Add non focusable components. (#172)

include/ftxui/component/component_base.hpp

@@ -51,6 +51,11 @@ class ComponentBase {
   // root component contains this object.
   virtual Component ActiveChild();
 
+  // Return true when the component contains focusable elements.
+  // The non focusable Component will be skipped when navigating using the
+  // keyboard.
+  virtual bool Focusable() const;
+
   // Whether this is the active child of its parent.
   bool Active() const;
   // Whether all the ancestors are active.

src/ftxui/component/button.cpp

@@ -53,6 +53,10 @@ class ButtonBase : public ComponentBase {
     return false;
   }
 
+  bool Focusable() const final {
+    return true;
+  }
+
  private:
   ConstStringRef label_;
   std::function<void()> on_click_;

src/ftxui/component/checkbox.cpp

@@ -71,6 +71,10 @@ class CheckboxBase : public ComponentBase {
     return false;
   }
 
+  bool Focusable() const final {
+    return true;
+  }
+
   ConstStringRef label_;
   bool* const state_;
   Box box_;

src/ftxui/component/component.cpp

@@ -106,6 +106,18 @@ Component ComponentBase::ActiveChild() {
   return children_.empty() ? nullptr : children_.front();
 }
 
+/// @brief Return true when the component contains focusable elements.
+/// The non focusable Components will be skipped when navigating using the
+/// keyboard.
+/// @ingroup component
+bool ComponentBase::Focusable() const {
+  for (const Component& child : children_) {
+    if (child->Focusable())
+      return true;
+  }
+  return false;
+}
+
 /// @brief Returns if the element if the currently active child of its parent.
 /// @ingroup component
 bool ComponentBase::Active() const {

src/ftxui/component/container.cpp

@@ -63,6 +63,25 @@ class ContainerBase : public ComponentBase {
 
   int selected_ = 0;
   int* selector_ = nullptr;
+
+  void MoveSelector(int dir) {
+    for (int i = *selector_ + dir; i >= 0 && i < (int)children_.size();
+         i += dir) {
+      if (children_[i]->Focusable()) {
+        *selector_ = i;
+        return;
+      }
+    }
+  }
+  void MoveSelectorWrap(int dir) {
+    for (size_t offset = 1; offset < children_.size(); ++offset) {
+      int i = (*selector_ + offset * dir + children_.size()) % children_.size();
+      if (children_[i]->Focusable()) {
+        *selector_ = i;
+        return;
+      }
+    }
+  }
 };
 
 class VerticalContainer : public ContainerBase {
@@ -81,13 +100,13 @@ class VerticalContainer : public ContainerBase {
   bool EventHandler(Event event) override {
     int old_selected = *selector_;
     if (event == Event::ArrowUp || event == Event::Character('k'))
-      (*selector_)--;
+      MoveSelector(-1);
     if (event == Event::ArrowDown || event == Event::Character('j'))
-      (*selector_)++;
+      MoveSelector(+1);
     if (event == Event::Tab && children_.size())
-      *selector_ = (*selector_ + 1) % children_.size();
+      MoveSelectorWrap(+1);
     if (event == Event::TabReverse && children_.size())
-      *selector_ = (*selector_ + children_.size() - 1) % children_.size();
+      MoveSelectorWrap(-1);
 
     *selector_ = std::max(0, std::min(int(children_.size()) - 1, *selector_));
     return old_selected != *selector_;
@@ -110,13 +129,13 @@ class HorizontalContainer : public ContainerBase {
   bool EventHandler(Event event) override {
     int old_selected = *selector_;
     if (event == Event::ArrowLeft || event == Event::Character('h'))
-      (*selector_)--;
+      MoveSelector(-1);
     if (event == Event::ArrowRight || event == Event::Character('l'))
-      (*selector_)++;
+      MoveSelector(+1);
     if (event == Event::Tab && children_.size())
-      *selector_ = (*selector_ + 1) % children_.size();
+      MoveSelectorWrap(+1);
     if (event == Event::TabReverse && children_.size())
-      *selector_ = (*selector_ + children_.size() - 1) % children_.size();
+      MoveSelectorWrap(-1);
 
     *selector_ = std::max(0, std::min(int(children_.size()) - 1, *selector_));
     return old_selected != *selector_;

src/ftxui/component/container_test.cpp

@@ -10,14 +10,24 @@
 
 using namespace ftxui;
 
+Component Focusable() {
+  return Button(L"", [] {});
+}
+Component NonFocusable() {
+  return Container::Horizontal({});
+}
+
 TEST(ContainerTest, HorizontalEvent) {
   auto container = Container::Horizontal({});
-  auto c0 = Container::Horizontal({});
+  auto c0 = Focusable();
-  auto c1 = Container::Horizontal({});
+  auto c1 = Focusable();
-  auto c2 = Container::Horizontal({});
+  auto c2 = Focusable();
   container->Add(c0);
   container->Add(c1);
+  container->Add(NonFocusable());
+  container->Add(NonFocusable());
   container->Add(c2);
+  container->Add(NonFocusable());
 
   // With arrow key.
   EXPECT_EQ(container->ActiveChild(), c0);
@@ -85,12 +95,15 @@ TEST(ContainerTest, HorizontalEvent) {
 
 TEST(ContainerTest, VerticalEvent) {
   auto container = Container::Vertical({});
-  auto c0 = Container::Horizontal({});
+  auto c0 = Focusable();
-  auto c1 = Container::Horizontal({});
+  auto c1 = Focusable();
-  auto c2 = Container::Horizontal({});
+  auto c2 = Focusable();
   container->Add(c0);
   container->Add(c1);
+  container->Add(NonFocusable());
+  container->Add(NonFocusable());
   container->Add(c2);
+  container->Add(NonFocusable());
 
   // With arrow key.
   EXPECT_EQ(container->ActiveChild(), c0);
@@ -158,9 +171,9 @@ TEST(ContainerTest, VerticalEvent) {
 
 TEST(ContainerTest, SetActiveChild) {
   auto container = Container::Horizontal({});
-  auto c0 = Container::Horizontal({});
+  auto c0 = Focusable();
-  auto c1 = Container::Horizontal({});
+  auto c1 = Focusable();
-  auto c2 = Container::Horizontal({});
+  auto c2 = Focusable();
   container->Add(c0);
   container->Add(c1);
   container->Add(c2);
@@ -215,12 +228,12 @@ TEST(ContainerTest, TakeFocus) {
   auto c1 = Container::Vertical({});
   auto c2 = Container::Vertical({});
   auto c3 = Container::Vertical({});
-  auto c11 = Container::Horizontal({});
+  auto c11 = Focusable();
-  auto c12 = Container::Horizontal({});
+  auto c12 = Focusable();
-  auto c13 = Container::Horizontal({});
+  auto c13 = Focusable();
-  auto c21 = Container::Horizontal({});
+  auto c21 = Focusable();
-  auto c22 = Container::Horizontal({});
+  auto c22 = Focusable();
-  auto c23 = Container::Horizontal({});
+  auto c23 = Focusable();
 
   c->Add(c1);
   c->Add(c2);

src/ftxui/component/input.cpp

@@ -163,6 +163,11 @@ class InputBase : public ComponentBase {
     }
     return true;
   }
+
+  bool Focusable() const final {
+    return true;
+  }
+
   StringRef content_;
   ConstStringRef placeholder_;
 

src/ftxui/component/menu.cpp

@@ -106,6 +106,10 @@ class MenuBase : public ComponentBase {
     return false;
   }
 
+  bool Focusable() const final {
+    return entries_->size();
+  }
+
   int& focused_entry() { return option_->focused_entry(); }
 
  protected:

src/ftxui/component/radiobox.cpp

@@ -119,6 +119,10 @@ class RadioboxBase : public ComponentBase {
     return false;
   }
 
+  bool Focusable() const final {
+    return entries_->size();
+  }
+
   int& focused_entry() { return option_->focused_entry(); }
 
   const std::vector<std::wstring>* const entries_;

src/ftxui/component/slider.cpp

@@ -84,6 +84,10 @@ class SliderBase : public ComponentBase {
     return false;
   }
 
+  bool Focusable() const final {
+    return true;
+  }
+
  private:
   StringRef label_;
   T* value_;

src/ftxui/component/toggle.cpp

@@ -107,6 +107,8 @@ class ToggleBase : public ComponentBase {
     return false;
   }
 
+  bool Focusable() const final { return entries_->size(); }
+
   int& focused_entry() { return option_->focused_entry(); }
 
   const std::vector<std::wstring>* const entries_;