Add hflow.

examples/component/gallery.cpp

@@ -73,7 +73,7 @@ class MyComponent : public Component {
         separator(),
         Render(L"radiobox", radiobox),
         separator(),
-        Render(L"input", input)
+        Render(L"input", input) | size(WIDTH, EQUAL, 20)
       ) | border;
   }
 };

examples/dom/CMakeLists.txt

@@ -16,4 +16,6 @@ example(style_dim)
 example(style_gallery)
 example(style_inverted)
 example(style_underlined)
+example(size)
 example(vbox_hbox)
+example(hflow)

examples/dom/hflow.cpp

@@ -0,0 +1,51 @@
+#include "ftxui/screen/screen.hpp"
+#include "ftxui/screen/string.hpp"
+#include "ftxui/dom/elements.hpp"
+#include <iostream>
+
+int main(int argc, const char *argv[])
+{
+  using namespace ftxui;
+  auto make_box = [](size_t dimx, size_t dimy) {
+    std::wstring title = to_wstring(dimx) + L"x" + to_wstring(dimy);
+    return
+      window(
+        text(title) | hcenter | bold,
+        text(L"content") | hcenter | dim
+      ) | size(WIDTH, EQUAL, dimx)
+        | size(HEIGHT, EQUAL, dimy)
+        ;
+  };
+
+  auto document =
+    hflow(
+      make_box(7,7),
+      make_box(7,5),
+      make_box(5,7),
+      make_box(10,4),
+      make_box(10,4),
+      make_box(10,4),
+      make_box(10,4),
+      make_box(11,4),
+      make_box(11,4),
+      make_box(11,4),
+      make_box(11,4),
+      make_box(12,4),
+      make_box(12,5),
+      make_box(12,4),
+      make_box(13,4),
+      make_box(13,3),
+      make_box(13,3),
+      make_box(10,3)
+    ) | size(WIDTH, GREATER_THAN, 20)
+      | border
+      | size(HEIGHT, GREATER_THAN, 30)
+      | size(WIDTH, LESS_THAN, 50)
+      ;
+
+  auto screen = Screen::TerminalOutput(document);
+  Render(screen, document.get());
+  std::cout << screen.ToString() << std::endl;
+
+  return 0;
+}

examples/dom/size.cpp

@@ -0,0 +1,30 @@
+#include "ftxui/screen/screen.hpp"
+#include "ftxui/screen/string.hpp"
+#include "ftxui/dom/elements.hpp"
+#include <iostream>
+
+int main(int argc, const char *argv[])
+{
+  using namespace ftxui;
+  auto make_box = [](const std::wstring title) {
+    return
+      window(
+        text(title) | hcenter | bold,
+        text(L"content") | hcenter | dim
+      );
+  };
+
+  Elements content;
+  for(int x = 3; x<30; ++x) {
+    content.push_back(
+      make_box(to_wstring(x))
+        | size(WIDTH, EQUAL, x)
+    );
+  }
+  auto document = hbox(std::move(content));
+  auto screen = Screen::FitDocument(document);
+  Render(screen, document.get());
+  std::cout << screen.ToString() << std::endl;
+
+  return 0;
+}

ftxui/CMakeLists.txt

@@ -19,6 +19,7 @@ add_library(dom
   src/ftxui/dom/frame.cpp
   src/ftxui/dom/gauge.cpp
   src/ftxui/dom/hbox.cpp
+  src/ftxui/dom/hflow.cpp
   src/ftxui/dom/inverted.cpp
   src/ftxui/dom/node.cpp
   src/ftxui/dom/node_decorator.cpp

ftxui/include/ftxui/dom/elements.hpp

@@ -33,9 +33,10 @@ Element bgcolor(Color, Element);
 
 // --- Layout ---
 // Horizontal, Vertical or stacked set of elements.
-Element vbox(Elements);
 Element hbox(Elements);
+Element vbox(Elements);
 Element dbox(Elements);
+Element hflow(Elements);
 
 // -- Flexibility ---
 // Define how to share the remaining space when not all of it is used inside a
@@ -73,6 +74,7 @@ Decorator operator|(Decorator, Decorator);
 TAKE_ANY_ARGS(vbox)
 TAKE_ANY_ARGS(hbox)
 TAKE_ANY_ARGS(dbox)
+TAKE_ANY_ARGS(hflow)
 
 };  // namespace ftxui
 

ftxui/include/ftxui/screen/screen.hpp

@@ -33,6 +33,7 @@ class Screen {
   // Constructor using the terminal.
   static Screen TerminalFullscreen();
   static Screen TerminalOutput(std::unique_ptr<Node>& element);
+  static Screen FitDocument(std::unique_ptr<Node>& element);
 
   // Node write into the screen using Screen::at.
   wchar_t& at(size_t x, size_t y);

ftxui/src/ftxui/dom/hflow.cpp

@@ -0,0 +1,59 @@
+#include "ftxui/dom/node.hpp"
+#include "ftxui/dom/elements.hpp"
+
+namespace ftxui {
+
+class HFlow : public Node {
+ public:
+  HFlow(Elements children) : Node(std::move(children)) {}
+  ~HFlow() {}
+
+  void ComputeRequirement() override {
+    requirement_.min.x = 0;
+    requirement_.min.y = 0;
+    requirement_.flex.x = 1;
+    requirement_.flex.y = 0;
+    for(auto& child : children)
+      child->ComputeRequirement();
+  }
+
+  void SetBox(Box box) override {
+    Node::SetBox(box);
+
+    // The position of the first component.
+    int x = box.x_min;
+    int y = box.y_min;
+    int y_next = y; // The position of next row of elements.
+
+    for (auto& child : children) {
+      Requirement requirement = child->requirement();
+
+      // Does it fit the end of the row?
+      if (x + requirement.min.x > box.x_max) {
+        // No? Use the next row.
+        x = box.x_min;
+        y = y_next;
+      }
+
+      // Does the current row big enough to contain the element?
+      if (y + requirement.min.y > box.y_max)
+        break; // No? Ignore the element.
+
+      Box children_box;
+      children_box.x_min = x;
+      children_box.x_max = x + requirement.min.x;
+      children_box.y_min = y;
+      children_box.y_max = y + requirement.min.y;
+      child->SetBox(children_box);
+
+      x = x + requirement.min.x + 1;
+      y_next = std::max(y_next, y + requirement.min.y + 1);
+    }
+  }
+};
+
+std::unique_ptr<Node> hflow(Elements children) {
+  return std::make_unique<HFlow>(std::move(children));
+}
+
+};  // namespace ftxui

ftxui/src/ftxui/dom/size.cpp

@@ -39,6 +39,8 @@ class Size : public Node {
 
   void SetBox(Box box) override {
     Node::SetBox(box);
+    if (constraint_ == LESS_THAN)
+      box.x_max = std::min(box.x_min + value_ + 1, box.x_max);
     children[0]->SetBox(box);
   }
 

ftxui/src/ftxui/screen/screen.cpp

@@ -109,6 +109,17 @@ Screen Screen::TerminalOutput(std::unique_ptr<Node>& element) {
   return Screen(size.dimx, element->requirement().min.y);
 }
 
+// static
+Screen Screen::FitDocument(std::unique_ptr<Node>& element) {
+  element->ComputeRequirement();
+  Terminal::Dimensions size = Terminal::Size();
+  return
+    Screen(
+      std::min(size.dimx, element->requirement().min.x),
+      std::min(size.dimy, element->requirement().min.y)
+    );
+}
+
 std::string Screen::ResetPosition() {
   std::stringstream ss;
   ss << MOVE_LEFT << CLEAR_LINE;