text_widget.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 "widget.hpp"
#include "../GUI/gui_event.hpp"
#include "../text/semantic_text_style.hpp"
#include "../text/text_selection.hpp"
#include "../text/text_shaper.hpp"
#include "../observable.hpp"
#include "../alignment.hpp"
#include "../i18n/translate.hpp"
#include "../undo_stack.hpp"
#include "../scoped_task.hpp"
#include <memory>
#include <string>
#include <array>
#include <optional>
#include <future>
#include <limits>
#include <chrono>
 
namespace hi::inline v1 {
 
class text_widget final : public widget {
public:
    using super = widget;
 
    observable<gstring> text;
 
    observable<alignment> alignment = hi::alignment::middle_center();
 
    observable<semantic_text_style> text_style = semantic_text_style::label;
 
    template<
        typename Text,
        typename Alignment = hi::alignment,
        typename VerticalAlignment = hi::vertical_alignment,
        typename TextStyle = hi::semantic_text_style>
    text_widget(
        gui_window& window,
        widget *parent,
        Text&& text,
        Alignment&& alignment = hi::alignment::middle_center(),
        TextStyle&& text_style = semantic_text_style::label) noexcept :
        text_widget(window, parent)
    {
        this->text = std::forward<Text>(text);
        this->alignment = std::forward<Alignment>(alignment);
        this->text_style = std::forward<TextStyle>(text_style);
    }
 
    widget_constraints const& set_constraints() noexcept override;
    void set_layout(widget_layout const& layout) noexcept override;
    void draw(draw_context const& context) noexcept override;
    bool handle_event(gui_event const& event) noexcept override;
    hitbox hitbox_test(point3 position) const noexcept override;
    [[nodiscard]] bool accepts_keyboard_focus(keyboard_focus_group group) const noexcept override;
private:
    enum class add_type { append, insert, dead };
 
    struct undo_type {
        gstring text;
        text_selection selection;
    };
 
    enum class cursor_state_type { off, on, busy, none };
 
    text_shaper _shaped_text;
    float _base_line;
 
    decltype(text)::token_type _text_cbt;
    decltype(text_style)::token_type _text_style_cbt;
 
    text_selection _selection;
 
    scoped_task<> _blink_cursor;
 
    observable<cursor_state_type> _cursor_state = cursor_state_type::none;
    decltype(_cursor_state)::token_type _cursor_state_cbt;
 
    bool _request_scroll = false;
 
    gui_event _last_drag_mouse_event = {};
 
    utc_nanoseconds _last_drag_mouse_event_next_repeat = {};
 
    float _vertical_movement_x = std::numeric_limits<float>::quiet_NaN();
 
    bool _overwrite_mode = false;
 
    grapheme _has_dead_character = {};
 
    undo_stack<undo_type> _undo_stack = {1000};
 
    text_widget(gui_window& window, widget *parent) noexcept;
 
    void update_shaped_text() noexcept;
 
    void scroll_to_show_selection() noexcept;
 
    void request_scroll() noexcept;
 
    void reset_state(char const *states) noexcept;
 
    [[nodiscard]] gstring_view selected_text() const noexcept;
    void undo_push() noexcept;
    void undo() noexcept;
    void redo() noexcept;
 
    scoped_task<> blink_cursor() noexcept;
 
    void fix_cursor_position() noexcept;
 
    void replace_selection(gstring const &replacement) noexcept;
 
    void add_character(grapheme c, add_type mode) noexcept;
    void delete_dead_character() noexcept;
    void delete_character_next() noexcept;
    void delete_character_prev() noexcept;
    void delete_word_next() noexcept;
    void delete_word_prev() noexcept;
};
 
} // namespace hi::inline v1