clear_under.cpp

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// 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.
#include <memory>   // for make_shared
#include <utility>  // for move
 
#include "ftxui/dom/elements.hpp"        // for Element, clear_under
#include "ftxui/dom/node.hpp"            // for Node
#include "ftxui/dom/node_decorator.hpp"  // for NodeDecorator
#include "ftxui/screen/box.hpp"          // for Box
#include "ftxui/screen/screen.hpp"       // for Cell, Screen
 
namespace ftxui {
 
namespace {
using ftxui::Screen;
 
class ClearUnder : public NodeDecorator {
 public:
  using NodeDecorator::NodeDecorator;
 
  void Render(Screen& screen) override {
    for (int y = box_.y_min; y <= box_.y_max; ++y) {
      for (int x = box_.x_min; x <= box_.x_max; ++x) {
        screen.CellAt(x, y) = Cell();
        screen.CellAt(x, y).character = " ";  // 視為已寫入的 Cell。
      }
    }
    Node::Render(screen);
  }
};
}  // namespace
 
/// @brief 在繪製 |child| 之前，先清除底下的儲存格。這在
///        搭配 dbox 使用時很有用。
/// @see ftxui::dbox
/// @ingroup dom
Element clear_under(Element element) {
  return std::make_shared<ClearUnder>(std::move(element));
}
 
}  // namespace ftxui