Support multiple kind of cursor shapes. (#505)

https://github.com/ArthurSonzogni/FTXUI/issues/424

examples/component/CMakeLists.txt

@@ -13,6 +13,7 @@ example(custom_loop)
 example(dropdown)
 example(flexbox_gallery)
 example(focus)
+example(focus_cursor)
 example(gallery)
 example(homescreen)
 example(input)

examples/component/focus_cursor.cpp

@@ -0,0 +1,39 @@
+#include <memory>  // for allocator, shared_ptr, __shared_ptr_access
+#include <string>  // for operator+, char_traits, to_string, string
+#include <vector>  // for vector
+
+#include "ftxui/component/component.hpp"       // for Slider, Renderer, Vertical
+#include "ftxui/component/screen_interactive.hpp"  // for ScreenInteractive
+#include "ftxui/dom/elements.hpp"  // for Elements, Element, operator|, separator, text, focusPositionRelative, size, border, flex, frame, bgcolor, gridbox, vbox, EQUAL, center, HEIGHT, WIDTH
+
+using namespace ftxui;
+
+Component Instance(std::string label, Decorator focusCursor) {
+  return Renderer([=](bool focused) {
+    if (focused) {
+      return hbox({
+          text("> " + label + " "),
+          focusCursor(text(" ")),
+      });
+    }
+    return text("  " + label + " ");
+  });
+};
+
+int main(int argc, const char* argv[]) {
+  auto screen = ScreenInteractive::Fullscreen();
+  screen.Loop(Container::Vertical({
+      Instance("focus", focus),
+      Instance("focusCursorBlock", focusCursorBlock),
+      Instance("focusCursorBlockBlinking", focusCursorBlockBlinking),
+      Instance("focusCursorBar", focusCursorBar),
+      Instance("focusCursorBarBlinking", focusCursorBarBlinking),
+      Instance("focusCursorUnderline", focusCursorUnderline),
+      Instance("focusCursorUnderlineBlinking", focusCursorUnderlineBlinking),
+  }));
+  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.