Add more documentation.

include/ftxui/component/checkbox.hpp

@@ -7,27 +7,29 @@
 
 namespace ftxui {
 
+/// @brief A Checkbox. It can be checked or unchecked.Display an element on a ftxui::Screen.
+/// @ingroup dom
 class CheckBox : public Component {
  public:
   // Constructor.
   CheckBox() = default;
   ~CheckBox() override = default;
 
-  bool state = false;
-  std::wstring label = L"label";
+  bool state = false; // The current state. true=checked, false:unchecked.
+  std::wstring label = L"label"; // The CheckBox label.
 
 #if defined(_WIN32)
-  std::wstring checked = L"[X] ";
-  std::wstring unchecked = L"[ ] ";
+  std::wstring checked = L"[X] "; /// Prefix for  a "checked" state.
+  std::wstring unchecked = L"[ ] "; /// Prefix for  an "unchecked" state.
 #else
-  std::wstring checked = L"▣ ";
-  std::wstring unchecked = L"☐ ";
+  std::wstring checked = L"▣ "; /// Prefix for  a "checked" state.
+  std::wstring unchecked = L"☐ "; /// Prefix for  a "unchecked" state.
 #endif
 
-  Decorator focused_style = inverted;
-  Decorator unfocused_style = nothing;
+  Decorator focused_style = inverted; /// Decorator used when focused.
+  Decorator unfocused_style = nothing; /// Decorator used when unfocused.
 
-  // State update callback.
+  /// Called when the user change the state of the CheckBox.
   std::function<void()> on_change = []() {};
 
   // Component implementation.

include/ftxui/component/component.hpp

@@ -9,6 +9,9 @@ namespace ftxui {
 class Delegate;
 class Focus;
 
+/// @brief It implement rendering itself as ftxui::Element. It implement
+/// keyboard navigation by responding to ftxui::Event.
+/// @ingroup component
 class Component {
  public:
   // Constructor/Destructor.
@@ -16,7 +19,7 @@ class Component {
   virtual ~Component();
 
   // Component hierarchy.
-  Component* Parent() { return parent_; }
+  Component* Parent();
   void Add(Component* children);
 
   // Renders the component.

include/ftxui/component/container.hpp

@@ -5,10 +5,7 @@
 
 namespace ftxui {
 
-// A component where focus and events are automatically handled for you.
-// List of container:
-//
-// Please use HorizontalContainer or VerticalContainer.
+/// @brief A component where focus and events are automatically handled for you.
 class Container : public Component {
  public:
   static Container Vertical();

include/ftxui/component/event.hpp

@@ -9,6 +9,9 @@
 
 namespace ftxui {
 
+/// @brief Represent an event. It can be key press event, a terminal resize, or
+/// more ...
+//
 // Documentation:
 // https://invisible-island.net/xterm/ctlseqs/ctlseqs.html
 //

include/ftxui/component/input.hpp

@@ -7,6 +7,8 @@
 
 namespace ftxui {
 
+/// @brief An input box. The user can type text into it.
+/// @ingroup component.
 class Input : public Component {
  public:
   // Constructor.

include/ftxui/component/menu.hpp

@@ -8,6 +8,8 @@
 
 namespace ftxui {
 
+/// @brief A list of items. The user can navigate through them.
+/// @ingroup component
 class Menu : public Component {
  public:
   // Constructor.

include/ftxui/component/radiobox.hpp

@@ -7,6 +7,9 @@
 
 namespace ftxui {
 
+/// @brief A list of selectable element. One and only one can be selected at
+/// the same time.
+/// @ingroup component
 class RadioBox : public Component {
  public:
   // Constructor.

include/ftxui/component/toggle.hpp

@@ -8,6 +8,8 @@
 
 namespace ftxui {
 
+/// @brief An horizontal list of elements. The user can navigate through them.
+/// @ingroup component
 class Toggle : public Component {
  public:
   // Constructor.

include/ftxui/dom/elements.hpp

@@ -61,13 +61,13 @@ Element flex(Element);         // Expand/Minimize if possible/needed.
 Element flex_grow(Element);    // Expand element if possible.
 Element flex_shrink(Element);  // Minimize element if needed.
 
-Element xflex(Element);         // Expand/Minimize if possible/needed.
-Element xflex_grow(Element);    // Expand element if possible.
-Element xflex_shrink(Element);  // Minimize element if needed.
+Element xflex(Element);         // Expand/Minimize if possible/needed on X axis.
+Element xflex_grow(Element);    // Expand element if possible on X axis.
+Element xflex_shrink(Element);  // Minimize element if needed on X axis.
 
-Element yflex(Element);         // Expand/Minimize if possible/needed.
-Element yflex_grow(Element);    // Expand element if possible.
-Element yflex_shrink(Element);  // Minimize element if needed.
+Element yflex(Element);         // Expand/Minimize if possible/needed on Y axis.
+Element yflex_grow(Element);    // Expand element if possible on Y axis.
+Element yflex_shrink(Element);  // Minimize element if needed on Y axis.
 
 Element notflex(Element);  // Reset the flex attribute.
 Element filler();          // A blank expandable element.

include/ftxui/util/autoreset.hpp

@@ -3,6 +3,7 @@
 
 namespace ftxui {
 
+/// Assign a value to a variable, reset its old value when going out of scope.
 template <typename T>
 class AutoReset {
  public: