Feature: Selection

Add support for selection content in the dom.

src/ftxui/dom/selection_style.cpp

@@ -0,0 +1,89 @@
+// Copyright 2024 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 <memory>   // for make_shared
+#include <utility>  // for move
+
+#include "ftxui/dom/elements.hpp"  // for Element, Decorator, bgcolor, color
+#include "ftxui/dom/node_decorator.hpp"  // for NodeDecorator
+#include "ftxui/screen/box.hpp"          // for Box
+#include "ftxui/screen/color.hpp"        // for Color
+#include "ftxui/screen/screen.hpp"       // for Pixel, Screen
+
+namespace ftxui {
+
+namespace {
+
+class SelectionStyleReset : public NodeDecorator {
+ public:
+  SelectionStyleReset(Element child) : NodeDecorator(std::move(child)) {}
+
+  void Render(Screen& screen) final {
+    auto old_style = screen.GetSelectionStyle();
+    screen.SetSelectionStyle([](Pixel& pixel) {});
+    NodeDecorator::Render(screen);
+    screen.SetSelectionStyle(old_style);
+  }
+};
+
+class SelectionStyle : public NodeDecorator {
+ public:
+  SelectionStyle(Element child, std::function<void(Pixel&)> style)
+      : NodeDecorator(std::move(child)), style_(style) {}
+
+  void Render(Screen& screen) final {
+    auto old_style = screen.GetSelectionStyle();
+    auto new_style = [&, old_style](Pixel& pixel) {
+      old_style(pixel);
+      style_(pixel);
+    };
+    screen.SetSelectionStyle(new_style);
+    NodeDecorator::Render(screen);
+    screen.SetSelectionStyle(old_style);
+  }
+
+  std::function<void(Pixel&)> style_;
+};
+
+}  // namespace
+
+/// @brief Reset the selection style of an element.
+/// @param child The input element.
+/// @return The output element with the selection style reset.
+Element selectionStyleReset(Element child) {
+  return std::make_shared<SelectionStyleReset>(std::move(child));
+}
+
+/// @brief Set the background color of an element when selected.
+/// Note that the style is applied on top of the existing style.
+Decorator selectionBackgroundColor(Color foreground) {
+  return selectionStyle([foreground](Pixel& pixel) {  //
+    pixel.background_color = foreground;
+  });
+}
+
+/// @brief Set the foreground color of an element when selected.
+/// Note that the style is applied on top of the existing style.
+Decorator selectionForegroundColor(Color foreground) {
+  return selectionStyle([foreground](Pixel& pixel) {  //
+    pixel.foreground_color = foreground;
+  });
+}
+
+/// @brief Set the color of an element when selected.
+/// @param foreground The color to be applied.
+/// Note that the style is applied on top of the existing style.
+Decorator selectionColor(Color foreground) {
+  return selectionForegroundColor(foreground);
+}
+
+/// @brief Set the style of an element when selected.
+/// @param style The style to be applied.
+/// Note that the style is applied on top of the existing style.
+Decorator selectionStyle(std::function<void(Pixel&)> style) {
+  return [style](Element child) -> Element {
+    return std::make_shared<SelectionStyle>(std::move(child), style);
+  };
+}
+
+}  // namespace ftxui