Feature: Add multi-line input. (#630)

examples/component/textarea.cpp

@@ -0,0 +1,35 @@
+#include <memory>  // for allocator, __shared_ptr_access, shared_ptr
+#include <string>  // for string
+
+#include "ftxui/component/captured_mouse.hpp"  // for ftxui
+#include "ftxui/component/component.hpp"  // for Input, Renderer, ResizableSplitLeft
+#include "ftxui/component/component_base.hpp"  // for ComponentBase, Component
+#include "ftxui/component/screen_interactive.hpp"  // for ScreenInteractive
+#include "ftxui/dom/elements.hpp"  // for operator|, separator, text, Element, flex, vbox, border
+
+int main(int argc, const char* argv[]) {
+  using namespace ftxui;
+
+  std::string content_1;
+  std::string content_2;
+  auto textarea_1 = Input(&content_1);
+  auto textarea_2 = Input(&content_2);
+  int size = 50;
+  auto layout = ResizableSplitLeft(textarea_1, textarea_2, &size);
+
+  auto component = Renderer(layout, [&] {
+    return vbox({
+               text("Input:"),
+               separator(),
+               layout->Render() | flex,
+           }) |
+           border;
+  });
+
+  auto screen = ScreenInteractive::Fullscreen();
+  screen.Loop(component);
+}
+
+// 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.