selection_widget.hpp

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// Copyright Take Vos 2020-2022.
// 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 "widget.hpp"
#include "label_widget.hpp"
#include "overlay_widget.hpp"
#include "scroll_widget.hpp"
#include "row_column_widget.hpp"
#include "menu_button_widget.hpp"
#include "selection_delegate.hpp"
#include "../observer/module.hpp"
#include "../macros.hpp"
#include <memory>
#include <string>
#include <array>
#include <optional>
#include <future>
 
namespace hi { inline namespace v1 {
 
template<typename Context>
concept selection_widget_attribute = label_widget_attribute<Context>;

class selection_widget final : public widget {
public:
    using super = widget;
    using delegate_type = selection_delegate;
 
    std::shared_ptr<delegate_type> delegate;

    observer<label> off_label;

    observer<alignment> alignment = hi::alignment::middle_flush();

    observer<semantic_text_style> text_style = semantic_text_style::label;
 
    ~selection_widget()
    {
        hi_assert_not_null(delegate);
        delegate->deinit(*this);
    }

    selection_widget(widget *parent, std::shared_ptr<delegate_type> delegate) noexcept :
        super(parent), delegate(std::move(delegate))
    {
        hi_assert_not_null(this->delegate);
 
        _current_label_widget = std::make_unique<label_widget>(this, alignment, text_style);
        _current_label_widget->mode = widget_mode::invisible;
        _off_label_widget = std::make_unique<label_widget>(this, off_label, alignment, semantic_text_style::placeholder);
 
        _overlay_widget = std::make_unique<overlay_widget>(this);
        _overlay_widget->mode = widget_mode::invisible;
        _scroll_widget = &_overlay_widget->make_widget<vertical_scroll_widget>();
        _column_widget = &_scroll_widget->make_widget<column_widget>();
 
        _off_label_cbt = this->off_label.subscribe([&](auto...) {
            ++global_counter<"selection_widget:off_label:constrain">;
            process_event({gui_event_type::window_reconstrain});
        });
 
        _delegate_cbt = this->delegate->subscribe([&] {
            _notification_from_delegate = true;
            ++global_counter<"selection_widget:delegate:constrain">;
            process_event({gui_event_type::window_reconstrain});
        });
 
        this->delegate->init(*this);
    }

    selection_widget(
        widget *parent,
        std::shared_ptr<delegate_type> delegate,
        selection_widget_attribute auto&& first_attribute,
        selection_widget_attribute auto&&...attributes) noexcept :
        selection_widget(parent, std::move(delegate))
    {
        set_attributes(hi_forward(first_attribute), hi_forward(attributes)...);
    }

    template<
        different_from<std::shared_ptr<delegate_type>> Value,
        forward_of<observer<std::vector<std::pair<observer_decay_t<Value>, label>>>> OptionList,
        selection_widget_attribute... Attributes>
    selection_widget(
        widget *parent,
        Value&& value,
        OptionList&& option_list,
        Attributes&&...attributes) noexcept requires requires
    {
        make_default_selection_delegate(hi_forward(value), hi_forward(option_list));
    } :
        selection_widget(
            parent,
            make_default_selection_delegate(hi_forward(value), hi_forward(option_list)),
            hi_forward(attributes)...)
    {
    }

    template<
        different_from<std::shared_ptr<delegate_type>> Value,
        forward_of<observer<std::vector<std::pair<observer_decay_t<Value>, label>>>> OptionList,
        forward_of<observer<observer_decay_t<Value>>> OffValue,
        selection_widget_attribute... Attributes>
    selection_widget(
        widget *parent,
        Value&& value,
        OptionList&& option_list,
        OffValue&& off_value,
        Attributes&&...attributes) noexcept requires requires
    {
        make_default_selection_delegate(hi_forward(value), hi_forward(option_list), hi_forward(off_value));
    } :
        selection_widget(
            parent,
            make_default_selection_delegate(hi_forward(value), hi_forward(option_list), hi_forward(off_value)),
            hi_forward(attributes)...)
    {
    }

    [[nodiscard]] generator<widget_intf&> children(bool include_invisible) noexcept override
    {
        co_yield *_overlay_widget;
        co_yield *_current_label_widget;
        co_yield *_off_label_widget;
    }
 
    [[nodiscard]] box_constraints update_constraints() noexcept override
    {
        hi_assert_not_null(_off_label_widget);
        hi_assert_not_null(_current_label_widget);
        hi_assert_not_null(_overlay_widget);
 
        if (_notification_from_delegate.exchange(false)) {
            repopulate_options();
        }
 
        _layout = {};
        _off_label_constraints = _off_label_widget->update_constraints();
        _current_label_constraints = _current_label_widget->update_constraints();
        _overlay_constraints = _overlay_widget->update_constraints();
 
        hilet extra_size = extent2{theme().size() + theme().margin<float>() * 2.0f, theme().margin<float>() * 2.0f};
 
        auto r = max(_off_label_constraints + extra_size, _current_label_constraints + extra_size);
 
        // Make it so that the scroll widget can scroll vertically.
        _scroll_widget->minimum.copy()->height() = theme().size();
 
        r.minimum.width() = std::max(r.minimum.width(), _overlay_constraints.minimum.width() + extra_size.width());
        r.preferred.width() = std::max(r.preferred.width(), _overlay_constraints.preferred.width() + extra_size.width());
        r.maximum.width() = std::max(r.maximum.width(), _overlay_constraints.maximum.width() + extra_size.width());
        r.margins = theme().margin();
        r.padding = theme().margin();
        r.alignment = resolve(*alignment, os_settings::left_to_right());
        hi_axiom(r.holds_invariant());
        return r;
    }
 
    void set_layout(widget_layout const& context) noexcept override
    {
        if (compare_store(_layout, context)) {
            if (os_settings::left_to_right()) {
                _left_box_rectangle = aarectangle{0.0f, 0.0f, theme().size(), context.height()};
 
                // The unknown_label is located to the right of the selection box icon.
                hilet option_rectangle = aarectangle{
                    _left_box_rectangle.right() + theme().margin<float>(),
                    0.0f,
                    context.width() - _left_box_rectangle.width() - theme().margin<float>() * 2.0f,
                    context.height()};
                _off_label_shape = box_shape{_off_label_constraints, option_rectangle, theme().baseline_adjustment()};
                _current_label_shape = box_shape{_off_label_constraints, option_rectangle, theme().baseline_adjustment()};
 
            } else {
                _left_box_rectangle = aarectangle{context.width() - theme().size(), 0.0f, theme().size(), context.height()};
 
                // The unknown_label is located to the left of the selection box icon.
                hilet option_rectangle = aarectangle{
                    theme().margin<float>(),
                    0.0f,
                    context.width() - _left_box_rectangle.width() - theme().margin<float>() * 2.0f,
                    context.height()};
                _off_label_shape = box_shape{_off_label_constraints, option_rectangle, theme().baseline_adjustment()};
                _current_label_shape = box_shape{_off_label_constraints, option_rectangle, theme().baseline_adjustment()};
            }
 
            _chevrons_glyph = find_glyph(elusive_icon::ChevronUp);
            hilet chevrons_glyph_bbox = _chevrons_glyph.get_metrics().bounding_rectangle * theme().icon_size();
            _chevrons_rectangle = align(_left_box_rectangle, chevrons_glyph_bbox, alignment::middle_center());
        }
 
        // The overlay itself will make sure the overlay fits the window, so we give the preferred size and position
        // from the point of view of the selection widget.
        // The overlay should start on the same left edge as the selection box and the same width.
        // The height of the overlay should be the maximum height, which will show all the options.
        hilet overlay_width = std::clamp(
            context.width() - theme().size(), _overlay_constraints.minimum.width(), _overlay_constraints.maximum.width());
        hilet overlay_height = _overlay_constraints.preferred.height();
        hilet overlay_x = os_settings::left_to_right() ? theme().size() : context.width() - theme().size() - overlay_width;
        hilet overlay_y = (context.height() - overlay_height) / 2;
        hilet overlay_rectangle_request = aarectangle{overlay_x, overlay_y, overlay_width, overlay_height};
        hilet overlay_rectangle = make_overlay_rectangle(overlay_rectangle_request);
        _overlay_shape = box_shape{_overlay_constraints, overlay_rectangle, theme().baseline_adjustment()};
        _overlay_widget->set_layout(context.transform(_overlay_shape, 20.0f));
 
        _off_label_widget->set_layout(context.transform(_off_label_shape));
        _current_label_widget->set_layout(context.transform(_current_label_shape));
    }
 
    void draw(draw_context const& context) noexcept override
    {
        if (*mode > widget_mode::invisible) {
            if (overlaps(context, layout())) {
                draw_outline(context);
                draw_left_box(context);
                draw_chevrons(context);
 
                _off_label_widget->draw(context);
                _current_label_widget->draw(context);
            }
 
            // Overlay is outside of the overlap of the selection widget.
            _overlay_widget->draw(context);
        }
    }
 
    bool handle_event(gui_event const& event) noexcept override
    {
        switch (event.type()) {
        case gui_event_type::mouse_up:
            if (*mode >= widget_mode::partial and _has_options and layout().rectangle().contains(event.mouse().position)) {
                return handle_event(gui_event_type::gui_activate);
            }
            return true;
 
        case gui_event_type::gui_activate_next:
            // Handle gui_active_next so that the next widget will NOT get keyboard focus.
            // The previously selected item needs the get keyboard focus instead.
        case gui_event_type::gui_activate:
            if (*mode >= widget_mode::partial and _has_options and not _selecting) {
                start_selecting();
            } else {
                stop_selecting();
            }
            ++global_counter<"selection_widget:gui_activate:relayout">;
            process_event({gui_event_type::window_relayout});
            return true;
 
        case gui_event_type::gui_cancel:
            if (*mode >= widget_mode::partial and _has_options and _selecting) {
                stop_selecting();
            }
            ++global_counter<"selection_widget:gui_cancel:relayout">;
            process_event({gui_event_type::window_relayout});
            return true;
 
        default:;
        }
 
        return super::handle_event(event);
    }
 
    [[nodiscard]] hitbox hitbox_test(point2 position) const noexcept override
    {
        hi_axiom(loop::main().on_thread());
 
        if (*mode >= widget_mode::partial) {
            auto r = _overlay_widget->hitbox_test_from_parent(position);
 
            if (layout().contains(position)) {
                r = std::max(r, hitbox{id, _layout.elevation, _has_options ? hitbox_type::button : hitbox_type::_default});
            }
 
            return r;
        } else {
            return {};
        }
    }
 
    [[nodiscard]] bool accepts_keyboard_focus(keyboard_focus_group group) const noexcept override
    {
        hi_axiom(loop::main().on_thread());
        return *mode >= widget_mode::partial and to_bool(group & hi::keyboard_focus_group::normal) and _has_options;
    }
 
    [[nodiscard]] color focus_color() const noexcept override
    {
        hi_axiom(loop::main().on_thread());
 
        if (*mode >= widget_mode::partial and _has_options and _selecting) {
            return theme().color(semantic_color::accent);
        } else {
            return super::focus_color();
        }
    }

private:
    notifier<>::callback_token _delegate_cbt;
    std::atomic<bool> _notification_from_delegate = true;
 
    std::unique_ptr<label_widget> _current_label_widget;
    box_constraints _current_label_constraints;
    box_shape _current_label_shape;
 
    std::unique_ptr<label_widget> _off_label_widget;
    box_constraints _off_label_constraints;
    box_shape _off_label_shape;
 
    aarectangle _left_box_rectangle;
 
    font_book::font_glyph_type _chevrons_glyph;
    aarectangle _chevrons_rectangle;
 
    bool _selecting = false;
    bool _has_options = false;
 
    std::unique_ptr<overlay_widget> _overlay_widget;
    box_constraints _overlay_constraints;
    box_shape _overlay_shape;
 
    vertical_scroll_widget *_scroll_widget = nullptr;
    column_widget *_column_widget = nullptr;
 
    decltype(off_label)::callback_token _off_label_cbt;
    std::vector<menu_button_widget *> _menu_button_widgets;
    std::vector<notifier<>::callback_token> _menu_button_tokens;
 
    void set_attributes() noexcept {}
    void set_attributes(label_widget_attribute auto&& first, label_widget_attribute auto&&...rest) noexcept
    {
        if constexpr (forward_of<decltype(first), observer<hi::label>>) {
            off_label = hi_forward(first);
        } else if constexpr (forward_of<decltype(first), observer<hi::alignment>>) {
            alignment = hi_forward(first);
        } else if constexpr (forward_of<decltype(first), observer<hi::semantic_text_style>>) {
            text_style = hi_forward(first);
        } else {
            hi_static_no_default();
        }
 
        set_attributes(hi_forward(rest)...);
    }
 
    [[nodiscard]] menu_button_widget const *get_first_menu_button() const noexcept
    {
        hi_axiom(loop::main().on_thread());
 
        if (ssize(_menu_button_widgets) != 0) {
            return _menu_button_widgets.front();
        } else {
            return nullptr;
        }
    }
 
    [[nodiscard]] menu_button_widget const *get_selected_menu_button() const noexcept
    {
        hi_axiom(loop::main().on_thread());
 
        for (hilet& button : _menu_button_widgets) {
            if (button->state() == button_state::on) {
                return button;
            }
        }
        return nullptr;
    }
 
    void start_selecting() noexcept
    {
        hi_axiom(loop::main().on_thread());
 
        _selecting = true;
        _overlay_widget->mode = widget_mode::enabled;
        if (auto selected_menu_button = get_selected_menu_button()) {
            process_event(gui_event::window_set_keyboard_target(selected_menu_button->id, keyboard_focus_group::menu));
 
        } else if (auto first_menu_button = get_first_menu_button()) {
            process_event(gui_event::window_set_keyboard_target(first_menu_button->id, keyboard_focus_group::menu));
        }
 
        request_redraw();
    }
 
    void stop_selecting() noexcept
    {
        hi_axiom(loop::main().on_thread());
        _selecting = false;
        _overlay_widget->mode = widget_mode::invisible;
        request_redraw();
    }
 
    void repopulate_options() noexcept
    {
        hi_axiom(loop::main().on_thread());
        hi_assert_not_null(delegate);
 
        _column_widget->clear();
        _menu_button_widgets.clear();
        _menu_button_tokens.clear();
 
        auto [options, selected] = delegate->options_and_selected(*this);
 
        _has_options = size(options) > 0;
 
        // If any of the options has a an icon, all of the options should show the icon.
        auto show_icon = false;
        for (hilet& label : options) {
            show_icon |= to_bool(label.icon);
        }
 
        decltype(selected) index = 0;
        for (hilet& label : options) {
            auto menu_button = &_column_widget->make_widget<menu_button_widget>(selected, index, label, alignment, text_style);
 
            _menu_button_tokens.push_back(menu_button->pressed.subscribe(
                [this, index] {
                    hi_assert_not_null(delegate);
                    delegate->set_selected(*this, index);
                    stop_selecting();
                },
                callback_flags::main));
 
            _menu_button_widgets.push_back(menu_button);
 
            ++index;
        }
 
        if (selected == -1) {
            _off_label_widget->mode = widget_mode::display;
            _current_label_widget->mode = widget_mode::invisible;
 
        } else {
            _off_label_widget->mode = widget_mode::invisible;
            _current_label_widget->label = options[selected];
            _current_label_widget->mode = widget_mode::display;
        }
    }
 
    void draw_outline(draw_context const& context) noexcept
    {
        context.draw_box(
            layout(),
            layout().rectangle(),
            background_color(),
            focus_color(),
            theme().border_width(),
            border_side::inside,
            theme().rounding_radius());
    }
 
    void draw_left_box(draw_context const& context) noexcept
    {
        hilet corner_radii = os_settings::left_to_right() ?
            hi::corner_radii(theme().rounding_radius<float>(), 0.0f, theme().rounding_radius<float>(), 0.0f) :
            hi::corner_radii(0.0f, theme().rounding_radius<float>(), 0.0f, theme().rounding_radius<float>());
        context.draw_box(layout(), translate_z(0.1f) * _left_box_rectangle, focus_color(), corner_radii);
    }
 
    void draw_chevrons(draw_context const& context) noexcept
    {
        context.draw_glyph(layout(), translate_z(0.2f) * _chevrons_rectangle, _chevrons_glyph, label_color());
    }
};
 
}} // namespace hi::v1