Introduce CatchEvent (#104)

.github/workflows/linux-clang.yaml

@@ -16,7 +16,7 @@ jobs:
           mkdir build;
           cd build;
           cmake ..
-          -DCMAKE_CXX_COMPILER=clang++-9
+          -DCMAKE_CXX_COMPILER=clang++
           -DFTXUI_BUILD_TESTS=ON;
           cmake --build . --config Release;
 

CMakeLists.txt

@@ -91,6 +91,7 @@ add_library(component STATIC
   include/ftxui/component/screen_interactive.hpp
   include/ftxui/component/toggle.hpp
   src/ftxui/component/button.cpp
+  src/ftxui/component/catch_event.cpp
   src/ftxui/component/checkbox.cpp
   src/ftxui/component/component.cpp
   src/ftxui/component/container.cpp

examples/component/button.cpp

@@ -14,8 +14,10 @@ int main(int argc, const char* argv[]) {
 
   // The tree of components. This defines how to navigate using the keyboard.
   auto buttons = Container::Horizontal({
-      Button("Decrease", [&] { value--; }),
-      Button("Increase", [&] { value++; }),
+      Button(
+          "[Decrease]", [&] { value--; }, false),
+      Button(
+          "[Increase]", [&] { value++; }, false),
   });
 
   // Modify the way to render them on screen:

examples/util/print_key_press.cpp

@@ -2,19 +2,19 @@
 // Use of this source code is governed by the MIT license that can be found in
 // the LICENSE file.
 
-#include <stddef.h>                                // for size_t
-#include <algorithm>                               // for max
-#include <ftxui/component/component.hpp>           // for Make
-#include <ftxui/component/screen_interactive.hpp>  // for ScreenInteractive
-#include <string>  // for allocator, operator+, wstring, char_traits, to_wstring, string
+#include <stddef.h>   // for size_t
+#include <algorithm>  // for max
+#include <memory>     // for shared_ptr
+#include <string>  // for allocator, char_traits, operator+, wstring, basic_string, to_wstring, string
 #include <utility>  // for move
 #include <vector>   // for vector
 
 #include "ftxui/component/captured_mouse.hpp"  // for ftxui
-#include "ftxui/component/component_base.hpp"  // for ComponentBase
+#include "ftxui/component/component.hpp"       // for CatchEvent, Renderer
 #include "ftxui/component/event.hpp"           // for Event
 #include "ftxui/component/mouse.hpp"  // for Mouse, Mouse::Left, Mouse::Middle, Mouse::None, Mouse::Pressed, Mouse::Released, Mouse::Right, Mouse::WheelDown, Mouse::WheelUp
-#include "ftxui/dom/elements.hpp"  // for text, vbox, window, Elements, Element
+#include "ftxui/component/screen_interactive.hpp"  // for ScreenInteractive
+#include "ftxui/dom/elements.hpp"  // for text, vbox, window, Element, Elements
 
 using namespace ftxui;
 
@@ -72,28 +72,22 @@ std::wstring Stringify(Event event) {
   return out;
 }
 
-class DrawKey : public ComponentBase {
- public:
-  ~DrawKey() override = default;
-
-  Element Render() override {
-    Elements children;
-    for (size_t i = std::max(0, (int)keys.size() - 20); i < keys.size(); ++i) {
-      children.push_back(text(Stringify(keys[i])));
-    }
-    return window(text(L"keys"), vbox(std::move(children)));
-  }
-
-  bool OnEvent(Event event) override {
-    keys.push_back(event);
-    return true;
-  }
-
- private:
-  std::vector<Event> keys;
-};
-
 int main(int argc, const char* argv[]) {
   auto screen = ScreenInteractive::TerminalOutput();
-  screen.Loop(Make<DrawKey>());
+
+  std::vector<Event> keys;
+
+  auto component = Renderer([&] {
+    Elements children;
+    for (size_t i = std::max(0, (int)keys.size() - 20); i < keys.size(); ++i)
+      children.push_back(text(Stringify(keys[i])));
+    return window(text(L"keys"), vbox(std::move(children)));
+  });
+
+  component = CatchEvent(component, [&](Event event) {
+    keys.push_back(event);
+    return true;
+  });
+
+  screen.Loop(component);
 }

include/ftxui/component/component.hpp

@@ -13,6 +13,7 @@
 namespace ftxui {
 
 class ComponentBase;
+struct Event;
 
 using Component = std::shared_ptr<ComponentBase>;
 using Components = std::vector<Component>;
@@ -30,10 +31,11 @@ Component Input(StringRef content, ConstStringRef placeholder);
 Component Menu(const std::vector<std::wstring>* entries, int* selected_);
 Component Radiobox(const std::vector<std::wstring>* entries, int* selected_);
 Component Toggle(const std::vector<std::wstring>* entries, int* selected);
-Component Renderer(Component child, std::function<Element()>);
-Component Renderer(std::function<Element()>);
 template <class T>  // T = {int, float}
 Component Slider(StringRef label, T* value, T min, T max, T increment);
+Component Renderer(Component child, std::function<Element()>);
+Component Renderer(std::function<Element()>);
+Component CatchEvent(Component child, std::function<bool(Event)>);
 
 namespace Container {
 Component Vertical(Components children);

include/ftxui/dom/node.hpp

@@ -35,7 +35,6 @@ class Node {
   // Step 3: Draw this element.
   virtual void Render(Screen& screen);
 
-
  protected:
   std::vector<Element> children_;
   Requirement requirement_;

src/ftxui/component/catch_event.cpp

@@ -0,0 +1,57 @@
+#include <functional>  // for function
+#include <memory>  // for __shared_ptr_access, __shared_ptr_access<>::element_type, shared_ptr
+#include <utility>  // for move
+
+#include "ftxui/component/component.hpp"  // for Component, Make, CatchEvent
+#include "ftxui/component/component_base.hpp"  // for ComponentBase
+#include "ftxui/component/event.hpp"           // for Event
+
+namespace ftxui {
+
+/// @brief A component executing a provided function for catching events.
+/// @ingroup component.
+class CatchEventBase : public ComponentBase {
+ public:
+  // Constructor.
+  CatchEventBase(std::function<bool(Event)> on_event)
+      : on_event_(std::move(on_event)) {}
+  ~CatchEventBase() override = default;
+
+  // Component implementation.
+  bool OnEvent(Event event) override {
+    if (on_event_(event))
+      return true;
+    else
+      return ComponentBase::OnEvent(event);
+  }
+
+ protected:
+  std::function<bool(Event)> on_event_;
+};
+
+/// @brief Return a component, using |on_event| to catch events. This function
+/// must returns true when the event has been handled, false otherwise.
+/// @param on_event The function drawing the interface.
+/// @ingroup component
+///
+/// ### Example
+///
+/// ```cpp
+/// auto screen = ScreenInteractive::TerminalOutput();
+/// auto renderer = Renderer([] {
+///   return text(L"My interface");
+/// });
+/// screen.Loop(renderer);
+/// ```
+Component CatchEvent(Component child,
+                     std::function<bool(Event event)> on_event) {
+  auto out = Make<CatchEventBase>(std::move(on_event));
+  out->Add(std::move(child));
+  return out;
+}
+
+}  // namespace ftxui
+
+// Copyright 2021 Arthur Sonzogni. All rights reserved.
+// Use of this source code is governed by the MIT license that can be found in
+// the LICENSE file.

src/ftxui/screen/string.cpp

@@ -1,7 +1,8 @@
 #include "ftxui/screen/string.hpp"
 
-#include <codecvt>
-#include <locale>
+#include <codecvt>  // for codecvt_utf8_utf16
+#include <locale>   // for wstring_convert
+#include <utility>  // for move
 
 namespace ftxui {
 #ifdef _MSC_VER