Feature: strikethrough and underlinedDouble decorator. (#561)

This resolves:
https://github.com/ArthurSonzogni/FTXUI/issues/560

examples/dom/CMakeLists.txt

@@ -26,7 +26,9 @@ example(style_color)
 example(style_dim)
 example(style_gallery)
 example(style_inverted)
+example(style_strikethrough)
 example(style_underlined)
+example(style_underlined_double)
 example(table)
 example(vbox_hbox)
 example(vflow)

examples/dom/style_gallery.cpp

@@ -10,14 +10,16 @@ int main(int argc, const char* argv[]) {
   // clang-format off
   auto document =
     hbox({
-      text("normal")                           , text(" ") ,
-      text("bold")      | bold                 , text(" ") ,
-      text("dim")       | dim                  , text(" ") ,
-      text("inverted")  | inverted             , text(" ") ,
-      text("underlined")| underlined           , text(" ") ,
-      text("blink")     | blink                , text(" ") ,
-      text("color")     | color(Color::Blue)   , text(" ") ,
-      text("bgcolor")   | bgcolor(Color::Blue),
+      text("normal")                                    , text(" ") ,
+      text("bold")               | bold                 , text(" ") ,
+      text("dim")                | dim                  , text(" ") ,
+      text("inverted")           | inverted             , text(" ") ,
+      text("underlined")         | underlined           , text(" ") ,
+      text("underlinedDouble")   | underlinedDouble     , text(" ") ,
+      text("blink")              | blink                , text(" ") ,
+      text("strikethrough")      | strikethrough        , text(" ") ,
+      text("color")              | color(Color::Blue)   , text(" ") ,
+      text("bgcolor")            | bgcolor(Color::Blue) ,
     });
   // clang-format on
   auto screen = Screen::Create(Dimension::Full(), Dimension::Fit(document));

examples/dom/style_strikethrough.cpp

@@ -0,0 +1,25 @@
+#include <ftxui/dom/elements.hpp>  // for text, operator|, strikethrough, Fit, hbox, Element
+#include <ftxui/screen/screen.hpp>  // for Full, Screen
+#include <memory>                   // for allocator
+
+#include "ftxui/dom/node.hpp"      // for Render
+#include "ftxui/screen/color.hpp"  // for ftxui
+
+int main(int argc, const char* argv[]) {
+  using namespace ftxui;
+  auto document =  //
+      hbox({
+          text("This text is "),
+          text("strikethrough") | strikethrough,
+          text(". Do you like it?"),
+      });
+  auto screen = Screen::Create(Dimension::Full(), Dimension::Fit(document));
+  Render(screen, document);
+  screen.Print();
+
+  return 0;
+}
+
+// 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.

examples/dom/style_underlined_double.cpp

@@ -0,0 +1,25 @@
+#include <ftxui/dom/elements.hpp>  // for text, operator|, underlinedDouble, Fit, hbox, Element
+#include <ftxui/screen/screen.hpp>  // for Full, Screen
+#include <memory>                   // for allocator
+
+#include "ftxui/dom/node.hpp"      // for Render
+#include "ftxui/screen/color.hpp"  // for ftxui
+
+int main(int argc, const char* argv[]) {
+  using namespace ftxui;
+  auto document =  //
+      hbox({
+          text("This text is "),
+          text("underlinedDouble") | underlinedDouble,
+          text(". Do you like it?"),
+      });
+  auto screen = Screen::Create(Dimension::Full(), Dimension::Fit(document));
+  Render(screen, document);
+  screen.Print();
+
+  return 0;
+}
+
+// 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.