Add MenuEntry. (#199)

This will address comments from:
https://github.com/ArthurSonzogni/FTXUI/issues/194

examples/component/CMakeLists.txt

@@ -11,6 +11,7 @@ example(input)
 example(menu)
 example(menu2)
 example(menu_multiple)
+example(menu_entries)
 example(menu_style)
 example(modal_dialog)
 example(print_key_press)

examples/component/menu_entries.cpp

@@ -0,0 +1,90 @@
+#include <functional>  // for function
+#include <iostream>  // for basic_ostream::operator<<, operator<<, endl, basic_ostream, basic_ostream<>::__ostream_type, cout, ostream
+#include <string>    // for string, basic_string, allocator
+#include <vector>    // for vector
+
+#include "ftxui/component/captured_mouse.hpp"      // for ftxui
+#include "ftxui/component/component.hpp"           // for Menu
+#include "ftxui/component/component_options.hpp"   // for MenuOption
+#include "ftxui/component/screen_interactive.hpp"  // for ScreenInteractive
+using namespace ftxui;
+
+// Define a special style for some menu entry.
+MenuEntryOption Colored(ftxui::Color c) {
+  MenuEntryOption special_style;
+  special_style.style_normal = Decorator(color(c));
+  special_style.style_focused = Decorator(color(c)) | inverted;
+  special_style.style_selected = Decorator(color(c)) | bold;
+  special_style.style_selected_focused = Decorator(color(c)) | inverted | bold;
+  return special_style;
+}
+
+int main(int argc, const char* argv[]) {
+  auto screen = ScreenInteractive::TerminalOutput();
+
+    //Black        = 0,
+    //Red          = 1,
+    //Green        = 2,
+    //Yellow       = 3,
+    //Blue         = 4,
+    //Magenta      = 5,
+    //Cyan         = 6,
+    //GrayLight    = 7,
+    //GrayDark     = 8,
+    //RedLight     = 9,
+    //GreenLight   = 10,
+    //YellowLight  = 11,
+    //BlueLight    = 12,
+    //MagentaLight = 13,
+    //CyanLight    = 14,
+    //White        = 15,
+
+  int selected = 0;
+  auto menu = Container::Vertical(
+      {
+          MenuEntry(" 1. improve"),
+          MenuEntry(" 2. tolerant"),
+          MenuEntry(" 3. career"),
+          MenuEntry(" 4. cast"),
+          MenuEntry(" 5. question"),
+
+          Renderer([] { return separator(); }),
+
+          MenuEntry(" 6. rear", Colored(Color::Red)),
+          MenuEntry(" 7. drown", Colored(Color::Yellow)),
+          MenuEntry(" 8. nail", Colored(Color::Green)),
+          MenuEntry(" 9. quit", Colored(Color::Cyan)),
+          MenuEntry("10. decorative", Colored(Color::Blue)),
+
+          Renderer([] { return separator(); }),
+
+          MenuEntry("11. costume"),
+          MenuEntry("12. pick"),
+          MenuEntry("13. oral"),
+          MenuEntry("14. minister"),
+          MenuEntry("15. football"),
+          MenuEntry("16. welcome"),
+          MenuEntry("17. copper"),
+          MenuEntry("18. inhabitant"),
+          MenuEntry("19. fortune"),
+      },
+      &selected);
+
+  // Display together the menu with a border
+  auto renderer = Renderer(menu, [&] {
+    return vbox({
+               hbox(text("selected = "), text(std::to_string(selected))),
+               separator(),
+               menu->Render() | frame | size(HEIGHT, LESS_THAN, 10),
+           }) |
+           border;
+  });
+
+  screen.Loop(renderer);
+
+  std::cout << "Selected element = " << selected << std::endl;
+}
+
+// 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/ftxui/component/component.hpp

@@ -37,6 +37,7 @@ Component Input(StringRef content,
 Component Menu(ConstStringListRef entries,
                int* selected_,
                Ref<MenuOption> = {});
+Component MenuEntry(ConstStringRef label, Ref<MenuEntryOption> = {});
 Component Radiobox(ConstStringListRef entries,
                    int* selected_,
                    Ref<RadioboxOption> option = {});

include/ftxui/component/component_options.hpp

@@ -23,6 +23,16 @@ struct MenuOption {
   Ref<int> focused_entry = 0;
 };
 
+/// @brief Option for the MenuEntry component.
+/// @ingroup component
+struct MenuEntryOption {
+  Decorator style_normal = nothing;    ///< style.
+  Decorator style_focused = inverted;  ///< Style when focused.
+  Decorator style_selected = bold;     ///< Style when selected.
+  Decorator style_selected_focused =
+      Decorator(inverted) | bold;  ///< Style when selected and focused.
+};
+
 /// @brief Option for the Button component.
 /// @ingroup component
 struct ButtonOption {

src/ftxui/component/menu.cpp

@@ -149,6 +149,51 @@ Component Menu(ConstStringListRef entries,
   return Make<MenuBase>(entries, selected, std::move(option));
 }
 
+Component MenuEntry(ConstStringRef label, Ref<MenuEntryOption> option) {
+  class Impl : public ComponentBase {
+   public:
+    Impl(ConstStringRef label, Ref<MenuEntryOption> option)
+        : label_(std::move(label)), option_(std::move(option)) {}
+
+   private:
+    Element Render() override {
+      bool focused = Focused();
+      auto style =
+          hovered_ ? (focused ? option_->style_selected_focused
+                              : option_->style_selected)
+                   : (focused ? option_->style_focused : option_->style_normal);
+      auto focus_management = focused ? select : nothing;
+      auto label = focused ? "> " + (*label_)  //
+                           : "  " + (*label_);
+      return text(label) | style | focus_management | reflect(box_);
+    }
+    bool Focusable() const override { return true; }
+    bool OnEvent(Event event) override {
+      if (!event.is_mouse())
+        return false;
+
+      hovered_ = box_.Contain(event.mouse().x, event.mouse().y);
+
+      if (!hovered_)
+        return false;
+
+      if (event.mouse().button == Mouse::Left &&
+          event.mouse().motion == Mouse::Released) {
+        TakeFocus();
+        return true;
+      }
+
+      return false;
+    }
+    ConstStringRef label_;
+    Ref<MenuEntryOption> option_;
+    Box box_;
+    bool hovered_ = false;
+  };
+
+  return Make<Impl>(std::move(label), std::move(option));
+}
+
 }  // namespace ftxui
 
 // Copyright 2020 Arthur Sonzogni. All rights reserved.