FTXUI/include/ftxui/dom/node.hpp

// Copyright 2020 Arthur Sonzogni. All rights reserved.
// Use of this source code is governed by the MIT license that can be found in
// the LICENSE file.
#ifndef FTXUI_DOM_NODE_HPP
#define FTXUI_DOM_NODE_HPP

#include <memory>  // for shared_ptr
#include <vector>  // for vector

#include "ftxui/dom/requirement.hpp"  // for Requirement
#include "ftxui/screen/box.hpp"       // for Box
#include "ftxui/screen/screen.hpp"

namespace ftxui {

class Node;
class Screen;

using Element = std::shared_ptr<Node>;
using Elements = std::vector<Element>;

class Node {
 public:
  Node();
  explicit Node(Elements children);
  Node(const Node&) = delete;
  Node(const Node&&) = delete;
  Node& operator=(const Node&) = delete;
  Node& operator=(const Node&&) = delete;

  virtual ~Node();

  // Step 1: Compute layout requirement. Tell parent what dimensions this
  //         element wants to be.
  //         Propagated from Children to Parents.
  virtual void ComputeRequirement();
  Requirement requirement() { return requirement_; }

  // Step 2: Assign this element its final dimensions.
  //         Propagated from Parents to Children.
  virtual void SetBox(Box box);

  // Step 3: Draw this element.
  virtual void Render(Screen& screen);

  // Layout may not resolve within a single iteration for some elements. This
  // allows them to request additionnal iterations. This signal must be
  // forwarded to children at least once.
  struct Status {
    int iteration = 0;
    bool need_iteration = false;
  };
  virtual void Check(Status* status);

  // Selection.
  // Propagated from Parents to Children.
  virtual void Select(Box selected_area) {
    // TODO: Implement this.
  }

 protected:
  Elements children_;
  Requirement requirement_;
  Box box_;
};

void Render(Screen& screen, const Element& element);
void Render(Screen& screen, Node* node);

}  // namespace ftxui

#endif  // FTXUI_DOM_NODE_HPP