Feature: Dropdown options with callback (#826)

Co-authored-by: ArthurSonzogni <sonzogniarthur@gmail.com>

examples/component/CMakeLists.txt

@@ -11,6 +11,7 @@ example(collapsible)
 example(composition)
 example(custom_loop)
 example(dropdown)
+example(dropdown_custom)
 example(flexbox_gallery)
 example(focus)
 example(focus_cursor)

examples/component/dropdown_custom.cpp

@@ -0,0 +1,104 @@
+// 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 <string>  // for basic_string, string, allocator
+#include <vector>  // for vector
+
+#include "ftxui/component/captured_mouse.hpp"  // for ftxui
+#include "ftxui/component/component.hpp"  // for Dropdown, Horizontal, Vertical
+#include "ftxui/component/screen_interactive.hpp"  // for ScreenInteractive
+
+int main() {
+  using namespace ftxui;
+
+  std::vector<std::string> entries = {
+      "tribute",     "clearance", "ally",        "bend",        "electronics",
+      "module",      "era",       "cultural",    "sniff",       "nationalism",
+      "negotiation", "deliver",   "figure",      "east",        "tribute",
+      "clearance",   "ally",      "bend",        "electronics", "module",
+      "era",         "cultural",  "sniff",       "nationalism", "negotiation",
+      "deliver",     "figure",    "east",        "tribute",     "clearance",
+      "ally",        "bend",      "electronics", "module",      "era",
+      "cultural",    "sniff",     "nationalism", "negotiation", "deliver",
+      "figure",      "east",
+  };
+
+  auto dropdown_1 = Dropdown({
+      .radiobox = {.entries = &entries},
+      .transform =
+          [](bool open, Element checkbox, Element radiobox) {
+            if (open) {
+              return vbox({
+                  checkbox | inverted,
+                  radiobox | vscroll_indicator | frame |
+                      size(HEIGHT, LESS_THAN, 10),
+                  filler(),
+              });
+            }
+            return vbox({
+                checkbox,
+                filler(),
+            });
+          },
+  });
+
+  auto dropdown_2 = Dropdown({
+      .radiobox = {.entries = &entries},
+      .transform =
+          [](bool open, Element checkbox, Element radiobox) {
+            if (open) {
+              return vbox({
+                  checkbox | inverted,
+                  radiobox | vscroll_indicator | frame |
+                      size(HEIGHT, LESS_THAN, 10) | bgcolor(Color::Blue),
+                  filler(),
+              });
+            }
+            return vbox({
+                checkbox | bgcolor(Color::Blue),
+                filler(),
+            });
+          },
+  });
+
+  auto dropdown_3 = Dropdown({
+      .radiobox =
+          {
+              .entries = &entries,
+              .transform =
+                  [](const EntryState& s) {
+                    auto t = text(s.label) | borderEmpty;
+                    if (s.active) {
+                      t |= bold;
+                    }
+                    if (s.focused) {
+                      t |= inverted;
+                    }
+                    return t;
+                  },
+          },
+      .transform =
+          [](bool open, Element checkbox, Element radiobox) {
+            checkbox |= borderEmpty;
+            if (open) {
+              return vbox({
+                  checkbox | inverted,
+                  radiobox | vscroll_indicator | frame |
+                      size(HEIGHT, LESS_THAN, 20) | bgcolor(Color::Red),
+                  filler(),
+              });
+            }
+            return vbox({
+                checkbox | bgcolor(Color::Red),
+                filler(),
+            });
+          },
+  });
+
+  auto screen = ScreenInteractive::FitComponent();
+  screen.Loop(Container::Horizontal({
+      dropdown_1,
+      dropdown_2,
+      dropdown_3,
+  }));
+}

examples/component/homescreen.cpp

@@ -494,11 +494,11 @@ int main() {
       "Exit", [&] { screen.Exit(); }, ButtonOption::Animated());
 
   auto main_container = Container::Vertical({
-    Container::Horizontal({
-        tab_selection,
-        exit_button,
-    }),
-    tab_content,
+      Container::Horizontal({
+          tab_selection,
+          exit_button,
+      }),
+      tab_content,
   });
 
   auto main_renderer = Renderer(main_container, [&] {