FTXUI/src/ftxui/component/toggle.cpp

#include "ftxui/component/toggle.hpp"
#include <algorithm>

namespace ftxui {

Element Toggle::Render() {
  bool is_focused = Focused();

  Elements children;
  for (size_t i = 0; i < entries.size(); ++i) {
    // Separator.
    if (i != 0)
      children.push_back(separator());

    // Entry.
    auto style = (selected != int(i))
                     ? normal_style
                     : is_focused ? focused_style : selected_style;
    auto focused = (selected != int(i)) ? nothing : is_focused ? focus : select;
    children.push_back(text(entries[i]) | style | focused);
  }
  return hbox(std::move(children));
}

bool Toggle::OnEvent(Event event) {
  int old_selected = selected;
  if (event == Event::ArrowLeft || event == Event::Character('h'))
    selected--;
  if (event == Event::ArrowRight || event == Event::Character('l'))
    selected++;
  if (event == Event::Tab && entries.size())
    selected = (selected + 1) % entries.size();
  if (event == Event::TabReverse && entries.size())
    selected = (selected + entries.size() - 1) % entries.size();

  selected = std::max(0, std::min(int(entries.size()) - 1, selected));
  return old_selected != selected;
}

}  // namespace ftxui