Feature: Selection

Add support for selection content in the dom.

src/ftxui/dom/flex.cpp

@@ -80,6 +80,7 @@ class Flex : public Node {
   }
 
   void SetBox(Box box) override {
+    Node::SetBox(box);
     if (children_.empty()) {
       return;
     }

src/ftxui/dom/hbox.cpp

@@ -64,6 +64,19 @@ class HBox : public Node {
       x = box.x_max + 1;
     }
   }
+
+  void Select(Selection& selection) override {
+    // If this Node box_ doesn't intersect with the selection, then no
+    // selection.
+    if (Box::Intersection(selection.GetBox(), box_).IsEmpty()) {
+      return;
+    }
+
+    Selection selection_saturated = selection.SaturateHorizontal(box_);
+    for (auto& child : children_) {
+      child->Select(selection_saturated);
+    }
+  }
 };
 
 }  // namespace

src/ftxui/dom/node.cpp

@@ -1,3 +1,4 @@
+#include <iostream>
 // 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.
@@ -27,6 +28,20 @@ void Node::SetBox(Box box) {
   box_ = box;
 }
 
+/// @brief Compute the selection of an element.
+/// @ingroup dom
+void Node::Select(Selection& selection) {
+  // If this Node box_ doesn't intersect with the selection, then no selection.
+  if (Box::Intersection(selection.GetBox(), box_).IsEmpty()) {
+    return;
+  }
+
+  // By default we defer the selection to the children.
+  for (auto& child : children_) {
+    child->Select(selection);
+  }
+}
+
 /// @brief Display an element on a ftxui::Screen.
 /// @ingroup dom
 void Node::Render(Screen& screen) {
@@ -42,15 +57,31 @@ void Node::Check(Status* status) {
   status->need_iteration |= (status->iteration == 0);
 }
 
+std::string Node::GetSelectedContent(Selection& selection) {
+  std::string content;
+
+  for (auto& child : children_) {
+    content += child->GetSelectedContent(selection);
+  }
+
+  return content;
+}
+
 /// @brief Display an element on a ftxui::Screen.
 /// @ingroup dom
 void Render(Screen& screen, const Element& element) {
-  Render(screen, element.get());
+  Selection selection;
+  Render(screen, element.get(), selection);
 }
 
 /// @brief Display an element on a ftxui::Screen.
 /// @ingroup dom
 void Render(Screen& screen, Node* node) {
+  Selection selection;
+  Render(screen, node, selection);
+}
+
+void Render(Screen& screen, Node* node, Selection& selection) {
   Box box;
   box.x_min = 0;
   box.y_min = 0;
@@ -73,12 +104,49 @@ void Render(Screen& screen, Node* node) {
     node->Check(&status);
   }
 
-  // Step 3: Draw the element.
+  // Step 3: Selection
+  if (!selection.IsEmpty()) {
+    node->Select(selection);
+  }
+
+  // Step 4: Draw the element.
   screen.stencil = box;
   node->Render(screen);
 
-  // Step 4: Apply shaders
+  // Step 5: Apply shaders
   screen.ApplyShader();
 }
 
+std::string GetNodeSelectedContent(Screen& screen,
+                                   Node* node,
+                                   Selection& selection) {
+  Box box;
+  box.x_min = 0;
+  box.y_min = 0;
+  box.x_max = screen.dimx() - 1;
+  box.y_max = screen.dimy() - 1;
+
+  Node::Status status;
+  node->Check(&status);
+  const int max_iterations = 20;
+  while (status.need_iteration && status.iteration < max_iterations) {
+    // Step 1: Find what dimension this elements wants to be.
+    node->ComputeRequirement();
+
+    // Step 2: Assign a dimension to the element.
+    node->SetBox(box);
+
+    // Check if the element needs another iteration of the layout algorithm.
+    status.need_iteration = false;
+    status.iteration++;
+    node->Check(&status);
+  }
+
+  // Step 3: Selection
+  node->Select(selection);
+
+  // Step 4: get the selected content.
+  return node->GetSelectedContent(selection);
+}
+
 }  // namespace ftxui

src/ftxui/dom/paragraph.cpp

@@ -20,6 +20,18 @@ Elements Split(const std::string& the_text) {
   }
   return output;
 }
+
+Element Split(const std::string& paragraph,
+              std::function<Element(std::string)> f) {
+  Elements output;
+  std::stringstream ss(paragraph);
+  std::string line;
+  while (std::getline(ss, line, '\n')) {
+    output.push_back(f(line));
+  }
+  return vbox(std::move(output));
+}
+
 }  // namespace
 
 /// @brief Return an element drawing the paragraph on multiple lines.
@@ -34,18 +46,22 @@ Element paragraph(const std::string& the_text) {
 /// @ingroup dom
 /// @see flexbox.
 Element paragraphAlignLeft(const std::string& the_text) {
-  static const auto config = FlexboxConfig().SetGap(1, 0);
-  return flexbox(Split(the_text), config);
-}
+  return Split(the_text, [](const std::string& line) {
+    static const auto config = FlexboxConfig().SetGap(1, 0);
+    return flexbox(Split(line), config);
+  });
+};
 
 /// @brief Return an element drawing the paragraph on multiple lines, aligned on
 /// the right.
 /// @ingroup dom
 /// @see flexbox.
 Element paragraphAlignRight(const std::string& the_text) {
-  static const auto config =
-      FlexboxConfig().SetGap(1, 0).Set(FlexboxConfig::JustifyContent::FlexEnd);
-  return flexbox(Split(the_text), config);
+  return Split(the_text, [](const std::string& line) {
+    static const auto config = FlexboxConfig().SetGap(1, 0).Set(
+        FlexboxConfig::JustifyContent::FlexEnd);
+    return flexbox(Split(line), config);
+  });
 }
 
 /// @brief Return an element drawing the paragraph on multiple lines, aligned on
@@ -53,9 +69,11 @@ Element paragraphAlignRight(const std::string& the_text) {
 /// @ingroup dom
 /// @see flexbox.
 Element paragraphAlignCenter(const std::string& the_text) {
-  static const auto config =
-      FlexboxConfig().SetGap(1, 0).Set(FlexboxConfig::JustifyContent::Center);
-  return flexbox(Split(the_text), config);
+  return Split(the_text, [](const std::string& line) {
+    static const auto config =
+        FlexboxConfig().SetGap(1, 0).Set(FlexboxConfig::JustifyContent::Center);
+    return flexbox(Split(line), config);
+  });
 }
 
 /// @brief Return an element drawing the paragraph on multiple lines, aligned
@@ -64,11 +82,13 @@ Element paragraphAlignCenter(const std::string& the_text) {
 /// @ingroup dom
 /// @see flexbox.
 Element paragraphAlignJustify(const std::string& the_text) {
-  static const auto config = FlexboxConfig().SetGap(1, 0).Set(
-      FlexboxConfig::JustifyContent::SpaceBetween);
-  Elements words = Split(the_text);
-  words.push_back(text("") | xflex);
-  return flexbox(std::move(words), config);
+  return Split(the_text, [](const std::string& line) {
+    static const auto config = FlexboxConfig().SetGap(1, 0).Set(
+        FlexboxConfig::JustifyContent::SpaceBetween);
+    Elements words = Split(line);
+    words.push_back(text("") | xflex);
+    return flexbox(std::move(words), config);
+  });
 }
 
 }  // namespace ftxui

src/ftxui/dom/selection.cpp

@@ -0,0 +1,168 @@
+// 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.
+
+#include "ftxui/dom/selection.hpp"  // for Selection
+#include <algorithm>                // for max, min
+
+#include "ftxui/dom/elements.hpp"        // for Element, inverted
+#include "ftxui/dom/node_decorator.hpp"  // for NodeDecorator
+
+namespace ftxui {
+
+namespace {
+class Unselectable : public NodeDecorator {
+ public:
+  using NodeDecorator::NodeDecorator;
+
+  void Select(Selection& selection) override {
+    // Overwrite the select method to do nothing.
+  }
+};
+}  // namespace
+
+/// @brief Create an empty selection.
+Selection::Selection() : empty_(true) {}
+
+/// @brief Create a selection.
+/// @param start_x The x coordinate of the start of the selection.
+/// @param start_y The y coordinate of the start of the selection.
+/// @param end_x The x coordinate of the end of the selection.
+/// @param end_y The y coordinate of the end of the selection.
+Selection::Selection(int start_x, int start_y, int end_x, int end_y)
+    : start_x_(start_x),
+      start_y_(start_y),
+      end_x_(end_x),
+      end_y_(end_y),
+      box_{
+          std::min(start_x, end_x),
+          std::max(start_x, end_x),
+          std::min(start_y, end_y),
+          std::max(start_y, end_y),
+      },
+      empty_(false) {}
+
+Selection::Selection(int start_x,
+                     int start_y,
+                     int end_x,
+                     int end_y,
+                     Selection* parent)
+    : start_x_(start_x),
+      start_y_(start_y),
+      end_x_(end_x),
+      end_y_(end_y),
+      box_{
+          std::min(start_x, end_x),
+          std::max(start_x, end_x),
+          std::min(start_y, end_y),
+          std::max(start_y, end_y),
+      },
+      parent_(parent),
+      empty_(false) {}
+
+/// @brief Get the box of the selection.
+/// @return The box of the selection.
+const Box& Selection::GetBox() const {
+  return box_;
+}
+
+/// @brief Saturate the selection to be inside the box.
+/// This is called by `hbox` to propagate the selection to its children.
+/// @param box The box to saturate the selection in.
+/// @return The saturated selection.
+Selection Selection::SaturateHorizontal(Box box) {
+  int start_x = start_x_;
+  int start_y = start_y_;
+  int end_x = end_x_;
+  int end_y = end_y_;
+
+  const bool start_outside = !box.Contain(start_x, start_y);
+  const bool end_outside = !box.Contain(end_x, end_y);
+  const bool properly_ordered =
+      start_y < end_y || (start_y == end_y && start_x <= end_x);
+  if (properly_ordered) {
+    if (start_outside) {
+      start_x = box.x_min;
+      start_y = box.y_min;
+    }
+    if (end_outside) {
+      end_x = box.x_max;
+      end_y = box.y_max;
+    }
+  } else {
+    if (start_outside) {
+      start_x = box.x_max;
+      start_y = box.y_max;
+    }
+    if (end_outside) {
+      end_x = box.x_min;
+      end_y = box.y_min;
+    }
+  }
+  return Selection(start_x, start_y, end_x, end_y, parent_);
+}
+
+/// @brief Saturate the selection to be inside the box.
+/// This is called by `vbox` to propagate the selection to its children.
+/// @param box The box to saturate the selection in.
+/// @return The saturated selection.
+Selection Selection::SaturateVertical(Box box) {
+  int start_x = start_x_;
+  int start_y = start_y_;
+  int end_x = end_x_;
+  int end_y = end_y_;
+
+  const bool start_outside = !box.Contain(start_x, start_y);
+  const bool end_outside = !box.Contain(end_x, end_y);
+  const bool properly_ordered =
+      start_y < end_y || (start_y == end_y && start_x <= end_x);
+
+  if (properly_ordered) {
+    if (start_outside) {
+      start_x = box.x_min;
+      start_y = box.y_min;
+    }
+    if (end_outside) {
+      end_x = box.x_max;
+      end_y = box.y_max;
+    }
+  } else {
+    if (start_outside) {
+      start_x = box.x_max;
+      start_y = box.y_max;
+    }
+    if (end_outside) {
+      end_x = box.x_min;
+      end_y = box.y_min;
+    }
+  }
+  return Selection(start_x, start_y, end_x, end_y, parent_);
+}
+
+void Selection::AddPart(const std::string& part, int y, int left, int right) {
+  if (parent_ != this) {
+    return parent_->AddPart(part, y, left, right);
+  }
+  [&] {
+    if (parts_.str().empty()) {
+      parts_ << part;
+      return;
+    }
+
+    if (y_ != y) {
+      parts_ << '\n' << part;
+      return;
+    }
+
+    if (x_ == left + 1) {
+      parts_ << part;
+      return;
+    }
+
+    parts_ << part;
+  }();
+  y_ = y;
+  x_ = right;
+}
+
+}  // namespace ftxui

src/ftxui/dom/selection_style.cpp

@@ -0,0 +1,89 @@
+// 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.
+#include <memory>   // for make_shared
+#include <utility>  // for move
+
+#include "ftxui/dom/elements.hpp"  // for Element, Decorator, bgcolor, color
+#include "ftxui/dom/node_decorator.hpp"  // for NodeDecorator
+#include "ftxui/screen/box.hpp"          // for Box
+#include "ftxui/screen/color.hpp"        // for Color
+#include "ftxui/screen/screen.hpp"       // for Pixel, Screen
+
+namespace ftxui {
+
+namespace {
+
+class SelectionStyleReset : public NodeDecorator {
+ public:
+  SelectionStyleReset(Element child) : NodeDecorator(std::move(child)) {}
+
+  void Render(Screen& screen) final {
+    auto old_style = screen.GetSelectionStyle();
+    screen.SetSelectionStyle([](Pixel& pixel) {});
+    NodeDecorator::Render(screen);
+    screen.SetSelectionStyle(old_style);
+  }
+};
+
+class SelectionStyle : public NodeDecorator {
+ public:
+  SelectionStyle(Element child, std::function<void(Pixel&)> style)
+      : NodeDecorator(std::move(child)), style_(style) {}
+
+  void Render(Screen& screen) final {
+    auto old_style = screen.GetSelectionStyle();
+    auto new_style = [&, old_style](Pixel& pixel) {
+      old_style(pixel);
+      style_(pixel);
+    };
+    screen.SetSelectionStyle(new_style);
+    NodeDecorator::Render(screen);
+    screen.SetSelectionStyle(old_style);
+  }
+
+  std::function<void(Pixel&)> style_;
+};
+
+}  // namespace
+
+/// @brief Reset the selection style of an element.
+/// @param child The input element.
+/// @return The output element with the selection style reset.
+Element selectionStyleReset(Element child) {
+  return std::make_shared<SelectionStyleReset>(std::move(child));
+}
+
+/// @brief Set the background color of an element when selected.
+/// Note that the style is applied on top of the existing style.
+Decorator selectionBackgroundColor(Color foreground) {
+  return selectionStyle([foreground](Pixel& pixel) {  //
+    pixel.background_color = foreground;
+  });
+}
+
+/// @brief Set the foreground color of an element when selected.
+/// Note that the style is applied on top of the existing style.
+Decorator selectionForegroundColor(Color foreground) {
+  return selectionStyle([foreground](Pixel& pixel) {  //
+    pixel.foreground_color = foreground;
+  });
+}
+
+/// @brief Set the color of an element when selected.
+/// @param foreground The color to be applied.
+/// Note that the style is applied on top of the existing style.
+Decorator selectionColor(Color foreground) {
+  return selectionForegroundColor(foreground);
+}
+
+/// @brief Set the style of an element when selected.
+/// @param style The style to be applied.
+/// Note that the style is applied on top of the existing style.
+Decorator selectionStyle(std::function<void(Pixel&)> style) {
+  return [style](Element child) -> Element {
+    return std::make_shared<SelectionStyle>(std::move(child), style);
+  };
+}
+
+}  // namespace ftxui

src/ftxui/dom/selection_test.cpp

@@ -0,0 +1,224 @@
+// Copyright 2022 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 <gtest/gtest.h>
+#include <csignal>  // for raise, SIGABRT, SIGFPE, SIGILL, SIGINT, SIGSEGV, SIGTERM
+
+#include "ftxui/component/component.hpp"  // for Input, Renderer, Vertical
+#include "ftxui/component/event.hpp"      // for Event
+#include "ftxui/component/loop.hpp"       // for Loop
+#include "ftxui/component/mouse.hpp"  // for Mouse, Mouse::Left, Mouse::Pressed, Mouse::Released
+#include "ftxui/component/screen_interactive.hpp"
+#include "ftxui/dom/elements.hpp"   // for text
+#include "ftxui/dom/node.hpp"       // for Render
+#include "ftxui/screen/screen.hpp"  // for Screen
+
+// NOLINTBEGIN
+namespace ftxui {
+
+namespace {
+Event MousePressed(int x, int y) {
+  Mouse mouse;
+  mouse.button = Mouse::Left;
+  mouse.motion = Mouse::Pressed;
+  mouse.shift = false;
+  mouse.meta = false;
+  mouse.control = false;
+  mouse.x = x;
+  mouse.y = y;
+  return Event::Mouse("", mouse);
+}
+
+Event MouseReleased(int x, int y) {
+  Mouse mouse;
+  mouse.button = Mouse::Left;
+  mouse.motion = Mouse::Released;
+  mouse.shift = false;
+  mouse.meta = false;
+  mouse.control = false;
+  mouse.x = x;
+  mouse.y = y;
+  return Event::Mouse("", mouse);
+}
+
+Event MouseMove(int x, int y) {
+  Mouse mouse;
+  mouse.button = Mouse::Left;
+  mouse.motion = Mouse::Moved;
+  mouse.shift = false;
+  mouse.meta = false;
+  mouse.control = false;
+  mouse.x = x;
+  mouse.y = y;
+  return Event::Mouse("", mouse);
+}
+
+}  // namespace
+
+TEST(SelectionTest, DefaultSelection) {
+  auto component = Renderer([&] { return text("Lorem ipsum dolor"); });
+  auto screen = ScreenInteractive::FixedSize(20, 1);
+  EXPECT_EQ(screen.GetSelection(), "");
+  Loop loop(&screen, component);
+  screen.PostEvent(MousePressed(3, 1));
+  screen.PostEvent(MouseReleased(10, 1));
+  loop.RunOnce();
+
+  EXPECT_EQ(screen.GetSelection(), "rem ipsu");
+}
+
+TEST(SelectionTest, SelectionChange) {
+  int selectionChangeCounter = 0;
+  auto component = Renderer([&] { return text("Lorem ipsum dolor"); });
+  auto screen = ScreenInteractive::FixedSize(20, 1);
+  screen.SelectionChange([&] { selectionChangeCounter++; });
+
+  Loop loop(&screen, component);
+  loop.RunOnce();
+  EXPECT_EQ(selectionChangeCounter, 0);
+
+  screen.PostEvent(MousePressed(3, 1));
+  loop.RunOnce();
+  EXPECT_EQ(selectionChangeCounter, 0);
+
+  screen.PostEvent(MouseMove(5, 1));
+  loop.RunOnce();
+  EXPECT_EQ(selectionChangeCounter, 1);
+
+  screen.PostEvent(MouseMove(7, 1));
+  loop.RunOnce();
+  EXPECT_EQ(selectionChangeCounter, 2);
+
+  screen.PostEvent(MouseReleased(10, 1));
+  loop.RunOnce();
+  EXPECT_EQ(selectionChangeCounter, 3);
+
+  screen.PostEvent(MouseMove(10, 1));
+  loop.RunOnce();
+  EXPECT_EQ(selectionChangeCounter, 3);
+
+  EXPECT_EQ(screen.GetSelection(), "rem ipsu");
+}
+
+// Check that submitting multiple mouse events quickly doesn't trigger multiple
+// selection change events.
+TEST(SelectionTest, SelectionOnChangeSquashedEvents) {
+  int selectionChangeCounter = 0;
+  auto component = Renderer([&] { return text("Lorem ipsum dolor"); });
+  auto screen = ScreenInteractive::FixedSize(20, 1);
+  screen.SelectionChange([&] { selectionChangeCounter++; });
+
+  Loop loop(&screen, component);
+  loop.RunOnce();
+  EXPECT_EQ(selectionChangeCounter, 0);
+
+  screen.PostEvent(MousePressed(3, 1));
+  screen.PostEvent(MouseMove(5, 1));
+  screen.PostEvent(MouseMove(7, 1));
+  loop.RunOnce();
+  EXPECT_EQ(selectionChangeCounter, 1);
+
+  screen.PostEvent(MouseReleased(10, 1));
+  screen.PostEvent(MouseMove(10, 1));
+  loop.RunOnce();
+  EXPECT_EQ(selectionChangeCounter, 2);
+
+  EXPECT_EQ(screen.GetSelection(), "rem ipsu");
+}
+
+TEST(SelectionTest, StyleSelection) {
+  int selectionChangeCounter = 0;
+
+  auto element = hbox({
+      text("Lorem "),
+      text("ipsum") | selectionColor(Color::Red),
+      text(" dolor"),
+  });
+
+  auto screen = ScreenInteractive::FixedSize(20, 1);
+  Selection selection(2, 0, 9, 0);
+
+  Render(screen, element.get(), selection);
+  for (int i = 0; i < 20; i++) {
+    if (i >= 2 && i <= 9) {
+      EXPECT_EQ(screen.PixelAt(i, 0).inverted, true);
+    } else {
+      EXPECT_EQ(screen.PixelAt(i, 0).inverted, false);
+    }
+
+    if (i >= 6 && i <= 9) {
+      EXPECT_EQ(screen.PixelAt(i, 0).foreground_color, Color::Red);
+    } else {
+      EXPECT_EQ(screen.PixelAt(i, 0).foreground_color, Color::Default);
+    }
+  }
+}
+
+TEST(SelectionTest, VBoxSelection) {
+  auto element = vbox({
+      text("Lorem ipsum dolor"),
+      text("Ut enim ad minim"),
+  });
+
+  auto screen = ScreenInteractive::FixedSize(20, 2);
+
+  Selection selection(2, 0, 2, 1);
+  Render(screen, element.get(), selection);
+
+  EXPECT_EQ(selection.GetParts(), "rem ipsum dolor\nUt ");
+  EXPECT_EQ(screen.ToString(),
+            "Lo\x1B[7mrem ipsum dolor\x1B[27m   \r\n"
+            "\x1B[7mUt \x1B[27menim ad minim    ");
+}
+
+TEST(SelectionTest, VBoxSaturatedSelection) {
+  auto element = vbox({
+      text("Lorem ipsum dolor"),
+      text("Ut enim ad minim"),
+      text("Duis aute irure"),
+  });
+
+  auto screen = ScreenInteractive::FixedSize(20, 3);
+  Selection selection(2, 0, 2, 2);
+  Render(screen, element.get(), selection);
+  EXPECT_EQ(selection.GetParts(), "rem ipsum dolor\nUt enim ad minim\nDui");
+
+  EXPECT_EQ(screen.ToString(),
+            "Lo\x1B[7mrem ipsum dolor\x1B[27m   \r\n"
+            "\x1B[7mUt enim ad minim\x1B[27m    \r\n"
+            "\x1B[7mDui\x1B[27ms aute irure     ");
+}
+
+TEST(SelectionTest, HBoxSelection) {
+  auto element = hbox({
+      text("Lorem ipsum dolor"),
+      text("Ut enim ad minim"),
+  });
+
+  auto screen = ScreenInteractive::FixedSize(40, 1);
+  Selection selection(2, 0, 20, 0);
+  Render(screen, element.get(), selection);
+  EXPECT_EQ(selection.GetParts(), "rem ipsum dolorUt e");
+  EXPECT_EQ(screen.ToString(),
+            "Lo\x1B[7mrem ipsum dolorUt e\x1B[27mnim ad minim       ");
+}
+
+TEST(SelectionTest, HBoxSaturatedSelection) {
+  auto element = hbox({
+      text("Lorem ipsum dolor"),
+      text("Ut enim ad minim"),
+      text("Duis aute irure"),
+  });
+
+  auto screen = ScreenInteractive::FixedSize(60, 1);
+
+  Selection selection(2, 0, 35, 0);
+  Render(screen, element.get(), selection);
+  EXPECT_EQ(selection.GetParts(), "rem ipsum dolorUt enim ad minimDui");
+  EXPECT_EQ(screen.ToString(),
+            "Lo\x1B[7mrem ipsum dolorUt enim ad minimDui\x1B[27ms aute irure   "
+            "         ");
+}
+
+}  // namespace ftxui
+// NOLINTEND

src/ftxui/dom/text.cpp

@@ -3,8 +3,9 @@
 // the LICENSE file.
 #include <algorithm>  // for min
 #include <memory>     // for make_shared
-#include <string>     // for string, wstring
-#include <utility>    // for move
+#include <sstream>
+#include <string>   // for string, wstring
+#include <utility>  // for move
 
 #include "ftxui/dom/deprecated.hpp"   // for text, vtext
 #include "ftxui/dom/elements.hpp"     // for Element, text, vtext
@@ -26,28 +27,68 @@ class Text : public Node {
   void ComputeRequirement() override {
     requirement_.min_x = string_width(text_);
     requirement_.min_y = 1;
+    has_selection = false;
+  }
+
+  void Select(Selection& selection) override {
+    if (Box::Intersection(selection.GetBox(), box_).IsEmpty()) {
+      return;
+    }
+
+    Selection selection_saturated = selection.SaturateHorizontal(box_);
+
+    has_selection = true;
+    selection_start_ = selection_saturated.GetBox().x_min;
+    selection_end_ = selection_saturated.GetBox().x_max;
+
+    std::stringstream ss;
+    int x = box_.x_min;
+    for (const auto& cell : Utf8ToGlyphs(text_)) {
+      if (cell == "\n") {
+        continue;
+      }
+      if (selection_start_ <= x && x <= selection_end_) {
+        ss << cell;
+      }
+      x++;
+    }
+    selection.AddPart(ss.str(), box_.y_min, selection_start_, selection_end_);
   }
 
   void Render(Screen& screen) override {
     int x = box_.x_min;
     const int y = box_.y_min;
+
     if (y > box_.y_max) {
       return;
     }
+
     for (const auto& cell : Utf8ToGlyphs(text_)) {
       if (x > box_.x_max) {
-        return;
+        break;
       }
       if (cell == "\n") {
         continue;
       }
       screen.PixelAt(x, y).character = cell;
+
+      if (has_selection) {
+        auto selectionTransform = screen.GetSelectionStyle();
+        if ((x >= selection_start_) && (x <= selection_end_)) {
+          selectionTransform(screen.PixelAt(x, y));
+        }
+      }
+
       ++x;
     }
   }
 
  private:
   std::string text_;
+  bool has_selection = false;
+  int selection_start_ = 0;
+  int selection_end_ = -1;
+  std::function<void(Pixel& pixel)> selectionTransform;
 };
 
 class VText : public Node {

src/ftxui/dom/vbox.cpp

@@ -64,6 +64,20 @@ class VBox : public Node {
       y = box.y_max + 1;
     }
   }
+
+  void Select(Selection& selection) override {
+    // If this Node box_ doesn't intersect with the selection, then no
+    // selection.
+    if (Box::Intersection(selection.GetBox(), box_).IsEmpty()) {
+      return;
+    }
+
+    Selection selection_saturated = selection.SaturateVertical(box_);
+
+    for (auto& child : children_) {
+      child->Select(selection_saturated);
+    }
+  }
 };
 }  // namespace