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.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;
 
    pixel_density pixel_density;
 
    hi::font_book::font_glyphs_type 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<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 const& style, hi::pixel_density pixel_density) noexcept :
        grapheme(grapheme),
        style(style),
        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 const& 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(find_font(style->family_id, style->variant));
    }
 
    void replace_glyph(char32_t code_point) noexcept
    {
        hi_axiom_not_null(glyphs.font);
        auto const& font = *glyphs.font;
        set_glyph(font_book::font_glyphs_type{font, font.find_glyph(code_point)});
 
        glyph_is_initial = false;
    }
 
    [[nodiscard]] font_metrics_px font_metrics() const noexcept
    {
        hi_axiom_not_null(glyphs.font);
        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_book::font_glyphs_type&& new_glyphs) noexcept
    {
        glyphs = std::move(new_glyphs);
        hi_axiom_not_null(glyphs.font);
        font_size = round(style->size * pixel_density, glyphs.get_font_metrics().x_height);
        metrics = font_size.in(pixels_per_em) * glyphs.get_starter_metrics();
    }
};
 
} // namespace hi::inline v1