_is_initial = true;
        }
    }

    void initialize_glyph() noexcept
    {
        return initialize_glyph(style.font_chain()[0]);
    }

    void replace_glyph(char32_t code_point) noexcept
    {
        set_glyph(find_glyph(glyphs.font, code_point));
        glyph_is_initial = false;
    }

    [[nodiscard]] font_metrics_px font_metrics() const noexcept
    {
        hi_axiom(not glyphs.font.empty());
        return font_size * glyphs.font->metrics;
    }
 
    [[nodiscard]] friend bool operator==(text_shaper_char const& lhs, char32_t const& rhs) noexcept
    {
        return lhs.grapheme == rhs;
    }
 
    [[nodiscard]] friend bool operator==(text_shaper_char const& lhs, char const& rhs) noexcept
    {
        return lhs.grapheme == rhs;
    }
 
private:
    void set_glyph(hi::font_glyph_ids&& new_glyphs) noexcept
    {
        glyphs = std::move(new_glyphs);
        hi_axiom(not glyphs.font.empty());
        font_size = round(style.size() * pixel_density, glyphs.font_metrics().x_height);
        metrics = font_size.in(unit::pixels_per_em) * glyphs.front_glyph_metrics();
    }
};
 
} // namespace hi::inline v1