Implement a lot of new features.

This commit deserve to be cut into at least 8 sub commit. Sorry, I
acknowledge this is bad... Here are the new features:

 * dom decorator: bold, dim, underlined, inverted.
 * component mechanism
 * components
   * menu
   * toogle

ftxui/CMakeLists.txt

@@ -2,23 +2,32 @@ cmake_minimum_required(VERSION 3.0)
 project(ftxui)
 
 add_library(ftxui
-  src/ftxui/core/component.cpp
-  src/ftxui/core/dom/frame.cpp
-  src/ftxui/core/dom/centered.cpp
-  src/ftxui/core/dom/flex.cpp
-  src/ftxui/core/dom/frame.cpp
-  src/ftxui/core/dom/gauge.cpp
-  src/ftxui/core/dom/hbox.cpp
-  src/ftxui/core/dom/node.cpp
-  src/ftxui/core/dom/separator.cpp
-  src/ftxui/core/dom/text.cpp
-  src/ftxui/core/dom/vbox.cpp
-  src/ftxui/core/screen.cpp
-  src/ftxui/core/terminal.cpp
+  src/ftxui/component/component.cpp
+  src/ftxui/component/component_direction.cpp
+  src/ftxui/component/component_horizontal.cpp
+  src/ftxui/component/component_vertical.cpp
+  src/ftxui/component/toggle.cpp
+  src/ftxui/component/menu.cpp
+  src/ftxui/dom/bold.cpp
+  src/ftxui/dom/dim.cpp
+  src/ftxui/dom/underlined.cpp
+  src/ftxui/dom/inverted.cpp
+  src/ftxui/dom/composite_decorator.cpp
+  src/ftxui/dom/flex.cpp
+  src/ftxui/dom/frame.cpp
+  src/ftxui/dom/frame.cpp
+  src/ftxui/dom/gauge.cpp
+  src/ftxui/dom/hbox.cpp
+  src/ftxui/dom/node.cpp
+  src/ftxui/dom/separator.cpp
+  src/ftxui/dom/text.cpp
+  src/ftxui/dom/vbox.cpp
+  src/ftxui/screen.cpp
+  src/ftxui/screen_interactive.cpp
+  src/ftxui/terminal.cpp
   src/ftxui/util/string.cpp
 )
 
-
 target_include_directories(ftxui
   PUBLIC include
   PRIVATE src
@@ -50,8 +59,9 @@ if (GTEST_FOUND AND THREADS_FOUND)
   endfunction(add_new_test)
 
   add_new_test(dom_tests
-    src/ftxui/core/dom/text_test.cpp
-    src/ftxui/core/dom/hbox_test.cpp
-    src/ftxui/core/dom/vbox_test.cpp
+    src/ftxui/dom/gauge_test.cpp
+    src/ftxui/dom/hbox_test.cpp
+    src/ftxui/dom/text_test.cpp
+    src/ftxui/dom/vbox_test.cpp
   )
 endif()

ftxui/include/ftxui/README.md

@@ -1 +1,31 @@
-State => Components => Document => Text.
+# 
+* Level 0: terminal output.
+* Level 1: ftxui::Screen               
+* Level 2: ftxui::dom::Node
+* Level 3: ftxui::component::Component
+
+## Level 0: terminal output.
+  The terminal you know, you can append text on it. It is represented by
+  std::cout.
+
+## Level 1: ftxui::Screen               
+  A rectangular grid of characters.
+  Use Terminal::ToString() to append its content into the console.
+
+## Level 2: ftxui::dom::Node
+  A hierarchical set of element.
+  They handle layout and Render themself on the screen.
+  See ftxui/dom/elements.hpp
+
+  You can make implement your own.
+
+## Level 3: ftxui::component::Component
+  A hierarchical set of component. A component render itself by producing
+  ftxui::dom::Node in Component::Render().
+  
+  Some component can handle events:
+    * keyboard
+    * mouse
+    * terminal event
+
+  You can make implement your own.

ftxui/include/ftxui/component/Event.hpp

@@ -0,0 +1,34 @@
+#ifndef FTXUI_COMPONENT_EVENT
+#define FTXUI_COMPONENT_EVENT
+
+namespace ftxui {
+namespace component {
+
+struct Event{
+  // --- Character ---
+  static Event Character(char);
+
+  // --- Arrow ---
+  static Event Arrow_Left;
+  static Event Arrow_Right;
+  static Event Arrow_Up;
+  static Event Arrow_Down;
+  
+  // --- Other ---
+  static Event Backspace;
+  static Event Delete;
+  static Event Escape;
+  static Event F1, F2, F3, F4, F5, F6, F7, F8, F9, F10, F11, F12;
+
+  // Internal representation.
+  int values [3];
+  Event(int values[3]) : values(values);
+
+};
+
+
+} // namespace component
+} // namespace ftxui
+
+
+#endif /* end of include guard: FTXUI_COMPONENT_EVENT */

ftxui/include/ftxui/component/component.hpp

@@ -0,0 +1,44 @@
+#ifndef FTXUI_COMPONENT_COMPONENT_HPP
+#define FTXUI_COMPONENT_COMPONENT_HPP
+
+#include "ftxui/dom/elements.hpp"
+#include "ftxui/component/delegate.hpp"
+
+namespace ftxui {
+namespace component {
+
+class Delegate;
+class Focus;
+
+class Component {
+ public:
+  // Constructor/Destructor.
+  Component(Delegate* delegate);
+  virtual ~Component();
+
+  // Render the component.
+  virtual dom::Element Render();
+
+  // Handle an event. By default, it calls this function on each children.
+  virtual bool Event(int key);
+
+  // If this component contains children, this indicates which one is active. It
+  // can be none of them.
+  // We say an element has the focus if the chain of GetActiveChild() from the
+  // root component contains this object.
+  virtual Component* GetActiveChild() { return nullptr; }
+  bool Active(); // True is this component is an active child.
+  bool Focused(); // True if all the ancestors are active childs.
+
+  Component* Parent();
+  Component* PreviousSibling();
+  Component* NextSibling();
+  
+ private:
+  Delegate* delegate_;
+};
+
+}  // namespace component
+}  // namespace ftxui
+
+#endif /* end of include guard: FTXUI_COMPONENT_COMPONENT_HPP */

ftxui/include/ftxui/component/component_direction.hpp

@@ -0,0 +1,25 @@
+#ifndef FTXUI_COMPONENT_COMPONENT_DIRECTION_H_
+#define FTXUI_COMPONENT_COMPONENT_DIRECTION_H_
+
+#include "ftxui/component/component.hpp"
+
+namespace ftxui {
+namespace component {
+
+// A component where focus and events are automatically handled for you.
+class ComponentDirection : public Component {
+ public:
+  ComponentDirection(Delegate* delegate);
+  bool Event(int key) override;
+  Component* GetActiveChild() override;
+
+ protected:
+  void Focus(Component* child);
+  virtual bool HandleDirection(int key) = 0;
+  Component* active_child_;
+};
+
+} // namespace component
+} // namespace ftxui
+
+#endif /* end of include guard: FTXUI_COMPONENT_COMPONENT_DIRECTION_H_ */

ftxui/include/ftxui/component/component_horizontal.hpp

@@ -0,0 +1,20 @@
+#ifndef FTXUI_COMPONENT_COMPONENT_HORIZONTAL_H_
+#define FTXUI_COMPONENT_COMPONENT_HORIZONTAL_H_
+
+#include "ftxui/component/component_direction.hpp"
+
+namespace ftxui {
+namespace component {
+
+// A component where focus and events are automatically handled for you.
+// It assumes its children are put in the horizontal direction.
+class ComponentHorizontal : public ComponentDirection {
+ public:
+  ComponentHorizontal(Delegate* delegate);
+  bool HandleDirection(int key) override;
+};
+
+} // namespace component
+} // namespace ftxui
+
+#endif /* end of include guard: FTXUI_COMPONENT_COMPONENT_HORIZONTAL_H_ */

ftxui/include/ftxui/component/component_vertical.hpp

@@ -0,0 +1,20 @@
+#ifndef FTXUI_COMPONENT_COMPONENT_VERTICAL_H_
+#define FTXUI_COMPONENT_COMPONENT_VERTICAL_H_
+
+#include "ftxui/component/component_direction.hpp"
+
+namespace ftxui {
+namespace component {
+
+// A component where focus and events are automatically handled for you.
+// It assumes its children are put in the vertical direction.
+class ComponentVertical : public ComponentDirection {
+ public:
+  ComponentVertical(Delegate* delegate);
+  bool HandleDirection(int key) override;
+};
+
+} // namespace component
+} // namespace ftxui
+
+#endif /* end of include guard: FTXUI_COMPONENT_COMPONENT_VERTICAL_H_ */

ftxui/include/ftxui/component/delegate.hpp

@@ -0,0 +1,34 @@
+#ifndef FTXUI_COMPONENT_DELEGATE_HPP
+#define FTXUI_COMPONENT_DELEGATE_HPP
+
+#include "ftxui/dom/elements.hpp"
+
+namespace ftxui {
+namespace component {
+
+class Component;
+
+class Delegate {
+ public:
+  Delegate() {}
+  virtual ~Delegate() {}
+
+  // A Delegate shadows a component.
+  virtual void Register(Component* component) = 0;
+  virtual Component* component() = 0;
+
+  // Create new children.
+  virtual Delegate* NewChild() = 0;
+  virtual std::vector<Delegate*> children() = 0;
+
+  // Navigate in the tree.
+  virtual Delegate* PreviousSibling() = 0;
+  virtual Delegate* NextSibling() = 0;
+  virtual Delegate* Parent() = 0;
+  virtual Delegate* Root() = 0;
+};
+
+}  // namespace component
+}  // namespace ftxui
+
+#endif /* end of include guard: FTXUI_COMPONENT_DELEGATE_HPP */

ftxui/include/ftxui/component/menu.hpp

@@ -0,0 +1,31 @@
+#ifndef FTXUI_COMPONENT_MENU
+#define FTXUI_COMPONENT_MENU
+
+#include "ftxui/component/component.hpp"
+#include <functional>
+
+namespace ftxui {
+namespace component {
+
+class Menu : public Component {
+ public:
+  // Constructor.
+  Menu(Delegate*);
+
+  // State.
+  std::vector<std::wstring> entries = {};
+  int selected = 0;
+
+  // State update callback.
+  std::function<void()> on_change = [](){};
+  std::function<void()> on_enter = [](){};
+
+  // Component implementation.
+  dom::Element Render() override;
+	bool Event(int key) override;
+};
+
+}  // namespace component
+}  // namespace ftxui
+
+#endif /* end of include guard: FTXUI_COMPONENT_MENU */

ftxui/include/ftxui/component/toggle.hpp

@@ -0,0 +1,31 @@
+#ifndef FTXUI_COMPONENT_TOGGLE_H_
+#define FTXUI_COMPONENT_TOGGLE_H_
+
+#include "ftxui/component/component.hpp"
+#include <functional>
+
+namespace ftxui {
+namespace component {
+
+class Toggle : public Component {
+ public:
+  // Constructor.
+  Toggle(Delegate*);
+
+  // State.
+  bool activated = true;
+  std::wstring on = L"On";
+  std::wstring off = L"Off";
+
+  // Callback.
+  std::function<void()> on_change = [](){};
+
+  // Component implementation.
+  dom::Element Render() override;
+	bool Event(int key) override;
+};
+
+}  // namespace component
+}  // namespace ftxui
+
+#endif /* end of include guard: FTXUI_COMPONENT_TOGGLE_H_ */

ftxui/include/ftxui/core/component.hpp

@@ -1,23 +0,0 @@
-#ifndef FTXUI_STATE_HPP
-#define FTXUI_STATE_HPP
-
-#include "ftxui/core/requirement.hpp"
-#include "ftxui/core/document.hpp"
-
-namespace ftxui {
-
-class Component {
- public:
-  virtual Document Render() = 0;
-
-  // Requirement -------------------------------------------------------------
-  virtual void ComputeRequirement();
-  Requirement requirement() { return requirement_; }
-
- private:
-  Requirement requirement_;
-};
-
-};  // namespace ftxui
-
-#endif /* end of include guard: FTXUI_STATE_HPP */

ftxui/include/ftxui/core/document.hpp

@@ -1,12 +0,0 @@
-#ifndef FTXUI_DOCUMENT_HPP
-#define FTXUI_DOCUMENT_HPP
-
-namespace ftxui {
-
-class Document {
-   
-};
-
-};
-
-#endif /* end of include guard: FTXUI_DOCUMENT_HPP */

ftxui/include/ftxui/core/screen.hpp

@@ -1,33 +0,0 @@
-#ifndef FTXUI_CORE_SCREEN
-#define FTXUI_CORE_SCREEN
-
-#include <string>
-#include <vector>
-#include <memory>
-
-namespace ftxui {
-namespace dom {
-  class Node;
-}
-
-class Screen {
- public:
-  Screen(size_t dimx, size_t dimy);
-  wchar_t& at(size_t x, size_t y);
-  std::string ToString();
-
-  size_t dimx() { return dimx_;}
-  size_t dimy() { return dimy_;}
-
-  static Screen WholeTerminal();
-  static Screen TerminalOutput(std::unique_ptr<dom::Node>& element);
-
- private:
-  size_t dimx_;
-  size_t dimy_;
-  std::vector<std::wstring> lines_;
-};
-
-};  // namespace ftxui
-
-#endif /* end of include guard: FTXUI_CORE_SCREEN */

ftxui/include/ftxui/dom/elements.hpp

@@ -1,16 +1,14 @@
-#ifndef FTXUI_CORE_DOM_ELEMENTS_HPP
-#define FTXUI_CORE_DOM_ELEMENTS_HPP
+#ifndef FTXUI_DOM_ELEMENTS_HPP
+#define FTXUI_DOM_ELEMENTS_HPP
 
-#include "ftxui/core/dom/node.hpp"
-#include <initializer_list>
+#include "ftxui/dom/node.hpp"
 
 namespace ftxui {
 namespace dom {
 
 using Element = std::unique_ptr<Node>;
 using Child = std::unique_ptr<Node>;
-using Children = std::vector<std::unique_ptr<Node>>;
-
+using Children = std::vector<Child>;
 
 // --- Layout ----
 Element vbox(Children);
@@ -22,7 +20,13 @@ Element text(std::wstring text);
 Element separator();
 Element gauge(float ratio);
 Element frame(Child);
-Element frame(std::wstring title, Child);
+Element frame(Child title, Child content);
+
+// -- Decorator (Style) ---
+Element bold(Element);
+Element dim(Element);
+Element inverted(Element);
+Element underlined(Element);
 
 // --- Decorator ---
 Element hcenter(Element);
@@ -31,23 +35,23 @@ Element center(Element);
 Element flex(Element);
 
 template <class... Args>
-std::vector<Element> unpack(Args... args) {
-  std::vector<Element> vec;
+Children unpack(Args... args) {
+  Children vec;
   (vec.push_back(std::forward<Args>(args)), ...);
   return vec;
 }
 
 template <class... Args>
-std::unique_ptr<Node> vbox(Args... children) {
+Element vbox(Args... children) {
   return vbox(unpack(std::forward<Args>(children)...));
 }
 
 template <class... Args>
-std::unique_ptr<Node> hbox(Args... children) {
+Element hbox(Args... children) {
   return hbox(unpack(std::forward<Args>(children)...));
 }
 
 };  // namespace dom
 };  // namespace ftxui
 
-#endif /* end of include guard: FTXUI_CORE_DOM_ELEMENTS_HPP */
+#endif /* end of include guard: FTXUI_DOM_ELEMENTS_HPP */

ftxui/include/ftxui/dom/node.hpp

@@ -1,12 +1,12 @@
-#ifndef CORE_DOM_NODE_HPP
-#define CORE_DOM_NODE_HPP
+#ifndef DOM_NODE_HPP
+#define DOM_NODE_HPP
 
 #include <memory>
 #include <vector>
 
-#include "ftxui/core/requirement.hpp"
-#include "ftxui/core/screen.hpp"
-#include "ftxui/core/box.hpp"
+#include "ftxui/requirement.hpp"
+#include "ftxui/screen.hpp"
+#include "ftxui/box.hpp"
 
 namespace ftxui {
 namespace dom {
@@ -41,4 +41,4 @@ void Render(Screen& screen, Node* node);
 };  // namespace dom
 };  // namespace ftxui
 
-#endif /* end of include guard: CORE_DOM_NODE_HPP */
+#endif /* end of include guard: DOM_NODE_HPP */

ftxui/include/ftxui/requirement.hpp

@@ -1,5 +1,5 @@
-#ifndef FTXUI_LAYOUT_REQUIREMENT_HPP
-#define FTXUI_LAYOUT_REQUIREMENT_HPP
+#ifndef FTXUI_REQUIREMENT_HPP
+#define FTXUI_REQUIREMENT_HPP
 
 namespace ftxui {
 
@@ -25,4 +25,4 @@ struct Requirement {
 
 };  // namespace ftxui
 
-#endif /* end of include guard: FTXUI_LAYOUT_REQUIREMENT_HPP */
+#endif /* end of include guard: FTXUI_REQUIREMENT_HPP */

ftxui/include/ftxui/screen.hpp

@@ -0,0 +1,55 @@
+#ifndef FTXUI_SCREEN
+#define FTXUI_SCREEN
+
+#include <string>
+#include <vector>
+#include <memory>
+
+namespace ftxui {
+namespace dom {
+  class Node;
+}
+
+struct Pixel {
+  wchar_t character = U' ';
+  bool bold = false;
+  bool inverted = false;
+  bool underlined = false;
+  bool dim = false;
+};
+
+class Screen {
+ public:
+  // Constructor.
+  Screen(size_t dimx, size_t dimy);
+
+  // Constructor using the terminal.
+  static Screen TerminalFullscreen();
+  static Screen TerminalOutput(std::unique_ptr<dom::Node>& element);
+
+  // dom::Node write into the screen using Screen::at.
+  wchar_t& at(size_t x, size_t y);
+  Pixel& PixelAt(size_t x, size_t y);
+
+  // Convert the screen into a printable string in the terminal.
+  std::string ToString();
+
+  // Get screen dimensions.
+  size_t dimx() { return dimx_;}
+  size_t dimy() { return dimy_;}
+
+  // Move the terminal cursor n-lines up with n = dimy().
+  std::string ResetPosition();
+
+  // Fill with space.
+  void Clear();
+
+ private:
+  size_t dimx_;
+  size_t dimy_;
+  std::vector<std::vector<Pixel>> pixels_;
+};
+
+};  // namespace ftxui
+
+#endif /* end of include guard: FTXUI_SCREEN */

ftxui/include/ftxui/screen_interactive.hpp

@@ -0,0 +1,34 @@
+#ifndef FTXUI_SCREEN_INTERACTIVE
+#define FTXUI_SCREEN_INTERACTIVE
+
+#include "ftxui/screen.hpp"
+#include <functional>
+#include <memory>
+
+namespace ftxui {
+
+namespace component {
+  class Delegate;
+  class Component;
+} // namespace component
+
+class ScreenInteractive : public Screen {
+  public:
+    ScreenInteractive(size_t dimx, size_t dimy);
+    ~ScreenInteractive();
+    component::Delegate* delegate();
+    void Loop();
+		std::function<void()> ExitLoopClosure();
+
+  private:
+   class Delegate;
+   std::unique_ptr<Delegate> delegate_;
+
+	 void Clear();
+	 void Draw();
+	 bool quit_ = false;
+};
+
+}  // namespace ftxui
+
+#endif /* end of include guard: FTXUI_SCREEN_INTERACTIVE */

ftxui/src/ftxui/component/component.cpp

@@ -0,0 +1,59 @@
+#include "ftxui/component/component.hpp"
+#include "ftxui/component/delegate.hpp"
+#include <assert.h>
+
+namespace ftxui {
+namespace component {
+
+Component::Component(Delegate* delegate) {
+  delegate_ = delegate;
+  delegate_->Register(this);
+}
+
+Component::~Component() {}
+
+dom::Element Component::Render() {
+  using namespace ftxui::dom;
+  return text(L"Not implemented component");
+}
+
+bool Component::Event(int key) {
+  return false;
+}
+
+bool Component::Focused() {
+  Delegate* current = delegate_->Root();
+  while (current) {
+    if (current == delegate_)
+      return true;
+
+    Component* active_child = current->component()->GetActiveChild();
+    current = active_child ? active_child->delegate_ : nullptr;
+  }
+  return false;
+}
+
+bool Component::Active() {
+  Delegate* parent = delegate_->Parent();
+  return parent && parent->component()->GetActiveChild() == this;
+}
+
+Component* Component::PreviousSibling() {
+  Delegate* sibling = delegate_->PreviousSibling();
+  return sibling ? sibling->component() : nullptr;
+}
+
+Component* Component::NextSibling() {
+  Delegate* sibling = delegate_->NextSibling();
+  return sibling ? sibling->component() : nullptr;
+}
+
+Component* Component::Parent() {
+  Delegate* parent_delegate = delegate_->Parent();
+  if (!parent_delegate)
+    return nullptr;
+  return parent_delegate->component();
+}
+
+}  // namespace component
+}  // namespace ftxui

ftxui/src/ftxui/component/component_direction.cpp

@@ -0,0 +1,31 @@
+#include "ftxui/component/component_direction.hpp"
+
+namespace ftxui {
+namespace component {
+
+ComponentDirection::ComponentDirection(Delegate* delegate)
+    : Component(delegate), active_child_(nullptr) {}
+
+bool ComponentDirection::Event(int key) {
+  if (!Focused())
+    return false;
+
+  if (!active_child_)
+    return false;
+
+  if (active_child_->Event(key))
+    return true;
+
+  return HandleDirection(key);
+}
+
+Component* ComponentDirection::GetActiveChild() {
+  return active_child_;
+}
+
+void ComponentDirection::Focus(Component* child) {
+  active_child_ = child;
+}
+
+} // namespace component
+} // namespace ftxui

ftxui/src/ftxui/component/component_horizontal.cpp

@@ -0,0 +1,32 @@
+#include "ftxui/component/component_horizontal.hpp"
+
+namespace ftxui {
+namespace component {
+
+ComponentHorizontal::ComponentHorizontal(Delegate* delegate)
+    : ComponentDirection(delegate) {}
+
+bool ComponentHorizontal::HandleDirection(int key) {
+  // Left pressed ?
+  if (key == 68 || key == 'h') {
+    Component* previous_sibling = active_child_->PreviousSibling();
+    if (previous_sibling) {
+      active_child_ = previous_sibling;
+      return true;
+    }
+  }
+
+  // Left pressed ?
+  if (key == 67 || key == 'l') {
+    Component* next_sibling = active_child_->NextSibling();
+    if (next_sibling) {
+      active_child_ = next_sibling;
+      return true;
+    }
+  }
+
+  return false;
+}
+
+}  // namespace component
+}  // namespace ftxui

ftxui/src/ftxui/component/component_vertical.cpp

@@ -0,0 +1,32 @@
+#include "ftxui/component/component_vertical.hpp"
+
+namespace ftxui {
+namespace component {
+
+ComponentVertical::ComponentVertical(Delegate* delegate)
+    : ComponentDirection(delegate) {}
+
+bool ComponentVertical::HandleDirection(int key) {
+  // Up pressed ?
+  if (key == 65 || key == 'k') {
+    Component* previous_sibling = active_child_->PreviousSibling();
+    if (previous_sibling) {
+      active_child_ = previous_sibling;
+      return true;
+    }
+  }
+
+  // Down pressed ?
+  if (key == 66 || key == 'j') {
+    Component* next_sibling = active_child_->NextSibling();
+    if (next_sibling) {
+      active_child_ = next_sibling;
+      return true;
+    }
+  }
+
+  return false;
+}
+
+}  // namespace component
+}  // namespace ftxui

ftxui/src/ftxui/component/menu.cpp

@@ -0,0 +1,53 @@
+#include "ftxui/component/menu.hpp"
+#include <algorithm>
+
+namespace ftxui {
+namespace component {
+
+Menu::Menu(Delegate* delegate) : Component(delegate) {}
+
+dom::Element Menu::Render() {
+  using namespace dom;
+  std::vector<Element> elements;
+  bool focused = Focused();
+  for (size_t i = 0; i < entries.size(); ++i) {
+    if (size_t(selected) == i) {
+      if (focused)
+        elements.push_back(inverted(text(L"> " + entries[i])));
+      else
+        elements.push_back(bold(text(L"> " + entries[i])));
+    }
+    else {
+      elements.push_back(text(L"  " + entries[i]));
+    }
+  }
+  return vbox(std::move(elements));
+}
+
+bool Menu::Event(int key) {
+  if (!Focused())
+    return false;
+
+  int new_selected = selected;
+  if (key == 65 || key == 'k')
+    new_selected--;
+  if (key == 66 || key == 'j')
+    new_selected++;
+  new_selected = std::max(0, std::min(int(entries.size())-1, new_selected));
+
+  if (selected != new_selected) {
+    selected = new_selected;
+    on_change();
+    return true;
+  }
+
+  if (key == 10) {
+    on_enter();
+    return true;
+  }
+
+  return false;
+}
+
+}  // namespace component
+}  // namespace ftxui

ftxui/src/ftxui/component/toggle.cpp

@@ -0,0 +1,47 @@
+#include "ftxui/component/toggle.hpp"
+
+namespace ftxui {
+namespace component {
+
+Toggle::Toggle(Delegate* delegate) : Component(delegate) {}
+
+dom::Element Toggle::Render() {
+  using namespace dom;
+  auto highlight = Focused() ? inverted : bold;
+
+  Children children;
+  children.push_back(text(L"["));
+  if (activated) {
+    children.push_back(highlight(text(on)));
+    children.push_back(text(L"|"));
+    children.push_back(dim(text(off)));
+  } else {
+    children.push_back(dim(text(on)));
+    children.push_back(text(L"|"));
+    children.push_back(highlight(text(off)));
+  }
+  children.push_back(text(L"]"));
+  return hbox(std::move(children));
+}
+
+bool Toggle::Event(int key) {
+
+  if (activated) {
+    if (key == 67 || key == 'l') {
+      activated = false;
+      on_change();
+      return true;
+    }
+  } else {
+    if (key == 68 || key == 'h') {
+      activated = true;
+      on_change();
+      return true;
+    }
+  }
+
+  return false;
+}
+
+}  // namespace component
+}  // namespace ftxui

ftxui/src/ftxui/core/component.cpp

@@ -1,5 +0,0 @@
-#include "ftxui/core/component.hpp"
-
-namespace ftxui {
-  void Component::ComputeRequirement() {}
-} // namespace ftxui.

ftxui/src/ftxui/core/dom/frame.cpp

@@ -1,57 +0,0 @@
-#include "ftxui/core/dom/node.hpp"
-#include "ftxui/core/dom/elements.hpp"
-
-namespace ftxui {
-namespace dom {
-
-static wchar_t charset[] = L"┌┐└┘─│";
-
-class Frame : public Node {
- public:
-  Frame(Child child) : Node(unpack(std::move(child))) {}
-  ~Frame() override {}
-
-  void ComputeRequirement() override {
-    children[0]->ComputeRequirement();
-    requirement_ = children[0]->requirement();
-    requirement_.min.x += 2;
-    requirement_.min.y += 2;
-  }
-
-  void SetBox(Box box) override {
-    Node::SetBox(box);
-    box.left++;
-    box.right--;
-    box.top++;
-    box.bottom--;
-    children[0]->SetBox(box);
-  }
-
-  void Render(Screen& screen) override {
-    if (box_.left >= box_.right || box_.top >= box_.bottom)
-      return;
-
-    screen.at(box_.left, box_.top) = charset[0];
-    screen.at(box_.right, box_.top) = charset[1];
-    screen.at(box_.left, box_.bottom) = charset[2];
-    screen.at(box_.right, box_.bottom) = charset[3];
-    for(float x = box_.left + 1; x<box_.right; ++x) {
-      screen.at(x, box_.top) = charset[4];
-      screen.at(x, box_.bottom) = charset[4];
-    }
-    for(float y = box_.top + 1; y<box_.bottom; ++y) {
-      screen.at(box_.left, y) = charset[5];
-      screen.at(box_.right,y) = charset[5];
-    }
-    children[0]->Render(screen);
-  }
- private:
-  float progress_;
-};
-
-std::unique_ptr<Node> frame(Child child) {
-  return std::make_unique<Frame>(std::move(child));
-}
-
-};  // namespace dom
-};  // namespace ftxui

ftxui/src/ftxui/core/screen.cpp

@@ -1,38 +0,0 @@
-#include "ftxui/core/screen.hpp"
-#include "ftxui/core/terminal.hpp"
-#include "ftxui/util/string.hpp"
-#include "ftxui/core/dom/node.hpp"
-
-#include <sstream>
-
-namespace ftxui {
-
-Screen::Screen(size_t dimx, size_t dimy)
-    : dimx_(dimx), dimy_(dimy), lines_(dimy, std::wstring(dimx, U' ')) {}
-
-std::string Screen::ToString() {
-  std::stringstream ss;
-  for (size_t y = 0; y < dimy_; ++y) {
-    ss << to_string(lines_[y]);
-    if (y + 1 < dimy_)
-      ss << '\n';
-  }
-  return ss.str();
-}
-
-wchar_t& Screen::at(size_t x, size_t y) {
-  return lines_[y][x];
-}
-
-Screen Screen::WholeTerminal() {
-  Terminal::Dimensions size = Terminal::Size();
-  return Screen(size.dimx, size.dimy);
-}
-
-Screen Screen::TerminalOutput(std::unique_ptr<dom::Node>& element) {
-  element->ComputeRequirement();
-  Terminal::Dimensions size = Terminal::Size();
-  return Screen(size.dimx, element->requirement().min.y);
-}
-
-};  // namespace ftxui

ftxui/src/ftxui/dom/bold.cpp

@@ -0,0 +1,37 @@
+#include "ftxui/dom/node.hpp"
+#include "ftxui/dom/elements.hpp"
+
+namespace ftxui {
+namespace dom {
+
+class Bold : public Node {
+ public:
+  Bold(Children children) : Node(std::move(children)) {}
+  ~Bold() override {}
+
+  void ComputeRequirement() override {
+    Node::ComputeRequirement();
+    requirement_ = children[0]->requirement();
+  }
+
+  void SetBox(Box box) override {
+    Node::SetBox(box);
+    children[0]->SetBox(box);
+  }
+
+  void Render(Screen& screen) override {
+    Node::Render(screen);
+    for (int y = box_.top; y <= box_.bottom; ++y) {
+      for (int x = box_.left; x <= box_.right; ++x) {
+        screen.PixelAt(x,y).bold = true; 
+      }
+    }
+  }
+};
+
+std::unique_ptr<Node> bold(Child child) {
+  return std::make_unique<Bold>(unpack(std::move(child)));
+}
+
+};  // namespace dom
+};  // namespace ftxui

ftxui/src/ftxui/dom/composite_decorator.cpp

@@ -1,5 +1,5 @@
-#include "ftxui/core/dom/node.hpp"
-#include "ftxui/core/dom/elements.hpp"
+#include "ftxui/dom/node.hpp"
+#include "ftxui/dom/elements.hpp"
 
 namespace ftxui {
 namespace dom {

ftxui/src/ftxui/dom/dim.cpp

@@ -0,0 +1,37 @@
+#include "ftxui/dom/node.hpp"
+#include "ftxui/dom/elements.hpp"
+
+namespace ftxui {
+namespace dom {
+
+class Dim : public Node {
+ public:
+  Dim(Children children) : Node(std::move(children)) {}
+  ~Dim() override {}
+
+  void ComputeRequirement() override {
+    Node::ComputeRequirement();
+    requirement_ = children[0]->requirement();
+  }
+
+  void SetBox(Box box) override {
+    Node::SetBox(box);
+    children[0]->SetBox(box);
+  }
+
+  void Render(Screen& screen) override {
+    Node::Render(screen);
+    for (int y = box_.top; y <= box_.bottom; ++y) {
+      for (int x = box_.left; x <= box_.right; ++x) {
+        screen.PixelAt(x,y).dim = true; 
+      }
+    }
+  }
+};
+
+std::unique_ptr<Node> dim(Child child) {
+  return std::make_unique<Dim>(unpack(std::move(child)));
+}
+
+};  // namespace dom
+};  // namespace ftxui

ftxui/src/ftxui/dom/flex.cpp

@@ -1,5 +1,5 @@
-#include "ftxui/core/dom/node.hpp"
-#include "ftxui/core/dom/elements.hpp"
+#include "ftxui/dom/node.hpp"
+#include "ftxui/dom/elements.hpp"
 
 namespace ftxui {
 namespace dom {

ftxui/src/ftxui/dom/frame.cpp

@@ -0,0 +1,92 @@
+#include "ftxui/dom/node.hpp"
+#include "ftxui/dom/elements.hpp"
+
+namespace ftxui {
+namespace dom {
+
+static wchar_t charset[] = L"┌┐└┘─│┬┴┤├";
+
+class Frame : public Node {
+ public:
+  Frame(Children children) : Node(std::move(children)) {}
+  ~Frame() override {}
+
+  void ComputeRequirement() override {
+    Node::ComputeRequirement();
+    requirement_ = children[0]->requirement();
+    requirement_.min.x += 2;
+    requirement_.min.y += 2;
+    if (children.size() == 2) {
+      requirement_.min.x =
+          std::max(requirement_.min.x, children[1]->requirement().min.x + 2);
+    }
+  }
+
+  void SetBox(Box box) override {
+    Node::SetBox(box);
+    if (children.size() == 2) {
+      Box title_box;
+      title_box.left = box.left + 1;
+      title_box.right = box.right - 1;
+      title_box.top = box.top;
+      title_box.bottom = box.top;
+      children[1]->SetBox(title_box);
+    }
+    box.left++;
+    box.right--;
+    box.top++;
+    box.bottom--;
+    children[0]->SetBox(box);
+  }
+
+  void Render(Screen& screen) override {
+    // Draw content.
+    children[0]->Render(screen);
+
+    // Draw the frame.
+    if (box_.left >= box_.right || box_.top >= box_.bottom)
+      return;
+
+    screen.at(box_.left, box_.top) = charset[0];
+    screen.at(box_.right, box_.top) = charset[1];
+    screen.at(box_.left, box_.bottom) = charset[2];
+    screen.at(box_.right, box_.bottom) = charset[3];
+    for(float x = box_.left + 1; x<box_.right; ++x) {
+      screen.at(x, box_.top) = charset[4];
+      screen.at(x, box_.bottom) = charset[4];
+    }
+    for(float y = box_.top + 1; y<box_.bottom; ++y) {
+      screen.at(box_.left, y) = charset[5];
+      screen.at(box_.right,y) = charset[5];
+    }
+
+    // Try to merge with separator.
+    for(float x = box_.left + 1; x<box_.right; ++x) {
+      if (screen.at(x, box_.top + 1) == charset[5])
+        screen.at(x, box_.top) = charset[6];
+      if (screen.at(x, box_.bottom - 1) == charset[5])
+        screen.at(x, box_.bottom) = charset[7];
+    }
+    for(float y = box_.top + 1; y<box_.bottom; ++y) {
+      if (screen.at(box_.left+1, y) == charset[4])
+        screen.at(box_.left, y) = charset[9];
+      if (screen.at(box_.right-1, y) == charset[4])
+        screen.at(box_.right,y) = charset[8];
+    }
+
+    // Draw title.
+    if (children.size() == 2)
+      children[1]->Render(screen);
+  }
+};
+
+std::unique_ptr<Node> frame(Child child) {
+  return std::make_unique<Frame>(unpack(std::move(child)));
+}
+
+std::unique_ptr<Node> frame(Child title, Child content) {
+  return std::make_unique<Frame>(unpack(std::move(content), std::move(title)));
+}
+
+};  // namespace dom
+};  // namespace ftxui

ftxui/src/ftxui/dom/gauge.cpp

@@ -1,5 +1,5 @@
-#include "ftxui/core/dom/node.hpp"
-#include "ftxui/core/dom/elements.hpp"
+#include "ftxui/dom/node.hpp"
+#include "ftxui/dom/elements.hpp"
 
 namespace ftxui {
 namespace dom {

ftxui/src/ftxui/dom/gauge_test.cpp

@@ -0,0 +1,34 @@
+#include "ftxui/dom/elements.hpp"
+#include "ftxui/screen.hpp"
+#include "gtest/gtest.h"
+
+namespace ftxui {
+namespace dom {
+
+TEST(GaugeTest, zero) {
+  auto root = gauge(0);
+  Screen screen(11,1);
+  Render(screen, root.get());
+
+  EXPECT_EQ("           ", screen.ToString());
+}
+
+TEST(GaugeTest, half) {
+  auto root = gauge(0.5);
+  Screen screen(11,1);
+  Render(screen, root.get());
+
+  EXPECT_EQ("█████▏▋    ", screen.ToString());
+//"  ▏▎▍▌▊▉█";
+}
+
+TEST(GaugeTest, one) {
+  auto root = gauge(1.0);
+  Screen screen(11,1);
+  Render(screen, root.get());
+
+  EXPECT_EQ("███████████", screen.ToString());
+}
+
+} // namespace dom
+} // namespace ftxui

ftxui/src/ftxui/dom/hbox.cpp

@@ -1,5 +1,5 @@
-#include "ftxui/core/dom/node.hpp"
-#include "ftxui/core/dom/elements.hpp"
+#include "ftxui/dom/node.hpp"
+#include "ftxui/dom/elements.hpp"
 
 namespace ftxui {
 namespace dom {

ftxui/src/ftxui/dom/hbox_test.cpp

@@ -1,5 +1,5 @@
-#include "ftxui/core/dom/elements.hpp"
-#include "ftxui/core/screen.hpp"
+#include "ftxui/dom/elements.hpp"
+#include "ftxui/screen.hpp"
 #include "gtest/gtest.h"
 
 namespace ftxui {

ftxui/src/ftxui/dom/inverted.cpp

@@ -0,0 +1,37 @@
+#include "ftxui/dom/node.hpp"
+#include "ftxui/dom/elements.hpp"
+
+namespace ftxui {
+namespace dom {
+
+class Inverted : public Node {
+ public:
+  Inverted(Children children) : Node(std::move(children)) {}
+  ~Inverted() override {}
+
+  void ComputeRequirement() override {
+    Node::ComputeRequirement();
+    requirement_ = children[0]->requirement();
+  }
+
+  void SetBox(Box box) override {
+    Node::SetBox(box);
+    children[0]->SetBox(box);
+  }
+
+  void Render(Screen& screen) override {
+    Node::Render(screen);
+    for (int y = box_.top; y <= box_.bottom; ++y) {
+      for (int x = box_.left; x <= box_.right; ++x) {
+        screen.PixelAt(x,y).inverted = true; 
+      }
+    }
+  }
+};
+
+std::unique_ptr<Node> inverted(Child child) {
+  return std::make_unique<Inverted>(unpack(std::move(child)));
+}
+
+};  // namespace dom
+};  // namespace ftxui

ftxui/src/ftxui/dom/node.cpp

@@ -1,4 +1,4 @@
-#include "ftxui/core/dom/node.hpp"
+#include "ftxui/dom/node.hpp"
 
 namespace ftxui {
 namespace dom {
@@ -8,10 +8,15 @@ Node::Node(std::vector<std::unique_ptr<Node>> children)
     : children(std::move(children)) {}
 Node::~Node() {}
 
-void Node::ComputeRequirement() {}
+void Node::ComputeRequirement() {
+  for(auto& child : children)
+    child->ComputeRequirement();
+}
+
 void Node::SetBox(Box box) {
   box_ = box;
 }
+
 void Node::Render(Screen& screen) {
   for(auto& child : children)
     child->Render(screen);

ftxui/src/ftxui/dom/separator.cpp

@@ -1,4 +1,4 @@
-#include "ftxui/core/dom/node.hpp"
+#include "ftxui/dom/node.hpp"
 
 namespace ftxui {
 namespace dom {

ftxui/src/ftxui/dom/text.cpp

@@ -1,4 +1,4 @@
-#include "ftxui/core/dom/node.hpp"
+#include "ftxui/dom/node.hpp"
 
 namespace ftxui {
 namespace dom {

ftxui/src/ftxui/dom/text_test.cpp

@@ -1,5 +1,5 @@
-#include "ftxui/core/dom/elements.hpp"
-#include "ftxui/core/screen.hpp"
+#include "ftxui/dom/elements.hpp"
+#include "ftxui/screen.hpp"
 #include "gtest/gtest.h"
 
 namespace ftxui {

ftxui/src/ftxui/dom/underlined.cpp

@@ -0,0 +1,37 @@
+#include "ftxui/dom/node.hpp"
+#include "ftxui/dom/elements.hpp"
+
+namespace ftxui {
+namespace dom {
+
+class Underlined : public Node {
+ public:
+  Underlined(Children children) : Node(std::move(children)) {}
+  ~Underlined() override {}
+
+  void ComputeRequirement() override {
+    Node::ComputeRequirement();
+    requirement_ = children[0]->requirement();
+  }
+
+  void SetBox(Box box) override {
+    Node::SetBox(box);
+    children[0]->SetBox(box);
+  }
+
+  void Render(Screen& screen) override {
+    Node::Render(screen);
+    for (int y = box_.top; y <= box_.bottom; ++y) {
+      for (int x = box_.left; x <= box_.right; ++x) {
+        screen.PixelAt(x,y).underlined = true; 
+      }
+    }
+  }
+};
+
+std::unique_ptr<Node> underlined(Child child) {
+  return std::make_unique<Underlined>(unpack(std::move(child)));
+}
+
+};  // namespace dom
+};  // namespace ftxui

ftxui/src/ftxui/dom/vbox.cpp

@@ -1,5 +1,5 @@
-#include "ftxui/core/dom/node.hpp"
-#include "ftxui/core/dom/elements.hpp"
+#include "ftxui/dom/node.hpp"
+#include "ftxui/dom/elements.hpp"
 
 namespace ftxui {
 namespace dom {

ftxui/src/ftxui/dom/vbox_test.cpp

@@ -1,5 +1,5 @@
-#include "ftxui/core/dom/elements.hpp"
-#include "ftxui/core/screen.hpp"
+#include "ftxui/dom/elements.hpp"
+#include "ftxui/screen.hpp"
 #include "gtest/gtest.h"
 
 namespace ftxui {

ftxui/src/ftxui/screen.cpp

@@ -0,0 +1,91 @@
+#include "ftxui/dom/node.hpp"
+#include "ftxui/screen.hpp"
+#include "ftxui/terminal.hpp"
+#include "ftxui/util/string.hpp"
+
+#include <sstream>
+
+namespace ftxui {
+
+Screen::Screen(size_t dimx, size_t dimy)
+    : dimx_(dimx), dimy_(dimy), pixels_(dimy, std::vector<Pixel>(dimx)) {}
+
+std::string Screen::ToString() {
+  std::wstringstream ss;
+  
+  Pixel previous_pixel;
+
+  for (size_t y = 0; y < dimy_; ++y) {
+    for (size_t x = 0; x < dimx_; ++x) {
+      if (pixels_[y][x].bold != previous_pixel.bold) {
+        if (pixels_[y][x].bold) {
+          ss << L"\e[1m";
+        } else {
+          ss << L"\e[0m";
+        }
+      }
+      if (pixels_[y][x].inverted != previous_pixel.inverted) {
+        if (pixels_[y][x].inverted) {
+          ss << L"\e[7m";
+        } else {
+          ss << L"\e[27m";
+        }
+      }
+      if (pixels_[y][x].underlined != previous_pixel.underlined) {
+        if (pixels_[y][x].underlined) {
+          ss << L"\e[4m";
+        } else {
+          ss << L"\e[24m";
+        }
+      }
+      if (pixels_[y][x].dim != previous_pixel.dim) {
+        if (pixels_[y][x].dim) {
+          ss << L"\e[2m";
+        } else {
+          ss << L"\e[22m";
+        }
+      }
+      ss << pixels_[y][x].character;
+      previous_pixel = pixels_[y][x];
+    }
+    if (y + 1 < dimy_)
+      ss << '\n';
+  }
+  return to_string(ss.str());
+}
+
+wchar_t& Screen::at(size_t x, size_t y) {
+  return pixels_[y][x].character;
+}
+
+Pixel& Screen::PixelAt(size_t x, size_t y) {
+  return pixels_[y][x];
+}
+
+// static
+Screen Screen::TerminalFullscreen() {
+  Terminal::Dimensions size = Terminal::Size();
+  return Screen(size.dimx, size.dimy);
+}
+
+// static
+Screen Screen::TerminalOutput(std::unique_ptr<dom::Node>& element) {
+  element->ComputeRequirement();
+  Terminal::Dimensions size = Terminal::Size();
+  return Screen(size.dimx, element->requirement().min.y);
+}
+
+std::string Screen::ResetPosition() {
+  std::stringstream ss;
+  for(size_t y = 1; y<dimy_; ++y) {
+    ss << "\e[2K\r\e[1A";
+  }
+  return ss.str();
+}
+
+void Screen::Clear() {
+  pixels_ = std::vector<std::vector<Pixel>>(dimy_,
+                                            std::vector<Pixel>(dimx_, Pixel()));
+}
+
+};  // namespace ftxui

ftxui/src/ftxui/screen_interactive.cpp

@@ -0,0 +1,112 @@
+#include "ftxui/screen_interactive.hpp"
+#include "ftxui/component/component.hpp"
+#include "ftxui/component/delegate.hpp"
+#include <iostream>
+#include <stdio.h>
+#include <termios.h>
+#include <unistd.h>
+
+namespace ftxui {
+
+class ScreenInteractive::Delegate : public component::Delegate {
+ public:
+  Delegate() : root_(this) {}
+
+  void Register(component::Component* c) override { component_ = c; }
+
+  std::vector<std::unique_ptr<Delegate>> child_;
+  Delegate* NewChild() override {
+    Delegate* child = new Delegate;
+    child->root_ = root_;
+    child->parent_ = this;
+
+    if (!child_.empty()) {
+      child_.back()->next_sibling_ = child;
+      child->previous_sibling_ = child_.back().get();
+    }
+
+    child_.emplace_back(child);
+    return child;
+  }
+
+  void Event(int key) { component_->Event(key); }
+
+
+  std::vector<component::Delegate*> children() override {
+    std::vector<component::Delegate*> ret;
+    for (auto& it : child_)
+      ret.push_back(it.get());
+    return ret;
+  }
+
+  Delegate* root_;
+  Delegate* parent_ = nullptr;
+  Delegate* previous_sibling_ = nullptr;
+  Delegate* next_sibling_ = nullptr;
+  component::Component* component_;
+
+  Delegate* Root() override { return root_; }
+  Delegate* Parent() override { return parent_; }
+  Delegate* PreviousSibling() override { return previous_sibling_; }
+  Delegate* NextSibling() override { return next_sibling_; }
+  component::Component* component() override { return component_; }
+};
+
+ScreenInteractive::ScreenInteractive(size_t dimx, size_t dimy)
+    : Screen(dimx, dimy), delegate_(new Delegate) {}
+ScreenInteractive::~ScreenInteractive() {}
+
+void ScreenInteractive::Loop() {
+  std::cout << "\033[?9h";    /* Send Mouse Row & Column on Button Press */
+  std::cout << "\033[?1000h"; /* Send Mouse X & Y on button press and release */
+  std::cout << std::flush;
+
+  // Save the old terminal configuration.
+  struct termios terminal_configuration_old;
+  tcgetattr(STDIN_FILENO, &terminal_configuration_old);
+
+  // Set the new terminal configuration
+  struct termios terminal_configuration_new;
+  terminal_configuration_new = terminal_configuration_old;
+
+  // Non canonique terminal.
+  terminal_configuration_new.c_lflag &= ~ICANON;
+  // Do not print after a key press.
+  terminal_configuration_new.c_lflag &= ~ECHO;
+  tcsetattr(STDIN_FILENO, TCSANOW, &terminal_configuration_new);
+
+  Draw();
+  while (!quit_) {
+    int key = getchar();
+    delegate_->Event(key);
+
+    Clear();
+    Draw();
+  }
+  std::cout << std::endl;
+  //Clear();
+
+  // Restore the old terminal configuration.
+  tcsetattr(STDIN_FILENO, TCSANOW, &terminal_configuration_old);
+}
+
+void ScreenInteractive::Draw() {
+  auto document = delegate_->component()->Render();
+  Render(*this, document.get());
+  std::cout << ToString() << std::flush;
+}
+
+void ScreenInteractive::Clear() {
+  std::cout << ResetPosition();
+  Screen::Clear();
+}
+
+component::Delegate* ScreenInteractive::delegate() {
+  return delegate_.get();
+}
+
+std::function<void()> ScreenInteractive::ExitLoopClosure() {
+  return [this]() { quit_ = true; };
+}
+
+}  // namespace ftxui

ftxui/src/ftxui/terminal.cpp

@@ -2,7 +2,7 @@
 #include <stdio.h>
 #include <unistd.h>
 
-#include "ftxui/core/terminal.hpp"
+#include "ftxui/terminal.hpp"
 
 namespace ftxui {