Feature: Selection

Add support for selection content in the dom.

include/ftxui/dom/elements.hpp

@@ -113,6 +113,11 @@ Decorator focusPositionRelative(float x, float y);
 Element automerge(Element child);
 Decorator hyperlink(std::string link);
 Element hyperlink(std::string link, Element child);
+Element selectionStyleReset(Element);
+Decorator selectionColor(Color foreground);
+Decorator selectionBackgroundColor(Color foreground);
+Decorator selectionForegroundColor(Color foreground);
+Decorator selectionStyle(std::function<void(Pixel&)> style);
 
 // --- Layout is
 // Horizontal, Vertical or stacked set of elements.

include/ftxui/dom/node.hpp

@@ -8,6 +8,7 @@
 #include <vector>  // for vector
 
 #include "ftxui/dom/requirement.hpp"  // for Requirement
+#include "ftxui/dom/selection.hpp"    // for Selection
 #include "ftxui/screen/box.hpp"       // for Box
 #include "ftxui/screen/screen.hpp"
 
@@ -40,9 +41,15 @@ class Node {
   //         Propagated from Parents to Children.
   virtual void SetBox(Box box);
 
-  // Step 3: Draw this element.
+  // Step 3: (optional) Selection
+  //         Propagated from Parents to Children.
+  virtual void Select(Selection& selection);
+
+  // Step 4: Draw this element.
   virtual void Render(Screen& screen);
 
+  virtual std::string GetSelectedContent(Selection& selection);
+
   // 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.
@@ -60,6 +67,10 @@ class Node {
 
 void Render(Screen& screen, const Element& element);
 void Render(Screen& screen, Node* node);
+void Render(Screen& screen, Node* node, Selection& selection);
+std::string GetNodeSelectedContent(Screen& screen,
+                                   Node* node,
+                                   Selection& selection);
 
 }  // namespace ftxui
 

include/ftxui/dom/selection.hpp

@@ -0,0 +1,50 @@
+// Copyright 2024 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_SELECTION_HPP
+#define FTXUI_DOM_SELECTION_HPP
+
+#include <functional>
+
+#include <sstream>
+#include "ftxui/screen/box.hpp"    // for Box
+#include "ftxui/screen/pixel.hpp"  // for Pixel
+
+namespace ftxui {
+
+/// @brief Represent a selection in the terminal.
+class Selection {
+ public:
+  Selection();  // Empty selection.
+  Selection(int start_x, int start_y, int end_x, int end_y);
+
+  const Box& GetBox() const;
+
+  Selection SaturateHorizontal(Box box);
+  Selection SaturateVertical(Box box);
+  bool IsEmpty() const { return empty_; }
+
+  void AddPart(const std::string& part, int y, int left, int right);
+  std::string GetParts() { return parts_.str(); }
+
+ private:
+  Selection(int start_x, int start_y, int end_x, int end_y, Selection* parent);
+
+  Selection* const parent_ = this;
+  const bool empty_ = true;
+  const int start_x_ = 0;
+  const int start_y_ = 0;
+  const int end_x_ = 0;
+  const int end_y_ = 0;
+  const Box box_ = {};
+  std::stringstream parts_;
+
+  // The position of the last inserted part.
+  int x_ = 0;
+  int y_ = 0;
+};
+
+}  // namespace ftxui
+
+#endif /* end of include guard: FTXUI_DOM_SELECTION_HPP */